Chapter_01_The_Cell
A_Microcosm_of_Life
Indicate whether the statement is true or false. 1. Most of the metabolic energy produced in cells is made in the mitochondria. a. True b. False 2. An increase in the concentration of a substrate will increase the rate of the enzyme-catalyzed reaction. a. True b. False 3. Polysomes function to transcribe mRNA into proteins. a. True b. False 4. If two enzymes (e.g., pyruvate dehydrogenase and pyruvate carboxylase) compete for the same substrate (pyruvate), the one with the higher Km has less affinity and will be more active when pyruvate concentrations are high. a. True b. False 5. Transcription of DNA cannot be altered. a. True b. False 6. The nuclear envelope is a single membrane structure that helps to isolate the nucleus from the rest of the cell. a. True b. False 7. The lipid bilayer determines the function of the plasma membrane, while the proteins are primarily responsible for the structure of the membrane. a. True b. False 8. When discussing enzyme kinetics, Km refers to the substrate concentration at which the enzyme is saturated and functioning at maximal velocity. a. True b. False 9. Peripheral proteins are involved in cell-cell recognition, whereas integral proteins function primarily as receptors/transporters. a. True b. False 10. The various components within a cell (e.g., mitochondria) are not “free-floating” in the cytosol, but rather, are held in place by the cytoskeleton. a. True b. False
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Chapter_01_The_Cell A_Microcosm_of_Life 11. Different cells express different proteins because they contain different sequences of DNA in the nucleus. a. True b. False 12. Oncosis results from cell injury and is associated with cellular swelling and swelling of the mitochondrial nucleus. a. True b. False 13. Allosteric regulation of enzymes is carried out by modulators, other proteins that bind to the enzyme to inhibit its activity. a. True b. False 14. Most cellular reactions are irreversible because the same enzyme that catalyzes the conversion cannot catalyze the reverse reaction. a. True b. False 15. The plasma membrane is a sheet-like structure composed solely of lipids. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Most receptor proteins are most likely which type? a. peripheral proteins b. internal proteins c. integral proteins d. glycoproteins 17. MicroRNAs are small noncoding RNAs that . a. enhance gene expression by activating mRNA expression b. silence gene expression by binding to mRNA to inhibit translation c. modify gene expression by replacing specific nucleotides in mRNA d. mediate DNA production in a reverse direction 18. All components of the electron transport chain are embedded in the a. mitochondrial inner membrane b. mitochondrial outer membrane c. mitochondrial matrix d. cytoplasmic matrix 19. The smooth endoplasmic reticulum (SER) is associated with a. lipid synthesis
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Chapter_01_The_Cell A_Microcosm_of_Life b. protein synthesis c. the calcium ion pump necessary for the contractile process d. ribosomes and cytochrome P450 enzymes 20. In the cell structure, the a. endoplasmic reticulum b. mitochondrion c. cytoskeleton d. matrix space
provides support and controls the movement of cell organelles.
21. What is released when nutrient molecules are oxidized? a. oxygen b. potential (or free) energy c. kinetic energy d. hydrogen 22. The cell organelle responsible for the initiation and regulation of most cellular activity is the a. cytoplast b. nucleus c. mitochondrion d. nucleolus
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23. What is the role of cholesterol in plasma membrane structure? a. to produce bile b. to regulate fluidity and permeability c. to reduce stability d. to produce hormones 24. Which organelle is composed of an extensive network of membranous channels that connects the nuclear membrane, the Golgi apparatus, and the plasma membrane? a. the lysosome b. the nucleolus c. the centrioles d. the endoplasmic reticulum 25. Which are highly specialized membrane proteins that modify the cell's response to its environment? a. transport proteins b. enzymes c. receptors d. peroxisomes 26. Elongation is the process by which . a. the mRNA strand is formed b. peptide bonds are formed between aligned amino acids after the amino acids are positioned
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Chapter_01_The_Cell A_Microcosm_of_Life c. amino acids are activated by ATP at their carboxyl end d. activated amino acids are transferred to their specific tRNAs that contain the anticodon complementary to each amino acid’s codon 27. One trigger of apoptosis is . a. overexpression of Bcl-2 b. inactivation of Casp-9 c. swelling of the cell d. release of mitochondrial cytochrome c 28. What is the major route for ATP production? a. oxidative phosphorylation b. hydrolysis c. peroxidation d. transformation 29. Cyclic AMP activates which enzymes? a. protein kinases b. restriction endonucleases c. allosteric enzymes d. adenyl (adenylyl) cyclases 30. Which organelle is capable of performing both fission and fusion? a. Golgi apparatus b. mitochondria c. rough endoplasmic reticulum d. nucleus 31. Enzymes of metabolic pathways within the cytoplasmic matrix are often oriented so that the product of one enzyme is released in close proximity to the next enzyme for which it is a substrate, to facilitate the velocity of the overall pathway. This arrangement includes enzymes of . a. beta-oxidation b. glycolysis c. ketone production d. the Krebs cycle 32. In addition to the mitochondria, which organelle possesses an inner and outer membrane? a. lysosome b. lysosome c. Golgi apparatus d. nucleus 33. Constitutive enzymes are . a. uninfluenced by external stimuli b. influenced by external stimuli
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Chapter_01_The_Cell A_Microcosm_of_Life c. synthesized at variable rates d. unaffected by induction 34. Transcription-level control mechanisms . a. determine the path by which mRNA can be translated into a polypeptide b. determine whether a particular mRNA is actually translated c. determine if a particular gene can be transcribed d. are driven by the interaction of tRNA and mRNA 35. DNA in the nucleus is wrapped around a. proteins called histones b. the nucleolus c. the nuclear envelope d. ribosomal RNA
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36. Molecular stimuli that bind specifically to receptors are known as a. ligands b. enzymes c. allosteric enzymes d. hydrolases
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37. Which enzyme is responsible for linking together the incoming nucleotides during DNA replication? a. DNA ligase b. helicase c. DNA polymerase d. reverse transcriptase 38. A researcher in the field of nutritional genomics is least likely to study . a. the interactions among genes and bioactive components in food that change gene expression without changing the DNA nucleotide sequence (nutritional epigenetics) b. inborn changes in DNA nucleotide sequences or gene variants (nutrigenetics) c. genetic alterations that can be compensated for by increasing or decreasing specific nutrients (nutrigenomics) d. the interaction between genetically engineered enzymes and their substrates 39. Genes contained in mitochondrial DNA are inherited only from the mother and code for a. all proteins functioning within the mitochondrial matrix b. nonfunctional ancient proteins considered remnants of evolution c. proteins vital to the production of ATP d. antioxidant proteins 40. Membrane lipid bilayers consist primarily of a. phospholipids b. cholesterol c. proteins
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Chapter_01_The_Cell A_Microcosm_of_Life d. saturated fatty acids 41. The organelle that serves as the digestive system for the cell is the a. polysome b. endosome c. lysosome d. ribosome
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42. In which organelle do the TCA cycle and fatty acid oxidation occur? a. Golgi apparatus b. nucleus c. microsomes d. mitochondrion 43. What structural body is made up of flattened cisternae flanked by tubular networks and thought to be an extension of the endoplasmic reticulum? a. nucleus b. cytoplasm c. lysosome d. Golgi apparatus 44. Which organelle prevents proteins that have not reached their normal tertiary or quaternary structure from reaching the cell surface? a. the endoplasmic reticulum b. the Golgi apparatus c. the nucleus d. the mitochondrion 45. Malformed Apaf-1 molecules in a cell might a. cause rapid apoptosis of the cell b. inactivate cytochrome c c. lead to the development of a tumor d. have no effect on apoptosis 46. Membrane proteins do not serve as a. pumps b. detoxifiers c. receptors d. enzymes
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47. Diagnostic enzymology focuses on . a. enzymes that are widely distributed among many tissues b. intracellular enzymes that express their activity in the blood abnormally due to a disease process c. secreted enzymes such as clotting proteins in blood d. nuclear enzymes
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Chapter_01_The_Cell A_Microcosm_of_Life 48. What lifestyle change would be most important to individuals with a common variant in the GST gene that impairs protection against toxins? a. increasing levels of daily exercise b. eating a low-fat diet c. increasing ingestion of cruciferous vegetables d. increasing intake of omega-3 fats 49. Transcription is the process by which . a. the genetic information in a single strand of DNA makes a specific sequence of bases in a messenger RNA (mRNA) chain b. genetic information in an mRNA molecule specifies the sequence of amino acids in the protein product c. amino acids are linked together to form the primary structure of a protein d. the primary structure of a protein is folded several times to become the quaternary structure 50. Damage to MTOCs will interfere with which cellular process? a. oxidative phosphorylation b. mitosis c. electron transport d. creation of an mRNA molecule 51. In muscle cells, creatine phosphate is used to replenish which substance? a. glucose b. pyruvic acid c. ATP d. calcium 52. Phosphorylation of a molecule is generally accomplished by transferring the terminal phosphate group from which substance? a. GTP b. pyruvic acid c. G6PD d. ATP 53. Proteins attached to the membrane through hydrophobic interactions and embedded in the membrane are called a. peripheral proteins b. rough endoplasmic reticula c. integral proteins d. Golgi apparatuses 54. Substances that bind with allosteric sites and alter the activity of regulatory enzymes are called a. transport proteins b. modulators c. Na pumps d. sarcoplasmic reticula
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Chapter_01_The_Cell A_Microcosm_of_Life 55. The primary mechanism by which gene expression is modified by bioactive factors in food appears to be a. mutations causing cancer b. interactions with transcription factors c. production of SNPs d. downregulation of translation
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56. Which nitrogenous base is unique to RNA? a. guanine b. uracil c. thymine d. cytosine 57. The organelle responsible for production of most of the metabolic energy (ATP) is the a. Golgi apparatus b. endoplasmic reticulum c. nucleus d. mitochondrion 58. A common mutation in the 5,10-methylenetetrahydrofolate reductase enzyme (MTHFR) a. prevents the individual from activating the B vitamin folate b. has no effect on the activity of the enzyme c. increases the activity of the enzyme d. modifies the folate molecule directly 59. The Golgi apparatus is prominent in neurons and secretory cells and functions a. to stop the synthesis of proteins that may need carbohydrate additions b. to add polysaccharide or lipid moieties to polypeptides c. only for constitutive secretion of proteins d. only for regulated secretion of proteins
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60. Microtubule organization centers (MTOCs) on the outer nuclear membrane are associated with which cellular process? a. oxidative phosphorylation b. electron transport c. mitosis d. protein synthesis 61. Which enzyme complex, used in metabolizing many drugs, is located on the rough endoplasmic reticulum in liver cells? a. chromatins b. lysozymes c. cytochromes d. polymerases
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Chapter_01_The_Cell A_Microcosm_of_Life 62. Which class of bioactive food components has the ability to get into the nucleus of cells and bind to DNA to influence gene expression? a. lipophilic, small-molecular-weight molecules b. glycoproteins c. phospholipids d. water-soluble vitamins 63. Destruction of which organelle(s) would cause the cell to cease to function due to a total loss of energy? a. the nucleus b. the Golgi apparatus c. the ribosomes d. the mitochondria 64. Translation is the process by which . a. the genetic information (base sequence) in a single strand of DNA is used to specify a complementary sequence of bases in an mRNA chain b. a daughter duplex DNA molecule that is identical to the parental duplex DNA is synthesized c. the polypeptide chain of the protein product is extended d. genetic information in an mRNA molecule specifies the sequence of amino acids in the protein product 65. The carbohydrate moieties of the plasma membrane glycoproteins and glycolipids are oriented a. outwardly, away from the cytoplasmic matrix b. inwardly, toward the lumen c. equally inwardly and outwardly to maintain symmetry d. between the bilayers of the membranes
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66. Signals generated at one part of a cell are transmitted quickly to other parts of the cell due to the interconnection of the cytosol and . a. glycoproteins b. microfilaments c. glycolipids d. integral proteins 67. The fluid portion of the cytoplasmic matrix does not contain a. amino acids b. glucose c. carbon dioxide d. urea
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68. Encoded within the nuclear DNA of each cell is . a. the entire genome for that organism b. the genes coding for proteins needed by that particular cell in the organism c. chromatin d. a cell-specific histone
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Chapter_01_The_Cell A_Microcosm_of_Life 69. The organelle that detoxifies by oxidizing molecules such as hydrogen peroxide and ethanol is the a. peroxisome b. endosome c. lysosome d. ribosome
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70. Digestive enzymes delivered to the small intestine from cells in the pancreas are able to leave those cells because of the functioning of the . a. endoplasmic reticulum b. ribosomes c. Golgi apparatus d. lysosomes
Enzyme Classification: Match the correct enzyme classification with the examples provided. a. enzymes that catalyze cleavage of C-C, C-S, and certain C-N bonds (excluding peptide bonds) without hydrolysis or oxidation-reduction b. enzymes forming bonds between carbon and other atoms, such as acetyl-CoA carboxylase, which adds bicarbonate to acetyl-CoA to initiate fatty acid synthesis in the cytoplast c. enzymes in the electron transport chain in the mitochondria d. enzymes that catalyze cleavage of bonds by addition of water, such as digestive enzymes e. enzymes that catalyze reactions, not oxidation or reduction, in which a functional group is moved from one substrate to another, such as transaminases 71. oxidoreductases 72. hydrolases 73. transferases 74. lyases 75. ligases Match each description to one of the following terms. a. free energy b. activation energy c. cellular energy d. transition state e. standard reduction potential 76. energy derived from a series of chemical reactions, each of which exhibits a free energy change 77. a higher energy level or barrier at which the exothermic conversion to products takes place 78. potential energy released from chemical bonds upon oxidation
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Chapter_01_The_Cell A_Microcosm_of_Life 79. the tendency of a compound to donate and receive electrons 80. the energy required to raise the reactants to their transition state
81. Describe the cytoskeleton (microtrabecular lattice) and its role as an intercommunication system of proteins and other macromolecules. 82. Why is cholesterol important in plasma membrane function? 83. Define and describe diagnostic enzymology. 84. Choose three of the following terms and in one sentence per term, provide a concise definition of that term: nucleus, mitochondria, RER, transcription, translation, apoptosis, and cell replication. 85. Describe the uphill-downhill concept. 86. Briefly describe the role of DNA in cell replication and transcription. 87. Describe the process of apoptosis in relation to the life span of the cell. 88. Describe the important implications of the high Km for glucokinase in terms of maintaining normal blood glucose after a meal and during fasting. 89. List the three mechanisms that can be used to regulate the function of a protein (e.g., an enzyme) and briefly (in one to two sentences) describe their key features. 90. Discuss the concept of coupled reactions in the transfer of energy.
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Chapter_01_The_Cell A_Microcosm_of_Life Answer Key 1. True 2. True 3. False 4. True 5. False 6. False 7. False 8. False 9. True 10. True 11. False 12. True 13. False 14. False 15. False 16. c 17. b 18. a 19. a 20. c 21. b 22. b 23. b 24. d 25. c
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Chapter_01_The_Cell A_Microcosm_of_Life 26. b 27. d 28. a 29. a 30. b 31. b 32. d 33. a 34. c 35. a 36. a 37. c 38. d 39. c 40. a 41. c 42. d 43. d 44. a 45. c 46. b 47. b 48. c 49. a 50. b 51. c
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Chapter_01_The_Cell A_Microcosm_of_Life 52. d 53. c 54. b 55. b 56. b 57. d 58. a 59. b 60. c 61. c 62. a 63. d 64. d 65. a 66. b 67. d 68. a 69. a 70. a 71. c 72. d 73. e 74. a 75. b 76. c
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Chapter_01_The_Cell A_Microcosm_of_Life 77. d 78. a 79. e 80. b 81. The answer should include the following items: • • • •
The cytoskeleton (microtrabecular lattice) consists of microtubules (hollow structures), microfilaments (made of actin), and intermediate filaments (found in cells like neurons and in muscle and epithelial cells that are subjected to physical stress). It provides a structure for organization of organelles and proteins such as enzymes to facilitate interactions with substrates such as glucose and oxygen, thus facilitating metabolic pathways in all cells. The cytoskeleton provides mechanism for cell locomotion in certain cells such as phagocytes. The microtrabecular lattice is vital for cell activation and survival.
82. The answer should include the following items: • • • •
The steroid rings containing the hydroxyl groups of cholesterol align near the polar head groups of the membrane phospholipids and the hydrocarbon tail aligns with the hydrophobic fatty acids on the phospholipid. This alignment allows cholesterol to stabilize the membrane and regulate fluidity. Changes in membrane fluidity alter the permeability of the membrane and control entrance and exit of molecules into and out of the cell. Membrane fluidity also affects the location and function of membrane proteins.
83.83. Diagnostic enzymology studies intracellular enzymes that, due to a problem within the cell, escape and act within the serum where they do not normally exist. The serum activity of these now displaced enzymes is measured, which allows for a determination of the site and extent of the cellular damage. An accurate determination of the site of the damage requires that the enzyme being measured must exhibit a high degree of organ or tissue specificity. 84. The nucleus is the largest organelle in the cell and, because it contains almost all of the cell’s DNA, it regulates most cellular activities. Mitochondria are the organelles in virtually all cells that are responsible for the major portion of energy (ATP) production, utilizing metabolic processes including the TCA cycle, β-oxidation, parts of gluconeogenesis, and the electron transport chain. The rough endoplasmic reticulum (RER) is studded with ribosomes and is intimately involved in protein synthesis. Transcription is the nuclear process of copying one strand of DNA into a single-stranded mRNA and substituting the base uracil in place of thymine. Translation is the process by which the genetic information carried by a molecule of mRNA becomes the sequence of amino acids in a protein. Apoptosis is programmed cell death brought about by several different mechanisms designed to regulate the number of cells in a tissue. Cell replication is the production of two daughter cells from a mother cell that includes the replication of a single DNA strand into two identical daughter DNA strands (one in each new cell). 85. The answer should include the following items:
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Chapter_01_The_Cell A_Microcosm_of_Life • • • •
Pushing a boulder uphill represents endothermic reactions, which require input of energy to occur. The products of such a reaction will contain greater potential energy than the reactants. It will be the sum of the energy in the reactants plus the energy put in to create the products. The boulder falling downhill represents exothermic reactions, which release energy as they occur. The products of such a reaction will contain less potential energy than the reactants because free energy, which can be used for work, is released. Whenever carbohydrates or fats are metabolized completely to carbon dioxide and water, free energy is partly released as heat and partly captured in ATP for use in work. In the case of downhill reactions, although the overall metabolic pathway is exothermic (energy-releasing), it is not spontaneous and some activation energy needs to be added to the potential energy in the reactants to allow the reaction to proceed. In the uphill-downhill concept, the activation energy is represented by adding energy to push the boulder up a short distance so it is in a position to fall and release some of the potential energy in the reactants as they become products.
86. Cell Replication:During cell division, DNA must be replicated into two daughter DNA molecules that are identical to the parental DNA molecule. The DNA molecule unzips and each strand of the double helix becomes a template used to synthesize a new complementary strand. The new strand is produced by the process of complementary base pairing. Nucleotide bases connect to the template at their complementary bases and become connected by phosphate diester bonds through the action of the enzyme DNA polymerase. In the end, two new DNA chains have joined with the two original DNA templates to form two new DNA molecules. Transcription: This process uses the gene sequence in a DNA strand to direct for the production of specific proteins. The base sequence of one strand of DNA acts as a template for the production of a single strand of mRNA. The same single strand of DNA may direct for the creation of many different strands of mRNA which will leave the nucleus and bring the genetic code to the ribosomes for protein production. Specific DNA codons (three bases in a row) act as either initiators of the production of mRNA or as terminators to specify the length of the mRNA strand. 87. The answer should include the following items: • • • • • •
Apoptosis refers to programmed cell death as distinguished from pathological cell death, which causes inflammation and possibly autoimmune reactions. Apoptosis can be beneficial during development of an organism when cells are no longer needed as development progresses. Apoptosis is thought to be detrimental when it leads to degenerative diseases such as Alzheimer’s. Thus, active research seeks to understand triggers and methods by which it might be controlled. DNA damage, hypoxia, or other intracellular insults can cause release of mitochondrial factors, especially cytochrome c, which activates caspases and results in the beneficial apoptosis (death) of that damaged cell. The mitochondrial membrane protein Bcl-2 can prevent apoptosis by blocking the release of cytochrome c. If Bcl2 is upregulated, it can cause cell survival. Survival of a damaged cell can allow it to continue to grow and cause cancer. Both the retinoic acid form of vitamin A and the active form of vitamin D are involved in these cell death and survival pathways. Research is needed to completely understand the beneficial control of cell death and survival.
88. The answer should include the following items: • •
The high Km for glucokinase means that it requires a high concentration of glucose in the blood to be active. Thus, it is not very active during fasting and so the glucose that comes into the liver during fasting can easily return to the blood for use by the brain and red blood cells.
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Chapter_01_The_Cell A_Microcosm_of_Life • •
After a meal, when a lot of glucose enters the liver, the glucose concentration is high enough that glucokinase phosphorylates glucose, trapping it inside the liver. This action is important for lowering blood glucose quickly after a meal.
89.89. Mechanism 1: Covalent modification—no change in the abundance of a protein. Here, preexisting protein is made active or inactive by covalently modifying it (involves making or breaking covalent bonds). Examples include phosphorylation, carboxylation, glycosylation, or proenzyme activation by breaking a peptide bond. Mechanism 2: Allosteric regulation—here we also are not changing the abundance of the protein (in this case an enzyme), but we are inhibiting or stimulating its activity—not by covalently modifying the protein, but by having something bind to it, resulting in a change in its conformation that affects its enzymatic activity. What are these things that bind to enzymes to affect their activity? NOT other proteins or enzymes—they are typically substrates, intermediates, or products along the pathway in which the enzyme participates. The book calls them modulators. A good example is ATP—ATP is the end point of a lot of pathways (glycolysis, TCA cycle) and as such, when it is abundant, that is a good sign that we have enough ATP/energy. Once the concentration of ATP reaches a certain level, it begins to bind some of the key enzymes in glycolysis and the TCA cycle and inhibits them. Why continue to make ATP if we have enough? Conversely, when ADP levels are higher than ATP (a sign we need energy), ADP binds to these same enzymes, but the result is not inhibition of their activity, but rather ADP stimulates them to be more active (and thus make more energy). Then, when ATP levels begin to rise again... we’re back where this paragraph started. Mechanism 3: Induction—inducing a gene to be expressed, thereby ultimately resulting in an increase in the abundance of a protein. This is accomplished by increasing transcription and/or translation of the corresponding gene/mRNA. [By definition, induction means to increase abundance; writing “increase and/or decrease” would be incorrect.] [Note: For mechanism 1 or 3, the proteins we are talking about can be enzymes, transporters, and so forth. For 2, we are only talking about enzymes. Don’t let the term active confuse you—we use it mostly when we talk about enzymes, but an “active protein” means it is carrying out its function, be it catalytic or transport or anything else. Also note that mechanisms 1 and 2 are fast, whereas mechanism 3 is slower.] 90. The answer should include the following items (note that students may provide other examples such as the coupling of phosphocreatine to creatine with the formation of ATP from ADP): • • • •
Coupled reactions allow metabolism to proceed because exothermic reactions that release energy are capable of driving endothermic reactions that require the energy released. In metabolism, ATP is involved as the ideal intermediate because the breakdown of high-energy phosphate compounds such as creatine phosphate can drive the formation of the intermediate-energy bond that creates ATP from ADP. In turn ATP can be hydrolyzed to form ADP and release the intermediate amount of energy in the bond in order to provide energy to, for example, add phosphate to glucose to form glucose-6-phosphate, the first step in the glycolytic breakdown of glucose. So the breakdown of ATP to ADP to release energy is said to be coupled to the input of energy required to add phosphate to glucose to create glucose-6-phosphate.
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Chapter_02_The_Digestive_System
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Mechanism_for_Nourishing_the_Body
Indicate whether the statement is true or false. 1. Eating a meal stimulates ghrelin secretion. a. True b. False 2. GIP stimulates the release of a hormone from the pancreatic β-cells. a. True b. False 3. The fundus of the stomach lies below the gastroesophageal sphincter. a. True b. False 4. CCK stimulates pancreatic zymogen release. a. True b. False 5. Leptin secretion stimulates the desire to eat. a. True b. False 6. Villi are s-designed to increase the absorptive surface area of the small a. True b. False 7. CCK stimulates the release of bile. a. True b. False 8. The predominant component of saliva is amylase. a. True b. False 9. Secretin stimulates gastric emptying. a. True b. False 10. Peptide YY stimulates gastric acid secretion. a. True b. False 11. Ghrelin increases satiety. a. True b. False
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12. Gastrin stimulates gastric acid secretion. a. True b. False 13. Short-chain fatty acids secreted by intestinal bacteria improve colonic and splanchnic blood flow. a. True b. False 14. Secretin stimulates HCl release. a. True b. False 15. Pancreatitis occurs when zymogens become activated within the pancreas. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Which cells, found in oxyntic glands in the body of the stomach, secrete pepsinogens? a. neck cells b. parietal cells c. chief cells d. enteroendocrine cells 17. Within the lamina propria, lying just below the epithelium, is the mucosa-associated lymphoid tissue (MALT), which . a. controls secretions from the mucosal glands b. contains white blood cells and protects against ingested microorganisms c. initiates peristalsis d. secretes mucus, hormones, and digestive juices into the lumen 18. Dumping syndrome may be caused by . a. bacterial infections b. viral infections c. partial removal of the stomach to treat obesity d. gall stones 19. A large gall stone blocking the cystic duct might result in a. a reduction in the production of bile by the liver b. an increase in bile production by the liver c. enhancement of fat digestion d. interference with fat digestion 20. Which substance is enterohepatically circulated? a. pancreatic enzymes
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b. bile c. glucose d. CCK 21. Which division of the nervous system decreases digestive tract motility and secretions? a. parasympathetic b. somatic c. adrenergic d. sympathetic 22. The chief cells secrete a. gastrin b. mucus c. zymogens d. hydrochloric acid
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23. Pyloric glands are located predominantly . a. at the juncture of the esophagus and the stomach b. in the fundus and the body of the stomach c. in the antrum of the stomach d. in the cardiac portion of the stomach 24. Deficiency of which vitamin is associated with neurological deficiencies? a. vitamin D b. vitamin C c. vitamin A d. thiamin 25. Gastrin stimulates which cells? a. oxyntic cells b. parietal and chief cells c. pancreatic exocrine cells d. alpha cells 26. The surface coat of microvilli is known as a. the glycocalyx b. the crypts of Lieberkühn c. motilin d. proteases
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27. The total bile acid pool in the human body is 2.5 to 5 g. What percentage of bile is reabsorbed in the distal ileum? a. 10 percent b. 30 percent c. 65 percent
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Chapter_02_The_Digestive_System
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Mechanism_for_Nourishing_the_Body
d. 90 percent 28. Which specialized cell of the gastric epithelium secretes a hormone? a. neck b. parietal c. chief d. G-cell 29. The parietal cells secrete . a. hydrochloric acid and intrinsic factor b. intrinsic factor and gastrin c. gastrin and zymogens d. zymogens and hydrochloric acid 30. In which organ are enzymes produced that are responsible for digestion of 50 percent of carbohydrate and protein and 90 percent of fat? a. liver b. esophagus c. pancreas d. gallbladder 31. Which phrase best describes the function of the crypt of Lieberkühn? a. mucus secretion b. glucose oxidation c. cellular differentiation d. amylase secretion 32. Bile is most important for the digestion and absorption of a. carbohydrates b. proteins c. fats d. vitamins
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33. Which hormone(s) is/are responsible for decreasing sodium absorption in the colon? a. glucocorticoids b. mineralocorticoids c. vasopressin d. glucagon 34. The product(s) of pepsin’s action is/are a. disaccharides b. amylose c. short-chain fatty acids d. hydrolyzed proteins
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Chapter_02_The_Digestive_System
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35. Taking antihistamines might lead to a(n) . a. increase in stomach acid production b. increase in bile release c. decrease in stomach acid secretion d. reduction in pancreatic enzyme production 36. Secretin is released from the enteroendocrine S-cell in the a. proximal small intestine b. gastric mucosa c. esophagus d. colon
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37. Which structure helps to prevent the migration of bacteria from the large intestine back into the small intestine? a. the cecum b. the appendix c. the ileocecal valve d. the ileum 38. Pepcid, a drug that is classified as an H2 receptor blocker, acts by a. inhibiting the secretion of hydrogen ions by the parietal cells b. inhibiting the release of acetylcholine by the vagus nerve c. inhibiting the binding of gastrin to the parietal cells d. inhibiting the binding of histamine to the parietal cells
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39. Among the regulatory peptide molecules, some are recognized as true hormones. Which substance is a paracrine rather than a hormone? a. somatostatin b. secretin c. cholecystokinin d. gastrin 40. Which nutritional deficiency occurs frequently following RYGB? a. vitamin D b. protein c. fat d. vitamin C 41. Which hormone’s major action is to alkalize intestinal contents by stimulating secretion of bicarbonate from the pancreas and by inhibiting gastric acid secretion and gastric emptying? a. gastrin b. secretin c. cholecystokinin d. GRP
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42. Bile salts are synthesized from cholesterol in the a. canaliculi b. common bile duct c. hepatocytes d. gallbladder
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43. A deficiency in secretion of cholecystokinin might lead to which problem? a. a reduction in gastric acid production b. difficulty digesting fats c. difficulty digesting proteins d. a buildup of intestinal gas 44. In which part of the brain is the swallowing center located? a. the hypothalamus b. the medulla oblongata c. the thalamus d. the pons 45. The hormone primarily responsible for contraction of the gallbladder and release of bile into the duodenum is a. gastrin b. secretin c. cholecystokinin d. GRP 46. Which process allows gastric expansion with food intake with minimal impact on intragastric pressure? a. peristalsis b. receptive relaxation c. segmentation d. pendular movement 47. Which hormone stimulates gall bladder contraction? a. motilin b. gastrin c. cholecystokinin d. secretin 48. The most common bariatric procedure performed in the United States is a. gastric banding b. sleeve gastrectomy c. RYGB d. biliopancreatic diversion 49. When diagnosing lactose intolerance, a. methane
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is measured in the breath following oral consumption of 50 g lactose.
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Mechanism_for_Nourishing_the_Body
b. hydrogen c. carbon dioxide d. sulfur 50. Which hormone diminishes gastric acid secretion? a. somatostatin b. gastrin c. cholecystokinin d. pancreatic polypeptide 51. Pancreatic juice that enters the duodenum through the sphincter of Oddi contains all of the following EXCEPT a. digestive enzymes b. intrinsic factor c. anions such as bicarbonate and chloride d. cations such as sodium, potassium, and calcium 52. Which structural component of the gastrointestinal tract lies within the muscularis externa and controls the contractions that cause motility? a. muscularis mucosae b. submucosal plexus c. myenteric plexus d. lumen 53. Which glycoproteins bind water and are gel-forming? a. mucins b. proteoglycans c. prostaglandins d. zymogens 54. What is the name of the digestive enzyme in saliva that digests starch? a. lipase b. synthetase c. amylase d. lactase 55. Lactose intolerance is least common in a. European Americans b. African Americans c. American Indians d. Asian Americans
.
56. Endocrine cells of the pancreas are found in which structure? a. the pancreatic duct b. the islets of Langerhans
.
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Chapter_02_The_Digestive_System
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Mechanism_for_Nourishing_the_Body
c. the sphincter of Oddi d. the beta cells 57. What product produced by neck cells in the oxyntic gland of the stomach protects the epithelium from mechanical and chemical damage? a. amylase b. pepsin c. gastrin d. mucus 58. Which medication inhibits hydrogen release into the gastric juice, which reduces GI mucosal irritation? a. Pepcid b. Nexium c. Tums d. Tagamet 59. Which structure is not considered an accessory organ? a. pancreas b. liver c. gallbladder d. spleen 60. Which cells, found both in the oxyntic glands and pyloric glands of the stomach, secrete hydrochloric acid and intrinsic factor? a. neck cells b. parietal cells c. chief cells d. enteroendocrine cells 61. RYGB surgery involves . a. creating a pouch after the proximal and distal portions of the stomach are separated b. placing a band on the stomach and creating a pouch c. removing 85 percent of the stomach surgically d. connecting the esophagus directly to the duodenum 62. Which hormone decreases appetite? a. peptide YY b. motilin c. secretin d. pancreatic polypeptide 63. The pancreas is a digestive system accessory organ with two types of active tissue—the ductless endocrine cells that secrete insulin and glucagon and the . a. liver-like cells that produce bile b. ductless absorptive tissue that controls bicarbonate
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Chapter_02_The_Digestive_System
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Mechanism_for_Nourishing_the_Body
c. acinar exocrine cells that produce digestive enzymes d. erythropoietic cells that produce red blood cells 64. Delayed gastric emptying is known as a. cholecystitis b. cholelithiasis c. gastritis d. gastroparesis
.
65. In general, in which portion of the gastrointestinal tract does most absorption occur? a. esophagus b. stomach c. small intestine d. colon 66. Which substance is not a component of saliva? a. mucus b. enzymes c. water d. proteases 67. A decrease in the function of the parotid glands is most likely to result in a. a lack of triglyceride digestion b. bolus that is difficult to form c. saliva that is too thin, that is, a high water to mucus ratio d. diarrhea due to malabsorption 68. A common cause of peptic ulcer disease (PUD) is the bacterium a. Escherichia coli b. Helicobacter pylori c. Staphylococcus aureus d. Enterobacter aerogenes 69. Deficiency of vitamin B12 occurs due to a. inflammation of the GI tract b. insufficient intrinsic factor c. a change in diet d. excessive stomach acid
.
.
.
70. When the pH of the stomach is increased to avoid GERD, over time, the stomach may not be acidic enough. What is the most likely outcome? a. lack of carbohydrate digestion b. decreased protein digestion c. destruction of bacteria in the stomach
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Chapter_02_The_Digestive_System
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d. gastric ulcer
Digestive Substances: Match the substance important for digestion with its site of production. a. hepatocytes b. gastric chief cells c. pancreatic exocrine tissue d. salivary glands e. small intestine 71. pepsinogen 72. trypsinogen 73. ptyalin 74. collagenase 75. cholic acid Match the corresponding action to the hormone. Each choice is used only once. a. stimulates insulin secretion b. stimulates pancreas juice secretion c. inhibits gall bladder contraction d. stimulates pepsinogen secretion e. decreases gastric emptying 76. somatostatin 77. secretin 78. glucagon-like peptides 79. pancreatic polypeptide 80. gastrin
81. Broad-spectrum antibiotics are capable of killing many different bacteria, including many of those that naturally live in the intestines. Develop a hypothesis regarding the effects of broad-spectrum antibiotics on the beneficial effects of gut flora. 82. Bariatric surgery involves removal or bypass of a large portion of the stomach. Speculate on how the production of ghrelin following bariatric surgery might affect appetite and explain your reasoning. 83. Describe the mechanisms by which resin-type drugs and functional foods containing phytostanols lower high blood cholesterol levels.
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Chapter_02_The_Digestive_System
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Mechanism_for_Nourishing_the_Body
84. Discuss three of the five mechanisms by which probiotics may be helpful in diarrheal illnesses. 85. How might an imbalance of the hormones ghrelin and leptin lead to obesity? 86. Discuss the role of drug therapies such as Tagamet, Zantac, and Pepcid in the treatment of peptic ulcers. 87. What happens to reabsorbed bile acids after transported back to the liver? 88. What are probiotics and prebiotics? Give examples of each. 89. Describe the beneficial effects of secretions released by colonic bacteria. 90. Discuss the functions and significance of the folds of Kerckring, the villi, and the microvilli.
Name:
Chapter_02_The_Digestive_System Answer Key 1. False 2. True 3. False 4. True 5. False 6. True 7. True 8. False 9. False 10. False 11. False 12. True 13. True 14. False 15. True 16. c 17. b 18. c 19. d 20. b 21. d 22. c 23. c 24. d 25. b
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Mechanism_for_Nourishing_the_Body
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Chapter_02_The_Digestive_System 26. a 27. d 28. d 29. a 30. c 31. c 32. c 33. c 34. d 35. c 36. a 37. c 38. d 39. a 40. b 41. b 42. c 43. b 44. b 45. c 46. b 47. c 48. c 49. b 50. a 51. b
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Mechanism_for_Nourishing_the_Body
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Chapter_02_The_Digestive_System 52. c 53. a 54. c 55. a 56. b 57. d 58. b 59. d 60. b 61. a 62. a 63. c 64. d 65. c 66. d 67. b 68. b 69. b 70. b 71. b 72. c 73. d 74. e 75. a 76. c
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Mechanism_for_Nourishing_the_Body
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Chapter_02_The_Digestive_System
Date:
Mechanism_for_Nourishing_the_Body
77. b 78. a 79. e 80. d 81. The answer should include the following items: • • •
Broad-spectrum antibiotics kill most “friendly” gut bacteria along with the pathogenic bacteria they are taken to kill. Therefore, the logical hypothesis is that many of the beneficial effects of gut flora are abrogated by antibiotics. Some of these effects that might be diminished are vitamin K and biotin production and generation of beneficial short-chain fatty acids for use by colon cells and absorption into the body.
82. The answer should include the following items: • •
Ghrelin is secreted primarily from endocrine cells of the stomach and acts in the brain to stimulate appetite. If fewer cells are present or active after removal or bypass of the stomach, less ghrelin is likely to be produced to stimulate appetite and food intake should fall.
83. The answer should include the following items: • • • •
Resins bind bile acids in the intestinal tract and interfere with recirculation of bile. Phytosterols and phytostanols bind both bile acids and cholesterol and enhance fecal excretion, limiting recirculation to the liver. As fewer recirculated bile acids return to the liver, hepatocytes must synthesize more new bile acids, using cholesterol to do so. This increased use of cholesterol decreases blood cholesterol.
84. The answer should include three of the following items: • • • • •
Enhance immune defense system by increasing IgA production, tightening the mucosal barrier, and enhancing cytokine release and phagocytic activity Displace or antagonize pathogenic bacteria from colonizing Acidify colonic pH by fermentation Promote excretion of toxic substances such as nitrosamines, and bile acids Enhance fecal bulk to speed up transit time and lower colon exposure to toxins
85. The answer should include the following items: Because ghrelin acts on the hypothalamus to stimulate appetite, and leptin suppresses food intake, an imbalance could affect an individual’s ability to control his or her appetite leading to obesity. 86. The answer should include the following items:
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Chapter_02_The_Digestive_System • • • •
Date:
Mechanism_for_Nourishing_the_Body
These drugs are H2 receptor blockers. They block the ability of histamine to bind to its H2 receptor. Therefore, acid release from the parietal cell is decreased. Less acid reduces irritation at the site of the peptic ulcer.
87. The answer should include the following items: Reabsorbed bile acids are reconjugated to amino acids and secreted into bile along with the newly synthesized bile acids. 88. The answer should include the following items: Probiotics are live microorganisms (that is, active cultures of specific strains of bacteria) that when administered in adequate amounts confer health benefits to its hosts. Prebiotics (discussed in more detail in Chapter 4) are substances that are not digested by human digestive enzymes but confer health benefits to the host by acting as substrates for the growth and/or activity of one or more species of healthful bacteria in the colon. The most common probiotic bacteria are lactic acid bacteria, usually strains of Lactobacillus and Bifidobacterium genera. To be considered a probiotic, the product must contain 100 million live active bacteria per gram. At present, probiotics are mostly consumed as yogurt with live cultures and as fermented or cultured milk and milk products (such as buttermilk and kefir). In the United States, yogurt is often fermented by Lactobacillus bulgaricus and Streptococcus thermophilus, and milk is usually fermented by L. acidophilus and L. casei. Other bacteria used to manufacture dairy products include Leuconostoc esntheroides, L. mesenteroides, and Lactococcus lactis. Other food sources of probiotics include miso, tempeh, and some soy beverages/products. 89. The answer should include the following items: • • • • • • • •
Acidify the luminal environment Serve as signaling molecules Exhibit trophic effects Improve colonic and splanchnic blood flow Increase water and sodium absorption Provide energy and serve as substrates for use within cells Possibly inhibit tumors Stimulate the immune system
90. The answer should include the following items: • • •
The folds of Kerckring, villi, and microvilli dramatically increase the surface area of the intestinal lumen exposed to products of digestion. Cells lining the villi also produce digestive enzymes and regulatory peptides. This is important because the large surface area maximizes absorption of nutrients and release of regulatory peptides produced in the gut.
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Chapter_03_Carbohydrates
Indicate whether the statement is true or false. 1. Glucose phosphorylation in the liver is catalyzed by glucokinase. a. True b. False 2. Glucose is transported from the lumen into the enterocyte by active transport using SGLT1 protein, which also requires Na as a co-transporter. a. True b. False 3. Pentose sugars provide more dietary energy than hexose sugars. a. True b. False 4. The Cori cycle would be active under anaerobic conditions, such as excessive muscle exertion. a. True b. False 5. The muscle is an important tissue in gluconeogenesis because it can use amino acids from protein breakdown and convert them to glucose, which it then secretes into the circulation for other tissues. a. True b. False 6. Because they do not have mitochondria, red blood cells generate a lot of lactate from glycolysis, which they in turn must convert into glucose to meet their energy needs. a. True b. False 7. All cells have mitochondria, which act as the main site for ATP production. a. True b. False 8. The process of gluconeogenesis occurs mainly in the liver and, in cases of starvation, in the kidneys as well. a. True b. False 9. Maintenance of normal blood glucose concentration is controlled by the small intestine, the liver, the kidneys, skeletal muscle, and adipose tissue. a. True b. False 10. Active transport requires energy for the Na-K pump to transport Na out of the cell, thereby driving the transport of another substance (e.g., glucose) when the Na re-enters the cell down its concentration gradient. a. True b. False
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Chapter_03_Carbohydrates 11. Fructose transport into the enterocyte relies on the facilitative transporter GLUT5. a. True b. False 12. The purpose of the pentose phosphate pathway is to generate ribose, for nucleic acid synthesis, and NAD, for oxidizing power. a. True b. False 13. Glycogenolysis in muscle cells provides glucose that can be transported through the bloodstream. a. True b. False 14. The abundance of GLUT4 is increased by induction in response to a high-CHO meal. a. True b. False 15. After hydrolysis of triacylglycerols stored in adipose tissue, free glycerol in the blood is converted in the liver to glucose via glycogenolysis. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. A ketopentose is a carbohydrate containing a. five carbons and a ketone group b. six carbons and an aldehyde group c. three carbons and an aldehyde group d. seven carbons and a ketone group
.
17. Glucagon, epinephrine, and norepinephrine enhance the regulation of a. glucose-1-phosphate b. phosphorylase c. coenzyme Q d. phosphofructokinase 18. The glucose transporter that is sensitive to insulin is a. GLUT1 b. GLUT2 c. GLUT4 d. SGLT1
.
.
19. Upon digestion, food carbohydrates yield four times more glucose than a. fructose b. galactose
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Chapter_03_Carbohydrates c. sucrose d. trehalose 20. Two hormones that stimulate glycogenolysis in the muscle and liver, respectively, are a. cortisol and epinephrine b. epinephrine and glucagon c. insulin and epinephrine d. glucagon and insulin
.
21. Due to a lack of the enzyme glucose-6-phosphatase, which tissue capable of glycogenesis cannot contribute to blood glucose levels between meals? a. liver b. muscle c. brain d. kidney 22. Name the model that depicts cyclized monosaccharides as lying in a horizontal plane with the hydroxyl groups pointing down or up from the plane. a. Haworth b. Fischer projection c. cyclized Fischer projection d. stereoisomer 23. Conversion of phosphorylase b to the active phosphorylase a is carried out by a. ADP b. AMP c. ATP d. cAMP 24. Gluconeogenesis is essentially the reversal of which pathway? a. glycogenesis b. glycolysis c. TCA cycle d. glycogenolysis 25. Choose the best description of the main method of glucose absorption. a. passive diffusion down a concentration gradient b. active transport with fructose c. facilitated transport d. active transport with sodium 26. The majority of energy in the typical American diet comes from a. fat b. protein c. carbohydrate
.
.
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Chapter_03_Carbohydrates d. vitamins 27. The enzyme needed to hydrolyze the α (1,6) bond of amylopectin is a. amylase; enterocyte b. sucrose; pancreas c. lactase; enterocyte d. isomaltase; enterocyte
, which is secreted by the
.
28. Chiral carbon atoms have . a. four hydrogens attached to them b. two methyl groups and two hydrogens attached to them c. three hydrogen atoms and one methyl group attached to them d. four different atoms or groups attached to them 29. The purpose of the hexose monophosphate shunt is to produce a. pentose phosphates and NADPH b. DNA and RNA c. fatty acids d. reducing substrates
.
30. The occurrence of a molecule in different spatial configurations is a. isotopism b. isomerism c. stereoisomerism d. rotationalism 31. A homopolysaccharide that is important in human diets is digestion of this homopolysaccharide is . a. cellulose; glucose b. lactose; galactose c. glycogen; glucose d. starch; glucose
.
and the end product formed from the complete
32. Which substance is converted into glycogen in the process of glycogenesis? a. 2-phosphoglycerate b. glucose-1-phosphate c. fructose-1-phosphate d. phosphoglyceraldehyde 33. What are the major dietary energy sources that are composed of two simple sugars? a. disaccharides b. polysaccharides c. monosaccharides d. trioses
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Chapter_03_Carbohydrates 34. Insulin is an anabolic hormone. Which process does insulin stimulate? a. lipolysis b. gluconeogenesis c. glycogenesis d. ketogenesis 35. When compounds with one or more chiral carbon atoms and the same formula are arranged as mirror images they are said to be . a. symmetrical b. enantiomers c. rotated d. linear 36. Cellulose is a polymer of glucose where the monomers are connected by β-linkages. Humans cannot digest this substance because . a. they only produce α-amylase b. they produce insufficient quantities of β-amylase c. cellulose is resistant to the human form of β-amylase d. the β-linkages are too strong to be hydrolyzed 37. Starches in the duodenum and jejunum are acted upon by a. β-amylase b. lipase c. sucrase d. α-amylase 38. α-dextrinase is also called a. β-amylase b. isomaltase c. α-amylase d. lactase
.
.
39. In skeletal muscle, hypercortisolism may lead to a. enlargement of muscle fibers b. reduction in the size of muscle fibers c. increased contractile strength of muscle fibers d. increased healing capability
.
40. People with type 1 diabetes have . a. slow translocation of GLUT4 receptors from the Golgi body b. lack of mRNA synthesis for GLUT4 receptors in adipocytes or myocytes c. increased glycogenesis in myocytes after a meal d. below-normal glucokinase activity because of low insulin levels 41. During the end reaction of the electron transport chain, molecular oxygen becomes
.
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Chapter_03_Carbohydrates a. oxidized to carbon dioxide b. reduced to water c. NADH + H+ d. FADH2 42. Alcohol in beverages is degraded mainly in the liver cytosol with the production of one NADH for each ethanol molecule. Predict what effect consumption of alcohol would have on the activity of the liver malate-aspartate shuttle. a. no change b. increased c. decreased d. reversed 43. Which hormonal changes occur in response to a fall in blood glucose concentration? a. increased insulin, decreased glucagon b. decreased insulin, increased glucagon c. decreased insulin, decreased glucocorticoids d. increased insulin, increased glucagon 44. If an individual with no blood sugar abnormalities when eating regularly presented with severe hypoglycemia after 30 hours of fasting, which enzyme would you suspect might be malfunctioning? a. phosphofructokinase b. pyruvate kinase c. fructose-1,6-bisphosphatase d. glucose-6-phosphatase 45. According to the USDA data for the year 2010, most of the carbohydrates in the American diet came from a. disaccharides b. monosaccharides c. grain products d. soft drinks
.
46. According to the USDA data for the years 1970-2010, which food source is the most abundant macronutrient (by weight) in the American diet? a. carbohydrates b. fats c. proteins d. nucleic acids 47. In the , galactose is eventually converted to a. liver; glucose b. Kupffer cell; fructose c. small intestine; glucose d. chylomicron; glucose
.
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Chapter_03_Carbohydrates 48. Which of the following homopolysaccharides made of glucose contributes the most energy to the ordinary diet? a. amylose b. amylopectin c. glycogen d. cellulose 49. In the complete oxidation of 1 mol of glucose, how many ATPs are formed? a. 4–6 b. 8–12 c. 18–24 d. 30–32 50. Where are the enzymes that catalyze the citric acid cycle located? a. cytoplasmic matrix b. endoplasmic reticulum c. mitochondrial matrix d. lysosome 51. Which tissue has the least activity of the pentose phosphate pathway? a. liver b. adrenal cortex c. mammary gland d. skeletal muscle 52. What is the key enzyme in digestion of polysaccharides? a. starch amylopectin b. β-amylase c. α-dextranase d. α-amylase 53. Sucrose digestion is initiated in the a. pylorus b. fundus c. duodenum d. mouth
.
54. All of the following are substrates for gluconeogenesis EXCEPT a. fatty acids b. lactate c. glycerol d. glucogenic amino acids
.
55. The conversion of pyruvate to oxaloacetate in gluconeogenesis allows which molecules to enter the gluconeogenic pathway? a. alcohols
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Chapter_03_Carbohydrates b. amino acids c. monosaccharides d. polysaccharides 56. Which sugar is not present in the systemic circulation due to efficient removal by the liver? a. glucose b. fructose c. galactose d. sucrose 57. Enterocytes absorb only one form of carbohydrate. This form is a. disaccharides b. polysaccharides c. monosaccharides d. trisaccharides 58. Glycemic load considers the in the food. a. protein and carbohydrate content b. fat and carbohydrate content c. fat to carbohydrate ratio d. quantity and quality of carbohydrate 59. Glucose phosphorylation in the liver is catalyzed by a. glucokinase b. hexokinase c. insulin d. glucagon 60. Which disaccharide is commonly found in mushrooms? a. glucose b. fructose c. trehalose d. galactose 61. What type of bond holds two monosaccharides together? a. ionic b. hydrogen c. covalent d. peptide 62. Glycolysis is a process involving . a. synthesis of fatty acids b. reactions that convert glucose to glycogen c. reactions that convert glucose to pyruvate
.
.
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Chapter_03_Carbohydrates d. reactions that convert glycogen to protein 63. In which cellular site is most of the energy released when carbohydrates are oxidized to carbon dioxide and water? a. cytoplast b. endothelium c. Golgi body d. mitochondrion 64. Which process produces glucose-6-phosphate from noncarbohydrate sources? a. glycolysis b. glycogenolysis c. glycogenesis d. gluconeogenesis 65. In order to be absorbed by the body, all digestible carbohydrates must be broken down into a. disaccharides b. monosaccharides c. trisaccharides d. oligosaccharides
.
66. In what part of the cell does glycolysis occur? a. mitochondrion b. cytosol c. nucleus d. endoplasmic reticulum 67. The second most abundant food sources of carbohydrates are a. complex carbohydrates b. sugars and sweeteners c. fruits and vegetables d. digested proteins
.
68. The poison, sodium cyanide, inhibits the enzyme cytochrome c oxidase. Why is ingestion of this poison usually fatal? a. It blocks the production of ATP in the cells. b. It causes cells to rupture. c. It changes membrane permeability allowing important molecules to leave the cell. d. It causes changes in the acetyl-coenzyme A molecule. 69. The enzyme ATP synthase is believed to catalyze the formation of ATP, as described by the a. leakage b. hydrogen pump c. protein channel d. chemiosmotic
theory.
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Chapter_03_Carbohydrates 70. The disaccharidases are synthesized by the a. pancreas b. liver c. enterocyte d. chief cell
.
71. What is the most common digestible homopolysaccharide existing as both amylose and amylopectin? a. glycogen b. cellulose c. hemicellulose d. starch
Enzymes: Match the enzymes with the pathway in which they function in carbohydrate metabolism. a. glycogenesis b. glycolysis c. gluconeogenesis d. glycogenolysis e. pentose phosphate pathway 72. phosphofructokinase 73. pyruvate carboxylase 74. glycogen phosphorylase 75. glucose-6-phosphate dehydrogenase 76. branching enzyme Transporter Proteins: Match the transporter proteins with their major site of expression. a. erythrocytes, CNS b. liver, β-cells, kidney c. brain, sperm, placenta d. muscle, heart, adipocytes e. intestine, kidney, brain, skeletal muscle, adipose 77. GLUT1 78. GLUT2 79. GLUT3 80. GLUT4 81. GLUT5
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Chapter_03_Carbohydrates
82. Enzymes are regulated by induction, covalent regulation (a form of posttranslational modification), and allosteric modification. Pick out any THREE (3) enzymes from the enzymes involved in glycolysis, the TCA cycle, gluconeogenesis, glycogenesis, or glycogenolysis. Then, indicate: the reaction that the enzyme catalyzes; what tissue(s) this occurs in; how it is regulated (via one of the mechanisms listed above); and what signals are involved in its regulation. NOTE: Long answers are unnecessary—this can be done in a relatively short single sentence. 83. Discuss why sucrose, ordinarily an easily digested carbohydrate, might present problems of flatulence and diarrhea in individuals with severe inflammatory bowel disease. 84. Describe the symport mechanism involving glucose and the NA+/K+-ATPase pump. 85. In anaerobic conditions the NADH produced in glycolysis is not reoxidized by oxygen in the mitochondria but is oxidized to NAD in the cytoplasm by an enzyme. What is the enzyme and what is the importance of this reaction for conditions of low oxygen level? 86. Discuss the chemiosmotic hypothesis of the mechanism by which the energy from electron transport is used to synthesize ATP. 87. Glycogenesis, glycogenolysis, gluconeogenesis, and glycolysis are tissue-specific—that is, either the pathway or certain aspects of the pathway are different for different tissues. Pick ONE metabolic process and describe what occurs, including what tissues are involved and any tissue-specific differences. Make sure to indicate any and all signals involved in this process. 88. Describe the process by which high levels of muscle lactate, produced by oxygen debt from exercise, are controlled/diminished by gluconeogenic action of the liver. 89. Following a meal containing carbohydrates, glucose enters the bloodstream and increases the circulating blood glucose concentration. Describe the changes in the levels of hormonal regulators (insulin, glucagon, and cortisol) in response to this high glucose concentration and their major functions in lowering glucose levels in the bloodstream back to normal. 90. Often you will hear the statement, “Insulin is important for the uptake of blood glucose by all tissues.” What is wrong with this statement? Be specific. 91. A number of metabolic pathways have a problem in that certain components required for them to function are found in either the cytosol or the mitochondria, and some intermediates cannot cross the membrane. This requires that certain compounds be shuttled from one compartment to the other. Explain this shuttling process for either: (a) glycolysis/TCA cycle OR (b) gluconeogenesis. Your answer should include what needs to be shuttled, why it needs to be shuttled, and how this is accomplished.
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Chapter_03_Carbohydrates Answer Key 1. True 2. True 3. False 4. True 5. False 6. False 7. False 8. True 9. True 10. True 11. True 12. False 13. False 14. False 15. False 16. a 17. b 18. b 19. a 20. b 21. b 22. a 23. b 24. b 25. d
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Chapter_03_Carbohydrates 26. c 27. d 28. d 29. a 30. c 31. d 32. b 33. a 34. c 35. b 36. a 37. d 38. b 39. b 40. d 41. b 42. b 43. b 44. c 45. c 46. a 47. a 48. b 49. d 50. c 51. d
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Chapter_03_Carbohydrates 52. d 53. c 54. a 55. b 56. b 57. c 58. d 59. a 60. c 61. c 62. c 63. d 64. d 65. b 66. b 67. b 68. a 69. d 70. c 71. d 72. b 73. c 74. d 75. e 76. a
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Chapter_03_Carbohydrates 77. c 78. d 79. a 80. b 81. e 82. [There are many examples, so just a few are listed below, but they are probably the most common.] Allosteric – all of the ones associated with ATP, ADP, NAD, and NADH are allosteric; ADP positively regulating PFK and ATP inhibiting it is an example. There are also isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and pyruvate dehydrogenase. Covalent regulation – insulin stimulating the enzyme phosphatase, which dephosphorylates glycogen synthase (that’s the covalent regulation part), thereby promoting glycogen synthesis. The opposite reaction is glucagon (or epinephrine) stimulating the kinase that phosphorylates the enzyme phosphorylase b to generate phosphorylase a, the active form that breaks down glycogen to glucose-1-phosphate. Note – the hormones do not directly carry out covalent regulation; they stimulate (note the word stimulate, not induce) the enzyme that post-translationally modifies a second enzyme by phosphorylation or dephosphorylation to make it active or inactive. Induction – many, many examples. Most common: insulin induces glucokinase (not hexokinase); PFK. Glucagon induces glucose-6-phosphatase; PEPCK. 83. Grading rubric – answer should include the following items: Sucrose is digested by the disaccharidase sucrase in the brush border of the small intestine. In inflammatory bowel disease the mucosal cells do not produce sufficient sucrase; thus, undigested molecules draw water by osmosis, causing diarrhea, and gut bacteria ferment some sucrose with production of gases (flatulence). 84. Grading rubric – answer should include the following items: • • • • •
Glucose is absorbed by active transport requiring the Na+/K+-ATPase pump. Transport protein SGLT1 is located on the enterocyte luminal surface (apical side of the enterocyte). SGLT1 simultaneously transports sodium and glucose (or galactose) into the enterocyte. The sugar can only bind if the sodium is already bound, thus exposing the sugar-binding site. Sodium moves down a concentration gradient and is released inside the cell, which then releases glucose inside the cell.
The sodium is pumped out against a concentration gradient into the extracellular fluid via the Na+/K+-ATPase pump on the basolateral membrane of the enterocyte and potassium is pumped into the cell against a concentration gradient in exchange. Use of ATP to make the exchange of sodium for potassium is a major energy demand of a body at rest (basal metabolic rate). 85. Grading rubric – answer should include the following items: The enzyme is lactate dehydrogenase, which, under anaerobic conditions, catalyzes the transfer of two H+ from NADH + H to pyruvate to create lactate. This is important to regenerate NAD so that it can be used again in glycolysis. Glycolysis needs to be ongoing in conditions of low oxygen in order to generate ATP because oxidative production of ATP is compromised in conditions of low oxygen.
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Chapter_03_Carbohydrates 86. Grading rubric – answer should include the following items: Electron transport and ATP synthesis are said to be coupled because the energy used to pump protons from the mitochondrial matrix into the intermembrane space (called translocation of the protons) creates potential energy that can be harnessed by the enzyme complex ATP synthase to make ATP from ADP. As electrons pass through Complexes I, III, and IV of electron transport, sufficient energy is released to pump protons into the intermembrane space. This creates both a proton gradient and an electrical gradient across the inner mitochondrial membrane. When these gradients are sufficiently large, protons enter the channels provided by the ATP synthase molecule imbedded in the mitochondrial membrane, the F0 portion. As the protons travel through the F1 portion of ATP synthase, which extends into the matrix and rotates as the protons pass through back into the matrix, the energy that causes the rotational movement drives the phosphorylation of ADP to create ATP. 87.87. Glycogenesis occurs in muscle and the liver [the student should choose one tissue]. For either tissue, the signal is high blood glucose, which results in the release of insulin. For liver tissue, insulin induces glucokinase to increase glucose uptake by the liver. Insulin also stimulates (NOT induces) the dephosphorylation of glycogen synthase, resulting in its activation and the synthesis of glycogen. Note that insulin stimulates the enzyme (glycogen synthase phosphatase, which carries out the dephosphorylation of glycogen synthase, an example of covalent modification). Glycogen synthase and glycogen synthase phosphatase (or glycogen synthase kinase for that matter) are separate enzymes. Except for hexokinase (not induced by insulin) instead of glucokinase, the same mechanism occurs in muscle. Glycogenolysis obviously also occurs in muscle and the liver. The signal is low blood glucose, resulting in the release of glucagon and epinephrine. For the liver, glucagon stimulates glycogen phosphatase b to a (same enzyme, a is just the phosphorylated form); it does this by stimulating the activity of a different enzyme, glycogen phosphatase kinase. In muscle, the signal is epinephrine, rather than glucagon. The result in both tissues is the breakdown of glycogen ultimately to glucose-6-phosphate. In liver tissue, glucagon also induces glucose-6-phophatase, the enzyme that converts glucose-6phosophate to glucose, which is then released into the blood. For muscle, there is no induction of glucose-6-phosphatase; thus, it simply proceeds through glycolysis/TCA to generate energy. So, liver glycogen results in glucose for the entire body; muscle glycogen only supplies energy for the muscle. Gluconeogenesis occurs primarily in the liver and to some extent in the kidney. It involves the conversion of non-CHO precursors (AAs, lactate, glycerol) into glucose, which is then released by the liver into the bloodstream. This pathway is stimulated in response to low blood glucose and the subsequent action of glucagon, released by the pancreas due to low blood glucose. Glucagon induces many of the key enzymes (pyruvate carboxylase, PEPCK, fructose bisphosphatase, and glucose-6-phosphatase). Amino acids are converted into their corresponding keto acid and ultimately oxaloacetate, which must leave the mitochondria and be converted to PEP, etc. Glycolysis is the oxidation of glucose to pyruvate, is cytosolic, and is anaerobic. Glycolysis occurs in all tissues/cells and is stimulated under fed conditions. High blood glucose leads to insulin secretion by the pancreas, which in turn induces glucokinase, PFK, and pyruvate kinase. Glucokinase is for liver tissue only—other tissues have hexokinase, which is not induced by insulin (but they still have PFK, etc.). 88. Grading rubric – answer should include the following items: Lactate from muscles is released into the blood, from which it is removed by the liver. In the liver, lactate is converted to pyruvate, which then enters the gluconeogenic pathway to be converted to glucose and returned to the blood for use by other tissues. This process is called the Cori cycle. 89. Grading rubric – answer should include the following items: Following a meal, circulating blood glucose increases, triggering insulin release from the beta cells of the pancreas. Insulin then interacts with the insulin receptors on the muscle cells and adipocytes to start an intracellular cascade that moves GLUT4 transporters to the cell membrane and allows blood glucose to enter the largest tissues in the body (muscle and fat). Other tissues also take up glucose via GLUT transporters that do not require the influence of insulin. Blood glucose quickly returns to normal levels. As the next meal approaches, blood glucose begins to decrease, which triggers
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Chapter_03_Carbohydrates release of glucagon from the alpha cells of the pancreas. Glucagon acts on liver cells to stimulate glycogenolysis and the liver releases stored glucose to keep blood glucose levels normal. Similarly, low blood glucose levels stimulate the release of cortisol from the adrenal cortex and cortisol supports the stimulation of gluconeogenesis, which also contributes to raising low blood glucose levels toward normal. 90. This is really a GLUT4 question—all tissues can take up glucose because they have transporters (even when there isn’t any insulin). Insulin stimulates increased uptake in muscle and adipose because it binds to the insulin receptor on these cells and causes the GLUT4 to translocate from the cytosol to the membrane. Note that insulin still binds to the insulin receptor on all the other cells—they all have changes in glycolytic enzymes, etc.—they just don’t have the right type of GLUT to translocate in response to insulin. Also note that insulin does not enter cells—it (like glucagon) binds to its receptor and various signals are transmitted into the cell (i.e., signal transduction), which results in various responses (induction of genes; stimulation of enzymes; translocation of GLUT4); some of these responses occur in all cells, some in only specific cells. 91. a) Glycolysis/TCA Cycle: The NADH generated by glycolysis needs to get in the mitochondrion for the electron transport chain (NADH from TCA cycle is already there). The malate-aspartate shuttle is used. Electrons (H+) from NADH are used to generate malate (from oxaloacetate), which crosses the membrane and gives them back to NAD to generate NADH (and oxaloacetate). Oxaloacetate is converted into aspartate, which crosses back to the cytosol and is metabolized to oxaloacetate to begin the process all over again. [Students may get this confused or mixed with the malateoxaloacetate shuttle involved in gluconeogenesis.] (b) Gluconeogenesis: The problem is the need to get oxaloacetate out of the mitochondrion into the cytosol where the final conversion to glucose (via PEP) occurs. The amino acid alanine as well as glycerol and lactate enter gluconeogenesis as pyruvate, whereas other AAs feed into the TCA cycle at points dependent on the length of their carbon skeleton. In any case, we convert pyruvate to oxaloacetate (via pyruvate carboxylase) or any other TCA cycle keto acid to oxaloacetate. Oxaloacetate can’t cross the membrane, so it is converted into malate (or aspartate); malate (or aspartate) crosses the membrane, and it is converted back to oxaloacetate. Now, oxaloacetate can be converted into PEP by PEPCK and continue to be metabolized to glucose.
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Chapter_04_Fiber
Indicate whether the statement is true or false. 1. Foods may be considered a “good” source of fiber if they contain at least 5% of recommendations. a. True b. False 2. High-fiber diets will raise blood glucose levels. a. True b. False 3. Pectins, gums, inulin and resistant starches are structurally longer-chain, water-soluble fibers. a. True b. False 4. Fibers that are not fermented will help reverse diarrhea. a. True b. False 5. Sandwich spreads and dips are naturally high in cellulose. a. True b. False 6. The repeating monosaccharide in stachyose and verbascose is fructose. a. True b. False 7. An individual who consumes large amounts of strawberries and carrots might develop diarrhea. a. True b. False 8. Ingesting large amounts of fiber in excess of recommended levels, may help to enhance absorption of iron and magnesium. a. True b. False 9. The bran component of cereals contains the most fiber. a. True b. False 10. An individual whose diet is lacking in pectins and β-glucans might suffer with hypercholesterolemia. a. True b. False 11. Dietary fiber is defined as nondigestible carbohydrates and lignin that are intact and intrinsic in plants. a. True b. False
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Chapter_04_Fiber 12. Hemicelluloses with acids in their side chains are fat soluble. a. True b. False 13. β-glucans are effective in reducing serum cholesterol. a. True b. False 14. All plant foods are high in cellulose. a. True b. False 15. No Tolerable Upper Intake Level for dietary fiber or functional fiber has been established. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Diets low in fat and rich in high-fiber foods may reduce the risk of a. certain cancers b. heart disease c. gastric ulcers d. duodenal ulcers
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17. Which of the following is considered a functional fiber? a. hemicellulose b. fructans c. psyllium d. lignin 18. Which component of the cell wall contributes to the fiber content of foods? a. waxes b. cutin c. bran layer d. suberin 19. The endosperm of the plant contains mainly which substance? a. cellulose b. starch c. hemicellulose d. resistant starch 20. Glycemic control is a. unchanged
in response to foods rich in fiber or to fiber supplements.
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Chapter_04_Fiber b. improved c. reduced d. not known 21. Which source of fiber would be the best to add to one’s diet in order to lower serum lipid concentrations? a. barley β-glucan and methylcellulose b. wheat dextrin c. pectin d. guar gum 22. Which substance is used to replace fat in fillings, dairy products, and dressings? a. fructooligosaccharides b. mucilages c. inulin d. β-glucans 23. The two main compounds in the flavonol subclass are a. quercetin and kaempferol b. apigenin and luteolin c. hesperetin and naringenin d. genistein and equol
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24. What are plant polysaccharides found in flax and psyllium that are effective in reducing serum LDL cholesterol? a. beta-glucans b. fructans c. mucilages d. chitin 25. Most fibers are strongly a. hydrophobic b. allosteric c. hydromorphic d. hydrophilic
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26. By what mechanism do soluble fibers decrease the absorption of lipids? a. by increasing growth of bacteria that use the lipids b. by lowering blood cholesterol c. by adsorbing/interacting with lipids d. by reducing mineral absorption 27. Which fiber type is slowly fermentable? a. lignin b. pectin c. gums
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Chapter_04_Fiber d. resistant starch 28. A manufacturer can claim that its product is an “excellent” source of fiber if the product contains at least what percentage of recommendations? a. 5 b. 10 c. 15 d. 20 29. An individual who consumed a diet extremely high in cellulose would most likely suffer with a. diarrhea b. constipation c. high blood pressure d. diabetes
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30. What is a water-soluble, gel-forming fiber that functions in the plant as intracellular cement and that is used commercially to make jellies and to provide fiber in enteral formulas? a. lignin b. gum c. pectin d. cellulose 31. Which group of high-fiber foods contains the greatest quantities of hemicellulose? a. legumes b. whole-grain cereals and bran c. fruits d. vegetables 32. Fiber-induced shifts in bile acid production from cholic acid toward chenodeoxycholic acid will act to a. reduce blood glucose levels b. inhibit cholesterol synthesis c. lower blood pressure d. reduce the production of stomach acid 33. Pectins are part of the cell wall and middle lamella and are not a. water soluble b. gel forming c. stable at acidic pHs d. stable at basic pHs
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34. A good choice of a food to add to one’s diet in an effort to increase fiber intake while not consuming large portions is . a. watermelon b. almonds c. grapes
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Chapter_04_Fiber d. white rice 35. What are the hydrocolloids that are secreted at a site of injury on a plant or surround the endosperm of some seeds and that are used as thickening agents? a. lignin b. cellulose c. pectins d. gums 36. Which scenario is NOT a typical gastrointestinal response to ingestion of dietary fiber? a. increased glucose absorption b. delayed gastric emptying c. increased bile acid excretion d. increased fecal bulk 37. Functional fiber is currently defined as . a. carbohydrates and lignin that are nondigestible by human enzymes and are intact and intrinsic in plants b. carbohydrates that are nondigestible by human enzymes; have been isolated, extracted or manufactured; and have been shown to have beneficial physiological effects in humans c. all dietary fiber d. the same as crude fiber 38. Dietary fibers are mainly provided by . a. proteins that have been heated with sugars b. plant cell walls c. chitin and chitosan d. plant gums 39. Hemicelluloses with acids in their side chains are more soluble in a. acids b. water c. oils d. alcohols
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40. A high-molecular-weight substance made up of a repeating chain is the definition of a(n) a. polymer b. monomer c. isomer d. disaccharide 41. Which of the following is a polysaccharide made of glucose and sorbitol? a. chitosan b. psyllium c. inulin d. polydextrose
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Chapter_04_Fiber 42. Ingesting foods rich in gel-forming fibers is associated with a. increased nutrient digestion b. increased convective movement of nutrients c. increased gastric distention d. increased nutrient diffusion rates
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43. Because fibers absorb primary bile acids to promote their excretion, they help to protect against a. colon cancer b. diarrhea c. prostate cancer d. melanoma 44. Viscous gel-forming fibers may contribute to satiety by a. elevating serum glucose levels b. elevating glucagon levels c. slowing gastric emptying d. reducing hydrochloric acid in the stomach
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45. Which of the following high-fiber foods are most effective in lowering serum cholesterol? a. corn and wheat b. chitosan and chitin c. rice bran and wheat bran d. oat bran 46. Gums are found in . a. nuts, peas, and root vegetables b. shells of crabs, shrimp, and lobster c. oatmeal, barley, and legumes d. citrus fruits, strawberries, and raspberries 47. Several flavonoids exhibit biological activities including antioxidant function, anticoagulant function, antiinflammatory functions and antiplatelet adhesion. This imparts protection against which type of disease? a. cancer b. heart disease c. aging d. diabetes 48. The health benefits of fiber are based on which two characteristics? a. viscosity and solubility b. viscosity and fermentability c. fermentability and solubility d. solubility and stability 49. Which cereals contain more fiber than other grains?
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Chapter_04_Fiber a. rye and barley b. wheat and corn c. rye and wheat d. oats and wheat 50. Phenolic acids are found in . a. grapes, grape juice, red wine, and strawberries b. cruciferous vegetables c. coffee, blueberries, apples, pears, and cherries d. tomatoes, pumpkins, squash, and carrots 51. Current studies of the effects of flavonoids in humans most support protection against which disease? a. cancer b. diabetes c. osteoporosis d. cardiovascular 52. The technical name for gums is a. hemicellulose b. pectin c. hydrocolloids d. β-glucans
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53. Which of the following fibers stimulates the growth of bifidobacteria and thus are considered prebiotics? a. lignins b. fructans c. β-glucans d. cellulose 54. Which mechanism is not associated with the manner in which fiber lowers serum cholesterol concentrations? a. decreased transit time b. increased excretion of bile acids in the feces c. a shift of bile acid pools toward chenodeoxycholic acid, which inhibits HMG-CoA reductase d. production of propionic acid from gut fermentation of fiber 55. Flavonoids that are helpful during perimenopause are a. flavonols b. flavones c. isoflavones d. anthocyanins
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56. Fiber fermentation in the colon may change glycogen catabolism due to the production of a. long-chain fatty acids b. chitosan
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Chapter_04_Fiber c. oligosaccharides d. short-chain fatty acids 57. Which fiber is often added to foods as a thickening or texturing agent? a. lignin b. gums c. cellulose d. hemicellulose 58. Which volatile short-chain fatty acid is believed to lower serum cholesterol by acting as an inhibitor of cholesterol biosynthesis? a. acetic b. butyric c. propionic d. palmitic 59. Common food sources of fructans are . a. strawberries, apples, and citrus fruits b. whole grains c. chicory, onions, and Jerusalem artichokes d. legumes 60. β-glucans are found in . a. oat products and barley b. citrus fruits, strawberries, and apples c. chicory, asparagus, and onions d. bran, nuts, and legumes 61. The predominant source of chitin is a. shells of crab, lobster, and shrimp b. bran c. vegetables d. fruits
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62. Which type of food does not contain cellulose purified from wood? a. canned green beans b. cake mixes c. sandwich spreads d. fruit juice mixes 63. What is the recommended amount each day of dietary fiber for most population groups? a. 15–24 g b. 19–38 g c. 50–60 g
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Chapter_04_Fiber d. 70–90 g 64. An example of an RS1 starch is a. unripe bananas b. whole grains and seeds c. avocados d. corn-based products
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65. Heating and enzymatically treating starch creates a. chitin b. lignins c. resistant dextrins d. mucilages 66. Ice cream with added gums will appear to be a. sweeter b. thinner c. creamier d. lighter
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67. Which type of bond imparts a three-dimensional structure to cellulose? a. covalent b. ionic c. hydrogen d. glycosidic 68. Which of the following types of foods contributes the most fiber in a usual serving? a. whole-grain breads b. legumes, beans c. meat, dairy d. leafy vegetables 69. Dietary fiber is currently defined as . a. carbohydrates and lignin that are nondigestible by human enzymes and are intact and intrinsic in plants b. carbohydrates that are nondigestible by human enzymes; have been isolated, extracted or manufactured; and have been shown to have beneficial physiological effects in humans c. crude fiber d. the same as functional fiber 70. Which plant polysaccharides have a structure similar to gums? a. mucilages b. fructans c. β-glucans d. pectins
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Chapter_04_Fiber 71. Which component of cereals contains the most fiber? a. germ layer b. endosperm c. husk d. bran
Health Benefits of Fiber: Match the condition with the benefit provided by the fiber. a. viscous, gel-forming fibers improve glycemic control b. non or less fermentable fibers increase fecal bulk c. fiber-rich foods and hormones such as ghrelin, peptide YY and cholecystokinin modulate appetite d. viscous, gel-forming fibers lower total and LDL cholesterol e. fiber reduces bile concentration, dilutes intestinal contents, and reduces colonic transit time 72. cardiovascular disease 73. diabetes mellitus 74. satiety 75. constipation 76. colon cancer Types of Fiber: Match the fiber with an appropriate description. a. The main noncarbohydrate component of fiber and a three-dimensional polymer of phenol. Found in carrots, berries, and wheat, and insoluble in water. b. A hydrocolloid composed of sugar and sugar derivatives commonly used as a food additive that is secreted from plant injuries or can also be found in oats, barley, and legumes. c. A long linear polymer that provides structure to the cell wall. Found in bran, legumes, root vegetables, and apples. d. Contains a number of sugars in its backbone and side chains. Some are water soluble and some are insoluble; found in bran and whole grains. e. A group of polysaccharides with galacturonic acid as a primary constituent. It is soluble and gel forming; plentiful in many fruits. 77. pectin 78. cellulose 79. gum 80. lignin 81. hemicellulose
82. What are the components that make up fermentable dietary fiber and in what foods are each found?
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Chapter_04_Fiber 83. Consistent evidence shows that soluble fibers can lower the levels of cholesterol in many people with high serum cholesterol. Discuss the three mechanisms by which fibers are proposed to lower serum cholesterol. 84. Discuss the benefits of fermentable fibers in terms of the production of short-chain fatty acids. 85. What are the components that make up non-fermentable dietary fiber and in what foods are each found? 86. Dr. Smith has prescribed a high-fiber diet (35–40 g/day) with special emphasis on the water-insoluble fibers for Mr. Brown. How would this diet protect against colorectal cancer? Give examples of foods that contain water-insoluble fibers. 87. Discuss the benefits of fermentable fibers in terms of their prebiotic function. 88. Discuss three health claims relating to fiber that have been approved by the U.S. Food and Drug Administration. 89. What associations have been found between high fiber intake and obesity? What mechanisms may be at work? How clear/consistent is the evidence? 90. Make an argument defending the statement: To remain healthy, it is best to eat foods containing a variety of fiber types each day. 91. Discuss the four significant characteristics of dietary fiber that affect its physiological and metabolic roles.
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Chapter_04_Fiber Answer Key 1. False 2. False 3. True 4. False 5. False 6. False 7. True 8. False 9. True 10. True 11. True 12. False 13. True 14. True 15. True 16. b 17. c 18. c 19. b 20. b 21. a 22. c 23. a 24. a 25. d
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Chapter_04_Fiber 26. c 27. a 28. d 29. a 30. c 31. b 32. b 33. d 34. b 35. d 36. a 37. b 38. b 39. b 40. a 41. d 42. c 43. a 44. c 45. d 46. c 47. b 48. b 49. a 50. a 51. d
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Chapter_04_Fiber 52. c 53. b 54. a 55. c 56. d 57. c 58. c 59. c 60. a 61. a 62. a 63. b 64. b 65. c 66. c 67. c 68. b 69. a 70. a 71. d 72. d 73. a 74. c 75. b 76. e
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Chapter_04_Fiber 77. e 78. c 79. b 80. a 81. d 82.82. Grading rubric – answer should include the following items (see Table 4.2): Fermentable fibers must be able to be digested (fermented) by gut bacteria. Examples of fermentable fibers and foods that contain them include: • • • • • • •
fructans (chicory, asparagus, onions, tomatoes, bananas; also added to yogurts, cereals) pectins (fruits, legumes, nuts) gums (guar gum, gum Arabic; added as food additives that thicken) beta-glucans (oats, barley, mushrooms) polydextrose (created from glucose; used as a food additive for bulk; a functional fiber) resistant dextrins (extracted from cooked and cooled wheat to be added to foods; considered a functional fiber rather than a natural fiber) resistant starch 3 (cooked and cooled rice, potatoes, pasta)
83. Grading rubric – answer should include the following items: • • •
First. Cholesterol and bile acids adhere to the soluble fibers and are removed as waste rather than recirculated to the liver. This forces the liver to make new bile acids from cholesterol, increases uptake of LDL cholesterol from the blood, and thereby lowers blood cholesterol. Second. Microbial fermentation of fermentable soluble fibers produces short-chain fatty acids. Propionic acid has been shown to inhibit the rate-limiting enzyme in the synthesis of cholesterol (HMG-CoA reductase) by the liver. When synthesis is slowed, less cholesterol enters the blood. Third. For reasons unknown, the shift by fiber-inhibition of recirculation of bile acids to creating additional new bile acids promotes increased chenodeoxycholic acid formation. This bile acid also inhibits HMG-CoA reductase and lowers synthesis of cholesterol.
84. Grading rubric – answer should include the following items: • • • • •
Fermentable fibers are used by gut bacteria to produce lactic acid and short-chain fatty acids that have several benefits. All these acids decrease the pH to a more acidic environment, reducing the solubility of bile acids and allowing calcium to bind them and make them less toxic to colon cells. The acidity also decreases growth of pathogenic bacteria. Short-chain fatty acids can be absorbed and used for energy. Butyric acid is a preferred food for colonic mucosal cells (supplying 67% of their energy) and likely keeps them healthy, perhaps preventing colon cancer. Propionic acid, when absorbed, can inhibit cholesterol synthesis, lowering blood cholesterol and risk for heart disease.
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Chapter_04_Fiber 85. Grading rubric – answer should include the following items: Non-fermentable fibers cannot readily be digested (fermented) by gut bacteria. Examples and the foods that contain this type of fiber include: • • •
Cellulose (cereal brans, legumes, nuts, root vegetables) Lignin (whole grains, especially wheat; mature root vegetables; seeds of berries; stalks of broccoli and asparagus) Waxes (suberin and cutin, which coat the external surfaces of apples, potatoes, and similar fruits and vegetables)
86. Grading rubric – answer should include the following items: • •
•
Water-insoluble fiber will add fecal bulk and speed transit time of food through the GI tract. Limited evidence suggests that fiber may reduce risk of cancer by several mechanisms including these: by adsorbing bile acids to promote their fecal excretion; by helping acidify the lumen of the colon, which keeps bile acids from being converted into more toxic secondary bile acids; by increasing fecal bulk to dilute concentrations of carcinogens from the diet; by shortening time undigested foods and toxins remain in the gut and so lessen exposure to toxins; by releasing calcium through fermentation to allow normal cells to grow as fast as cancer cells; and by producing butyric acid through fermentation to maintain health of colon cells. Whole grains and vegetables have substantial amounts of insoluble cellulose and lignin.
87. Grading rubric – answer should include the following items: • •
Certain fermentable fibers promote the growth of beneficial gut bacteria, particularly lactobacilli and bifidobacteria, because they are preferred food for growth of those bacteria. This extra growth in numbers of the beneficial bacteria promotes gut health because the beneficial bacteria can crowd out pathogenic bacteria and lower their numbers.
88. Grading rubric – answer should include the following items: • • •
Diets low in fat and rich in high-fiber foods (or rich in fruits and vegetables) may reduce the risk of certain cancers. Diets low in saturated fat (or low in fat) and rich in soluble fiber (or rich in whole oats and psyllium seed husk) may reduce the risk of heart disease. Diets low in total fat, saturated fat, and cholesterol and rich in whole grains and other plant foods may help reduce the risk of heart disease.
89. Grading rubric – answer should include the following items: • •
Fairly consistent evidence supports the consumption of a high-fiber diet for weight control. Possible mechanisms include more bulk causing a full feeling, less calories provided because of the indigestibility of fiber, and reduction of hunger through satiety-inducing hormones.
90.90. Grading rubric – answer should include the following items: Different fibers have different helpful characteristics. Examples include: •
Cellulose, which increases fecal bulk and speeds transit time to remove toxins and carcinogens more quickly from
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Chapter_04_Fiber • •
the gut, likely reducing the risk of cancer. Pectins and beta-glucans, which can keep bile acid and cholesterol from being absorbed into the blood, thereby reducing blood cholesterol and risk of heart disease. Fermentable fibers such as fructans and gums can produce beneficial short-chain fatty acids to reduce risk of both cancer and heart disease.
To gain all these benefits, a variety of foods containing different fiber types need to be included in the diet daily. 91. Grading rubric – answer should include the following items: •
•
•
•
Solubility/insolubility in water. Pectins, gums, beta-glucans, fructans, psyllium, some resistant starches, and some hemicelluloses are soluble. Cellulose, lignin, some hemicelluloses and pectins, some resistant starches, chitosan, and chitin are insoluble. In general, soluble fibers delay gastric emptying and slow down transit time through the GI tract and slow glucose entry into the blood. Insoluble fibers increase fecal bulk and speed up transit time, which may expose the colon to fewer toxins. Water-holding/hydration capacity and viscosity. Soluble fibers have greater water-holding capacity, which traps nutrients and slows absorption, than insoluble fibers. Characteristics other than solubility that affect water-holding capacity are pH of the GI tract and particle size of the fiber (coarsely ground has more holding capacity). The more coarsely ground whole grains hold more water, slow gastric emptying, and reduce enzyme functions by separating enzymes from substrates. Adsorption or binding ability. Lignin, gums, pectins, beta-glucans, and a few other fibers attach to substances such as enzymes and nutrients and keep them from being absorbed. This is important for increasing fecal bile acid excretion, which helps lower blood cholesterol. This characteristic can also negatively affect the ability of some minerals and phytochemicals such as carotenes to be absorbed into the enterocytes and eventually into the blood for use. Degradability/fermentability. Fiber always reaches the colon undigested because it cannot be digested by human enzymes. Gut bacteria can digest (i.e., ferment) some fibers. This helps gut bacteria grow and prebiotic fibers in particular support the growth of nonpathogenic, acid-producing bacteria that improve gut health. Some products of fermentation of fibers are the short-chain fatty acids that can improve health of colon cells and may inhibit synthesis of cholesterol to lower blood cholesterol levels. Short-chain fatty acids may also enhance gut immune function. Poorly fermentable fibers such as cellulose and lignin increase fecal bulk and speed transit time to promote more frequent defecation and quicker removal of toxins that might harm colon cells.
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Chapter_05_Lipids
Indicate whether the statement is true or false. 1. Adipocytes’ primary function is to store fat as triacylglycerol; thus, they do not require glycolysis and the TCA cycle for energy needs. a. True b. False 2. Bile is the GI enzyme that hydrolyzes dietary triacylglycerol into free fatty acids and glycerol. a. True b. False 3. Fatty acids are converted into glucose by gluconeogenesis and used for energy during starvation. a. True b. False 4. The regulation of fatty acid synthesis and oxidation is closely linked to carbohydrate status. a. True b. False 5. Moderate alcohol intake is associated with an increased risk of coronary heart disease. a. True b. False 6. Ketogenesis is the synthesis of ketone bodies from fatty acids for energy under conditions of excess glucose, such as in the fed state. a. True b. False 7. Essential fatty acids are classified as such because we cannot synthesize them from other fatty acids and they are required for the synthesis of prostaglandins, thromboxanes, and leukotrienes. a. True b. False 8. Unlike long-chain fatty acids, short-chain fatty acids from the diet leave the enterocyte via the portal vein and go directly to the liver. a. True b. False 9. One of the primary functions of a phospholipid is possible because of its structure, which allows it to be both hydrophobic and hydrophilic. a. True b. False 10. The conversion of linoleic acid (18:2) to arachidonic acid (20:4) involves the addition of two carbons to the methyl end and two double bonds at the n-3 and n-6 positions of the omega end. a. True
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Chapter_05_Lipids b. False 11. HMG-CoA reductase is a key enzyme in the synthesis of cholesterol from acetyl-CoA. a. True b. False 12. Brown fat contains more mitochondria than white fat and is involved in thermogenesis. a. True b. False 13. Once a micelle, containing lipids and lipid-soluble compounds, enters the enterocyte, it is referred to as a chylomicron. a. True b. False 14. The key organ in clearing (i.e., breaking down) lipoproteins is the liver. a. True b. False 15. Most Americans consume approximately half of their total dietary lipid as triacylglycerols, and the other half as cholesterol; very little is taken in as phospholipids. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. What is formed when fatty acids are oxidized in the mitochondria (i.e., what is the end product of beta-oxidation)? a. glycerol b. pyruvate c. acetyl-CoA d. triacylglycerol 17. Which of the following lipoproteins is normally NOT present in blood in the fasting state? a. VLDL b. chylomicrons c. LDL d. HDL 18. Abnormal LDL receptors fail to remove cholesterol from the bloodstream, resulting in a. suppression of acyl-CoA cholesteryl acyl transferase (ACAT) b. suppression of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase c. hypertriglyceridemia d. familial hypercholesterolemia
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19. What is the most important unsaturated fatty acid serving as a precursor for eicosanoid synthesis? a. arachidonic acid
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Chapter_05_Lipids b. palmitoleic acid c. oleic acid d. linoleic acid 20. Ketogenesis would be the HIGHEST a. after a high-CHO meal b. after a high-protein meal c. after a high-fat meal d. during prolonged starvation
.
21. In the small intestine, which enzyme hydrolytically activates a pancreatic zymogen so that lipid digestion can occur? a. pepsin b. trypsin c. colipase d. maltase 22. Lipolysis is stimulated by . a. epinephrine alone b. epinephrine and natriuretic peptides c. natriuretic peptides alone d. norepinephrine and epinephrine 23. How does orlistat reduce absorption of dietary fat? a. by replacing dietary fat with a synthetic, indigestible substitute b. by inhibiting the activity of pancreatic lipase c. by binding free fatty acids and causing their excretion d. by inhibiting HMG-CoA reductase 24. What is the carrier molecule needed for mitochondrial membrane transport of long-chain fatty acids and their CoA derivatives? a. carnitine b. creatine c. creatinine d. cysteine 25. Which apolipoprotein is key to the delivery of triacylglycerol to tissues? a. apoC-2 b. apoA-1 c. apoE d. apoB-100 26. Choose the correct sequential order for participants in lipid digestion. a. colipase, pancreatic lipase, bile, micelles b. bile, colipase, pancreatic lipase, micelles
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Chapter_05_Lipids c. bile, enterokinase, colipase, micelles d. micelles, bile, pancreatic lipase, colipase 27. In what form is most body fat stored? a. fatty acids b. triacylglycerols c. cholesterol d. phospholipids 28. Phosphatidylinositol is a membrane phospholipid that can a. anchor membrane proteins that are attached to lipids b. stabilize the cytoplasm c. create pores in the cell membrane d. act as a receptor for viruses
.
29. Which drug therapy is associated with reduced cholesterol synthesis in the liver? a. insulin b. niacin c. gene therapy d. HMG-CoA reductase inhibitors 30. Which one of the following events will occur in the signaling pathway mediated by natriuretic peptides? a. increased intracellular cAMP activates protein kinase G b. ANP and BNP bind to type-B natriuretic peptide receptors c. activated receptors interact with guanylyl cyclase d. activated guanylyl cyclase converts intracellular AMP to cAMP 31. Choose the list of molecules that would be found in a micelle. a. vitamin A (retinol), glycerol, 2-monoacylglycerols, linolenic acid b. glycerol, butyric acid, cholesterol, 2-monoacylglycerols c. linolenic acid, 2-monoacylglycerols, cholesterol, fat-soluble vitamins d. fructose, glucose, glycerol, vitamin A 32. Which of the following lipoproteins is the major carrier of cholesterol to tissues for use in construction of membranes or steroid hormones? a. VLDL b. HDL c. LDL d. chylomicrons 33. Ketones are produced from a. cholesterol b. hormones c. amino groups
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Chapter_05_Lipids d. acetyl-CoA 34. Cholesterol serves as a precursor for all of the following EXCEPT a. phospholipids b. estrogens and androgens c. bile acids d. vitamin D
.
35. Cocoa butter contains which saturated fatty acid? a. palmitic b. stearic c. arachidic d. myristic 36. Undigested lipid in the stomach creates satiety because it a. speeds the rate of emptying of the stomach b. delays the rate of emptying of stomach contents c. enhances gastric motility d. suppresses GIP and secretin 37. Mono- and diacylglycerols are used in processed foods as a. thickening agents b. emulsifying agents c. antioxidants d. food preservatives
.
.
38. The key to the cell’s internalization of LDL is the interaction between the receptors and a. cholesterol acyltransferase b. HMG-CoA reductase c. apolipoprotein B-100 d. apolipoprotein C-100
.
39. What is the best description of the action of bile? a. Bile hydrolyzes ester bonds of the triacylglycerols. b. Bile anchors into dietary lipid so that pancreatic lipase can act. c. Bile emulsifies dietary lipid to increase its surface area. d. Bile digests the ester bond of the dietary cholesteryl ester. 40. The HDL accomplishes its function in reverse cholesterol transport in two ways. Choose the phrase that does NOT describe one of these. a. increased apoC-2 activity to reduce its triacylglycerol content b. increased activity of LCAT on vascular endothelial cells c. increased activity of transferring cholesterol to other lipoproteins d. using its apoE component to bind to LDL receptors
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Chapter_05_Lipids 41. Reverse cholesterol transport that removes cholesterol from peripheral cells and returns it to the liver is carried out by . a. LDL b. HDL c. VLDL d. lipoprotein lipase 42. Triacylglycerols with saturated fatty acids of longer chain length tend to be a. liquid oils b. emulsified c. nonesterified fats d. solid fats
at room temperature.
43. What are some products of the reaction catalyzed by pancreatic lipase? a. 2-monoacylglycerols, free fatty acids b. free fatty acids, glycerol, cholesterol c. 2-monoacylglycerols, free fatty acids, phospholipids d. free fatty acids, glycerol, cholesteryl esters 44. When foam cells, additional monocytes, mast cells, and T-cells build up in the media and intima of an artery, which structure is formed? a. atheroma b. hamartoma c. neuroma d. arterioma 45. An individual whose diet includes foods fried in vegetable oil, flaxseed oil supplements, and very little fish will have an abundance of which category of fatty acids? a. n-3 b. n-6 c. n-7 d. n-9 46. What is considered the toxic level of blood ethanol? a. less than 10 mg/dL b. 11–24 mg/dL c. 25–45 mg/dL d. 50–80 mg/dL 47. Lipids are different from other major nutrients because they a. contain carbon, hydrogen, and oxygen b. are soluble in organic solvents c. provide energy d. are digestible
.
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Chapter_05_Lipids 48. Large arteries contain which protein? a. albumin b. elastin c. fibrin d. plasmin 49. Which type of acid is linoleic acid? a. n-9 b. n-7 c. n-6 d. n-3 50. What is the carrier for medium-chain fatty acids in portal circulation? a. triacylglycerides b. cholesterol c. chylomicrons d. albumin 51. Gastric lipase works best in which environment? a. alkaline b. neutral c. acidic d. either alkaline or acidic 52. What is the normal product of the fatty acid synthase system? a. triacylglycerol b. myristate c. palmitate d. butyrate 53. Fat digestion does not require a. pancreatic lipase b. colipase c. bile d. leucine
.
54. Identify a nonspecific response to injury involving phagocytic cells, neutrophils, and macrophages. a. inflammation b. atherosclerotic plaque formation c. blood clotting d. thermogenesis 55. Where does pancreatic lipase begin to work? a. the duodenum
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Chapter_05_Lipids b. the stomach c. the large intestine d. the last portion of the small intestine 56. Which organ provides the major site for lipoprotein formation from exogenously derived lipids? a. pancreas b. adipose tissue c. intestine d. liver 57. Trans fatty acids are considered to be dangerous to human health because they a. elevate serum glucose levels b. raise LDL-C c. lower HDL-C d. raise LDL-C and lower HDL-C at the same time
.
58. Which unsaturated fatty acid is found in fish oil? a. alpha-linolenic b. eicosapentaenoic c. arachidonic d. oleic 59. The process by which bile salts are absorbed in the small intestine and return to the liver is called salts. a. micelle induction b. resecretion c. conjugation d. enterohepatic circulation 60. Carbon-carbon double bonds in the trans form . a. result in a kinking of the fatty acid into a U-shape b. extend the fatty acid into a linear shape c. are required to create saturated fatty acids d. are the hallmark of essential fatty acids 61. When fatty acids are completely oxidized, the end products are a. fatty acid and glycerol b. carbon dioxide, energy, and water c. urea and acetate d. carbon, hydrogen, and phosphate
.
62. Apolipoproteins are unable to . a. stimulate enzymatic reactions that regulate the metabolic functions of lipoproteins b. stabilize circulating lipoproteins in the blood
of the bile
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Chapter_05_Lipids c. decrease the density of the lipoprotein d. confer specificity for recognition by receptors on cells 63. The highest concentration of sphingolipids is found in cells of the a. cardiovascular system b. digestive system c. reproductive system d. central nervous system
.
64. In response to excess dietary carbohydrate and chylomicron remnants, which substances does the liver synthesize to transport triacylglycerol? a. chylomicrons b. VLDLs c. LDLs d. HDLs 65. Which fatty acid is considered essential and must be supplied by the diet? a. arachidonic acid b. omega-9 fatty acid c. linoleic acid d. oleic acid 66. If a blood clot develops in a coronary artery that contains atherosclerotic plaque, which event may occur? a. hypertension b. aneurysm c. hypotension d. myocardial infarction 67. What is the most common lipid found in animals that is characterized by a four-ring core structure? a. prostaglandins b. leukotrienes c. cholesterol d. glycolipids 68. The fatty acid chains found in foods and body tissues range from a. 1 to 3 b. 2 to 6 c. 3 to 12 d. 4 to 24 69. Polymolecular aggregates called micelles are small enough to . a. enter the enterocytes b. stabilize circulating lipoproteins in the blood c. enter the intramicrovillus spaces to interact with the brush border
carbon atoms in length.
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Chapter_05_Lipids d. confer specificity for recognition by receptors on cells 70. How does hypertension increase the risk for CVD? a. It damages white blood cells. b. It damages red blood cells. c. It leads to a disturbed repair process in arteries leading to aneurysms. d. It increases the risk of thromboses in veins.
Enzymes: Match the enzymes with their functions in lipid metabolism. a. creates a double bond in a fatty acid b. removes triacylglycerol from plasma c. mobilizes stored triacylglycerols from adipocytes d. rate-limiting enzyme in cholesterol synthesis e. creates prostaglandins 71. lipoprotein lipase 72. intracellular lipase 73. HMG-CoA reductase 74. cyclo-oxygenase 75. desaturase Cardiovascular Disease Risk: Match the lipid with the cardiovascular disease risk. a. atherogenic fatty plaque b. hypercholesterolemia c. raise LDL-C/lower HDL-C d. structural homology with plasminogen; increased risk of CVD e. increases LDL’s affinity for macrophage receptors causing plaque 76. trans fatty acids 77. lipoprotein (a) 78. saturated and unsaturated fatty acids 79. apolipoprotein E 80. cholesterol
81. Describe the transport system that allows for fatty acid synthesis and the molecules involved in transferring acetylCoA into cytoplasm.
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Chapter_05_Lipids 82. Explain how the HMG-CoA reductase regulates cholesterol synthesis. 83. Describe the process of fat storage (triacylglycerol synthesis) AND mobilization (triacylglycerol lipolysis) in adipose tissue—be sure to include how these processes are regulated (i.e., the signals involved). 84. Discuss three things that cannot be correct in the notation 18:2Δ8,9,19 when using the delta system of designating fatty acids.* *Source: Brody T, Nutritional Biochemistry, 2nd ed. Academic Press, San Diego, CA, 1999. page 643. 85. Describe fat metabolism in the adipose cell following a meal. 86. Describe three detrimental physiological effects of excess alcohol consumption and three beneficial effects of moderate alcohol consumption. 87. Explain the role of the MEOS and cytochrome P-450 in developing metabolic tolerance to ethanol. 88. Explain the regulation of the allosteric enzyme acetyl-CoA carboxylase by citrate and palmitoyl-CoA. 89. Which factors contribute to the color of brown fat and why does it generate heat? 90. Briefly describe the mechanism by which increased uncoupling protein opposes storage of energy as fat.
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Chapter_05_Lipids Answer Key 1. False 2. False 3. False 4. True 5. False 6. False 7. True 8. True 9. True 10. False 11. True 12. True 13. False 14. True 15. False 16. c 17. b 18. d 19. a 20. d 21. b 22. b 23. b 24. a 25. a
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Chapter_05_Lipids 26. b 27. b 28. c 29. d 30. c 31. c 32. c 33. d 34. a 35. b 36. b 37. b 38. c 39. c 40. a 41. b 42. d 43. a 44. a 45. b 46. d 47. b 48. b 49. c 50. d 51. c
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Chapter_05_Lipids 52. c 53. d 54. a 55. a 56. c 57. d 58. b 59. d 60. b 61. b 62. c 63. d 64. b 65. c 66. d 67. c 68. d 69. c 70. c 71. b 72. c 73. d 74. e 75. a 76. c
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Chapter_05_Lipids 77. d 78. b 79. e 80. a 81. Grading rubric – answer should include the following items: • • • •
Because acetyl-CoA is formed in the mitochondria and fatty acids are synthesized in the cytoplasm, a carrier system is required to transfer acetyl-CoA to the cytoplasm. Citrate from the combination of acetyl-CoA and oxaloacetate (first step of the TCA cycle) is able to pass through the mitochondrial membrane into the cytoplasm. In the cytoplasm, citrate is cleaved by citrate lyase to reform acetyl-CoA and oxaloacetate in the cytoplasm. The acetyl-CoA is then ready to be processed by acetyl-CoA carboxylase so that fatty acid synthesis can occur.
82. Grading rubric – answer should include the following items: • • •
HMG-CoA reductase catalyzes the reduction of 3-hydroxy-3-methylglutaryl-CoA to mevalonate, which is the rate-limiting step in the synthesis of cholesterol. This enzyme is inhibited by cholesterol to slow the in vivo production when dietary cholesterol is high or in vivo production has increased concentration of cholesterol sufficiently. This enzyme can be inhibited by statin drugs or by propionic acid from fermentation of dietary fiber.
83.83. Triacylglycerol synthesis – CM or VLDL, both containing TAG, deliver their contents to adipose tissue. Lipoprotein lipase is present on the capillary membrane that passes through the adipose tissue to hydrolyze the TAG inside to FAs, so they can cross the membrane and enter the adipocyte. Once inside, they are reassembled into TAG for storage. Insulin (fed state; high blood glucose) induces lipoprotein lipase activity and inhibits hormone-sensitive triacylglycerol lipase (which breaks down stored TAG to FAs inside the adipocyte). Triacylglycerol lipolysis – in the fasted state (low blood glucose), glucagon induces TAG lipase; the resulting FAs in the adipocyte can leave the cell and are transported by albumin to tissues for use as energy. [To answer this question, it is not necessary to talk about how insulin or glucagon stimulates FA synthesis or FA oxidation, respectively—just with respect to lipid storage and/or breakdown in adipose tissue.] 84. Grading rubric – answer should include the following items: • • •
There are only two double bonds, but three locations for double bonds One location is at carbon 19, which does not exist in an 18-carbon chain Two double-bonds cannot be on two adjacent carbons (e.g., 8 and 9)
85. Grading rubric – answer should include the following items: • •
Following a meal, insulin increases the activity of lipoprotein lipase (LPL) in the blood vessels traversing the adipose tissue. LPL hydrolyzes triglycerides in the chylomicrons delivered in the blood and fatty acids and monoacylglycerol are
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Chapter_05_Lipids taken up into the adipocytes.
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Chapter_05_Lipids • •
Insulin also increases the entry of glucose into the adipocytes and stimulates glycolysis. Acetyl-CoA from glycolysis not needed for energy production is used to create fatty acids through fatty acid synthase, also stimulated by insulin.
86. Grading rubric – answer should include the following items: • • • • • •
Detrimental effects include induced metabolic tolerance, which allows heavy consumption of alcohol. Alcohol dehydrogenase is the same enzyme that is called retinol dehydrogenase and that metabolizes vitamin A (retinol). As cytochrome P-450 is induced, a vitamin A deficiency can be developed unless extra vitamin A is eaten. A high NADH:NAD ratio can result from metabolism of excess alcohol. This promotes use of acetyl-CoA from alcohol metabolism to synthesize fatty acids and can result in fatty liver. Lactic academia is also a result of the high NADH:NAD ratio. Impaired TCA cycle function and gluconeogenesis can also result from the NADH:NAD ratio because the reversible reaction catalyzed by isocitrate dehydrogenase favors the formation of glutamate in the presence of excess NADH. Beneficial effects of moderate alcohol consumption include the inverse relationship with heart disease in epidemiological studies; elevation of HDL, which may protect against atherosclerosis; and a beneficial relationship of moderate alcohol consumption with risk of dementia. In addition, polyphenols found in red wine may dampen reactive oxygen species and thus protect against excess inflammation that may exacerbate atherosclerosis.
87. Grading rubric – answer should include the following items: • • •
When more ethanol than can be metabolized by the alcohol dehydrogenase pathway is present, the excess is metabolized through the cytochrome P-450 enzymes of the MEOS system. The enzymes and cytochromes of the MEOS system are inducible and increase over time with excess ingestion of alcohol. The more enzyme activity present in the system, the quicker that ethanol can be metabolized, and thus the more ethanol that can be ingested before intoxication begins.
88.88. Citrate – allosterically stimulates acetyl-CoA carboxylase to promote FA synthesis Palmitate – allosterically inhibits acetyl-CoA carboxylase in FA synthesis 89. Grading rubric: answer should include the following items: • • • •
Brown fat is highly vascularized Brown fat contains in its adipocytes many mitochondria that contain cytochrome (a pigment) Other oxidative pigments associated with electron transport also have color Brown fat mitochondria contain uncoupling protein 1 (UCP1) that promotes thermogenesis at the expense of producing ATP
90. Grading rubric – answer should include the following items: • •
Energy is trapped as ATP because of the coupling of electron transport and oxidative phosphorylation. The coupling occurs because hydrogen ions are pumped through the inner mitochondrial membrane into the
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Chapter_05_Lipids
• •
•
intermembrane space during electron transport, and the tremendous gradient that builds up as a result has sufficient energy to create ATP when hydrogen ions flow back down the gradient into the mitochondrial matrix through the ATP synthase structures F0 and F1. The energy released in electron transport that is not trapped by ATP is released as heat. Uncoupling protein is an integral protein in the inner mitochondrial membrane that functions as a hydrogen ion channel, allowing hydrogen ions to seep back into the mitochondrial matrix without passing through ATP synthase structures. This “uncouples” electron transport from oxidative phosphorylation. Electron transport still creates metabolic water, but much of the energy released becomes heat and is not trapped as ATP. This uncoupling “wastes” food energy because less is trapped as ATP and more is released as heat. Such an inefficient production of ATP from food energy would result in greater energy expenditure and less energy available for storage of energy as fat.
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Chapter_06_Protein
Indicate whether the statement is true or false. 1. In both sexes, serum testosterone levels rise during adolescence. a. True b. False 2. In addition to protein synthesis, the brain uses amino acids for the synthesis of other N-containing compounds such as neurotransmitters. a. True b. False 3. Lysosomes are found in all mammalian cells. a. True b. False 4. For a transport protein that spans a cell membrane, one would expect to find hydrophobic amino acids clustered together within the membrane. a. True b. False 5. It is estimated that the intestine uses 30-40% of some of the essential amino acids absorbed from the diet. a. True b. False 6. A mutation in the genetic code (i.e., DNA) could result in the wrong amino acid inserted into the synthesis of a given protein, thereby affecting the ability of the protein to function properly due to changes in its conformation. a. True b. False 7. A variety of transporters exist on cell membranes to handle all of the different types of amino acids. a. True b. False 8. Under fasting conditions, one would expect to find large amounts of free ammonia in the bloodstream due to the breakdown of amino acids for energy. a. True b. False 9. Urea synthesis only occurs in the liver and kidneys. a. True b. False 10. Dietary proteins must be completely hydrolyzed to free amino acids, because only free amino acids are absorbed by the enterocyte. a. True b. False
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Chapter_06_Protein 11. Total body water increases steadily from birth to 12 months of age, after which it begins to decrease at a similar rate in all adults. a. True b. False 12. When BCAAs are catabolized to their corresponding keto acid in muscle, the nitrogen must be transported directly to the kidney as glutamine. a. True b. False 13. Bile is needed to produce taurocholate and glycocholate. a. True b. False 14. Incomplete proteins are derived from foods of animal origin such as eggs, milk, cheese, meat, and fish. a. True b. False 15. The liver is the site for transamination of all amino acids. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Three important enzymes remove ammonia from body cells. One is carbamoyl phosphate synthetase I. What are the other two? a. branched-chain alpha-keto acid dehydrogenase and phenylalanine hydroxylase b. alanine aminotransferase and aspartate aminotransferase c. glutaminase and threonine dehydratase d. glutamate dehydrogenase and glutamine synthetase 17. The Estimated Average Requirement for protein for adults (men and women aged 19 years and older) is a. 5 g of protein per kg of body weight b. 2 g of tyrosine protein per kg of body weight c. 0.66 g of protein per kg of body weight d. 0.5 g of protein per kg of body weight 18. The measure of how much nitrogen is retained in the body for maintenance and growth rather than absorbed is the . a. protein efficiency ratio b. biological value c. net protein utilization d. Tolerable Upper Intake Level 19. In cases of stress and/or an inflammatory response, which functions does the body prioritize? a. digestion and absorption
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Chapter_06_Protein b. wound repair and host defense c. respiration and excretion d. circulation and reproduction 20. One of the body’s responses to metabolic stress is a. reduction in blood glucose levels b. loss of sodium c. an increase in blood glucose levels d. retention of fat
.
21. Serotonin is made from which amino acid? a. tyrosine b. niacin c. threonine d. tryptophan 22. A function of hydrochloric acid in gastric juice during protein digestion is to a. neutralize the acidity of the stomach b. inactivate pepsinogen by suppressing pepsin formation c. denature the quaternary, tertiary, and secondary structures of protein d. cleave peptide bonds
.
23. Amino acids that are metabolized mostly in skeletal muscles are those with side chains a. containing aromatic rings b. that are branched c. containing basic groups d. containing sulfur atoms
.
24. What two major systems are used for protein degradation in most cells? a. mitochondrial and cytosolic b. u-calpain and m-calpain c. GTP-requiring and GTP-independent d. lysosomal and ubiquitin-proteosomal 25. The product(s) of pepsin’s action is/are a. disaccharides b. amylose c. short-chain fatty acids d. hydrolyzed proteins
.
26. Which level of organization determines the final form of a protein molecule consisting of several polypeptide chains? a. primary b. secondary c. tertiary
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Chapter_06_Protein d. quaternary 27. What is the current Tolerable Upper Intake Level established for protein and amino acids? a. ingestion of a diet supplying > 30% energy from protein b. two times the RDA c. 42 mg/kg/day d. no Tolerable Upper Intake Level has been established 28. Name the genetic disease associated with the lack of the liver enzyme necessary to convert phenylalanine to tyrosine. a. maple syrup urine disease b. phenylketonuria c. homocystinuria d. lactase deficiency 29. The branched-chain amino acids found in the systemic circulation include a. glycine, alanine, threonine b. phenylalanine, tyrosine, tryptophan c. valine, leucine, isoleucine d. arginine, lysine, histidine 30. Carbamoyl aspartate can only be used for a. pyrimidine b. purine c. urea d. creatine
.
synthesis.
31. Which regulatory peptides in the pancreatic phase of digestion activate the release of brush-border enzymes such as enteropeptidase? a. trypsinogen and trypsin b. cholecystokinin and secretin c. carboxypeptidase A and B d. elastin and chymotrypsin 32. What is one of the more common ways to evaluate protein quality in a food that does not involve nitrogen balance studies? a. chemical score b. net dietary protein calories percentage c. biological value d. net protein utilization 33. Zwitterions are amino acids that have no net electrical charge because a. their side chains are not charged b. they migrate to a neutral place in an electrical field c. they are essential/indispensable d. they have an amino group in their side chain
.
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Chapter_06_Protein 34. Which organ serves as the primary site of amino acid metabolism? a. kidney b. muscles c. liver d. neuropeptides 35. A genetic defect diminishing branched-chain alpha-keto acid dehydrogenase (BCKAD) complex activity results in . a. phenylketonuria b. homocystinuria c. cystathioninuria d. maple syrup urine disease 36. A particular amino acid is very important for several metabolic pathways in enterocytes and so it is often added to nutritional mixtures used for hospitalized patients. The important amino acid is . a. tryptophan b. glutamine c. glycine d. asparagine 37. If you were deficient in vitamins B6 and B12 and had high blood levels of homocysteine, what dietary substance could remove some of the homocysteine by donating a methyl group to form methionine? a. biotin b. betaine c. serine d. creatine 38. When the body is “insulted,” what is one way systems react to protect it? a. aldosterone and ADH help to retain fluid b. digestion slows down c. glycogenolysis decreases d. muscle proteolysis slows down 39. Using two high-energy bonds, arginosuccinate synthetase joins aspartate and citrulline to produce arginosuccinate in the cytosol. This is the rate-limiting step in synthesis. a. pyrimidine b. purine c. urea d. creatine 40. Legumes are limited in sulfur-containing amino acids, methionine and cysteine. What food group is considered complementary because it supplies these amino acids? a. fruits b. nuts
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Chapter_06_Protein c. grains d. starchy vegetables 41. The DIAAS assesses the digestibility of the amino acids in the a. ileum versus the colon b. ileum versus the jejunum c. ileum versus the duodenum d. duodenum versus the colon
.
42. Which protein does the FDA specify as a standard for comparison of protein quality? a. casein b. albumin c. globulin d. gluten 43. Which three amino acids cannot undergo transamination to an appreciable extent, making provision of their alpha-keto acids ineffective in lowering blood nitrogen concentrations in kidney disease patients? a. leucine, isoleucine, valine b. lysine, threonine, histidine c. valine, tryptophan, phenylalanine d. methionine, cysteine, phenylalanine 44. The measurement of food nitrogen consumed rather than retention of food nitrogen absorbed is called the a. protein efficiency ratio b. biological value c. chemical score d. net protein utilization 45. During protein digestion, peptides are broken into free amino acids mainly a. in the mouth b. in the stomach c. at the brush border d. within the enterocyte 46. Succinyl-CoA is generated by the oxidation of a. leucine b. isoleucine c. methionine d. valine
.
.
47. Which amino acid, when oxidized, spares the essential gluconeogenic precursors pyruvate and lactate? a. cysteine b. alanine c. leucine
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Chapter_06_Protein d. glutamine 48. The indispensable amino acid with the lowest Recommended Dietary Allowance is a. leucine b. valine c. histidine d. tryptophan 49. It has been suggested that adults over the age of 65 maintain a daily intake of protein in excess of a. 1 g/kg of body weight b. 2 g/kg of body weight c. 3.5 g/kg of body weight d. 5.2 g/kg of body weight
.
50. Damage-associated molecular patterns (DAMPs) are released in response to which process? a. dehydration b. increased urinary output c. reduced intestinal motility d. inflammation 51. When evaluating protein quality, which of the following measures represents the gain in body weight on a test protein divided by the grams of protein consumed? a. chemical score b. BV (biological value) c. PER (protein efficiency ratio) d. NPU (net protein utilization) 52. Choose the correct order of enzyme activities in protein digestion. a. tripeptidases, carboxypeptidases, pepsin, free amino acids b. trypsin, pepsin, collagenase, dipeptidases c. pepsin, trypsin, chymotrypsin, carboxypeptidase d. trypsinogen, enteropeptidase, dipeptidase, chymotrypsin 53. The production of glucose from a noncarbohydrate source is a. glycogenolysis b. glycolysis c. glycogenesis d. gluconeogenesis 54. An intracellular deficiency of protease will interfere with a. protein degradation b. alcohol metabolism c. autophagy d. glycogenolysis
.
.
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Chapter_06_Protein 55. The amino acid reference pattern established for all people (except infants) is the amino acid requirements of a. high school students aged 15–18 b. middle school children aged 11–13 c. preschool children aged 1–3 d. adolescents aged 13–16 56. Stimulation of phagocytosis and activation of complement proteins are functions of a. C-reactive protein b. orosomucoid c. serum amyloid A d. fibrinogen 57. Purine degradation results in the formation of xanthine and creation of a. polyamines b. gout c. citric acid d. uric acid 58. Assessment of nitrogen intake is based on a. amino acid intake b. protein intake c. carbohydrate intake d. lipid intake
.
.
by xanthine oxidase.
.
59. When the amino group has been removed from an amino acid, the carbon skeleton or α-keto acid may be used in many different ways. Which of the following is NOT a possible fate for the carbon skeleton? a. conversion to glucose b. oxidation for energy c. production of ketone bodies d. synthesis of creatine 60. What percentage of resting energy expenditure is attributed to protein synthesis and degradation? a. 9% b. 10–25% c. 30–40% d. 45–55% 61. What is the primary mechanism for regulation of amino acids in excess of need for synthesis of protein, providing about 50% of the liver energy needs after a meal? a. oxidation b. decarboxylation c. phosphorylation d. hydrogenation 62. Which of the following amino acids is ketogenic?
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Chapter_06_Protein a. glycine b. alanine c. leucine d. aspartate 63. Which of the following is a nitrogen-containing, nonprotein compound that performs an important function in the body? a. glutathione b. methionine c. pepsin d. actin 64. Which two substances promote amino acid degradation? a. acetyl-CoA and dihydroxy acetone phosphate b. insulin and glucagon c. glucocorticoids and glucagon d. acetoacetate and acetaldehyde 65. Which amino acid is used to synthesize glutathione? a. leucine b. tryptophan c. cysteine d. valine 66. In general, most amino acids are absorbed from the a. stomach b. duodenum and jejunum c. ileum d. colon
.
67. Which process is NOT a source of ammonia ions in the body? a. creation of urea by the liver b. generation by deamination of amide groups from glutamine c. ingestion and absorption from foods d. generation by bacterial lysis of urea and amino acids in the GI tract 68. Urea synthesis occurs partly in the mitochondria and partly in the cytosol of the a. glomeruli b. tubules c. enterocytes d. hepatocytes 69. Which enzyme’s activity is dependent on vitamin B6? a. phenylalanine hydroxylase
.
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Chapter_06_Protein b. tyrosine aminotransferase c. tyrosine hydroxylase d. tryptophan dioxygenase 70. When the diet is lacking in the amino acids lysine and threonine, . a. proteins will be made without one amino acid b. the body will synthesize them c. protein synthesis will be limited d. another amino acid will be substituted so that synthesis is uninterrupted
Amino Acid Precursors: Match the amino acid to its precursor(s). a. glutamate, ammonia b. glutamate c. phenylalanine d. methionine, serine e. glutamine or glutamate, aspartate 71. tyrosine 72. cysteine 73. proline 74. arginine 75. glutamine Protein Functions: Match the category of physiological proteins with their function. a. chemical messengers secreted by endocrine tissue and transported to target organs where they regulate metabolic processes b. combine with nutrients and regulate their circulation and their flow into and out of cells c. bind to antigens and inactivate them or cause them to be destroyed d. catalysts that change the rate of reactions occurring in the body e. fibrous and contractile proteins found in bone, teeth, skin, muscles, blood vessels, and hair 76. enzymes 77. hormones 78. structural proteins 79. immunoproteins 80. transport proteins
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Chapter_06_Protein 81. Transamination and Deamination: What are these two reactions in amino acid metabolism (draw a diagram if that is helpful)? Why are they important? (Hint—transamination is important for two reasons; deamination, essentially one.) How do different tissues factor into these reactions? 82. What is the role of the liver in amino acid metabolism? Discuss three actions that occur in the liver as amino acids from the portal vein enter the liver. Your answer should include the types of compounds that are synthesized and the metabolic reactions involved. 83. Several companies are now enriching enteral and parenteral nutrition products with glutamine. What is the rationale for this procedure? 84. What are the indicators of visceral protein status and why are some more sensitive to changes than others? 85. What is meant by protein turnover? What general types of protein compounds are made in cells via protein synthesis? How do amino acid catabolism and dietary amino acids factor into protein turnover? 86. Explain why genetic defects that prevent the synthesis of functional transporters may be serious. Give an example of a disease where this occurs and describe the symptoms associated with it. 87. Explain why serum levels of ALT and AST are good indicators for trauma or disease, and specify which tissues relate to which aminotransferase. 88. Explain the concept of the first limiting amino acid in a protein and how this concept might be used to ensure adequate protein nutriture. 89. Changes in hormone balance serve as the primary mechanism for adjustment to starvation. What changes occur and how do they facilitate adjustment to starvation? 90. During fasting conditions, the circulating levels of glutamine and alanine are elevated—why is this? Hint: this question is focused primarily on the muscle, but also includes other tissues.
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Chapter_06_Protein Answer Key 1. True 2. True 3. False 4. True 5. True 6. True 7. True 8. False 9. False 10. False 11. False 12. False 13. True 14. False 15. False 16. d 17. c 18. b 19. b 20. c 21. d 22. c 23. b 24. d 25. d
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Chapter_06_Protein 26. d 27. d 28. b 29. c 30. a 31. b 32. a 33. a 34. c 35. d 36. b 37. b 38. a 39. c 40. c 41. a 42. a 43. b 44. d 45. d 46. c 47. c 48. d 49. a 50. d 51. c
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Chapter_06_Protein 52. c 53. d 54. a 55. c 56. a 57. d 58. b 59. d 60. b 61. a 62. c 63. a 64. c 65. c 66. b 67. a 68. d 69. b 70. c 71. c 72. d 73. b 74. e 75. a 76. d
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Chapter_06_Protein 77. a 78. e 79. c 80. b 81. Transamination: amino acid1 + ketoacid2 ⇔ ketoacid1 + amino acid2 e.g., alanine + α-ketoglutarate ⇔ pyruvate + glutamate This reaction is important for (1) providing a carbon skeleton from amino acids for energy (like pyruvate), and (2) synthesizing nonessential amino acids (like glu). You can view this reaction in the opposite direction as well, generating energy as α-ketoglutarate and a non-essential amino acid (ala). Deamination: amino acid ==> α-ketoacid + NH3 e.g., glutamate ==> α-ketoglutarate + NH3 This reaction is important to get any NH3 generated from transamination into a form in which it can be used to synthesize urea and then be excreted by the kidney. Most transamination occurs in the liver (gluconeogenesis) and some occurs in the kidney (gluconeogenesis), except for BCAAs, which undergo transamination in the muscle. Urea synthesis occurs in the liver. That said, remember that transamination and deamination can occur in many cell types, but the subsequent steps of gluconeogenesis (i.e., PEPCK, etc.) and urea synthesis are only in the liver/kidney and liver, respectively. 82. Synthesize proteins: This includes making the enzymes required by the liver and other hepatic proteins, as well as proteins that will be secreted into the circulation, like albumin and lipoproteins. Also included here is the synthesis of Ncontaining compounds (although these are not proteins per se, they are made from amino acids), such as glutathione, carnitine, and creatine. •
• •
Catabolize amino acids: this involves transamination to produce carbon skeletons and glutamate. The carbon skeletons can be used for energy directly or to synthesize glucose (gluconeogenesis). Transamination also can be used to synthesize non-essential amino acids (from essential AAs or other NEAAs). The glutamate can be used as is, for other reactions, or simply as an intermediate to donate the amine group towards urea synthesis. Some amino acids (BCAAs) are not metabolized by the liver and are simply left in the circulation unchanged. Synthesize urea for disposal of ammonia.
83. Glutamine is necessary for cells such as the gut mucosa and immune cells to support their rapid cell proliferation. During times of trauma or infection, these cells need more glutamine than can be released by the muscle. Provision of glutamine in formula aids recovery. 84. Proteins such as albumin or transthyretin in the blood that have been produced by the liver are used as indicators of internal organ protein status. Low levels indicate poor status. The proteins with a shorter half-life (transthyretin and retinol-binding protein) are more sensitive indicators of a change in visceral protein status. 85. Protein turnover means that our bodies are continuously breaking down proteins and making new ones in order to adapt to our ever-changing conditions and the fact that all proteins have a given life span. Amino acids from breakdown join dietary amino acids in the body pool and can be used to synthesize proteins or other nitrogen-containing compounds. Enrichment: One way we favor synthesis over degradation is that the enzymes involved in synthesis have a lower Km
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Chapter_06_Protein compared to the enzymes involved in catabolism. So, when there are amino acids “lying around,” such as after protein degradation, the enzymes required to make new proteins out of them “win out” over the enzymes involved in catabolizing them. However, when there is an overabundance of amino acids (high concentration), then the synthesizing enzymes are saturated, and now the catabolizing enzymes can take over. 86. Non-functional amino acid transporters in enterocytes will interfere with the absorption of amino acids in the intestines thus making them unavailable in the blood stream. This will deprive various body tissues from using the amino acids and functioning properly. In cases of lysinuric protein intolerance, the basic transporters in the intestines, liver and kidneys are defective. This leads to poor absorption of lysine, arginine and ornithine and low serum levels of these amino acids resulting in interference with protein synthesis and the urea acid cycle. Symptoms include growth retardation, hyperammonemia, muscle weakness, hepatomegaly, and hypotonia. 87. ALT and AST are very active aminotransferases in liver and heart, respectively. Normal serum levels of these two enzymes are low because they act intracellularly. If liver cells have been damaged, ALT and other liver enzymes will be found in the blood in higher than normal concentrations. Similarly, if AST is elevated in blood, heart damage is indicated. 88. The first limiting amino acid in a protein is the essential amino acid provided by that protein in the least adequate amount compared with that same amino acid in a reference protein (usually whole egg protein or the reference pattern for population groups) expressed as a percentage. It determines the chemical amino acid score for that protein. A refinement takes into consideration the digestibility of the protein and the method is called the protein digestibility-corrected amino acid score (PDCAAS). The chemical score is multiplied by the percentage digestibility of the food because that gives an estimate of the amount of the first limiting amino acid available to be absorbed and used from protein in that food. Highly digestible animal foods have a higher PDCAAS (100 for some foods such as egg white) than less digestible plant foods such as legumes (which range in PDCAAS from <50 to 70). Foods with a higher amino acid score have higher protein quality and can better support adequate protein nutriture. 89. During starvation, insulin decreases dramatically. As a result, protein synthesis drops. Decreased insulin is accompanied by increased secretion of the counter-regulatory hormones glucagon, cortisol, and epinephrine, which increase protein catabolism to support gluconeogenesis and release of alanine to be converted to glucose. As adaptation to starvation proceeds and use of ketones from fat increases in the brain, secretion of cortisol drops and metabolic rate diminishes due to lower tri-iodothyronine. These adaptations reduce muscle catabolism so that nitrogen loss from muscle becomes very small, with only 4 to 5 g per day lost in urine. 90.90. •
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Generation of alanine from pyruvate – muscle sends the alanine to the liver where via gluconeogenesis it is converted to glucose. The liver in turn sends the glucose back to the muscle for more energy. In addition to providing glucose, alanine (like glutamine below) can be used as a means to transport nitrogen to the liver for its disposal as urea (muscle does not have the ability to synthesize urea). This is important, especially during fasting, when a lot of protein is used for energy and thus a lot of nitrogen is generated. Following the generation of glutamate (via transamination), an additional amine group is added to glutamate to form glutamine, which can then be sent to the liver to dispose of the amine groups as urea. Urea is secreted by the liver into the circulation, where it goes to the kidney and is excreted in the urine.
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise
Indicate whether the statement is true or false. 1. Glucagon and insulin control metabolic pathways that reflect a fasting and fed state, respectively; the primary signal to initiate this hormonal control is the glucose concentration in the bloodstream. a. True b. False 2. Acetyl-CoA is a junction point for a number of metabolic processes, including metabolism of carbohydrate, lipid, and cholesterol. a. True b. False 3. Most regulatory enzymes act in a bidirectional manner. a. True b. False 4. Carbohydrate loading is a dietary and exercise strategy aimed at maximizing glycogenolysis in muscle and liver. a. True b. False 5. The end products of the oxidative system are acetyl-CoA and glucose-6-phosphate dehydrogenase. a. True b. False 6. Muscle supplies its own glucose for energy needs by first using glycogen stores, and then converting amino acids to glucose. a. True b. False 7. The red color of muscle is due to the presence of myoglobin. a. True b. False 8. The postabsorptive state evolves into the fasting state after 36–72 hours of no food intake. a. True b. False 9. Most nutrients absorbed by the small intestine first pass through the liver. a. True b. False 10. All tissues prefer glucose first, and then fatty acids, to meet their energy needs. a. True b. False 11. A fasted state is characterized by protein synthesis.
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise a. True b. False 12. The metabolic effects of glucagon occur in an effort to allow ATP production in the absence of dietary carbohydrate. a. True b. False 13. The Cori cycle would be active under anaerobic conditions, such as excessive muscle exertion. a. True b. False 14. During very prolonged starvation nearing death, the body shifts from using protein for energy to using fat stores. a. True b. False 15. Gluconeogenesis occurs exclusively in the liver. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Training enhances utilization of fat as the primary energy substrate during submaximal exercise due to a. enhanced activity of glycolytic enzymes b. fatty acid oxidation inhibiting glucose uptake and glycolysis c. enhanced glucose uptake d. decreased carnitine acyltransferase 17. A deficiency in carnitine acyltransferase I (CAT I) could lead to interference with a. glycolysis b. gluconeogenesis c. ATP production d. CO2 production
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18. Under the influence of insulin, which of the following pathways is increased? a. glycogenesis b. glycogenolysis c. phosphorylation of glycogen synthase d. phosphorylation of glycogen phosphorylase 19. An individual who has not eaten in five days will most likely have an elevated level of which hormone? a. insulin b. norepinephrine c. glucagon d. ACTH
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise 20. Which GLUT protein is the only one whose function is dependent on insulin? a. GLUT1 b. GLUT2 c. GLUT3 d. GLUT4 21. Carbohydrate loading is a dietary and exercise strategy used to maximize a. glycogenolysis b. glycolysis c. lipolysis d. glycogen storage in muscle and live
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22. In which organ does urea synthesis occur? a. kidney b. spleen c. liver d. pancreas 23. Only the glycerol portion of triacylglycerols can be converted into a. fatty acids b. alcohols c. protein d. carbohydrate 24. Most nutrients absorbed by the small intestine first pass through the a. liver b. pancreas c. spleen d. lymphatic system 25. The lactic acid system is also referred to as a. aerobic metabolism b. anaerobic metabolism c. aerobic glycolysis d. anaerobic glycolysis
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26. Following a carbohydrate-rich meal, skeletal and cardiac muscle express which protein on their cell surfaces? a. GLUT1 b. GLUT2 c. GLUT3 d. GLUT4 27. What amino acid plays an important role in controlling toxicity from ammonia released during amino acid catabolism by the glutamate dehydrogenase reaction? a. glutamine
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise b. glycine c. serine d. valine 28. The ingestion of nitrate through nitrate-rich foods or supplementation will lead to an increase in generation of a. nitrous oxide b. nitric acid c. calcium nitrate d. nitric oxide 29. Which amino acid is considered purely ketogenic? a. methionine b. histidine c. tryptophan d. leucine 30. How does creatine enhance muscle performance? a. It reduces the muscle’s oxygen requirement. b. It speeds up ATP utilization. c. It improves contractile performance and brings about hypertrophy. d. It helps to add more muscle fibers to the muscle. 31. One of the regulated enzymes when glycolysis occurs is a. isocitrate dehydrogenase b. pyruvate dehydrogenase c. fructose-1,6-bisphosphatase d. phosphofructokinase
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32. When the cellular energy status favors anabolic reactions, pyruvate is converted to a. fructose b. glucose c. succinyl-CoA d. NADPH
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33. At rest, the brain uses what percentage of available energy? a. 5–10% b. 15–20% c. 20–25% d. 30–40% 34. AMP-activated protein kinase (AMPK) controls both anabolic and catabolic pathways involving all a. macronutrients b. fatty acids c. micronutrients
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise d. amino acids 35. One of the problems associated with the use of dietary supplements used to enhance athletic performance is a. they are difficult to obtain b. there is little scientific evidence to prove that they are effective c. there are many supplements that are considered to be performance enhancing d. advertising for these products is often based on research that the layperson has difficulty understanding
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36. Amino acids from muscle breakdown provide the chief substrate for which metabolic process? a. glycolysis b. gluconeogenesis c. glycogenesis d. pentose phosphate pathway 37. What is the primary communication system that assesses the body’s status in relation to its environment and relays appropriate commands to tissues/organs? a. endocrine system b. nervous system c. vascular system d. respiratory system 38. The most accepted dietary compound used to enhance performance is/are a. caffeine b. creatine c. buffering agents d. carbohydrate supplements
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39. Citrate that moves from the mitochondria into the cytoplasm is converted by which enzyme into oxaloacetate and acetyl-CoA? a. citrate lyase b. citrate decarboxylase c. citrate hydrogenase d. citrate synthase 40. In humans, fatty acids cannot be used to synthesize glucose because we lack the enzymes needed to convert a. acetyl-CoA to lactate b. glycogen to acyl-CoA c. acetyl-CoA to pyruvate d. acyl-CoA to acetyl-CoA 41. Supplementation with proteins and amino acids in conjunction with resistance training is aimed at a. increasing muscle mass b. speeding up muscle contraction c. adding more muscle fibers to the muscle d. reducing reliance on oxygen
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise 42. Which substances become the main fuel for high-intensity exercise lasting more than one hour? a. plasma fatty acids b. glucose and fructose c. glycogen and glucose d. ketone bodies 43. The correct order of the pathway leading to glycogen production is a. pyruvate, alanine, glucose, glycogen b. alanine, glucose, pyruvate, glycogen c. pyruvate, glucose, alanine, glycogen d. alanine, pyruvate, glucose, glycogen 44. The brain cannot use fatty acids for energy because a. it lacks enzymes for oxidation of fats b. it lacks mitochondria c. glycerol cannot cross the blood-brain barrier d. fatty acids cannot cross the blood-brain barrier
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45. An increase in glycolysis is accompanied by an increase in a. pyruvate dehydrogenase b. isocitrate dehydrogenase c. pyruvate kinase d. fructose-1,6-bisphosphatase
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46. Malonyl-CoA plays a regulatory role in which two processes? a. glycogenesis and gluconeogenesis b. fatty acid synthesis and β-oxidation c. glycolysis and protein degradation d. gluconeogenesis and glycolysis 47. What are the two compounds that connect the metabolism of carbohydrates, lipids, and proteins? a. citrate and oxaloacetate b. succinyl-CoA and malate c. pyruvate and acetyl-CoA d. CO2 and NADPH 48. Skeletal muscle accounts for what percentage of protein turnover? a. 10–15% b. 15–20% c. 20–25% d. 25–35% 49. Fatty acids with an even number of carbons are degraded exclusively into
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise a. glucose b. fructose c. acetyl-CoA d. triacylglycerols 50. What is the term used to represent maximum oxygen consumption relating to exercise capacity? a. respiratory quotient b. VO2 max c. ATP-CP d. lactic acid system 51. During the postabsorptive state, the major provider of glucose to the blood is a. hepatic glycolysis b. hepatic glycogenolysis c. renal gluconeogenesis d. hepatic gluconeogenesis 52. The precursors for insulin’s stimulation of fatty acid synthesis are excess a. sucrose and maltose b. glucose and sucrose c. fructose and sucrose d. glucose and fructose
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53. Which of the following conditions is attributed to a primary failure of the β-cells of the pancreas to secrete insulin? a. hyperinsulinism b. hyperglycemia c. hyperlipidemia d. hyperphosphatemia 54. How long does it take for the postabsorptive state to evolve into the fasting state? a. 12–18 hours b. 18–48 hours c. 24–36 hours d. 36–72 hours 55. The adipocytes of an individual with hypoglycemia would have difficulty producing a. glycerol-3-phosphate b. acetyl-CoA c. acyl-CoA d. glucose-6-phosphate dehydrogenase 56. What is the preferred source of energy used by muscles to spare protein during prolonged starvation? a. ketones b. glucose
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise c. fatty acids d. amino acids 57. The majority of energy for ATP production is provided by dietary a. protein b. protein and lipid c. carbohydrate and protein d. carbohydrate and lipid
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58. When glucose exceeds the glycogen storage capacity of the liver, the excess glucose can be converted to a. acetyl-CoA b. fructose c. glucose-6-phosphate dehydrogenase d. fatty acids and triacylglycerols 59. An individual with a deficiency of glycerol-3-phosphate would have difficulty synthesizing a. fatty acids b. triacylglycerols c. acetyl-CoA d. glucose
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60. Which of the following amino acids is glucogenic in the postabsorptive state? a. taurine b. leucine c. alanine d. lysine 61. The fed state of the fed-fast cycle lasts about how long and is characterized by secretion of which hormone? a. 1 hour/insulin b. 2 hours/insulin c. 3 hours/insulin d. 4 hours/insulin 62. The lack of which muscle enzyme causes glucose, when phosphorylated in the muscle, to be trapped? a. glucose-6-phosphatase b. glycerol-3-phosphatase c. 6-phosphoglycerate dehydrogenase d. glucokinase 63. A protein-sparing shift in metabolism from gluconeogenesis to lipolysis occurs during the a. early fasting state b. fasting state c. starvation state d. fed state
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise 64. In the human, most triacylglycerols are synthesized by the a. adipose tissue b. heart c. liver d. brain
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65. Muscle and adipose tissue must obtain glycerol-3-phosphate through a. gluconeogenesis b. glycolysis c. glycogenolysis d. glycogenesis
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66. Amino acids used primarily by muscle for synthesis of dispensable amino acids and for protein synthesis are a. branched-chain amino acids b. aromatic amino acids c. basic amino acids d. acidic amino acids 67. The metabolic fuel shifts associated with the starvation state are designed to spare body a. protein b. carbohydrates c. lipids d. glycogen
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68. Time frames assigned to each of the phases of the fed-fast cycle are strongly influenced by an individual's a. metabolic rate b. age c. gender d. ethnic background
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69. After several weeks of starvation, what proportion of the energy needs of the brain is supplied by β-hydroxybutyrate and acetoacetate? a. one-fourth b. one-third c. one-half d. two-thirds 70. Which hormone has the primary responsibility for directing energy metabolism in the fed state? a. growth hormone b. cortisol c. glucagon d. insulin
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise Hormones: Match the regulatory hormones with their primary functions in integrative metabolism. a. stimulates liver glycogenolysis and gluconeogenesis b. stimulates lipolysis and increases triacylglycerol uptake from VLDL c. stimulates gluconeogenesis and glycogenolysis in the liver d. stimulates removal of glucose from the blood and anabolic reactions e. produced from phenylalanine and tyrosine; functions as a neurotransmitter and a stress hormone 71. growth hormone 72. insulin 73. epinephrine 74. glucagon 75. cortisol Metabolism: Match the metabolic activity to the correct organ. a. relies solely on glucose for energy b. fatty acids/glucose are the major fuel c. stores large amounts of triacylglycerols d. uses little glucose-6-phosphate and stores much glycogen e. can adapt to using ketone bodies during prolonged energy deficit 76. muscle 77. liver 78. adipose tissue 79. brain 80. red blood cell
81. Metabolic pathways are regulated to maintain homeostasis in the face of changing environmental conditions, such as nutrient supply. Describe how this is accomplished during the fed-fast cycle, that is, the progression from a fed state, to a postabsorptive/fasting state, to starvation, to prolonged starvation. Your answer should include specific processes/ metabolic pathways that are favored under each condition—make sure to cover pathways that are important to all three macronutrients (CHOs, lipids, protein). Also indicate the signal(s) involved in modulating these pathways. An example is provided in the table. Fed
Postabsorptive/ Fasting
Starvation
Prolonged Starvation
↑ glycolysis 82. In general, describe how opposing pathways are regulated during fasting versus fed conditions. What are the primary
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise signals involved? What would be an example of two opposing pathways? How is one pathway favored over the other (you don’t need to name specific proteins/ enzymes here)? 83. The tricarboxylic acid cycle (TCA cycle) is used to produce ATP. It includes several intermediates that enter into anabolic pathways. List three of these intermediates and briefly describe their functions. 84. Explain how endurance training increases an athlete’s ability to perform more aerobically. 85. Describe the various functions of insulin in the fed state. 86. Define the two categories of metabolic pathways and explain the main purpose of each one. 87. Pick two (2) of the examples from question 3 and indicate specifically how the signal you indicated in your answer is altering the pathway listed. For each example, write a one-sentence answer that includes the condition, the signals, the mechanism, the protein/enzyme, the tissue, and the result (all underlined in the example below). Example: Under fed conditions, high blood glucose leads to insulin secretion by the pancreas, which in turn induces expression of the key glycolytic enzyme phosphofructokinase in all cells, thereby increasing glycolysis. 88. What is the significant difference between red blood cells and other cells of the body? How does this affect their metabolism and why is this an advantage and a disadvantage at the same time? 89. Name the three systems that play a role in supplying energy during movement/exercise. Describe briefly how they supply energy, and discuss the temporal relationship between them during prolonged exercise. Any figures should be completely labeled and explained. 90. Describe the four phases of the fed-fast cycle and include the time frames associated with each state.
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise Answer Key 1. True 2. True 3. False 4. False 5. False 6. False 7. True 8. False 9. True 10. False 11. False 12. True 13. True 14. False 15. False 16. b 17. c 18. a 19. c 20. d 21. d 22. c 23. d 24. a 25. d
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise 26. d 27. a 28. d 29. d 30. c 31. d 32. b 33. c 34. a 35. b 36. b 37. b 38. a 39. a 40. c 41. a 42. a 43. d 44. d 45. c 46. b 47. c 48. d 49. c 50. b 51. b
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise 52. d 53. b 54. b 55. a 56. a 57. d 58. d 59. b 60. c 61. c 62. a 63. c 64. c 65. b 66. a 67. a 68. a 69. d 70. d 71. b 72. d 73. e 74. a 75. c 76. b
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise 77. d 78. e 79. c 80. a 81.81. Fed ↑ glycolysis
Postabsorptive/ Fasting
Starvation
Prolonged Starvation
Signal: insulin (in response to high blood glucose)
Signal: glucagon (in response to low blood glucose) and epinephrine and cortisol
Signal: glucagon (in response to low blood glucose) and epinephrine and cortisol
Signal: glucagon (in response to low blood glucose) and epinephrine and cortisol
Increases in: Glycolysis
Increases in: Glycogenolysis
Increases in: Gluconeogenesis
Glucose uptake (via GLUT 4 translocation)
Gluconeogenesis
Increases in: Lipolysis (glycogen stores are gone & need to spare body protein)
Urea synthesis
Ketogenesis
Glycogenesis Protein degradation
Protein degradation (lipid stores are depleted; all that is left is body protein, including visceral sources)
Lipogenesis Lipolysis (a little) Protein synthesis 82. A fed state is characterized by high blood glucose, which results in the pancreas releasing insulin into the circulation. Insulin promotes glucose uptake, glycolysis/TCA, glycogenesis, and lipogenesis by various mechanisms (including translocation, enzyme stimulation, enzyme induction, etc.). A fasted state is characterized by low blood glucose levels, resulting in the release of glucagon. Glucagon promotes gluconeogenesis, lipolysis, and glycogenolysis. Epinephrine also plays a role in this, but more so under exercise and stress conditions to promote glycogenolysis in muscle rather than fasting conditions. For both fed and fasting, all of these pathways also regulate themselves in the sense that high concentrations of products (e.g., ATP, citrate, NADH) allosterically inhibit many enzymes involved in their production, whereas high concentrations of substrates (e.g., ADP, NAD) allosterically stimulate these same enzymes. 83. Any three may be selected by the students. The following three examples may be used: • • •
Citrate: moves from mitochondria into the cytosol. There, it is acted upon by citrate lyase, which causes it to cleave into oxaloacetate and acetyl-CoA. The acetyl-CoA is used for fatty acid synthesis. Malate: this is acted upon by NADP+-linked malic enzyme. This reaction may provide a portion of the NADPH required for reduction reactions in fatty acid synthesis. Succinyl-CoA: this intermediate may combine with glycine in mitochondria to form ∆-aminolevulinic acid, which leads to heme synthesis.
84. Endurance training increases the number and size of mitochondria, which increases the oxidative capacity of the muscle and allows a faster rate of ATP production per minute. This capacity is amplified because cardiovascular and lung
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise capacity to deliver oxygen to the muscle is also improved by exercise. Thus it is possible for the trained athlete to use fatty acids at a higher intensity of exercise because the capacity/rate of total aerobic ATP production has improved. Glycogen is spared and duration of exercise can be longer. In addition, the capacity for glycogen storage is increased. 85. Insulin is the most important anabolic hormone in the fed state as it has an impact on blood glucose levels, fatty acid synthesis and protein synthesis and storage. It has several important functions. • • • • • • •
Promotes the uptake of glucose into muscle and adipose tissue by stimulating the translocation of GLUT4 from storage vesicles to the cell surface. Increases glycogen synthesis in the liver and skeletal muscle Inhibits gluconeogenesis in the liver Stimulates fatty acid synthesis from glucose and fructose precursors leading to increased triacylglycerol assembly for energy storage Inhibits lipolysis in adipose tissue Inhibits proteolysis in muscle Promotes protein synthesis in muscle, liver and other tissues
86.86. • • •
The two pathways are catabolic or degradative and anabolic or synthetic. Catabolic reactions break down macronutrients, so energy can be released and turned into ATP. Anabolic reactions synthesize complex molecules from simple precursors by using ATP for energy (and in some cases GTP and UTP).
87. Many potential examples – Students should follow the format in the example and not leave out what cells or tissues in which the example was occurring, or fail to mention the name of the enzyme. One example: Under starvation conditions, low blood glucose levels lead to epinephrine secretion by the adrenal glands, which stimulates hormone-sensitive lipase in the adipocytes to increase lipolysis of stored triacylglycerols, thereby increasing the use of fatty acids to produce ATP. 88. The mature red blood cell does not possess a nucleus or any other organelles. They rely exclusively on glucose as their energy source. Because they have no mitochondria, they must produce ATP via anaerobic glycolysis. This means that they will not consume any of the oxygen they are transporting which makes them very efficient at delivering the oxygen to all of the cells of the body. The disadvantage is that glycolysis is an inefficient means of producing ATP from glucose. This is overcome by the liver’s ability to use the lactate created from the pyruvate generated by glycolysis to synthesize glucose via gluconeogenesis. 89.89. •
•
ATP-Phosphocreatine (PC) System – PC is a “storage” form of phosphate (in muscle) that can be used to generate ATP from ADP—quick energy for short bursts of exercise. Aerobic system – same as above, but now, in the presence of oxygen, we can take the pyruvate generated from glucose and/or glycogen, and allow it to enter the TCA cycle to generate even more energy, rather than going to lactate. Also, this is ongoing along with other systems, but it becomes the major contributor later on. This system generates the most energy and also allows other sources of energy (e.g., fatty acids) to contribute more. Lactic acid system – this is basically anaerobic glycolysis. We generate energy (ATP) from glucose or glycogen, but once we get to pyruvate, it goes to lactate rather than acetyl-CoA. [Students may imply that we get energy from lactate (which we can, if we use gluconeogenesis), but that is not what this is. It is simply glycolysis.] This
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Chapter_07_Integration_and_Regulation_of_Metabolism_and_the_Impact_of_Exercise system functions for a little longer than ATP-PC, but at the same time. The lactate system doesn’t merely take over when the ATP-PC is exhausted. Both operate simultaneously; it’s just that the contribution of one system is favored over the other as a function of time. [If students redraw the graph in Figure 7.12 here to show the relationship between these systems and their contribution to meeting energy needs as a function of time, that is fine as long as it was appropriately drawn, labeled, and explained.] 90.90. • • • •
The fed phase begins after ingestion of a meal and is associated with secretion of insulin. This phase lasts about three hours. The postabsorptive phase occurs between three and 18 hours following the meal and is associated with a rise in glucagon secretion. The fasting phase occurs when no additional food is ingested after the initial meal and is associated with a continued rise in glucagon levels. This phase lasts from 18 hours to approximately two days. The starvation phase, which is also called a long-term fast, occurs when the individual is deprived of food for longer than two days. At this point, the body is fully adapted and will survive for a variable length of time depending on factors such as body constitution, initial body weight (mass of stored fat) and other underlying factors relating to the individual’s health.
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Chapter_08_Energy_Expenditure
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Body_Composition and_Healthy_Weight
Indicate whether the statement is true or false. 1. A BMI in children between the 75th and 85th percentiles is considered overweight. a. True b. False 2. Obesogens stimulate body fat accumulation by binding to hormone receptors and either stimulating or inhibiting the signaling pathway. a. True b. False 3. The body’s core temperature varies from about 98.2°F to 98.6°F. a. True b. False 4. Lean body mass has a higher metabolic activity than adipose tissue. a. True b. False 5. Type 2 diabetes is associated with very low or absent insulin. a. True b. False 6. Peptide YY is the only known orexigenic hormone. a. True b. False 7. Experts agree that moderate weight loss (5–10 kg) consisting of both fat mass and fat-free mass can be achieved by calorie restriction alone. a. True b. False 8. The density of body fat is about 0.9g/mL. a. True b. False 9. Because BMI has limitations, many health professionals also measure BMR. a. True b. False 10. When an individual is in positive energy balance over time, excess energy will be stored as glycogen in muscle and liver tissue. a. True b. False 11. All individuals will experience a reduction in hunger if given leptin injections.
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Chapter_08_Energy_Expenditure
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Body_Composition and_Healthy_Weight
a. True b. False 12. Hormones that regulate appetite target the region of the hypothalamus known as the arcuate nucleus. a. True b. False 13. Leptin decreases the urge to eat and increases physical activity to produce a negative energy balance. a. True b. False 14. Five sites commonly used for measuring skin fold thickness are the triceps, subscapula, suprailiac, abdomen, and thigh. a. True b. False 15. Adiponectin levels decrease with decreased fat mass and increase with increased fat mass. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Statistically, what percentage of individuals with anorexia nervosa recover completely? a. about 40–50% b. about 20–30% c. about 15–25% d. about 10–15% 17. Which body component comprises more diverse tissues? a. lean body mass b. fat mass c. fat-free mass d. skinfold thickness 18. In a clinical setting, which RQ suggests that the patient is not using fat as a source of calories? a. <0.70 b. <0.80 c. <0.90 d. 1.00 19. Respectively, the reference man and reference woman have what total percentage of body fat? a. 27%, 15% b. 18%, 28% c. 15%, 27% d. 12%, 28%
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Chapter_08_Energy_Expenditure
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Body_Composition and_Healthy_Weight
20. Which RQ would not be possible for an ordinary mixed diet of carbohydrate, protein, and fat? a. 0.85 b. 0.80 c. 0.75 d. 0.15 21. The incidence of obesity has increased rapidly in the last 30 years and is associated with increased risk for which of the following disorders? a. stunting, wasting b. stroke, sleep apnea c. osteoporosis, osteopenia d. hepatitis, tuberculosis 22. When oxidized, which nutrient(s) provide(s) the lowest respiratory quotient? a. carbohydrate b. protein c. fat d. mixed diet 23. Quantification of total energy expenditure may be calculated using a. neutron activation b. infrared light c. high-frequency ultrasonic energy d. the doubly labeled water method
.
24. The typical bulimic . a. is overly concerned with losing weight and being very thin b. seeks to eat without gaining weight c. is usually diagnosed with the female athlete triad d. characteristically experiences premature osteoporosis 25. The ratio of carbon dioxide produced relative to oxygen consumed is known as the a. respiratory quotient b. respiratory balance c. respiratory deficit d. respiratory ratio
.
26. Bioelectrical impedance analysis, a method used to determine body composition, is based on which principle? a. Atomic nuclei behave like magnets when an external magnetic field is applied across the body. b. Adipose tissue is denser than lean body tissue. c. Electrical conductivity is greater in lean tissue than in adipose tissue. d. Fat-free mass is proportional to total body potassium. 27. Thermogenesis is associated with
.
Name:
Chapter_08_Energy_Expenditure
Class:
Date:
Body_Composition and_Healthy_Weight
a. generation of water b. ingestion of food c. synthesis of fat d. processing of food 28. Name the psychiatric disorder associated with the highest mortality rate. a. female athlete triad b. bulimia nervosa c. binge eating disorder d. anorexia nervosa 29. A recommended measurement to determine energy expenditure is a. basal metabolic rate b. resting metabolic rate c. urinary nitrogen excretion d. thermic effect of food
.
30. Physical activity typically accounts for what percentage of total energy expenditure? a. 10–20% b. 15–30% c. 20–35% d. 25–35% 31. Thermoregulation refers to . a. alterations in metabolism to maintain body core temperature b. alterations in food energy due to cooking c. the increase in energy expenditure associated with the body’s processing of food d. the body’s storage of food as fat for insulation 32. Difficulties in getting accurate calculations of RMR based on the various equations developed arise in which group of people? a. people with excess body fat b. people who are lean c. adolescents d. young adults 33. The thermic effect of food represents the . a. BMR minus the energy used in physical activity b. decrease in food energy due to cooking c. increase in energy expenditure associated with the body’s processing of food d. body’s storage of food as fat for insulation 34. Bioelectrical methods of determining the two-compartment model are based on a. capacitance
.
Name:
Chapter_08_Energy_Expenditure
Class:
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Body_Composition and_Healthy_Weight
b. resistance c. voltage d. impedance 35. Which of the following techniques for measuring body composition makes use of small exposures to radiation? a. MRI b. DEXA c. TOBEC d. BIA 36. The connection between body, weight, body fat, and health were recognized centuries ago by a. Hippocrates b. Socrates c. Galen d. Plato
.
37. Which factor is a strong determinant of the microbiota composition in the gastrointestinal tract? a. gender b. diet c. age d. hormones 38. Which of the following contributes the highest thermic effect of food? a. fats b. mixed diet with at least 50% carbohydrate c. carbohydrates d. proteins 39. Why should a person with more than the average amount of body fat feel less hungry? a. increased body fat means increased leptin that suppresses hunger b. increased body fat means more stored calories c. increased body fat insulates causing increased body temperature d. increased body fat means more ketones are available for energy 40. Where is insulin produced? a. stomach and duodenum b. β-cells of pancreas c. intestine d. white adipose tissue 41. In degrees Fahrenheit, how much of a change in body temperature both up and down is tolerable before death results? a. 10 up, 10 down b. 5 up, 10 down c. 10 up, 5 down
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Chapter_08_Energy_Expenditure
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Body_Composition and_Healthy_Weight
d. 5 up, 5 down 42. Which factor may be a cause of weight loss that is not associated with an eating disorder in female athletes? a. the female athlete triad b. the feeling of comfort and well-being associated with certain foods c. inadequate energy intake associated with failure to meet the high energy needs of the sport d. excessive food restriction 43. Cold environments can increase BMR due to a. lowering metabolic rate b. increasing the rate of digestion c. shivering d. reduction in sweating
.
44. Which of the following hormones or molecules increases the urge to eat? a. leptin b. ghrelin c. adiponectin d. insulin 45. The highest incidence of heat-related deaths occurs among a. high school baseball players b. professional football players c. high school football players d. professional soccer players 46. Excess body fat increases the risk of developing a. hyperthyroidism b. breast and endometrial cancer c. hypothyroidism d. rheumatoid arthritis
.
.
47. Central obesity, increased plasma fasting glucose, increased fasting plasma triglyceride, hypertension, and decreased plasma HDL cholesterol are associated with . a. diabetes b. insulin resistance c. metabolic syndrome d. Cushing’s disease 48. Basal metabolic rate represents . a. the rate of energy expenditure that sustains basic life processes in all cells in the awake state b. the rate of energy expenditure when the body is at rest and no food has been eaten in 4 hours c. minimal energy expenditure over a period of 24 hours d. all energy expenditure except that is attributable to physical activity
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Chapter_08_Energy_Expenditure
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Body_Composition and_Healthy_Weight
49. Receptors for which hormone are located in the hypothalamus, skeletal muscle, liver, and smooth muscle? a. adiponectin b. cholecystokinin c. pancreatic polypeptide d. GLP-1 50. Energy expenditure can be quantified by measuring a. the amount of water consumed in one hour b. water vapor output in one hour c. heat dissipated by the body d. the change in muscle tone after exercise
.
51. Historically, the gross anatomy and chemical composition of the human body were determined using a. athletes b. premenopausal women c. cadavers d. postmenopausal women 52. Where is ghrelin produced? a. white adipose tissue b. pancreas c. intestine d. stomach and duodenum 53. Diet-induced thermogenesis is also called a. basal metabolic rate b. resting metabolic rate c. thermal regulation d. thermic effect of food
.
54. Of the following statements, one is NOT true regarding anorexia. Choose the correct statement. a. Of psychiatric disorders, anorexia has the highest mortality rate. b. Anorectics simply restrict calories severely and never binge and purge. c. People with anorexia have a distorted body image and fear weight gain. d. Anorectics often consume less than 800 kcal/day. 55. In the reference man and woman, respectively, what percentage of body weight is fat? a. 10%, 20% b. 15%, 27% c. 30%, 40% d. 45%, 55% 56. Which of the following represents a BMI range considered to be healthy for most adult men and women? a. <18.5
.
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Chapter_08_Energy_Expenditure
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Body_Composition and_Healthy_Weight
b. 15–18 c. 18.5–24.9 d. >30 57. A clustering of factors that occur together more often than expected on chance alone is a a. symptom b. syndrome c. disease d. condition 58. Quantifying the energy expenditure of physical activity requires measuring a. RMR (BMR) b. RQ c. thermal effect of food d. thermoneutrality
.
.
59. Leptin and one other hormone have similar effects on orexigenic and anorexigenic neurons. That hormone is a. ghrelin b. adiponectin c. peptide yy d. insulin
.
60. Underwater weighing, a method used to determine body composition, is based on which principle? a. Lean body tissue is denser than adipose tissue. b. Adipose tissue is denser than lean body tissue. c. Adipose tissue is composed mostly of water. d. Body fluids are not being weighed using this method. 61. Which of the following is a suggested reason for the persistent feeling of hunger in the presence of increased leptin levels? a. lack of leptin receptors b. ghrelin overproduction c. leptin resistance d. damage to the hypothalamus 62. The generally accepted respiratory quotient (RQ) value for carbohydrate is a. 0.53 b. 0.70 c. 0.82 d. 1.0
.
63. A twofold increase in risk for CVD, myocardial infarction, stroke and CVD-related mortality is associated with a. hyperthyroidism b. diabetes
.
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Chapter_08_Energy_Expenditure
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Body_Composition and_Healthy_Weight
c. metabolic syndrome d. obesity 64. In order to determine disease risk, many health professionals use BMI and which other measurement? a. body temperature b. tibial length c. head diameter d. waist circumference 65. The adjustments in metabolism necessary to maintain the body’s core temperature are referred to as a. thermoneutrality b. thermal effects c. thermal control d. thermoregulation 66. The main target of hormones that regulate hunger and satiety is the a. medulla oblongata b. cerebellum c. hypothalamus d. thalamus
.
.
67. Which method of assessing energy expenditure requires the measurement of food intake? a. doubly labeled water method b. Harris-Benedict prediction equation c. Mifflin-St. Jeor equation d. estimated energy requirement equation 68. What is the BMI of a man who weighs 220 lbs and is 6 feet tall? a. 54.9 b. 36.7 c. 29.9 d. 24.0 69. Which of the following methods of estimating energy expenditure does NOT require knowledge of the individual’s age? a. doubly labeled water method b. Harris-Benedict prediction equation c. Mifflin-St. Jeor equation d. estimated energy requirement equation 70. The activity that requires the greater amount of energy expended is a. cross-country skiing at 8 mph b. vigorous, full-court basketball c. vigorous soccer
.
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Chapter_08_Energy_Expenditure
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Body_Composition and_Healthy_Weight
d. running at 9 mph 71. Body mass index (BMI) is one way to estimate a. appropriate weight for height b. actual body adiposity c. body fat distribution d. risk factors associated with obesity
.
Formulas: Match each clinically useful method or index with the formula for its calculation. a. 66.5 + (13.7 weight in kg) + (5.0 height in cm) – (6.8 age in years) b. weight in kilograms divided by the square of height in meters c. 48.1 kg + 2.7 kg/in > 5 ft d. (99.9 × W) + (6.25 × H) – (4.92 × A) + 5 e. created by the life insurance industry 72. BMI 73. IBW 74. Mifflin-St. Jeor Equations 75. desirable body weight calculation 76. Harris-Benedict equation Measurable Characteristics: Match each clinically useful method or index with the trait that it estimates. a. resting metabolic rate in kcal/day b. appropriateness of an individual’s weight for height c. ideal body weight for height d. improves the accuracy of RMR measurements in people with excess body fat e. appropriate body weight target when reducing body fat to a lower level 77. BMI 78. IBW 79. Mifflin-St. Jeor Equations 80. desirable body weight calculation 81. Harris-Benedict equation
82. Explain the principles underlying the use of doubly labeled water to assess total energy expenditure. Include a discussion of the main source of error.
Name:
Chapter_08_Energy_Expenditure
Class:
Date:
Body_Composition and_Healthy_Weight
83. Describe leptin’s association with white adipose tissue and explain why the body reacts to it as it does. 84. What is the main factor that determines whether body weight remains stable, increases or decreases? Which diseases are associated with excess body fat? What is one drawback of using only body weight as an indicator of health? 85. Delineate the six levels of disease risk relative to normal BMI and waist circumference in both males and females. 86. Explain why a high protein diet that includes a low carbohydrate intake and an average fat intake would lead to weight loss as long as the caloric intake did not exceed energy expenditure. 87. Which gland, and specifically, which region of that gland, controls appetite? Describe how hunger and satiety are achieved and which hormones are responsible for both. 88. Explain the difference between direct calorimetry and indirect calorimetry. 89. What relationship does insulin resistance have to metabolic syndrome? What are the causes of these associations? 90. Define basal metabolic rate and delineate the percentage of energy used at rest by the liver, brain, kidneys, heart and skeletal muscle. 91. Describe metabolic syndrome and give the criteria for its clinical diagnosis.
Name:
Chapter_08_Energy_Expenditure Answer Key 1. False 2. True 3. True 4. True 5. False 6. False 7. True 8. True 9. False 10. False 11. False 12. True 13. True 14. True 15. False 16. a 17. c 18. d 19. c 20. d 21. b 22. c 23. d 24. b 25. a
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Body_Composition and_Healthy_Weight
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Chapter_08_Energy_Expenditure 26. c 27. d 28. d 29. c 30. b 31. a 32. a 33. c 34. d 35. b 36. a 37. b 38. d 39. a 40. b 41. b 42. c 43. c 44. b 45. c 46. b 47. c 48. a 49. a 50. c 51. c
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Body_Composition and_Healthy_Weight
Date:
Name:
Chapter_08_Energy_Expenditure 52. d 53. d 54. b 55. b 56. c 57. b 58. a 59. d 60. a 61. c 62. d 63. c 64. d 65. d 66. c 67. a 68. a 69. a 70. a 71. a 72. b 73. c 74. d 75. e 76. a
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Body_Composition and_Healthy_Weight
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Name:
Chapter_08_Energy_Expenditure
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Body_Composition and_Healthy_Weight
77. b 78. c 79. d 80. e 81. a 82. Doubly labeled water uses stable isotopes of both hydrogen and oxygen to assess the total energy expenditure over several days. The isotopes equilibrate with body water in about 5 hours. Labeled hydrogen leaves the body as labeled water in sweat, urine, and exhaled water vapor. Labeled oxygen leaves the body as labeled water or carbon dioxide. The disappearance of water with labeled oxygen and with labeled hydrogen is measured over time (usually 3 weeks). The disappearance of labeled hydrogen represents water turnover alone. Labeled oxygen, however, can leave as either water or carbon dioxide. Therefore, the difference in the disappearance of hydrogen-labeled water and oxygen-labeled water represents the oxygen leaving as carbon dioxide. The food quotient is measured by keeping a food record during the experimental period. Oxygen consumption can be calculated from the food quotient and the calculated carbon dioxide production. The main source of error is the inaccuracy associated with use of food records. 83. Leptin interacts with the hypothalamus to reduce hunger. It is produced by white adipose tissue. When leptin binds to its receptors, orexigenic neurons are inhibited and the production of NPY and AgRP is reduced. At the same time, anorexigenic neurons are stimulated to release POMC peptides. Studies have shown that when the amount of body fat increases, leptin levels increase as well. This suppresses hunger. Less body fat means less leptin resulting in a lower level of appetite suppression. This makes sense from a biochemical point of view as individuals with more body fat should eat less and those with lower levels of body fat should have the desire to eat more. 84.84. The main factor that determines the stability of body weight is the extent to which total energy expenditure is being met or exceeded by energy intake. If intake is equal to expenditure, the weight remains stable. Excess intake will lead to weight gain while insufficient intake will result in weight loss. Excess body fat is associated with an increased risk of heart disease, stroke, diabetes mellitus, hypertension, osteoarthritis, infertility and cancers such as breast, endometrial, colon and kidney. Using only body weight as an indicator of health may be inaccurate if an individual has added body weight by increasing muscle mass instead of adding fat. Adding muscle mass makes the body healthier whereas adding fat reduces the health of the body. 85. Refer to Table 8.5 (p. 283), which lists the overall disease risks associated with six levels of BMI categories for both males and females. 86. The thermic effect of food plays an important role in this type of weight loss diet. Because protein in foods has the greatest thermic effect (20–30%), more energy will be expended in digesting these foods than would be expended digesting carbohydrates (5–10%) or fats (0–5%). Because the diet is low in carbohydrates, that portion of the energy Expenditure would be minimal. Also, since the energy expenditure for fats is so low, a normal fat intake would not use very much energy. All of these factors combined would lead to weight loss. 87. The gland that regulates appetite is the hypothalamus. The specific area of this gland is the arcuate nucleus, which contains specialized neurons. One population of neurons have hormone receptors that, when stimulated, release orexigenic peptides that stimulate appetite. These include neuropeptide Y (NPY) and agouti-related peptide (AgRP). The second population of neurons produces anorexigenic peptides that inhibit appetite. These belong to the pro-opiomelanocortin (POMC) family. These work in other areas of the hypothalamus as well as in other parts of the brain to curb appetite.
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Chapter_08_Energy_Expenditure
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Body_Composition and_Healthy_Weight
88. Both direct and indirect calorimetry assess total energy expenditure. Direct calorimetry measures the heat dissipation from an organism using an isothermal principle, a gradient-layer system, or a water-cooled garment. Indirect calorimetry measures oxygen consumed and carbon dioxide breathed out and total energy expenditure can be calculated from the respiratory quotient (RQ). This method also allows calculation of the substrate (fat or carbohydrate) being oxidized. Urinary nitrogen can be measured in addition to oxygen consumption and carbon dioxide production in order to estimate protein oxidation. 89. Insulin resistance is associated with excess body fat, elevated blood glucose levels, elevated triacylglycerols and high blood pressure. These conditions are the diagnostic criteria for metabolic syndrome. Insensitivity to insulin occurs primarily in muscle and adipose tissue. The muscle loses its ability to uptake glucose. Resistant adipose tissue is no longer inhibited from releasing free fatty acids. Liver and kidney do not exhibit insulin resistance. The liver is able to respond to the elevated insulin levels by synthesizing triacylglycerol from the excess free fatty acids, thus elevating fasting serum triacylglycerol levels. In addition, the elevated triacylglycerol levels in the liver lead to nonalcoholic fatty liver disease. The kidney responds to elevated insulin levels by increasing renal sodium retention and decreasing uric acid clearance. Essential hypertension develops due to a higher level of retained water. 90.90. Basal metabolic rate (BMR) represents the amount of energy needed to sustain basic life processes such as respiration, heartbeat, renal function, brain and nerve function, blood circulation, active transport and synthesis of proteins and other molecules. Most of the energy used at rest is used by the liver (27%), brain (19%), kidneys (10%), heart (7%), and skeletal muscle (18%). 91. Metabolic syndrome is a group of risk factors that are associated with an increased risk of cardiovascular disease. The risk factors include central obesity, increased fasting plasma glucose, increased fasting plasma triglyceride, decreased plasma HDL cholesterol and hypertension. The criteria for the clinical diagnosis of metabolic syndrome will come from Table 8.7.
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Chapter_09_Water_Soluble_Vitamins
Indicate whether the statement is true or false. 1. High circulating levels of homocysteine (i.e., hyperhomocysteinemia) have been implicated in a number of pathologies including cardiovascular disease. a. True b. False 2. Pellagra symptoms may appear during B6 deficiency because this vitamin is required in the process of obtaining niacin from tryptophan. a. True b. False 3. An example of a cleavage reaction requiring PLP is the degradation of thiamin into its pyrimidine and thiazole moieties. a. True b. False 4. The primary role of vitamin C is as a reducing agent, particularly for the mineral component of a number of enzymes that becomes oxidized following catalysis of a reaction. a. True b. False 5. Water-soluble vitamins are not stored, but readily excreted—the one exception is that we can store folate in the liver. a. True b. False 6. Increases in plasma holotranscobalamin TCII concentrations provide an indication of vitamin B12 absorption. a. True b. False 7. Fish are a major source of thiamin. a. True b. False 8. Large doses of nicotinic acid are used to treat certain types of hyperlipidemias. a. True b. False 9. Most thiamin in the American diet comes from products that have been enriched. a. True b. False 10. Biotin appears to be a very safe vitamin supplement as there has been no toxicity reported from oral biotin ingestion nor is there a Tolerable Upper Intake Level established. a. True b. False
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Chapter_09_Water_Soluble_Vitamins
11. Pernicious anemia can be due to folate or B12 deficiency. a. True b. False 12. Vitamin C’s antioxidant abilities may inhibit high-density lipoprotein (HDL) oxidation, which may diminish plaque formation associated with heart disease. a. True b. False 13. Initial research on vitamin B6 was aimed at correcting dermatitis in rats. a. True b. False 14. Abnormally high urinary excretion of xanthurenic acid may be an indication of niacin deficiency. a. True b. False 15. Impaired folding and secretion of proteins have been observed with thiamin deficiency. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Burning foot syndrome may be caused by a deficiency of a. pantothenic acid b. ascorbic acid c. folate d. biotin
.
17. A deficiency of which vitamin is associated with these symptoms: hallucinations, lethargy, skin rash, alopecia, and muscle pain? a. biotin b. thiamin c. vitamin C d. vitamin B12 18. Vitamin B12 is absorbed in the a. duodenum b. jejunum c. ileum d. colon
.
19. Methylation of DNA influences gene expression. Which vitamin is important in this process? a. niacin
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Chapter_09_Water_Soluble_Vitamins b. folate c. pantothenic acid d. riboflavin 20. A major function of B vitamins is to serve as a. antibodies b. a source of energy c. a part of a coenzyme d. electrolytes
.
21. Folate and participate in the regeneration of methionine from homocysteine. a. niacin b. riboflavin c. vitamin B6 d. vitamin B12 22. Pyridoxine is found almost exclusively in a. seafood b. beef and pork c. plant foods d. chicken and turkey
.
23. 5-methyl THF requires the action of which vitamin in order to form THF? a. B12 b. B2 c. niacin d. C 24. Intrinsic factor is required for the majority of absorption of which vitamin? a. C b. B6 c. B12 d. B2 25. Most animals synthesize their own ascorbic acid from a. glucose b. glutamine c. glycogen d. alanine
.
26. Nutrients can be used to compensate for some gaps in our DNA. For example: a. Individuals with a change in the base sequence for the phenylalanine hydroxylase gene can correct the sequence of bases by eating a lot of phenylalanine.
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Chapter_09_Water_Soluble_Vitamins b. Obese individuals can lose body weight by eating fewer calories than they expend. c. Omega-3 fatty acids can upregulate genes encoding for fat oxidation. d. Individuals with a polymorphism that decreases activity of a folate-metabolizing enzyme, methylene tetrahydrofolate reductase, may have more elevated plasma homocysteine than those with a normal enzyme while more folate intake can normalize plasma homocysteine for those with this polymorphism. 27. Which vitamin is most involved in amino acid metabolism? a. biotin b. vitamin E c. vitamin A d. vitamin B6 28. Consumption of raw eggs causes a biotin deficiency due to the binding of absorption. a. heparin b. carnitine c. avidin d. pyruvate 29. Vitamin C acts as a cofactor by maintaining iron in a reduced state in a. collagen synthesis b. methylation of homocysteine c. release of energy from nutrients d. red blood cell synthesis
to the biotin, thus preventing its
.
30. Vitamin C’s actual participation in biochemical reactions usually involves its antioxidant ability. Choose the description of this activity. a. donates an electron or electrons to oxidize a mineral cofactor b. accepts an electron or electrons to reduce a mineral cofactor c. donates an electron or electrons to reduce a mineral cofactor d. accepts an electron from the quinone form of vitamin E 31. Free pyridoxine is yielded by the action of a. acid phosphatase b. creatine phosphokinase c. lactate dehydrogenase d. alkaline phosphatase
.
32. Tetrahydrofolate is vitally important for dividing cells during growth and cancer and knowledge of this need is used in cancer treatment by giving the drug methotrexate to inhibit the enzyme . a. folylpolyglutamate synthetase b. dihydrofolate reductase c. formimino glutamate d. conjugase
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Class:
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Chapter_09_Water_Soluble_Vitamins 33. When ascorbic acid becomes dehydroascorbic acid, it has a. lost two electrons b. lost one electron c. gained two electrons d. gained one electron
.
34. Synthesis of coenzyme A starts with the phosphorylation of which vitamin? a. pyridoxal phosphate b. pantothenic acid c. vitamin E d. folic acid 35. Decarboxylation of pyruvate is achieved by the interaction of pantothenic acid with thiamin, riboflavin, and a. ascorbic acid b. vitamin B12 c. folate d. niacin
.
36. In what way are water-soluble vitamins absorbed? a. directly into the lymphatic system b. into the portal blood c. attached to proteins in the large intestine d. through the stomach wall into capillaries 37. When water-soluble vitamins are consumed in excess of body needs, generally the excess is a. excreted in the feces b. stored in liver, bone, and adipose tissue c. excreted in the urine d. not absorbed 38. Erythrocyte transketolase activity is an assay to assess the status of a. thiamin b. B6
.
.
c. riboflavin d. B12 39. Folic acid fortification has . a. not caused the decrease in NTDs that was expected b. had no effect on the number of NTDs in this country c. caused a greater decrease in NTDs than was expected d. reduced the number of various NTDs by 11–50% in different studies 40. Which water-soluble vitamin contributes to “intracellular cement” in the formation of scar tissue and wound healing? a. thiamin
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Chapter_09_Water_Soluble_Vitamins b. riboflavin c. vitamin C d. vitamin B12 41. Folate’s discovery resulted from the search to cure a. aplastic anemia b. hemolytic anemia c. Fanconi’s anemia d. megaloblastic anemia
.
42. When the diet is adequate in protein, the body can synthesize niacin from which amino acid? a. phenylalanine b. valine c. tyrosine d. tryptophan 43. Which classical vitamin deficiency is known for the four Ds: dermatitis, dementia, diarrhea, and death? a. thiamin b. niacin c. biotin d. folic acid 44. The B vitamin that is involved in hematopoiesis (production of blood cells) is a. vitamin B12 b. vitamin B6 c. biotin d. vitamin B2
.
45. Folate is vitally important for dividing cells during growth and cancer because of its essential role in the synthesis of . a. lipid bilayers b. mitochondria c. lysosomes and peroxisomes d. purines and pyrimidines 46. A major role for thiamin is a. energy production b. blood coagulation c. collagen formation d. erythrocyte synthesis
.
47. The RDA for vitamin C for adult men is a. 75 mg; 500 mg
and the UL is
.
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Chapter_09_Water_Soluble_Vitamins b. 100 mg; 500 mg c. 90 mg; 2,000 mg d. 200 mg; 2,000 mg 48. A primary function of vitamin C is to act as an a. antiviral agent b. antioxidant c. antirachitic agent d. acyl transferase 49. Without enough vitamin C, collagen would a. be too tightly coiled b. be overhydroxylated c. be underhydroxylated d. too strong and less flexible
.
.
50. FMN and FAD act as prosthetic groups for enzymes called a. apoenzymes b. flavokinases c. bound enzymes d. flavoproteins
.
51. A cobalt deficiency may lead to . a. pellagra b. megaloblastic macrocytic anemia c. beriberi d. neurologic symptoms 52. Beriberi is a deficiency syndrome associated with a. vitamin B12 b. vitamin B1 c. vitamin B2 d. vitamin B6
.
53. Cheilosis is a symptom of a dietary deficiency of which vitamin? a. niacin b. ascorbic acid c. riboflavin d. biotin 54. The necessity of ascorbic acid for its role in and are very tired. a. collagen synthesis
is believed to be the reason that people with scurvy have no energy
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Chapter_09_Water_Soluble_Vitamins b. creatine synthesis c. hormone activation d. carnitine synthesis 55. The organ that is most commonly used as a storage site for B vitamins is the a. kidney b. heart c. brain d. liver 56. Riboflavin is found most often in a. meats b. green leafy vegetables c. seafood d. milk and milk products
.
.
57. Methionine is used to synthesize S-adenosylmethionine (SAM). This is important so that a. 5-methyl THF is formed b. dUMP is catalyzed to dTMP c. fatty acids with an odd-numbered chain can be metabolized d. methyl groups are available
.
58. Which of the water-soluble vitamins is found widely distributed in all plant and animal foods, which makes a deficiency unlikely? a. riboflavin b. folic acid c. pantothenic acid d. pyridoxine 59. Which of the following reflects long-term folate status? a. serum folate b. red blood cell folate c. homocysteine concentration in blood d. serum methylmalonic acid 60. Hair loss associated with eating raw eggs may be reversed by treatment with a. niacin b. thiamin c. biotin d. ascorbic acid 61. The best sources of niacin are a. fish and meats b. beans
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Chapter_09_Water_Soluble_Vitamins c. green leafy vegetables d. yellow vegetables 62. Folate in foods can only be absorbed in the monoglutamate form; therefore, digestive enzymes called important for folate nutriture. a. hydrolases b. lipases c. carboxypeptidases d. legumes
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63. The degradation of provides the majority of one-carbon groups for pyrimidine synthesis. In this process, formed. a. methionine; tetrahydrofolate b. serine; 5,10-methylene tetrahydrofolate c. uridine; tetrahydrofolate d. homocysteine; 5-methyl tetrahydrofolate 64. A consequence of thiamin deficiency is a. pellagra b. megaloblastic anemia c. beriberi d. rickets
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65. A genetic polymorphism that decreases the activity of N5,N10 methylene tetrahydrofolate reductase has been identified. This would cause . a. an accumulation of 5-methyl THF b. an increase in the homocysteine concentration in the cell c. a decreased risk for megaloblastic anemia d. a decreased risk for heart disease 66. The last vitamin to be discovered was a. pantothenic acid b. folate c. vitamin B6 d. vitamin B12
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67. How do we know that folate fortification has improved the biochemical folate status of Americans? a. More folate is being consumed. b. More Americans are meeting recommendations for folate intakes. c. There is a decline in NTDs. d. RBC folate levels have increased. from resulting. Over time, the 68. Large amounts of folic acid can mask a vitamin B12 deficiency and prevent . symptoms unique to a vitamin B12 deficiency will occur, and these are related to the
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Chapter_09_Water_Soluble_Vitamins a. microcytic anemia; muscular system b. DNA and RNA synthesis; vascular system c. one-carbon transfer; nervous system d. macrocytic anemia; nervous system 69. Thiamin is important to fatty acid synthesis due to its requirement as a coenzyme for the pentose phosphate pathway enzyme . a. dopamine monooxygenase b. transketolase c. alpha-ketoglutarate dehydrogenase d. phenylalanine hydroxylase 70. What is the criterion for a genetic difference to be called a “polymorphism”? a. It has to be lethal within 6 months of life. b. It causes a miscarriage 50% of the time. c. More men than women have the genetic difference. d. More than 1% of the population has the variation.
Vitamin Characteristics: Match the nutrient listed to the phrase or word given. Nutrient choices may be used more than once. a. vitamin B12 b. vitamin B6 c. folate or folic acid d. vitamin C 71. hypochromic, microcytic anemia 72. prolyl hydroxylase 73. Latin word means “leaf”; Italian word means “foliage” 74. pernicious anemia is a lack of absorption of this 75. gulonolactone oxidase Vitamins as Coenzymes: Match the coenzyme form of a vitamin with an enzyme and significant function. a. proline and hydroxyproline; provide rigidity to newly formed collagen b. pyruvate dehydrogenase; important for decarboxylations in carbohydrate catabolism c. glutathione reductase; important for red blood cell antioxidant integrity and a sensitive measure of riboflavin nutriture d. aldehyde dehydrogenase; important for catabolism of vitamin B6 (pyridoxal to pyridoxic acid) e. acetyl-CoA carboxylase; important to form malonyl-CoA and commit acetyl-CoA to fatty acid synthesis 76. thiamin diphosphate
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Chapter_09_Water_Soluble_Vitamins 77. flavin adenine dinucleotide 78. nicotinamide adenine dinucleotide 79. biotin 80. prolyl-4-hydroxylase
81. What is the significance of vitamin C to carnitine and fat metabolism? 82. Discuss niacin equivalents and how they are calculated based on protein intake. 83. One method to assess nutrient status is to measure the activity of an enzyme that requires the vitamin as a cofactor. Explain how this works—first in a conceptual way, and then specifically using an example. Your specific example choices are thiamin, riboflavin, or folate (pick one). Do you think this is a good assessment method? Why or why not? 84. Explain the relationship of folate to vitamin B12 in the various anemias. 85. Vitamins and Hematology: Folate and B12 have an important role in hematology (“blood-related” processes) such that a deficiency of either of these vitamins can result in anemia. Discuss the interrelationship between these vitamins and why a deficiency of either of them results in megaloblastic anemia. Your answer will likely need to talk to some extent about the methyl-folate trap hypothesis. Make sure to relate any metabolic description of folate and B12 to the basis for anemia resulting from a deficiency. 86. One method to assess vitamin status is using a “load test.” Explain how this works—first in a conceptual way, and then specifically using one example. Your specific example can be chosen from either tryptophan or histidine (pick one). Do you think this is a good assessment method? Why or why not? 87. Describe the process by which vitamin B12 is digested and absorbed. 88. Vitamins and Energy Metabolism: Vitamins play a big role in our ability to acquire energy from macronutrients. Pick one macronutrient and discuss how vitamins are involved in procuring energy; choose from: (1) carbohydrates (glycolysis/TCA); (2) lipids (lipolysis/β-oxidation); or (3) protein/amino acids (gluconeogenesis). Your answer should be as specific as possible: names of vitamins and what they do with respect to the macronutrient you’ve chosen to help generate energy. A diagram may be especially useful. Hint: There are four vitamins for (1), three to five vitamins for (2), and two to four vitamins for (3)—the range for (2) and (3) is because it depends on the FA or AA you start with. 89. Although for micronutrients increasing the amount of a protein by directly inducing gene expression is certainly a common mechanism, we have encountered other mechanisms by which vitamins can regulate proteins. Give two examples of how posttranslational modification is involved in this—be as specific as possible. 90. Vitamins – One-sentence Descriptions: For each vitamin listed below, indicate: (1) the active form of the vitamin, (2) the general function of the vitamin, and (3) an example of the general function (this could be a specific reaction or simply indicate a pathway/ process where it occurs). An example is provided; as you can see, your answers do not need to be long!
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Chapter_09_Water_Soluble_Vitamins Vitamins: Biotin, pantothenate, riboflavin, vitamin B6, thiamin, vitamin C, folate Example: Niacin (1) NAD(H) or NADP(H) (2) Oxidation-reduction reactions (3) TCA cycle reaction or….
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Chapter_09_Water_Soluble_Vitamins Answer Key 1. True 2. True 3. False 4. True 5. False 6. True 7. False 8. True 9. True 10. True 11. False 12. False 13. True 14. False 15. False 16. a 17. a 18. c 19. b 20. c 21. d 22. c 23. a 24. c 25. a
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Chapter_09_Water_Soluble_Vitamins 26. d 27. d 28. c 29. a 30. c 31. d 32. b 33. a 34. b 35. d 36. b 37. c 38. a 39. d 40. c 41. d 42. d 43. b 44. a 45. d 46. a 47. c 48. b 49. c 50. d 51. b
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Chapter_09_Water_Soluble_Vitamins 52. b 53. c 54. d 55. d 56. d 57. d 58. c 59. b 60. c 61. a 62. c 63. b 64. c 65. b 66. d 67. c 68. d 69. b 70. d 71. b 72. d 73. c 74. a 75. d 76. b
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Chapter_09_Water_Soluble_Vitamins 77. c 78. d 79. e 80. a 81. Grading rubric – answer should include the following items: Vitamin C functions as a reducing agent, specifically reducing the iron atom from the ferric state (Fe 3+) back to the ferrous state (Fe2+) for the reactions catalyzed by trimethyllysine hydroxylase and 4-butyrobetaine hydroxylase in the synthesis of carnitine. The carnitine shuttle is required for fatty acid oxidation by allowing entry of long-chain fatty acids into the mitochondria for beta-oxidation. 82. Grading rubric – answer should include the following items: Assume that 1 g of complete, high-quality protein = 10 mg of tryptophan. This estimate means that an intake of 60 g of complete protein, for example, would provide 600 mg of tryptophan (10 mg tryptophan/1 g protein × 60 g protein = 600 mg tryptophan). Then, because it takes 60 mg of tryptophan to generate 1 mg of NE, 600 mg of tryptophan would generate 10 NEs (600 mg tryptophan × 1 mg NE/60 mg tryptophan = 10 NEs). 83. Conceptual: If one knows of a specific enzyme that requires a vitamin as a cofactor to be active, its activity can be measured in an individual. Then, exogenous vitamin is provided (in the test tube, not to the person), and the activity is measured again. If the activity increases with extra vitamin provided, that tells you that the enzyme must have been deficient to begin with. Specific: Thiamin – transketolase requires TPP to be active. It can be measured in red blood cells as is, and in the presence of extra TPP added to the assay. An increase of >25% indicates deficiency. Called erythrocyte transketolase activity (ETKA) test. Riboflavin – glutathione reductase requires FAD. The enzyme is measured with and without extra FAD and a ratio of the two is determined (i.e., ratio of activity with versus without). A ratio greater than 1.4 (that’s an increase of 40%) indicates deficiency. Folate – thymidylate synthetase is measured in cultured lymphoctyes or bone marrow cells with and without folate. If vitamin B12 is deficient, that also diminishes thymidylate synthetase. If a person were folate deficient, adding folate—but not vitamin B12—would normalize enzyme activity. Likewise, if a person were vitamin B12 deficient, adding vitamin B12—and not folate—would normalize thymidylate synthetase activity. 84. Grading rubric – answer should include the following items: Without vitamin B12, folate coenzymes are reduced to 5-methyl folate (the methyl-folate trap) and cannot be converted to the coenzyme forms 10-formyl THF and 5,10-methylene THF, which are needed for synthesis of the purine ring and thymidylate, respectively. Consequently, DNA synthesis becomes deranged, along with cell differentiation and maturation, and this negatively impacts cells, especially those with rapid turnover such as blood cells. Megaloblastic, macrocytic anemia results. 85. B12 is required for homocysteine methylation to generate methionine. The methyl group comes from 5-methyl THF and THF is left over. Thus, without B12, folate accumulates as 5-methyl THF because it cannot be used for homocysteine remethylation, and it cannot be metabolized back to 5,10-methylene THF (one-way pathway). The result is that all other (besides 5-methyl THF) forms of folate decrease, including 5,10-methyhlene THF—the methylene group is used for DNA synthesis. Without DNA synthesis, RBCs cannot replicate and divide (hence, megaloblastic anemia).
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Chapter_09_Water_Soluble_Vitamins 86. Conceptual: If it is known that a vitamin is required at a given step in a metabolic pathway, one can challenge that pathway by providing a large load of substrate. If the vitamin is present, it will be metabolized normally. If not, the substrate will either be metabolized down a different pathway and products of that will appear in the urine, or the intermediate compound just before the vitamin-requiring step will build up and be excreted in the urine. Specific: FIGLU – Histidine loading will cause elevated FIGLU in urine because folate is required for the degradation of histidine. Therefore, with a folate deficiency, FIGLU accumulates in the blood and is excreted in higher than normal concentrations in the urine. With adequate folate, FIGLU is converted to glutamate, with little or no FIGLU appearing in the urine. 87. Grading rubric – answer should include the following items: Ingested cobalamins are released from the proteins/polypeptides to which they are linked in foods through the actions of pepsin and hydrochloric acid in the stomach. Free vitamin B12 binds to an R protein that is found in saliva and gastric juice. Within the alkaline environment of the small intestine, the R protein is hydrolyzed by pancreatic proteases, and free vitamin B12 is released and binds to intrinsic factor (IF). The vitamin B12-IF complex travels from the duodenum to the ileum, where it interacts with a protein receptor (called cubilin, IF receptor, or cubam). Cubilin then interacts with another protein, amnionless, which facilitates cubilin’s attachment to the ileal cell’s plasma membrane. Binding of the vitamin B12-IF complex to the receptor triggers active endocytotic internalization. Vitamin B12 is absorbed throughout the ileum, especially the distal third. Within the enterocyte, the vitamin is released from the IF complex. Next, in or before it is transported across the ileum’s basolateral membrane, vitamin B12 binds to the protein transcobalamin II for transport in portal blood. 88. Carbohydrates: Vitamins involved are thiamin (TPP; pyruvate dehydrogenase and α-ketoglutarate dehydrogenase; transketolase is with the pentose phosphate pathway); niacin (NADH, glycolysis/TCA; NADPH from HMS); riboflavin (FADH2 from TCA); and pantothenic acid as CoA. Lipids: For FA oxidation you use niacin and riboflavin (NADH and FADH2) and get acetyl-CoA (pantothenate). For oddchain FA oxidation, you again generate acetyl-CoA and have those three vitamins, as well as biotin (propionyl-CoA carboxylase) and B12 (methylmalonyl-CoA mutase). You could also include TPP here in the TCA cycle. Protein: For amino acid metabolism, you need B6 (transamination of amino acids to ketoacids), and if the ketoacid obtained is pyruvate, biotin for pyruvate carboxylase; all of this is for gluconeogenesis. However, if the amino acid has more than 3 carbons, it will feed into the TCA cycle at the corresponding carbon length ketoacid; thus, NAD, FAD, and TPP all come into play (as well as CoA with succinyl-CoA). [Remember, this question is geared to obtaining energy; thus students don’t need to mention e.g., biotin for FA synthesis. For example, why show glycogenesis? That does not produce ATP. Why show amino acid or FAs feeding into the TCA cycle or pyruvate? That is not part of confining the answer to carbohydrates.] 89. With posttranslational modification (altering the function of an existing protein by forming a covalent bond without changing its abundance), pantothenic acid, as CoA, is involved in the acetylation of proteins. This means to “make a covalent bond” that consists of adding an acetate group (CH3COO-) to a protein to activate it. Another PTM example is the role of vitamin C in collagen synthesis. Really, this should be called collagen modification—we are not increasing the synthesis of collagen, we are modifying its structure so that it can form crosslinks with other collagen molecules. Hydroxylation of the lysine or proline residues in collagen allows collagen to form cross-links (making it strong), and this process requires vitamin C. Vitamin C is not required directly in the hydroxylation
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Chapter_09_Water_Soluble_Vitamins step (which is why it is not considered a cofactor), but rather it is required to regenerate the enzyme that performs the actual hydroxylation. This enzyme contains Fe++ as a cofactor, which is oxidized to Fe+++ following the reaction; vitamin C functions to reduce the Fe+++ back to Fe++, thus allowing the enzyme to function again. Other vitamin C-dependent hydroxylation reactions are identical to this, with the exception that the substrate that is being hydroxylated is not a protein; thus, by definition it does not constitute posttranslational modification. 90.90. Biotin (1) Biotin (2) Carboxylation (3) Acetyl-CoA carboxylase (FA synthesis), pyruvate carboxylase (gluconeogenesis), propionyl-CoA carboxylase (oddchain FA degradation/ oxidation) Pantothenic Acid (1) CoA (2) Activates substrates/ intermediates; protein acetylation (3) Many examples (acetyl-CoA, malonyl-CoA, etc.) in glycolysis/ TCA; FA synthesis and oxidation, etc. Riboflavin (1) FAD(H2) (2) Oxidation-reduction reactions (3) TCA cycle; FA β-oxidation B6 (1) PLP (2) Transamination; decarboxylation; transsulfuration; glycogenolysis (3) AA to KA (gluconeogenesis); heme synthesis; neurotransmitter synthesis; homocysteine to cystathionine and then to cysteine Thiamin (1) TPP or TDP (2) Oxidative decarboxylation (3) Pyruvate to acetyl-CoA; α-ketoglutarate to succinyl-CoA; HMS as transketolase Vitamin C (1) Vitamin C or ascorbic acid (2) Hydroxylation (3) Collagen synthesis (OH of pro and lys in collagen); carnitine synthesis; neurotransmitter synthesis Folate (1) Tetrahydrofolate (polyglutamates) (2) One-carbon transfer (3) DNA synthesis (uridylate to thymidylate); homocysteine to methionine
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Chapter_10_Fat_Soluble_Vitamins
Indicate whether the statement is true or false. 1. Because β-carotene can be converted into retinol, plant sources are referred to as preformed vitamin A. a. True b. False 2. Subclinical vitamin K deficiency may be associated with diminished bone mineral density and increased fracture rates. a. True b. False 3. Many anticoagulants work by inhibiting the regeneration of active vitamin K (i.e., dihydrovitamin KH2) during the vitamin K cycle. a. True b. False 4. 7-dehydrocholesterol is the form of vitamin D that is added to fortify milk. a. True b. False 5. Production of active vitamin D requires skin, sunlight, cholesterol, the liver, and the kidneys. a. True b. False 6. Vitamin A enhances vitamin K absorption and increases the plasma concentration of vitamin E. a. True b. False 7. Rhodopsin is simply the opsin protein after it has been activated by 11-cis-retinal. a. True b. False 8. Many anticoagulants inhibit the vitamin K cycle, thereby preventing activation of clotting proteins. a. True b. False 9. Calcium homeostasis in the blood depends on intestinal absorption, bone resorption, and kidney reabsorption. a. True b. False 10. All three forms of vitamin A (retinol, retinal, and retinoic acid) are stored in the liver as retinyl esters. a. True b. False 11. All of the functions of vitamin A are carried out by retinoic acid via transcriptional mechanisms. a. True b. False
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Chapter_10_Fat_Soluble_Vitamins 12. Vitamin D increases the abundance of calbindin (Ca++ transporter) in enterocytes by increasing the transcription of the calbindin gene. a. True b. False 13. Absorption of vitamins A, D, E, and K is closely associated with the absorption and transport of ingested proteins. a. True b. False 14. Inadequate vitamin D intake has been associated with autoimmune conditions such as rheumatoid arthritis, Crohn’s disease, multiple sclerosis, and type I diabetes. a. True b. False 15. A good source of vitamin D is milk, because it is fortified with 1,25-(OH)2-vitamin D3. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Would you recommend β-carotene supplementation to a smoker to decrease the risk of lung cancer? a. Yes—β-carotene can quench singlet oxygen. b. Yes—smoking increases free radical formation; β-carotene can decrease free radicals. c. No—β-carotene supplements may be harmful to smokers and their use is not advised for the general public. d. No—β-carotene supplements can cause vitamin A toxicity and liver cirrhosis. 17. Which vitamin is considered to be a secosteroid? a. choline b. vitamin A c. vitamin D d. vitamin E 18. The vitamin D response element (VDRE) is found a. on the enterocyte membrane b. on the renal tubule c. in the nucleus d. in the pancreatic duct cell
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19. What vitamin is associated with diminished proliferation and enhanced differentiation of cells, which serves as a basis for its use as treatment of skin diseases such as psoriasis? a. A b. E c. K d. D
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Chapter_10_Fat_Soluble_Vitamins 20. How will retinol, once secreted from the liver, be found in the blood? a. attached to RBP and transthyretin b. attached to albumin c. attached to a chylomicron d. attached to RBP and stellate cells 21. The majority of vitamin A is stored in the liver, while carotenoids are stored mainly in the a. muscle b. eye c. adipose d. skin 22. Instructions: Use the molecules below to answer the next three questions.
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Which molecule is retinyl palmitate? a. A b. B c. C d. D 23. Choose the correct statement about the quenching of singlet oxygen by carotenoids. a. Carotenoids donate an electron to the singlet oxygen to make it stable. b. Carotenoids covalently bond with the singlet oxygen to make it stable. c. Carotenoids donate energy so that the excited electron returns to its orbital. d. Carotenoids absorb the extra energy that is held by the singlet oxygen.
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Chapter_10_Fat_Soluble_Vitamins 24. Which vitamin D molecule would you expect to see in fortified foods? a. ergocalciferol—vitamin D2 b. calcidiol—25-OH D3 c. calcitriol—1,25-OH2 D3 d. cholecalciferol—vitamin D3 25. For which vitamin is the Tolerable Upper Intake Level set because of increased tendency for bleeding? a. A b. D c. E d. K 26. The best source of vitamin D per recommended serving is a. liver b. tuna fish c. swordfish d. cod liver oil
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27. Which is the strongest antioxidant? a. beta-carotene b. alpha-tocopherol c. beta-cryptoxanthin d. lycopene 28. Dietary cholecalciferol must be further hydroxylated in order to be active vitamin D. The first hydroxylation occurs in the to produce . a. liver; 25-hydroxycholecalciferol b. kidney; 25-hydroxycholecalciferol c. skin; 7-dehydrocholesterol d. kidney; 1-hydrocholesterol 29. Structurally, vitamin D is derived from a. a steroid b. an amino acid c. a fatty acid d. calcium 30. Peroxynitrate is a(n) a. cation b. free radical c. anion d. antioxidant
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31. Immediately following a balanced meal that contained vitamin E (such as fortified milk), where would you most likely
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Chapter_10_Fat_Soluble_Vitamins find most of the vitamin E in the body? a. in the portal blood as α-tocopherol b. inside cells as free α-tocopherol c. stored in adipose tissue d. in chylomicrons in the lymphatic vessels and general circulation 32. Which antioxidant is most effective in rapidly eliminating hydroxyl radicals prior to initiation of oxidative damage? a. vitamin E b. vitamin C c. vitamin K d. beta-carotene 33. Calcitroic acid and vitamin D metabolites are excreted primarily through a. urine b. sweat c. urine and sweat combined d. feces
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34. Which of the carotenoid pigments has the greatest provitamin A activity? a. alpha-carotene b. beta-carotene c. gamma-carotene d. delta-carotene 35. The current thought about using antioxidant supplements versus eating antioxidant-rich foods to decrease risk of cancer and heart disease is . a. more is better b. eat antioxidant-rich foods instead c. vitamin E supplements work; β-carotene does not d. studies are inconclusive relating to consumption of antioxidant-rich foods and supplements are not that effective 36. Which tocopherol form of vitamin E has biologic activity? a. alpha b. beta c. gamma d. delta 37. What happens to retinal in the enterocyte? a. It is esterified. b. It is reduced to retinol. c. It is transported into the portal blood. d. 15, 15' dioxygenase acts to form beta-carotene. 38. Who discovered vitamin E?
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Chapter_10_Fat_Soluble_Vitamins a. Evans and Bishop b. McCollum and Davis c. Mellanby and Hopkins d. Simon and Garfunkel 39. Anticoagulant drugs that act by inhibiting vitamin K activity do so by which mechanism? a. inhibiting the formation of the active form of vitamin K b. interfering with micelle formation such that vitamin K is not absorbed c. not allowing calcium to interact with Gla residues d. stimulating osteocalcin synthesis 40. Which of the fat-soluble vitamins is consumed in the form of phylloquinone from plant foods? a. A b. D c. E d. K 41. A deficiency of vitamin A, in addition to causing visual problems, might also lead to a. muscular problems b. cardiovascular disease c. impaired height and improperly developed bones d. damage to the choroid layer of the eye 42. Risk of vitamin K deficiency is greatest in a. newborns b. children c. adolescents d. older people
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43. The electron transport chain produces superoxide radicals as a result of a. autoxidation reactions b. interaction with carbon dioxide c. emission of alpha particles d. reduction in oxygen concentration 44. Choose the food that is rich in vitamin A palmitate. a. spinach b. liver c. carrots d. pumpkin 45. What percentage of vitamin D from the diet is absorbed? a. 20% b. 30%
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Chapter_10_Fat_Soluble_Vitamins c. 40% d. 50% 46. The diet that has shown some promise in reducing the risk of progression to advanced macular degeneration is the diet. a. Paleo b. Mediterranean c. Atkins d. gluten-free 47. Choose the ONE correct statement. a. Beta-carotene is hydrolyzed in the jejunum before it is absorbed. b. Retinol does not need to form a micelle to cross the USW. c. Beta-carotene dioxygenase activity occurs in the lumen of the ileum. d. Retinol must be reesterified to be carried in the chylomicron. 48. Which vitamin has as its primary function the maintenance of calcium homeostasis? a. A b. D c. E d. K 49. Choose the correct order of the phrases below to explain the response of the body to a decline in serum calcium levels. Choose the BEST answer. 1. increased release of PTH 2. decreased release of PTH 3. increased synthesis of calbindin 4. increased synthesis of 1,25-(OH)2 D3 5. increased bone absorption 6. increased calcium absorption 7. decreased bone resorption 8. increased calcium excretion 9. increased bone resorption a. 1, 5, 4, 8 b. 1, 3, 5, 9 c. 2, 3, 9, 6 d. 1, 4, 3, 6 50. Nausea, vomiting, double or blurred vision, headaches, vertigo, and muscle incoordination are some of the symptoms of . a. hypervitaminosis A b. hypervitaminosis D c. hypervitaminosis K d. hypovitaminosis A 51. In order to be carried in the chylomicron, retinol (once in the enterocyte) is
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Chapter_10_Fat_Soluble_Vitamins a. esterified by lecithin retinol acyl transferase b. converted to retinaldehyde by retinaldehyde reductase c. attached to a VLDL d. attached to an RXR receptor on the nucleus 52. How does alpha-tocopherol differ from beta-tocopherol? a. saturation of side chain b. number and location of methyl groups c. source in the diet d. ionic versus covalent bonding 53. Where would you find retinoid X receptors (RXR)? a. in cytosol b. in the nucleus c. in mitochondria d. in the Golgi apparatus 54. A deficiency of vitamin A will lead to night blindness. This is due to . a. damage to the retina b. inability to produce rhodopsin c. damage to the area of the brain that interprets incoming visual signals d. damage to the rods 55. Vitamin A will work in conjunction with which vitamin to help protect cells from singlet oxygen? a. niacin b. thiamin c. pantothenic acid d. ascorbic acid 56. If asked about the relationship of vitamin D to autoimmune disease, the best information for a dietetic professional to provide is . a. that the evidence does not support a relationship at this time b. that the evidence is only in animals, not humans c. that some evidence suggests a protective effect of vitamin D d. to take a supplement containing 2000 IU vitamin D each day 57. A deficiency of which vitamin is commonly associated with rickets? a. A b. D c. E d. K 58. The RDA for vitamin D for people over the age of 70 is how many times greater than that for adolescents? a. 2.0
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Chapter_10_Fat_Soluble_Vitamins b. 1.33 c. equal d. 0.75 59. Instructions: Use the molecules below to answer the next three questions.
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Which molecule is β-carotene? a. A b. B c. C d. D 60. The overall efficiency of the formation of retinal from beta-carotene is estimated at approximately what percentage? a. 20% b. 35% c. 50% d. 65% 61. Which is NOT related to the functions of vitamin A? a. neurological function b. growth c. immunity d. cell differentiation 62. Imagine you are a nutritionist working in a country other than the United States. Which is an assumption about vitamin D status that is NOT true? a. The latitude makes a difference as regards how much vitamin D can be self-synthesized.
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Chapter_10_Fat_Soluble_Vitamins b. Customs of dress make a difference as regards how much vitamin D can be self-synthesized. c. Cow’s milk is a reliable source of vitamin D in the food supply. d. Skin color makes a difference as regards how much sun is needed to synthesize vitamin D. 63. Which substance accounts for almost half of the antioxidant capacity of human plasma? a. albumin b. uric acid c. citric acid d. carbonic acid 64. Instructions: Use the molecules below to answer the next three questions.
A
B
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D
Which is molecule is retinoic acid? a. A b. B c. C d. D 65. In what cells will you find most of the retinol and vitamin A stored? a. stellate b. gallbladder c. fundus d. antrum 66. The action of vitamin K in the posttranslational synthesis of blood clotting factors occurs in the a. blood b. liver
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Chapter_10_Fat_Soluble_Vitamins c. small intestine d. bone marrow 67. Which vitamin directs cellular differentiation of epithelial cells? a. riboflavin b. vitamin K c. vitamin E d. vitamin A 68. Within the nucleus, all trans-retinoic acid and/or 9-cis retinoic acid bind to a. nuclear retinoic acid receptors b. mannosylated glycoproteins c. cell aggregates d. transcription factors 69. Most of the vitamin E in the blood is carried by a. water b. albumin c. hemoglobin d. LDLs and HDLs
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70. Which vitamin is said to be essential for growth and immune system function? a. K b. A c. D d. E
Vitamers: Match each vitamer with its function. a. interacts with nuclear VDR to increase calbindin b. required for carboxylation of glutamic acid c. needed for binding with opsin in the photoreceptor rod cells d. transported into nucleus to affect gene transcription of keratin proteins e. donates hydrogens to terminate propagation of membrane lipid peroxidation chain reactions 71. 11-cis retinal 72. retinoic acid 73. alpha-tocopherol 74. calcitriol 75. hydroquinone (KH2)
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Chapter_10_Fat_Soluble_Vitamins Factors: Match the factor to its correct action. a. becomes activated in the presence of thromboplastin b. creates insoluble fibrin for final clot formation c. converts prothrombin into thrombin d. works with factor IXa to activate factor X e. activates factor IX 76. VIIa 77. Xa 78. XIa 79. VII 80. XIIIa
81. Regulation of Proteins by Vitamins: Micronutrients, such as vitamins, typically regulate gene expression (i.e., induction) directly. Use either vitamin D or vitamin A to illustrate this concept—be complete and thorough in your answer. Do not simply draw a diagram; include some discussion and make sure everything is labeled and/or defined. 82. Explain the process by which rhodopsin is formed. 83. Discuss the role of calcitonin in maintaining normal blood calcium concentration. 84. Although for micronutrients increasing the amount of a protein by directly inducing gene expression is certainly a common mechanism, we have encountered other mechanisms by which vitamins can regulate proteins. Provide one example of posttranslational modification, being as specific as possible. 85. Why are vitamins A and E said to be antagonists of vitamin K? 86. Which bacteria produce vitamin K and in what form? Because this production is not sufficient to meet the body’s needs, name five foods that provide large amounts of vitamin K and in which form. 87. Describe how vitamin A affects bone growth. 88. What is singlet molecular oxygen, how does it form and why is it dangerous? How does vitamin E protect against singlet molecular oxygen? 89. In certain groups of people, it is recommended that higher doses of vitamin D be ingested. Which groups are included in this recommendation and why? 90. Indicate: (1) the active form of vitamin K, (2) the general function of vitamin K, and (3) an example of the general function (this could be a specific reaction or simply indicate a pathway/ process where it occurs). Your answers do not need to be long!
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Chapter_10_Fat_Soluble_Vitamins Answer Key 1. False 2. True 3. True 4. False 5. True 6. False 7. True 8. True 9. True 10. False 11. False 12. True 13. False 14. True 15. False 16. c 17. c 18. c 19. d 20. a 21. c 22. b 23. d 24. d 25. c
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Chapter_10_Fat_Soluble_Vitamins 26. d 27. d 28. a 29. a 30. c 31. d 32. b 33. d 34. b 35. d 36. a 37. a 38. a 39. a 40. d 41. c 42. a 43. a 44. b 45. d 46. b 47. d 48. b 49. d 50. a 51. a
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Chapter_10_Fat_Soluble_Vitamins 52. b 53. b 54. b 55. d 56. c 57. b 58. b 59. d 60. c 61. a 62. c 63. b 64. c 65. a 66. b 67. d 68. a 69. d 70. b 71. c 72. d 73. e 74. a 75. b 76. d
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Chapter_10_Fat_Soluble_Vitamins 77. c 78. e 79. a 80. b 81. As stated, we are talking about induction—that means we are increasing the abundance of a particular protein by increasing gene expression. Two good examples of this are vitamin D and vitamin A. Induction means an increase in the amount of the protein. Micronutrients such as vitamin A and vitamin D accomplish this by directly increasing the transcription of a given gene. A good example for vitamin D is its ability to increase the number of calcium transporters in the intestinal cell. It does this by binding in the cytosol to a vitamin D-binding protein (VDBP), which delivers it to the nucleus. In the nucleus, another protein, the vitamin D receptor (VDR), binds vitamin D and a second protein, the retinoid X receptor (RXR), binds to them. Collectively, this complex (VDR-RXR) can then bind to the vitamin D response element (VDRE) located in the promoter region of the gene that encodes for calcium binding proteins. When the VDRE is activated by the VDR-RXR complex, it increases the transcription of calcium binding proteins; thus, there are more calcium binding proteins made in the cell and more calcium is transported in. You can discuss a very similar scenario for vitamin A (i.e., retinoic acid). You have cytosolic proteins (CRABP) to take the retinoic acid to the nucleus, where it binds to a retinoic acid receptor (RAR) and then RXR. Together, they (RARRXR) bind to the retinoic acid response element (RARE) located on specific genes (such as the gene encoding for growth hormone receptor) to increase the transcription of that gene; thus, more protein, like growth hormone, is made. Remember that regulation of gene expression by vitamin D and vitamin A is cell type-specific depending on the protein that is being induced. For calcium-binding proteins, this occurs in the enterocyte, but not other tissues. For growth hormone, this will occur in certain brain cells, but nowhere else. We don’t produce growth hormone and calcium-binding proteins in every cell that is exposed to vitamin A or D. Also, remember that once the expression of a gene is turned on, that results in making more mRNA corresponding to that gene (via transcription), and then the mRNA leaves the nucleus—it is translated into the desired protein. 82. Grading rubric – answer should include the following items: For vision to occur, 11-cis retinol must bind to the visual pigment opsin in the rods of the retina to form rhodopsin. Subsequently when light hits the retina, the energy from the light splits opsin from rhodopsin and releases vitamin A as all-trans-retinal. This reaction is called bleaching because loss of rhodopsin decreases pigment color. The reaction sets off a cascade of reactions involving a G protein called transducin, causing the rod to hyperpolarize from blockage of sodium channels, which in turn sends signals through the optic nerve to the brain. To finish the cycle, all-trans-retinal is reconverted in a series of steps to 11-cis retinol and reunited with opsin to reform rhodopsin. 83. Grading rubric – answer should include the following items: Calcitonin is released from the thyroid parafollicular cells in response to elevated serum calcium and functions to restore serum levels back down to normal. Calcitonin inhibits osteoclasts, thus diminishing the release of calcium and phosphorus from bone and it stimulates osteoblasts. It diminishes kidney reabsorption of calcium and phosphorus and promotes excretion of calcium and phosphorus in urine. 84. A possible example is vitamin K, which is required for the carboxylation of a number of proteins involved in coagulation (e.g., prothrombin to thrombin) to make them more active. It also covalently modifies bone proteins. In both cases, the carboxylation of glutamate residues in the protein allows the protein to bind Ca++, thus making it more active in coagulation or bone formation.
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Chapter_10_Fat_Soluble_Vitamins 85. Grading rubric – answer should include the following items: Excess intake of vitamins A and E interfere with absorption of vitamin K. In addition, vitamin E interferes with metabolism of MK-4 and may increase degradation of all forms of vitamin K in the liver. 86. Grading rubric – answer should include the following items: Intestinal bacteria produce menaquinones. Some of the bacteria that produce these are Bacteroides, Bacillus fragilis, Eubacteria. Propionibacteria, and Arachnia. Because bacterial synthesis does not meet the body’s needs, dietary supplementation is necessary. Five foods that provide large amounts of vitamin K include broccoli, kale, turnips, spinach and salad greens. 87. Grading rubric – answer should include the following items: Bone growth and resorption rely on cells called osteoblasts and osteoclasts, respectively. A vitamin A deficiency will cause excess deposition of bone by osteoblasts and a reduction in bone degradation by osteoclasts because it stimulates the former and suppresses the latter. An excess of vitamin A will cause the reverse to occur. Osteoclasts will be stimulated causing excess bone resorption and osteoblasts will be suppressed leading to a decrease in bone density. This might lead to an increased risk of bone fracture. 88. Grading rubric – answer should include the following items: Singlet molecular oxygen is formed from lipid peroxidation of membranes, photochemical reactions or enzymatic reactions occurring in neutrophils. It is dangerous because it reacts with organic molecules such as proteins, lipids, and DNA causing damage unless it is removed. Vitamin E has oxygen-quenching abilities because it has a free hydroxyl group in position 6 of its chromane ring. Alpha tocopherol is the most effective form of vitamin E in protecting against singlet molecular oxygen. 89. Grading rubric – answer should include the following items: Because vitamin D is a fat-soluble vitamin and is sequestered in adipose tissue, obese individuals may require two to three times the recommended dose to prevent and/or treat deficiency. In addition, any individual who suffers with a malabsorption syndrome or who is taking medications that interfere with vitamin D metabolism should take higher doses of the vitamin to avoid deficiencies. 90. Vitamin K (1) Dihydrovitamin KH2 or hydroquinone (2) Carboxylation (3) Activation of clotting proteins (prothrombin to thrombin); activation of bone proteins (osteocalcin)
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Chapter_11_Major_Minerals
Indicate whether the statement is true or false. 1. A magnesium deficiency might contribute to the disruption of the cell membrane. a. True b. False 2. Meats and grains are poor sources of calcium. a. True b. False 3. Phosphorous absorption takes place in the small intestine but predominantly in the jejunum. a. True b. False 4. Thyroid hormone increases serum calcium concentrations. a. True b. False 5. Vitamin D, fructose, and oligosaccharides may increase magnesium absorption. a. True b. False 6. Aluminum and magnesium hydroxides and calcium carbonates and acetates are used today for the treatment of hyperphosphatemia in individuals with renal failure. a. True b. False 7. A majority of the calcium in the body is responsible for a variety of nonosseous functions. a. True b. False 8. Calcium is the most abundant divalent cation in the body. a. True b. False 9. Calcitriol enhances calcium reabsorption in the kidneys. a. True b. False 10. Calcium absorption occurs in the large intestine. a. True b. False 11. Ingestion of calcium, magnesium, and aluminum, along with phosphorus, will enhance its absorption. a. True b. False
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Chapter_11_Major_Minerals 12. Regardless of age, the level of calcium absorption is the same. a. True b. False 13. Absorption of magnesium decreases with increased intracellular magnesium concentrations. a. True b. False 14. A chronic phosphorous deficiency in children will cause the development of osteomalacia. a. True b. False 15. Phosphorous is second to calcium in abundance in the body. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Calcitriol can stimulate the absorption of calcium from the intestines by enhancing synthesis of proteins. a. calsequestrin b. calcitonin c. calmodulin d. calbindin 17. Resorption of phosphate from bone may take place through a. enhanced acid phosphatase activity b. enhanced alkaline phosphatase activity c. diminished acid phosphatase activity d. diminished alkaline phosphatase activity
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18. Most phosphorus, regardless of its dietary form, is absorbed from the gastrointestinal tract a. bound to proteins b. as free inorganic phosphate ions c. bound to carbohydrates d. bound to fats 19. Uptake of phosphorus into cells is thought to occur via a. active transport b. facilitated diffusion c. passively, driven by the chemical gradient d. Brownian movement
and related
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20. Dietary protein promotes bone growth by providing amino acids needed for bone protein and by
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Chapter_11_Major_Minerals a. stimulating insulin-like growth hormone 1 b. interacting with calcium to form spongy bone c. attaching to cartilage that precedes bone growth d. inhibiting PTH 21. Calcium is transported in the blood in three ways with the exception of a. bound to proteins b. complexed with anions c. ionized in the free form d. bound to hemoglobin 22. The most abundant divalent cation in the body is a. iron b. calcium c. selenium d. iodine
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23. In the renal system, which mineral regulates body fluid pH by reacting with secreted hydrogen ions, releasing sodium ions in the process? a. sulphur b. magnesium c. calcium d. phosphorus 24. Rickets is caused by a deficiency in a. magnesium b. calcium c. iron d. zinc
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25. About 99% of the body’s calcium is found in a. blood plasma b. liver and kidneys c. bones and teeth d. extracellular fluid
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26. Magnesium is absorbed in the small intestine through diffusion and a. carrier-mediated active transport b. osmosis c. facilitated diffusion d. peristalsis 27. Phosphate balance is achieved largely by a. renal excretion
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Chapter_11_Major_Minerals b. fecal excretion c. control of absorption by vitamin D d. control of absorption by phytates 28. Ionized calcium is removed from the blood via each of the following except a. secretion into the digestive tract b. excretion in the urine c. mixed into perspiration d. uptake by tissues 29. Food sources of calcium include a. fish and eggs b. nuts c. leafy green vegetables d. canned sardines
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30. Which two minerals are the major part of the crystal, hydroxyapatite, formed in ossification of bone? a. sodium, chloride b. sulphur, magnesium c. calcium, phosphorus d. calcium, potassium 31. A dietary mineral that is an important component of DNA and RNA is a. calcium b. magnesium c. sulfur d. phosphate
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32. Which substance can improve calcium absorption? a. lactose b. unabsorbed fatty acids c. phytic acid d. magnesium 33. The condition associated with decreased bone strength accompanied by the deterioration of the microarchitecture of bone tissue and low mineral density is . a. osteopetrosis b. osteoporosis c. osteomalacia d. osteogenesis imperfecta 34. Major minerals include calcium, phosphorus, magnesium, sodium, potassium, and a. chloride b. manganese
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Chapter_11_Major_Minerals c. sulfur d. nitrogen 35. The majority of magnesium in the plasma/serum is a. bound to albumin b. complexed with citrate c. complexed with phosphate d. found free in its ionic form
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36. One of the two mechanisms involved in calcium absorption in the small intestine is a. diffusion b. osmosis c. facilitated diffusion d. Brownian movement
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37. Deficiency of which major mineral is usually associated with muscular weakness, neuromuscular hyperexcitability, and tetany? a. magnesium b. calcium c. sulphur d. chloride 38. Premature infants are at risk for phosphorus deficiency due to . a. their poor absorption from the intestines b. their higher need for the mineral and the insufficient amount in human milk c. their highly active cytochrome P450 system d. their poorly developed intestines 39. A factor that enhances calcium absorption is a. fat intake b. carbohydrate intake c. protein intake d. fruit juice intake
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40. A deficiency of magnesium may lead to hypocalcemia due to a. a reduction in PTH levels b. inhibition of calcium absorption c. stimulation of calcium release from cells d. an increase in PTH levels 41. By what mechanism is vitamin K thought to protect bone health? a. buffering for acid-base balance b. diminishing bone resorption c. used for the formation of Gla protein in bone
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Chapter_11_Major_Minerals d. contributing to the integrity of bone collagen 42. Which mineral participates in all aspects of energy metabolism including glycolysis, beta-oxidation, and the TCA cycle? a. calcium b. iron c. magnesium d. sulphur 43. Choose one of the following choices that is not one of calcium’s nonosseous functions. a. skeletal muscle contraction b. hair growth c. generating action potentials in nerves d. changes in membrane permeability 44. Per serving, the best source of phosphorus would be a. milk and yogurt b. dry roasted pecans c. an egg d. cheeses
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45. Which mineral makes up about 40% of the body’s mineral mass? a. phosphorus b. magnesium c. calcium d. potassium 46. Which mineral is LEAST likely to be deficient in anyone's diet? a. calcium b. phosphorus c. iodine d. zinc 47. Which mineral, when combined with unabsorbed dietary fat, forms soaps that cannot be absorbed and are excreted in the feces? a. calcium b. sulphur c. potassium d. chloride 48. Major calcium loss from the body occurs via feces and urine. Which other process is associated with large losses of calcium? a. hyperventilation b. extreme sweating c. letting hair grow very long
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Chapter_11_Major_Minerals d. allowing nails to grow very long 49. Paracellular absorption of calcium . a. occurs by diffusion mainly in the jejunum and ileum b. requires a membrane channel protein called TRPV6 c. requires energy and is saturable d. increases with low dietary calcium intakes 50. Which mineral has as its primary function to bind phosphate groups in ATP and ATP-dependent enzyme reactions? a. calcium b. magnesium c. potassium d. sodium 51. Malnourished individuals being refed who exhibit the “refeeding syndrome” may have low serum concentrations of . a. calcium b. sodium c. phosphorus d. chloride 52. Choose which one of the following statements is not correct. a. About half of magnesium in the body is associated with the bones. b. Intracellular and serum magnesium levels are rigidly maintained. c. Magnesium in cells is associated with phospholipids and proteins. d. Magnesium metabolism is regulated by several hormones. 53. One health claim for calcium states that levels above a. 800 mg/day b. 1000 mg/day c. 1200 mg/day d. 2000 mg/day 54. The active form of vitamin D in the body is a. calsequestrin b. calcitriol c. calcitonin d. calbindin
are unlikely to provide additional benefit.
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55. The majority of phosphorus not bound to protein that is filtered by the glomerulus is actively reabsorbed by the a. distal tubule b. collecting duct c. loop of Henle d. proximal tubule
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Chapter_11_Major_Minerals 56. Which of the following statements is true? a. In smooth muscle contraction, the roles of calcium and magnesium are antagonistic, with calcium promoting the process and magnesium being the inhibitor if bound to sites that are normally occupied by calcium. b. Magnesium promotes phosphorus absorption. c. Calcium and magnesium promote each other’s reabsorption in the kidney. d. Calcium may cause an alteration in magnesium distribution by changing the flux of magnesium across the cell membrane or displacing it on its binding sites. 57. The binding protein that regulates many of the calcium-dependent enzymes is a. calcitonin b. calmodulin c. albumin d. globulin 58. The element that serves as an intracellular buffer is a. phosphorus b. calcium c. magnesium d. sodium
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59. By what mechanism is vitamin C thought to protect bone health? a. buffering for acid-base balance b. diminishing bone resorption c. carboxylation of osteocalcin and matrix Gla protein d. contributing to the integrity of bone collagen 60. The Tolerable Upper Limit for phosphorus drops after age 70 due to a. a slower metabolic rate in the elderly b. a reduced need for phosphorus c. a greater need for calcium d. a greater likelihood of impaired renal function
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61. Which mineral is part of the green chlorophyll pigment in green leafy vegetables? a. magnesium b. sodium c. potassium d. sulfur 62. Magnesium deficiency may develop due to mutations in a. PTH b. phytic acid c. claudin-16 d. FGF23 63. Phosphorus is absorbed primarily in the
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Chapter_11_Major_Minerals a. duodenum b. stomach c. ileum d. jejunum 64.
is secreted in response to low plasma calcium concentrations and acts on the kidney to increase synthesis of , which promotes renal reabsorption of calcium. a. Parathyroid hormone; calcitonin b. Parathyroid hormone; calcitriol c. Calcitonin; calcitriol d. Calcitriol; calmodulin
65. Calcium-sensing receptors (CaSR) are located on the a. thyroid gland b. hypothalamus c. parathyroid glands d. liver
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66. Which hormone both increases release of bone phosphorus into the blood and promotes urinary excretion of phosphorus? a. calcitonin b. calcitriol c. parathyroid hormone d. insulin 67. Most phosphorus is found in the blood as a. HPO4
.
2-
b. H2PO4c. PO 34
d. H3PO4268. During which period of the life cycle does peak bone mass occur? a. childhood b. puberty c. early adulthood d. middle age 69. Which cells are considered the bone-building cells? a. osteonectins b. osteopontins c. osteoclasts d. osteoblasts 70. Kyphosis as a result of osteoporosis leads to shortness of breath and abdominal pain due to
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Chapter_11_Major_Minerals a. biochemical changes in the respiratory and digestive systems b. a reduction in blood circulation to the chest and abdomen c. compression of the aorta and superior vena cava d. reduction in the spaces of the chest and abdominal cavities
Macromineral Functions: Match each macromineral with one of its major functions or characteristics. a. forms a complex with ATP for use in glycolysis b. required for blood clotting c. forms part of the linear backbone of DNA d. found as part of structures of vitamins and some amino acids e. absorption inhibited by excessive calcium 71. calcium 72. phosphorus 73. magnesium 74. iron 75. sulfur Deficiency Symptoms: Match each macromolecule with its deficiency symptoms. a. neuromuscular hyperexcitability, and CNS effects b. rickets, osteoporosis, tetany c. osteomalacia, neuromuscular, cardiac, and hematologic manifestations d. a deficiency of methionine or cysteine, both containing this element, that might lead to alkalosis e. affects oxygen carrying capacity 76. calcium 77. phosphorus 78. magnesium 79. iron 80. sulfur
81. What effect does taking a calcium supplement have on iron absorption, and what advice would you give to maximize the benefit from both minerals? 82. What conditions may lead to a phosphorus deficiency? How is a deficiency manifested in the individual? 83. How does phosphate regulate acid-base balance?
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Chapter_11_Major_Minerals 84. Compare calcium, phosphorus and magnesium as to their physiological functions, symptoms of a deficiency and some of their food sources. You may write out your response or set it up in table form. 85. Describe the process by which serum calcium concentrations increase in response to the removal of ionized calcium from the blood. 86. What role does magnesium play in maintaining calcium homeostasis? 87. Describe the mechanism for paracellular absorption of calcium. 88. How is calcium status assessed? 89. Explain the rationale for a common treatment of hyperphosphatemia associated with chronic kidney failure. 90. How is magnesium associated with bone mineralization?
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Chapter_11_Major_Minerals Answer Key 1. True 2. True 3. True 4. False 5. True 6. False 7. False 8. True 9. False 10. False 11. False 12. False 13. True 14. False 15. True 16. d 17. b 18. b 19. c 20. a 21. d 22. b 23. d 24. b 25. c
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Chapter_11_Major_Minerals 26. a 27. a 28. c 29. d 30. c 31. d 32. a 33. b 34. a 35. d 36. a 37. a 38. b 39. c 40. a 41. c 42. c 43. b 44. a 45. c 46. b 47. a 48. b 49. a 50. b 51. c
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Chapter_11_Major_Minerals 52. d 53. d 54. b 55. d 56. a 57. b 58. a 59. d 60. d 61. a 62. c 63. d 64. b 65. c 66. c 67. a 68. c 69. d 70. d 71. b 72. c 73. a 74. e 75. d 76. b
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Chapter_11_Major_Minerals 77. c 78. a 79. e 80. d 81. Grading rubric – answer should include the following items: Calcium supplements inhibit the absorption of iron, especially nonheme iron, likely by causing the ferroportin protein to disengage from the basolateral membrane, diminishing iron absorption. Because this lower iron absorption has been shown to be temporary, an adaptation likely occurs that does not affect the iron status of the body. 82.82. Grading rubric – answer should include the following items: Although phosphorus deficiency is rare, it is seen in premature infants because they have a higher need for it and human milk has a low level of the mineral. In addition, malnourished individuals who are being fed through a tube or intravenously must receive additional phosphorus or they will develop a deficiency. Alkalosis (elevated pH of the blood), critical illnesses, and alcoholism are all associated with hypophosphatemia. Genetic disorders associated with hypophosphatemia include X-linked hypophosphatemia and hypophosphatemic rickets. Both conditions are caused by defects in phosphorus reabsorption in the kidneys and lead to excess phosphorus in the urine. Because bone is composed mainly of calcium and phosphorus, a deficiency will have serious effects. Rickets occurs in infants and children due to inadequate mineralization of the bone matrix and growth plate cartilage. In adults, a condition called osteomalacia develops associated with soft bones due to failure of the bone matrix to mineralize. If a phosphorus deficiency is severe, the individual will suffer from reduced oxygen transport and delivery, reduced cardiac output, arrhythmias (irregular heartbeats), respiratory failure, damage to heart and skeletal muscles and neurological problems. 83.83. Grading rubric – answer should include the following items: Phosphate acts as an intracellular buffer to help regulate acid-base balance. In the kidneys, secreted hydrogen ions react with filtered phosphate causing the release of sodium ions according to the following reaction: Na2HPO4 + H+ → NaH2PO4 + Na+ Because this reaction removes free hydrogen ions, the pH increases. An additional reaction also increases the pH: HPO2– + H+ → H2PO4 + Na+ If the pH drops, these reactions may be reversed. 84. The students will use the information in Table 11.1 to answer this question, leaving out the columns for body content and RDA. 85.85. Grading rubric – answer should include the following items: Calcium-sensing receptors on the parathyroid glands and some other tissues monitor blood calcium concentrations. When a drop in serum calcium concentration occurs, the parathyroid gland releases PTH into the blood. This will increase serum calcium concentrations via actions in the kidneys and the bones. In the kidneys, the hormone stimulates transcription of 1-hydroxylase yielding synthesis of calcitriol from 25-OH vitamin D. This leads to increased renal absorption of filtered calcium by interacting with nuclear vitamin D receptors to induce transcription of the gene that codes for calbindin D28k. In the bones, PTH attaches to receptors on osteoblasts. These cells can differentiate into osteoclasts that degrade bone.
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Chapter_11_Major_Minerals They promote the release of calcium from the bones into the blood, which brings about an increase in serum calcium levels. The calcitriol that was produced acts in the small intestine to increase calcium absorption by interacting with nuclear vitamin D receptors to induce transcription of the gene that codes for calbindin D9k. This substance binds protein to allow for transport of calcium through the cytosol. In addition, calcitriol enhances calcium absorption at the brush border of the enterocytes by increasing TRPV6 channels and, at the basolateral membrane, by increasing calcium ATP-ase pumps. 86. Grading rubric – answer should include the following items: Magnesium (Mg) is a divalent cation that sometimes mimics calcium (Ca) and sometimes competes with Ca. Mg competes with Ca for reabsorption by the kidney. Mg can decrease calcium flux across cell membranes. It can inhibit Ca release from the sarcoplasmic reticulum and activate the Ca-ATPase pump to decrease intracellular Ca. In addition, Mg competes with Ca to bind sites on smooth muscle, thus inhibiting contraction, which is likely one mechanism by which adequate Mg decreases risk for hypertension. 87. Paracellular absorption of calcium occurs by diffusion where no carriers or energy are needed. It occurs throughout the small intestine, predominantly in the jejunum and ileum and is concentration dependent. This kind of absorption occurs between cells and is affected by tight junctions that are controlled by occludins and claudins and appear to exhibit properties similar to ion channels. This type of absorption occurs when high calcium concentrations are present in the lumen, creating a gradient of calcium concentrations between the lumen and the basolateral side of the enterocyte. Permeability is increased through the junctions by a series of reactions and calcium absorption is facilitated. 88. Grading rubric – answer should include the following items: Because of the precise regulation of serum calcium, there is no routine biochemical method of serum calcium status. In certain disease states, abnormal serum calcium levels develop. This is particularly true in cases of cancer and renal failure. Also, changes in blood pH and albumin may bring about changes in serum calcium concentrations. So, checking serum albumin levels is important. If serum albumin is normal, the ratio between bound calcium and ionized calcium remains constant. If albumin levels drop, protein-bound calcium will also drop and treatment is needed to correct the situation. Another means of assessment is measuring bone mineral density since most calcium is found in the bones. This is done using dual-energy X-ray absorptiometry (DEXA or DXA), computerized tomography (CT), and single-photon absorptiometry. 89. Grading rubric – answer should include the following items: Kidney failure results in greatly elevated concentrations of phosphate in blood. Calcium supplements given so that the ratio of calcium to phosphorus is 3:1 or greater effectively inhibit the absorption of phosphate from the intestines. This treatment is now less common because of the risk of hypercalciuria, calcium-alkali syndrome, and calcium phosphate deposition in soft tissues. 90.90. Grading rubric – answer should include the following items: Most of the body’s magnesium is found in the bones in several forms including Mg(OH)2 and Mg3(PO4)2. Approximately 30% of bone magnesium is on the surface of the bones in an amorphous form and is used as an available pool that maintains plasma magnesium concentrations. The remainder of magnesium is found with calcium and phosphorus in the crystal lattice within the bone. It is most likely that this magnesium is deposited when the bone is formed and plays a crucial role in mineralization.
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Chapter_12_Water_and_Electrolytes
Indicate whether the statement is true or false. 1. To maintain the cell’s resting membrane potential, potassium’s intracellular to extracellular ratio is important. a. True b. False 2. Nearly all chloride consumed in the diet comes from consumed sodium chloride (salt). a. True b. False 3. Buffers exist individually as either acids or bases. a. True b. False 4. Most sodium absorption occurs in the small intestine and the proximal portion of the colon. a. True b. False 5. Stimulation of reabsorption of water in the kidneys is mediated by angiotensin I. a. True b. False 6. Factors that determine the Adequate Intake (AI) of water include age, gender, environment, level of physical activity and rate of metabolism. a. True b. False 7. In the kidneys, 80% of plasma that does not enter the glomerulus flows through the afferent arterioles. a. True b. False 8. The major regulatory factor controlling sodium and chloride balance in the body is the bicarbonate-carbonic acid system. a. True b. False 9. Hydrostatic pressure affects water movement between the interstitial fluid and the plasma. a. True b. False 10. The concentration of proteins is much higher in the plasma than in the interstitial fluid because proteins are too large to pass through the capillary endothelium. a. True b. False 11. Diffusion refers to the movement of water across a semipermeable membrane based on differences in solute
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Chapter_12_Water_and_Electrolytes concentrations. a. True b. False 12. Water moves among the various body compartments in a regulated manner strongly affected by sodium in the intracellular fluid compartment. a. True b. False 13. Electrolytes in the fluid compartments are distributed in such a way that within the compartment, electrical neutrality is always maintained. a. True b. False 14. An acid, as it relates to fluid acid-base regulation, is a substance that accepts protons. a. True b. False 15. Urinary loss of water averages approximately 1–2 L/day. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Which of the following foods is associated with reduced blood pressure? a. sugar b. alcohol c. red meat d. nuts 17. The majority of water in the gastrointestinal tract is absorbed in the a. duodenum b. jejunum and ileum c. ascending colon d. transverse colon
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18. Which organs are responsible for regulation of extracellular water osmolarity and volume? a. hypothalamus and kidney b. liver and pancreas c. pancreas and kidney d. spleen and bone marrow 19. Sodium, potassium, calcium, and magnesium are considered a. organic acids b. inorganic acids
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Chapter_12_Water_and_Electrolytes c. buffers d. cationic electrolytes 20. Of these blood proteins, which one contributes most to buffering? a. albumin b. gamma globulins c. hemoglobin d. transthyretin 21. The major filtration force in capillaries is a. diffusion b. hydrostatic pressure c. facilitated diffusion d. Brownian movement
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22. Which cation is most abundant in plasma? a. magnesium b. calcium c. sodium d. potassium 23. Which hormone hydrolyzes angiotensinogen, thus generating angiotensin I? a. renin b. aldosterone c. angiotensin-converting enzyme d. atrial natriuretic peptide 24. Acid-base balance refers to . a. the ratio of acidic and basic foods consumed each day b. the concentration of the bicarbonate ion in the red blood cells c. the control of the hydrogen ion concentration in body fluids d. homeostasis 25. Which of the following is NOT a cationic electrolyte of extracellular fluid? a. sodium b. potassium c. calcium d. bicarbonate 26. When hyperventilation occurs there is a(n) . a. increased loss of CO2 and a decreased production of carbonic acid b. decreased loss of CO2 and an increased production of carbonic acid c. decrease in both CO2 and carbonic acid levels
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Chapter_12_Water_and_Electrolytes d. increase in both CO2 and carbonic acid levels 27. What percentage of the glomerular filtrate volume is excreted as urine each day? a. 100% b. 50% c. 25% d. 1% 28. Which hormone, stimulated by increased blood pressure stretching the heart, functions to inhibit sodium reabsorption to promote sodium excretion? a. vasopressin b. atrial natriuretic peptide c. aldosterone d. angiotensin II 29. The major source of water to the body is . a. beverages and foods b. water as a byproduct of metabolism c. inhaled water vapor from the atmosphere d. subcutaneous fluid absorption 30. Interstitial fluid . a. directly bathes the cells b. is the fluid portion of the blood c. is fluid that is redirected to the blood plasma from interstitial spaces d. is a water-containing and sometimes viscous fluid 31. When a person hyperventilates and “blows off” CO2, what effect does this have on pH? a. lowers it b. raises it c. does not alter it significantly d. delays any changes in it 32. Bone contains what percentage of water? a. 25% b. 31% c. 43% d. 51% 33. Which buffer is controlled by the kidneys? a. bicarbonate b. carbonic acid c. protein d. ammonium
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Chapter_12_Water_and_Electrolytes 34. The most abundant cation in blood plasma is a. potassium b. magnesium c. manganese d. sodium
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35. The reaction H2O + CO2 ↔ H2CO3 ↔ HCO3- + H+ represents water’s role in a. protein transport b. ammonium ion excretion c. acid-base balance d. temperature regulation
.
36. Water accounts for what percentage of the body weight in a normal adult? a. 20% b. 40% c. 60% d. 80% 37. Which characteristic of water gives it the ability to regulate body temperature? a. high solubility coefficient b. hydrogen bonding between molecules c. high specific heat d. polar covalent bonding of the water molecules 38. The movement of water among the various body compartments is regulated by the presence of a. potassium in the extracellular fluid compartment b. sodium in the extracellular fluid compartment c. potassium in the intracellular fluid compartment d. chloride in the intracellular fluid compartment
.
39. Which of the physiological buffers is able to neutralize both acids and bases? a. bicarbonate-carbonic acid system b. hydrochloric acid system c. phosphates d. proteins 40. Aldosterone secretion is stimulated by angiotensin and a. decreased plasma potassium b. increased plasma sodium c. decreased concentrations of natriuretic peptides d. renin
.
41. Significant loss of what mineral occurs when one exercises vigorously while the temperature is high?
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Chapter_12_Water_and_Electrolytes a. sulphur b. phosphorus c. sodium d. potassium 42. Maintenance of blood volume is directly related to control of a. appetite b. thyroid hormone level c. respiratory rate d. blood pressure
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43. Which fluid makes up the highest percentage of body weight? a. intracellular water b. total body water c. extracellular water d. interstitial fluid 44. The anions in extracellular fluid (ECF) are a. chloride and ammonium b. bicarbonate and ammonium c. chloride and phosphate d. chloride and bicarbonate
.
45. What is a major function of chloride? a. protein synthesis in cells b. the principal intracellular electrolyte c. wound healing d. maintenance of gastric acidity 46. Dietary intake of which mineral correlates positively with blood pressure? a. magnesium b. calcium c. potassium d. sodium 47. Which mineral is the most abundant anion found in extracellular fluid? a. sodium b. chloride c. phosphorus d. magnesium 48. What is the major filtration force in the capillaries that is responsible for controlling movement of water from plasma to interstitial fluid and from interstitial fluid into plasma? a. colloid osmotic pressure
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Chapter_12_Water_and_Electrolytes b. theoretic osmotic pressure c. hydrostatic pressure d. effective osmotic pressure 49. Which body water reservoir is made up of plasma and interstitial fluid? a. intracellular b. extracellular c. total body water d. glomerular filtrate 50. Recent research has shown that a moderate intake of which substance can lower blood pressure? a. sodium b. alcohol c. calcium d. magnesium 51. What is the condition that may result in cardiac arrhythmias when extracellular potassium is increased? a. hypernatremia b. hypokalemia c. hyperkalemia d. hyponatremia 52. What is the condition that occurs in starvation or diabetes in which there is an increase in the urinary excretion of ammonia? a. metabolic alkalosis b. metabolic acidosis c. respiratory alkalosis d. respiratory acidosis 53. Which hormone, mediated by the enzyme renin, is primarily responsible for active reabsorption of sodium ions in the distal and collecting tubules? a. antidiuretic hormone b. aldosterone c. androsterone d. adrenocortical 54. Which enzyme facilitates formation of carbonic acid? a. renin b. angiotensinogen c. angiotensin d. carbonic anhydrase 55. A food may be labeled “low sodium” if each serving provides less than a. 5 mg b. 35 mg
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Chapter_12_Water_and_Electrolytes c. 140 mg d. 240 mg 56. Which process gives the body the capacity to maintain constancy in the internal environment? a. osmotic pressure b. osmolality c. homeostasis d. acid-base balance 57. In the body, water moves . a. from where solute concentrations are low to where solute concentrations are high b. from where solute concentrations are high to where solute concentrations are low c. across membranes regardless of solute concentrations d. from where water concentrations are low to where water concentrations are high 58. Increased intakes of which mineral have been shown to lower blood pressure, especially in those with hypertension? a. sodium b. calcium c. potassium d. magnesium 59. Some research has shown that supplements of which mineral are associated with significant reductions in both systolic and diastolic blood pressure, especially in individuals with hypertension? a. magnesium b. calcium c. potassium d. sodium 60. Acidosis occurs when . a. the plasma concentration of H ions falls below the normal range b. the plasma concentration of H ions exceeds the normal range c. chloride ion concentration exceeds hydrogen ion concentration d. sodium ion concentration exceeds chloride ion concentration 61. Not including physically active adults, the recommended fluid intake for the average adult is approximately water per kg of body weight. a. 15–35 mL b. 20–50 mL c. 25–40 mL d. 40–60 mL 62. A good predictor of hypertension is a measurement of a. serum sodium concentration
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Chapter_12_Water_and_Electrolytes b. urinary sodium excretion c. average daily sodium intake d. sodium filtration rate by the kidney 63. Approximately how much water is released into the gastrointestinal tract daily as part of secretions? a. 9 L b. 7 L c. 4 L d. 3 L 64. Which of the following is NOT one of the principal regulatory mechanisms for guarding against fluctuation in pH? a. temperature variation b. buffer systems c. respiratory center d. renal regulation 65. Colloid osmotic pressure attracts water into the plasma and is mainly due to a. large protein molecules b. the pumping of the heart c. sodium ions d. chloride ions
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66. According to the DASH study, which type of diet is effective in lowering blood pressure? a. low-fat rich in fruits and vegetables and low-fat dairy b. average fat, low in fruits and vegetables c. low fat, low in fruits and vegetables d. low fat, average fruits and vegetables 67. Which mineral serves as the major intracellular fluid cation? a. calcium b. chloride c. sodium d. potassium 68. Water is lost from the body each day primarily through a. feces b. sweat c. urine d. evaporation from respiration
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69. Which of the components comprising the nephron includes the capillary network called the glomerulus? a. collecting duct b. distal convoluted tubule c. loop of Henle
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Chapter_12_Water_and_Electrolytes d. Bowman’s capsule 70. Which is the chief cation of intracellular fluid for which maintenance of normal levels is essential to life of the cells? a. calcium b. sodium c. potassium d. bicarbonate
Hormones and Enzymes: Match each hormone or enzyme with its site of production and function in regulating fluid and electrolyte balance. a. hormone produced in atrial cells of the heart; functions to inhibit sodium reabsorption in the kidney, thereby promoting fluid loss b. hormone produced in hypothalamus; functions to conserve water by increasing reabsorption of water by the kidneys c. hormone produced in adrenal cortex; functions to stimulate active reabsorption of sodium by the kidneys, thereby promoting fluid retention d. enzyme produced by kidney; functions to hydrolyze angiotensinogen to angiotensin I e. active hormone produced by angiotensin-converting enzyme in the lungs; functions as vasoconstrictor, as stimulator for release of aldosterone, and as stimulator of hypothalamus to release vasopressin 71. vasopressin 72. aldosterone 73. renin 74. angiotensin II 75. atrial natriuretic peptide (ANP) Deficiency Symptoms: Match the deficiency symptom with the hormone or electrolyte. a. muscular weakness, paralysis b. anorexia, muscle atrophy c. decreased BP, reduced GFR d. sodium loss, dehydration e. weakness, lethargy 76. sodium 77. potassium 78. aldosterone 79. chloride 80. angiotensin II
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Chapter_12_Water_and_Electrolytes
81. What is the normal serum sodium concentration? Why are serum sodium concentrations indicative of fluid balance? 82. What is the basis for replacing some of the NaCl in the diet with KCl, and how does it work? 83. Explain the relationship between dietary sodium intake and essential hypertension. 84. If an individual is suffering from hypertension and has been advised to reduce his or her sodium intake, what foods should be avoided? How much sodium is present in a teaspoon of table salt? 85. Describe three mechanisms by which the kidneys conserve/excrete potassium or maintain potassium balance. 86. A chloride deficiency might lead to problems in which systems? Give details. 87. Explain how ACE inhibitors work to treat hypertension. 88. What are the recommended Adequate Intake (AI) values of water for adults? What factors will cause modifications in these values? 89. Discuss the sequence of events of the maintenance of fluid homeostasis by the renin-angiotensin-aldosterone system. 90. How does potassium help to maintain acid-base balance?
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Chapter_12_Water_and_Electrolytes Answer Key 1. True 2. True 3. False 4. True 5. False 6. True 7. False 8. False 9. True 10. True 11. False 12. False 13. True 14. False 15. True 16. d 17. b 18. a 19. d 20. c 21. b 22. c 23. a 24. c 25. d
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Chapter_12_Water_and_Electrolytes 26. a 27. d 28. b 29. a 30. a 31. b 32. a 33. a 34. d 35. c 36. c 37. c 38. b 39. d 40. c 41. c 42. d 43. b 44. d 45. d 46. d 47. b 48. c 49. b 50. b 51. c
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Chapter_12_Water_and_Electrolytes 52. b 53. b 54. d 55. c 56. c 57. a 58. c 59. a 60. b 61. c 62. c 63. b 64. a 65. a 66. a 67. d 68. c 69. d 70. c 71. b 72. c 73. d 74. e 75. a 76. b
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Chapter_12_Water_and_Electrolytes 77. a 78. d 79. e 80. c 81. Grading rubric – answer should include the following items: The normal serum sodium concentration is 135-145 mEq/L. The concentrations are indicative of fluid balance as a reflection of the level of dilution. Low sodium concentrations (hyponatremia) reflect excessive fluid in the plasma which means that the concentration is diluted by the additional fluid. High sodium concentrations (hypernatremia) reflect fluid loss so that the sodium is more concentrated due to the lower water levels. 82. Grading rubric – answer should include the following items: The basis for replacing NaCl with KCl is that potassium has been associated with lower calcium urinary excretion, whereas sodium increases it. Studies where KCl replaces some NaCl, as well as studies with supplemental potassium citrate demonstrate reduced urinary calcium with the increased potassium. 83. Grading rubric – answer should include the following items: Accumulation of sodium in body water is followed by retention of water and therefore expansion of blood volume, which increases intravascular pressure, resulting in hypertension. For those who do not excrete sodium normally, high dietary intake of sodium, which is almost completely absorbed, will result in essential hypertension. 84. Grading rubric – answer should include the following items: Certain foods, particularly those that are processed, contain large amounts of sodium in the form of sodium chloride. If an individual has been advised to restrict sodium intake, certain foods should be avoided due to their high sodium content. These include cold cuts/cured meats, soups, pizza, pickled foods, condiments such as ketchup and mustard and snack foods such as potato chips, salted nuts, corn chips, pretzels and other snacks that come with salt added. Smoked, processed or cured meats (luncheon meats, hot dogs, ham, corned beef) also contain high levels of sodium. Soy sauce is particularly high in sodium (>1000 mg/tablespoon). A teaspoon of salt contains 2,300 mg of sodium. Knowing this will allow an individual to estimate how much sodium is contained in a specific food by reading the nutrition label. 85. Grading rubric – answer should include the following items: Extracellular potassium, especially the blood level, is tightly regulated because it can be lethal if the concentration is too high or too low. If blood potassium is too high, aldosterone is released to enhance the excretion of potassium and also causes more potassium to be secreted into the glomerular filtrate. Similarly, vasopressin can enhance excretion. If blood potassium is too low, less aldosterone is stimulated and more potassium is retained by the kidneys. A third mechanism that is less well understood can control potassium levels and acts especially after a high-potassium meal to prevent hyperkalemia. It involves the actions of insulin, glucagon, and a kidney protein that quickly removes potassium from the blood to prevent blood concentrations from becoming too high. 86. Grading rubric – answer should include the following items: Because chloride has several functions in the body, different systems will be affected by a deficiency. Since chloride is a basic component of the hydrochloric acid in the stomach, a deficiency will lead to a decrease in the production of HCl, thus affecting digestion. In the immune system, chloride is released by white blood cells during phagocytosis to assist in destruction of foreign substances. A deficiency will interfere with the phagocytic process and will reduce the efficiency of the immune system. Because chloride acts as the exchange anion for bicarbonate in red blood cells allowing for transport of tissue-derived CO2 back to the lungs, a respiratory acidosis might develop as less CO2 is expelled due to reduced transport.
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Chapter_12_Water_and_Electrolytes 87. Grading rubric – answer should include the following items: Angiotensin II is created from angiotensin I in the lungs by the action of angiotensin converting enzyme (ACE). Angiotensin II has several roles in raising blood pressure including causing an increase in thirst, an increase in secretion of vasopressin leading to water retention and an increase in secretion of aldosterone from the adrenal cortex that leads to sodium retention and water retention. All of these will raise blood pressure. By inhibiting ACE, none of these effects will occur and blood pressure will become lower. 88. Grading rubric – answer should include the following items: The AI recommendation for adult females is 2.7 L and for adult males is 3.7 L, which allows for intake from foods and beverages consumed daily. These amounts will vary based on age, gender, environment, level of physical activity, rate of metabolism, level of energy intake and body weight. 89. Grading rubric – answer should include the following items: The rennin-angiotensin-aldosterone system controls thirst and both sodium and water excretion to maintain fluid balance. When dehydration occurs and plasma volume falls or blood pressure falls in the glomerulus, active renin is secreted by the kidneys. Renin is an enzyme that converts angiotensinogen (made in the liver) in the bloodstream to angiotensin I. As angiotensin I passes through the lungs, angiotensin-converting enzyme changes it to angiotensin II. Angiotensin II has three important actions to restore blood volume. It acts on the hypothalamus to stimulate thirst and acts on the hypothalamus to stimulate production of vasopressin, which in turn acts on the kidney to retain water. Angiotensin II also acts on the adrenal cortex to stimulate production of aldosterone, which in turn acts on the kidney to increase reabsorption of sodium in the kidney tubules. Increased thirst and drinking behavior, plus increased retention of water and sodium by the kidney, serve to normalize fluid balance. 90. Grading rubric – answer should include the following items: Potassium is involved in the cellular ion exchange system. The ionic form will move into and out of the cell in exchange for hydrogen ions based on the blood pH. In cases of acidosis where the blood pH is less than 7.35, potassium ions move out of the cells into the plasma while hydrogen ions move out of the plasma into the cells. This lowers the hydrogen ion concentration of the plasma, thus raising the pH. In cases of alkalosis where the blood pH is greater than 7.45, potassium ions move into the cells from the plasma while hydrogen ions move out of the cells into the plasma. This lowers the plasma pH.
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals
Indicate whether the statement is true or false. 1. Albumin carries zinc and copper in the portal circulation to all tissues in the body. a. True b. False 2. Metallothionein is a storage protein for excess zinc, copper, and iron. a. True b. False 3. Hemochromatosis is a genetic disorder that ultimately results in the excessive accumulation of iron in certain tissues. a. True b. False 4. Milk and dairy products are excellent sources of copper. a. True b. False 5. Zinc supplementation, if started within the first 24 hours of the onset of cold symptoms, may reduce the duration and severity of the symptoms. a. True b. False 6. Iron regulatory protein (IRE-BP) is activated (i.e., to bind IREs) by iron. a. True b. False 7. Calcium compounds have the ability to enhance the absorption of iron. a. True b. False 8. Copper deficiency can result in iron-deficiency anemia. a. True b. False 9. Zinc deficiency could result in a secondary deficiency of folate, because polyglutamate hydrolase is a zinc-containing enzyme. a. True b. False 10. Studies have shown that a combination of zinc, vitamins C and E, and beta-carotene may protect against age-related macular degeneration. a. True b. False 11. Most copper circulating in the blood is in the form of hCtr1.
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals a. True b. False 12. Endocytosis is the mechanism for a transferrin receptor transporting iron into a cell. a. True b. False 13. Overall, assessing the status of zinc is difficult and requires multiple measures. a. True b. False 14. Trace minerals are required by the body in amounts of less than 1 mg/day. a. True b. False 15. Manganese functions both as an enzyme activator and as a constituent of metalloenzymes. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Hemoglobin and hematocrit are common measurements for assessment of nutriture for which mineral? a. iodine b. zinc c. chromium d. iron 17. Nutrient-drug interactions caused by drugs such as statins used to treat cardiovascular disease are most likely to result in . a. poor absorption of vitamins b. poor metabolism of the drug when taken with grapefruit c. enhanced metabolism of the drug, rendering it less effective when taken on an empty stomach d. enhanced excretion of potassium and other electrolytes 18. The enzyme that converts retinol to retinal and ethanol to acetylaldehyde contains four a. copper b. iodine c. zinc d. iron
atoms.
19. Which mineral serves as a cofactor in xanthine oxidase in the metabolism of purines, pyrimidines, and pteridines? a. manganese b. molybdenum c. copper d. chromium
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals 20. Which mineral facilitates transfer of electrons in the electron transport chain? a. calcium b. nickel c. zinc d. iron 21. Which statement about selenium metabolism is true? a. Free selenide can be converted into selenophosphate. b. Selenocysteine is degraded to yield selenomethionine. c. Dietary selenocysteine can be utilized directly to produce selenium-dependent enzymes. d. Significant cellular damage occurs only with complete cessation of selenoprotein synthesis. 22. The binding of iron by proteins defends the cells against a. iron deposition in kidneys and other organs b. oxidative damage from free radicals c. tissue hypoxia d. stellate cells
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23. Nutrient-drug interactions caused by antacids used to treat GERD are most likely to result in . a. poor absorption of nutrients such as iron b. poor absorption of the drug when taken with grapefruit c. enhanced metabolism of the drug, rendering it less effective when taken on an empty stomach d. enhanced excretion of potassium and other electrolytes 24. Absorption of dietary iron is regulated by , produced by the liver when iron stores are high and released to the blood to act at the surface of enterocytes and macrophages. a. hepcidin b. hephaestin c. ferroportin d. hemoglobin 25. Acute iron toxicity is observed mostly with a. excess ferroxidase levels b. accidental iron overload c. hemochromatosis d. excess plasma ferritin
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26. The primary physiological role of which mineral is to act as a constituent in the thyroid hormones? a. fluorine b. iodine c. selenium d. chromium 27. Which trace mineral is important for activating a key enzyme in gluconeogenesis?
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals a. iron b. copper c. iodine d. manganese 28. In addition to an actual deficiency of iron, iron-deficiency anemia may develop when normal iron levels are present, when there is a deficiency of . a. copper b. zinc c. selenium d. iodine 29. Excessive chronic intake of zinc results in a deficiency of a. iron b. copper c. selenium d. molybdenum
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30. People living in regions that contain high soil molybdenum levels may develop a. gout b. heart disease c. reduced urea production d. cretinism 31. Zinc is important for taste perception as a component of a. carbonic anhydrase b. alcohol dehydrogenase c. gustin d. metallothionein
.
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32. The addition to the diet of which food will alleviate the problem of endemic goiter? a. cabbage b. broccoli c. cassava d. iodized salt 33. Which mineral is an essential factor in the action of glutathione peroxidase (GPX) in the reduction of organic peroxides and hydrogen peroxide? vanadium a. molybdenum b. selenium c. silicon d. vanadium
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals 34. Which two minerals are readily oxidized within tissues? a. iron and copper b. zinc and molybdenum c. iodine and manganese d. zinc and copper 35. Which micromineral is necessary for iodine metabolism? a. fluorine b. manganese c. chromium d. selenium 36. Which mineral is critical for oxidizing iron to be bound by transferrin for delivery to the tissues from the gut and liver? a. zinc b. manganese c. copper d. chromium 37. Which mineral is thought to potentiate the action of insulin? a. chromium b. manganese c. copper d. cobalt 38. Arginase, a key enzyme in liver urea production, requires four a. iron b. copper c. zinc d. manganese
atoms per molecule.
39. Zinc is found in foods complexed with amino acids in which family? a. eicosanoids b. steroids c. peptides and proteins d. amines 40. Nutrient-drug interactions caused by anticonvulsants such as phenobarbital used to treat seizures are most likely to result in . a. poor absorption of nutrients such as iron b. poor absorption of the drug when taken with grapefruit c. reduced metabolism of vitamins d. enhanced excretion of potassium and other electrolytes 41. Selenium deficiency is linked to which disease?
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals a. Menkes b. Wilson’s c. Kashin-Beck d. Keshan 42. Which of the microminerals is considered essential for normal brain function? a. chromium b. fluorine c. vanadium d. manganese 43. Which element, if present in high concentrations in the body, disrupts normal zinc functions? a. cadmium b. chromium c. selenium d. molybdenum 44. ZIP4 . a. mutations result in zinc toxicity due to acrodermatitis enteropathica b. is the primary transporter of zinc into enterocytes c. is expressed only in the liver d. degrades more rapidly when zinc intakes are low 45. In the presence of low intracellular iron, the binding of iron regulatory protein (IRP) to iron response elements (IREs) present on the ferritin mRNA . a. results in a decrease in ferritin abundance b. results in an increase in ferritin abundance c. occurs only when intracellular iron concentrations are high d. does not occur 46. Heme is readily absorbed intact in the a. colon b. distal jejunum and ileum c. duodenum and proximal jejunum d. stomach and duodenum
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47. The chemistry of selenium is similar to that of a. phosphorus b. sulfur c. chloride d. bromine
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48. Which trace mineral participates in the greatest number of enzyme systems? a. zinc
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals b. iron c. selenium d. copper 49. Which amino acid may enhance copper absorption? a. alanine b. serine c. cysteine d. lysine 50. Nutrient-drug interactions caused by consuming amines in foods such as aged cheeses with monoamine oxidase inhibitors used to treat depression are most likely to result in . a. high blood pressure and cardiac dysrhythmia b. poor absorption of the drug when taken with grapefruit c. enhanced metabolism of the drug, rendering it less effective when taken on an empty stomach d. enhanced excretion of potassium and other electrolytes 51. Iron-deficiency anemia related to copper deficiency occurs due to the reduced activity of a. cytochrome c oxidase b. lysyl oxidase c. pteridines d. ceruloplasmin
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52. What genetic disorder causes copper toxicity? a. hemochromatosis b. Keshan disease c. Menkes disease d. Wilson’s disease 53. The protein that plays a dual function in both iron and copper homeostasis is a. ferritin b. transferrin c. metallothionein d. ceruloplasmin
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54. Excessive intake of nonheme iron interferes with absorption of which mineral by an unknown mechanism? a. manganese b. zinc c. chromium d. selenium 55. When superoxide radicals accumulate, superoxide dismutase catalyzes the formation of hydrogen peroxide. What happens to the hydrogen peroxide? a. It freely dissociates to water. b. It is excreted in the urine and through the lungs.
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals c. It is converted to water and oxygen via catalase or glutathione peroxidase. d. It is used in the synthesis of DNA and RNA. 56. Which of the following dietary components impedes copper absorption? a. gluconate b. phosphate c. citric acid d. phytic acid 57. Which statement is false? a. Hemosiderin as a storehouse of iron predominates when iron concentrations in the liver are low. b. Iron is stored mainly in the liver, bone marrow, and spleen. c. Iron is released more slowly from hemosiderin than from ferritin. d. Ferritin is an unstable compound that is constantly being degraded and resynthesized. 58. Which nonmetal nutrient deficiency is associated with Keshan disease, characterized by cardiomyopathy? a. iodine b. zinc c. selenium d. molybdenum 59. Hypochromic, microcytic anemia is associated with a deficiency of a. selenium b. iron c. copper d. molybdenum
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60. Which vitamins/minerals are required for heme synthesis? a. vitamin E, vitamin C, and iron b. folate, B12, and iron c. B6, zinc, and iron d. copper, zinc, and folate 61. Lithium carbonate is one of the medications used to treat bipolar disorder. A condition that might develop in patients using this medication is . a. iron-deficiency anemia b. glucose intolerance c. Keshan disease d. hypothyroidism 62. Peroxynitrite is synthesized by activated white blood cells from which radicals? a. superoxide b. glutathione c. nitrogen monoxide
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals d. iodothyronine 63. Zinc used intranasally has been shown to cause a. an eroded septum b. nosebleeds c. anosmia d. chronic congestion
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64. Iodine deficiency associated with neurological problems in infants results in a. cretinism b. Keshan disease c. goitrin d. goiter
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65. At the cellular level, which mineral interacts with vitamin A by promoting growth and helping to synthesize retinolbinding protein? a. cobalt b. zinc c. silicon d. chromium 66. Iron content of the average American diet is estimated to be about a. 1–4 mg iron per 1,000 kcal b. 5–7 mg iron per 1,000 kcal c. 8–15 mg/day d. 18 g /day 67. Chromium absorption is inhibited by a. antacids; picolinate b. methionine; phytic acid c. picolinic acid; vitamin C d. phenylalanine; histidine
and enhanced by
.
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68. Which of the following dietary substances inhibits uptake of nonheme iron? a. ascorbic acid b. lactic acid c. tea d. MFP 69. Nutrient-drug interactions caused by diuretics used to treat high blood pressure are most likely to result in a. poor absorption of vitamins b. poor absorption of the drug when taken with grapefruit c. enhanced metabolism of the drug, rendering it less effective when taken on an empty stomach d. enhanced excretion of potassium and other electrolytes
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals 70. Where would you find iron regulatory protein (IRPs)? a. cytosol b. nucleus c. mitochondria d. Golgi apparatus
Mineral Functions: Match each mineral with a representative enzyme and the physiological roles for which that mineral is important. a. superoxide dismutase and brain and CNS function b. myeloperoxidase and amino acid metabolism c. carbonic anhydrase and sexual maturation d. dopamine monooxygenase and synthesis of neurotransmitters e. glutathione peroxidase and protection from oxidant damage 71. iron 72. zinc 73. copper 74. selenium 75. manganese Mineral Deficiencies: Match each mineral with the symptoms of its deficiency. a. urinary sulfate and urate excretion b. poor wound healing, anorexia, subnormal growth c. goiter d. glucose intolerance e. anemia, neutropenia, bone abnormalities 76. iodine 77. chromium 78. molybdenum 79. copper 80. zinc
81. Describe the process for transport of chromium and explain how it is absorbed into cells. 82. Explain copper’s role in normal iron metabolism and how a deficiency causes anemia.
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals 83. Certain foods have been classified as containing goitrogens. List three of these foods and tell how they affect iodide uptake in the thyroid. 84. Explain the influences of zinc on carbohydrate metabolism, BMR, and taste. 85. Detail the absorption of iodine. Be sure to include the tissues where iodine ends up after absorption. 86. Protein Regulation by Minerals: Zinc, copper, and iron regulate the expression of specific proteins, particularly those that are involved in ensuring cells receive these minerals, and those involved in preventing any toxicity associated with too much of a given mineral. Describe how excess zinc (or copper, but not both) and iron regulate the expression of a protein involved in their storage. Be specific—name any proteins and define all abbreviations. 87. Discuss the following measurements of red blood cells, telling what they are and how they are used in assessment of iron nutriture: hemoglobin, hematocrit, MCV, MCH, MCHC. 88. Which factors inhibit the absorption of zinc and by what mechanisms do they act? 89. Explain the uses of peroxidases. 90. List five dietary factors that influence iron absorption and indicate what each factor does.
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals Answer Key 1. True 2. False 3. True 4. False 5. True 6. False 7. False 8. True 9. True 10. True 11. False 12. True 13. True 14. False 15. True 16. d 17. b 18. c 19. b 20. d 21. a 22. b 23. a 24. a 25. b
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals 26. b 27. d 28. a 29. b 30. a 31. c 32. d 33. b 34. a 35. d 36. c 37. a 38. d 39. c 40. c 41. d 42. d 43. a 44. b 45. a 46. c 47. b 48. a 49. c 50. a 51. d
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals 52. d 53. d 54. b 55. c 56. d 57. a 58. c 59. c 60. c 61. d 62. a 63. c 64. a 65. b 66. b 67. a 68. c 69. d 70. a 71. b 72. c 73. d 74. e 75. a 76. c
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals 77. d 78. a 79. e 80. b 81. Grading rubric – answer should include the following items: Chromium is transported in the blood the same way that iron is transported. That is, it is bound to transferrin. Because iron may be attached to the transferrin, thus not leaving any space for the chromium, it is believed that albumin takes over the transport of chromium. In addition, if chromium is present in high concentrations, globulins and lipoproteins also transport the mineral. It is also possible that some unbound chromium circulates in the blood. In order to enter into cells, the chromium is taken in by the process of endocytosis and is released from the endosome once it is inside of the cell. 82. Grading rubric – answer should include the following items: Copper is necessary for the proper functioning of the ferroxidse activity of hephaestin and ceruloplasmin that oxidizes iron to its trivalent state. A deficiency of copper will reduce the activity of ceruloplasmin and the expression of hephaestin causing iron to remain trapped inside of cells. So a copper deficiency will result in a secondary microcytic iron-deficiency anemia caused by impaired mobilization and use of iron. Treatment with copper is necessary to reverse the anemia. 83. Grading rubric – answer should include the following items: Foods of the cabbage family (broccoli, cauliflower, kale, rutabaga, turnips) contain glucosinolates, which compete with iodide for uptake into the thyroid gland. Cassava contains linamarin (also known as goitrin), which breaks down into thiocyanate, which competes with iodide for uptake into the thyroid gland. Lima beans, flaxseed, linseed, sorghum, and sweet potatoes also contain cyanogenic glucosides similar to linamarin. 84. Grading rubric – answer should include the following items: Zinc is needed by pancreatic beta cells for production of insulin and thus influences carbohydrate metabolism. Zinc deficiency causes impaired glucose tolerance. Zinc is important for thyroid hormone production and so zinc deficiency can result in a lower BMR. Zinc is a component of gustin, which is important for perception of taste sensations. 85. Grading rubric – answer should include the following items: Iodide is absorbed predominantly in the stomach and secondarily from the duodenum. Most ingested iodide (90%) is absorbed, after which free iodide appears in the blood. At this point, it is capable of permeating all tissues, although it actually concentrates in the thyroid gland. Lesser amounts appear in the ovaries, skin and salivary, gastric, and mammary glands. 86. For Zn and Cu, as the intracellular concentration increases, they bind to metal-binding protein in the nucleus, which in turn binds to the metal response element of specific regions of DNA. One of these regions is present for the metallothionein, resulting in increased transcription. Thus, high levels of Zn and/or Cu induce the expression of a protein that can serve as a storage site and prevent toxicity of these metals. Cu can use the same mechanism to increase transcription of superoxide dismutase. For iron, to prevent toxicity one needs to increase the abundance of ferritin as iron concentrations rise in the cell. However, this is done at a posttranscriptional level (i.e., increasing the translation of existing mRNA for ferritin). High iron levels result in inactive IRP, which does not bind to the IRE present in the 5' untranslated region of ferritin mRNA, allowing it to be translated at a greater rate. In contrast, when iron levels are low, IRP is active, binds the ferritin mRNA IRE, and inhibits translation. 87. Grading rubric – answer should include the following items:
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals • • •
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Hemoglobin is the amount of iron-containing protein found in red blood cells per unit, usually deciliter or liter, of blood. When this drops below normal, anemia occurs. Hematocrit is a measurement of the proportion of the total blood volume that is red blood cells. When this drops below normal, anemia occurs. MCV is mean corpuscular volume and indicates the size of the red blood cell. If cell size is large, then macrocytic anemia may indicate a folate or B12 deficiency. Microcytic anemia or small cell size may indicate iron-deficiency anemia. MCH is mean corpuscular hemoglobin and indicates the average hemoglobin content of each cell. MCHC is mean corpuscular hemoglobin concentration and indicates the amount of hemoglobin per deciliter of red blood cells. If MCH and MCHC are low, iron-deficiency anemia is indicated.
88. Grading rubric – answer should include the following items: •
• •
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Phytic acid, which is found in plant foods (legumes, lentils, nuts, seeds and whole-grain cereals), binds to zinc via oxygen within the compound’s phosphate groups. The zinc-phytic acid complex is large and also insoluble, thus making absorption very difficult. If the phytate-to-zinc molar ratio is greater than 15 to 1, reductions in zinc bioavailability are greatest. Oxalic acid (oxalate) occurs in a variety of foods, especially in spinach chard, berries, chocolate and tea. The zincoxalic acid complex is also difficult to absorb and lowers serum zinc levels. Polyphenols (e.g., tannins and gallic acid) are found in tea and coffee, some fibers, whole grains, fruits and vegetables. The amount consumed determines how much interference to zinc absorption occurs. In addition, the combination of how much polyphenol is consumed and how much additional zinc is in the diet work together to determine the impact on the individual’s zinc status. Other minerals, such as iron and calcium, may or may not impact zinc absorption. Iron intake of 20–25 mg or more, or in a ratio with zinc of 2 (or higher) to 1, will impair zinc absorption if they are consumed in a solution, but not if they are part of a meal. As for calcium, studies are conflicting. Some show that ingestion of calcium in the form of calcium carbonate, hydroxyapatite, or calcium citrate malate at levels of 500 mg–2 g has no effect on zinc absorption. Other studies showed that calcium taken in the form of calcium in milk, calcium phosphate and calcium carbonate led to a reduction in zinc absorption. So, the form of calcium taken in may or may not interfere with zinc absorption.
89. Grading rubric – answer should include the following items: Peroxidases are used to protect the body from harmful substances. They exist in several forms, each of which has a different function. Catalases are used to convert hydrogen peroxide (known to cause cellular damage) to water and molecular oxygen. This is one of the major antioxidant enzymes. Myeloperoxidase is located in both the plasma and in neutrophils, one of the five types of white blood cells. When neutrophils perform phagocytosis, myeloperoxidase enters the phagocytic vesicle and catalyzes hydrogen peroxide and the chloride ion that are present in the vesicle into water and hypochlorite. The hypochlorite is a powerful oxidant that destroys bacteria. Thyroperoxidase is needed for organification of iodide. It also conjugates thyroglobulins to form the thyroid hormones. 90. Grading rubric – answer should include the following items: • • • •
Sugars serve as ligands that help absorption of iron. Acids (lactate, ascorbate, citrate) act as reducing agents to increase absorption. Meat, poultry, and fish promote absorption, although the mechanism is unclear. Phytic acid and oxalic acid both form insoluble complexes with iron that keep it from being absorbed.
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Chapter_13_Essential_Trace_and_Ultratrace_Minerals •
Antacid medications inhibit absorption by making the environment more alkaline.
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals
Indicate whether the statement is true or false. 1. More than 85% of ingested boron is absorbed as boric acid by passive diffusion. a. True b. False 2. Cobalt was used to preserve foods such as fish, meat cream and butter for over 50 years. a. True b. False 3. Even though fluoride is a gaseous chemical, it is usually found bound to a metal, nonmetal, or organic compound. a. True b. False 4. Quartz is possibly the most well-known form of silicon in nature. a. True b. False 5. No Tolerable Upper Level for nickel has been established in humans. a. True b. False 6. Nickel is considered an essential element and is crucial for several body functions. a. True b. False 7. The highest concentrations of nickel in the body are found in the skin and skeletal muscles. a. True b. False 8. Vanadium should be a useful supplement to aid in glucose management by diabetics. a. True b. False 9. Boron deficiency may affect attention, mental alertness, and memory. a. True b. False 10. Table salt may contain silicon to prevent caking in damp weather. a. True b. False 11. Boron may alter the ability of some hormones to exert their effects on target cells. a. True b. False
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals 12. Generally, silicon concentrates in the body’s connective tissue, such as bone, tendons, and cartilage. a. True b. False 13. Black-foot disease is associated with high nickel exposure. a. True b. False 14. Although fluoride is used to strengthen teeth and bones, fluoride toxicity (fluorosis) is associated with an increased bone fracture risk. a. True b. False 15. In the United States, there are strict federal limits controlling the acceptable levels of arsenic in foods. a. True b. False
Indicate the answer choice that best completes the statement or answers the question. 16. Nickel decreases the absorption of which mineral? a. sodium b. chloride c. iodine d. iron 17. Which ultratrace element, in pharmacological quantities, mimics the action of insulin? a. boron b. silicon c. nickel d. vanadium 18. Toxicity of which element results in green tongue, diarrhea, and GI cramps? a. vanadium b. silicon c. arsenic d. boron 19. Which ultratrace element is a constituent of vitamin B12? a. arsenic b. vanadium c. boron d. cobalt 20. The weathering of rocks and volcanic emissions release which element into the environment that eventually ends up in the food supply?
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals a. arsenic b. nickel c. vanadium d. cobalt 21. There is little evidence that cobalt plays a role in human nutrition. However, it is part of a metallovitamin that is crucial for human survival. That vitamin is . a. vitamin B6 b. vitamin B3 c. vitamin B12 d. vitamin B1 22. Where might one expect to find a higher incidence of arsenic toxicity? a. Europe b. Asia c. United States d. Africa 23. Which mineral replaces some of the hydroxide ions in hydroxyapatite to help protect against cavities in teeth? a. cobalt b. vanadium c. boron d. silicon 24. Which ultratrace element may be absorbed through inhalation and via the skin? a. boron b. arsenic c. vanadium d. nickel 25. Arsenic exists mostly in which forms? a. monovalent and trivalent b. bivalent and pentavalent c. monovalent and bivalent d. trivalent and pentavalent 26. Arsenic’s toxicity is directly related to its interaction with which part of proteins? a. amino groups b. carboxyl groups c. sulfhydryl groups d. side chains on amino acids 27. Which ultratrace element effects the composition, structure, and strength of bones as well as cell membrane stability and inflammation?
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals a. vanadium b. cobalt c. arsenic d. boron 28. Which element has a positive influence on collagen synthesis and bone mineralization? a. silicon b. vanadium c. arsenic d. nickel 29. Nausea, vomiting, diarrhea, acidosis, and cardiac arrhythmias are associated with acute toxicity from a. arsenic b. vanadium c. nickel d. fluoride
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30. Which categories of food provide the most nickel? a. red meats b. nuts, legumes, and grains c. fish d. milk and milk products 31. In animals, a deficiency of which element is associated with diminished growth, abnormal reproduction, reduced conception rate, and increased neonatal mortality? a. arsenic b. vanadium c. boron d. silicon 32. Which ultratrace element is normally consumed at <100 µg/day, mainly from nuts, legumes, grains, and chocolate, and has been assigned a Tolerable Upper Intake Level of 1 mg/day? a. nickel b. silicon c. cobalt d. boron 33. Which micromineral plays a contributing role in the formation of hydroxyapatite crystals that are more resistant to acid erosion? a. arsenic b. selenium c. fluoride d. nickel 34. Human toxicity has been shown as black foot disease, a peripheral vascular condition, in individuals drinking water
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals contaminated with a. boron b. arsenic c. silicon d. vanadium
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35. The richest dietary sources of vanadium are a. fats and oils b. cereal and grain products c. sweeteners d. milk products
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36. Because of its anti-inflammatory actions, which element may reduce the severity of inflammation associated with injury or infection? a. cobalt b. boron c. silicon d. arsenic 37. An ultratrace element that can inhibit many systems that require phosphate, such as phosphotransferases, is a. nickel b. arsenic c. vanadium d. boron
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38. No federal limits in foods or juices have been established for which ultratrace element, which is well known for its toxicity? a. arsenic b. cobalt c. boron d. vanadium 39. Which of the following would NOT be a Red Flag of Junk Science? a. dire warnings of danger from a single product or regimen b. lists of “good” and “bad” foods c. recommendations from studies that ignore individual or group differences d. recommendations based on peer-reviewed studies 40. Which element is second only to oxygen in abundance on earth? a. nickel b. vanadium c. silicon d. cobalt 41. What foods are rich sources of silicon?
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals a. whole grains and root vegetables b. coffee and beer c. milk and milk products d. meats, poultry, and fish 42. What ultratrace element has been shown to inhibit Na+/K+-ATPase function and the absorption of amino acids at higher concentrations? a. vanadium b. arsenic c. cobalt d. boron 43. Toxicity levels of arsenic are best detected by a. serum testing b. hair analysis c. skin biopsy d. saliva analysis
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44. Before it is absorbed, fluoride in foods, often bound to proteins, must be hydrolyzed by a. pepsin b. amylase c. lipase d. ATPase
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45. Which ultratrace element is not required by humans in its ionic form, but is a necessary component of the coenzyme form of a vitamin? a. iron b. boron c. cobalt d. vanadium 46. Dietary inhibits absorption of silicon. a. iron b. lactose c. fiber d. alkalinity 47. Why are manufacturers of dietary supplements not required to secure approval to sell their products? a. because they are not medicines b. because they are always safe c. because they actually are not effective d. because they are sold in very low doses 48. Antacids, antidiarrheal agents and analgesics often have which element added?
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals a. cobalt b. nickel c. vanadium d. silicon 49. Which ultratrace element was used as a preservative for meat, fish, and dairy products in the early 1900s, considered dangerous for humans in the 1920s, and today, is considered beneficial for humans? a. cobalt b. arsenic c. boron d. vanadium 50. Fish, sardines with bones, clams, lobster, crab, and shrimp are good sources of a. cobalt b. fluoride c. vanadium d. silicon
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51. Which mineral is contained in a preformed metallovitamin essential for humans that cannot be synthesized from dietary sources? a. cobalt b. silicon c. nickel d. boron 52. One of the pathways of arsenic metabolism involves conjugation with a. glutathione b. choline c. phospholipids d. SAM
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53. Abdominal pain, vomiting, diarrhea, muscle cramping numbness and tingling in the extremities, and liver damage are associated with acute toxicity from . a. arsenic b. vanadium c. silicon d. boron 54. Which element is thought to work by its interactions with SAM and NAD+? a. vanadium b. silicon c. boron d. nickel
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals 55. Which of the following groups of foods are richest in boron, providing 1.0–4.5 mg/100 g? a. raisins, legumes, nuts, and avocados b. pork, beef, and poultry c. milk, butter, cheese, and yogurt d. fish and shellfish 56. A derivative of which element is approved for treatment of promyelocytic leukemia? a. boron b. cobalt c. nickel d. arsenic 57. Which element is found as a contaminant in lipsticks, soap, some antibiotics, and gastric antacids? a. cobalt b. arsenic c. silicon d. boron 58. The form of fluoride in toothpaste is a. hydrofluoric acid b. calcium fluoride c. potassium fluoride d. sodium fluoride
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59. The Dietary Supplement Health and Education Act (DSHEA) of 1994 requires that manufacturers . a. secure prior approval to sell their products b. demonstrate that the supplements are safe c. provide a disclaimer on the label stating that “this statement has not been evaluated by the Food and Drug Administration” d. provide proof of the dietary supplement’s effectiveness 60. It has been suggested that which element modulates osteoblast and/or osteoclast activity in bones? a. boron b. arsenic c. fluoride d. nickel 61. S-adenosylmethionine most likely provides most of the methyl groups needed for methylation of which element? a. silicon b. vanadium c. arsenic d. boron 62. The development of bluish skin and nails resulting from ingestion of silver over a period of time is called a. ichthyosis
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals b. argyria c. progeria d. urticaria 63. Which ultratrace element enters the cell through transport systems for phosphate, with which it competes? a. nickel b. boron c. vanadium d. cobalt 64. Which of the following interacts with fluoride in such a way as to inhibit absorption? a. aluminum b. phosphate c. calcium d. sodium 65. The major detrimental effect of a long-term excess of dietary silicon, usually in the form of antacids, is a. cancer b. asthma c. diabetes d. kidney stones 66. In humans, signs of nickel a. toxicity b. deficiency c. subclinical deficiency d. carcinogenesis
include nausea, vomiting, and difficulty breathing.
67. Boron is associated with which of the following functions? a. metabolism of methionine and methylation of DNA b. bone development and mediation of the inflammatory response c. synthesis of glucosamine, chondroitin sulfate, and collagen d. insulin action 68. Nanoparticles have a particle size between a. 1 and 100 nm b. 10 and 200 nm c. 100 and 200 nm d. 200 and 400 nm
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69. Acute toxicity with which element causes nausea, vomiting, diarrhea, dermatitis, and lethargy? a. arsenic b. boron c. cadmium
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals d. vanadium 70. Which mineral has beneficial effects on the brain, bones, and the immune system? a. boron b. cobalt c. silicon d. nickel
Deficiency Symptoms: Match each ultratrace mineral with its associated deficiency symptoms. a. decreased collagen, long bone, and skull abnormalities b. paired fertility, reduced survival, growth, and development c. impaired growth and reproduction d. impaired bone health, cognitive/brain function, and immune response e. depressed reproduction and growth; impaired hematopoiesis 71. arsenic 72. boron 73. nickel 74. silicon 75. vanadium Mineral Functions: Match each ultratrace mineral with its associated functions. a. reduction in dental caries b. methyl group use c. bone development, immune system function, and brain function d. connective tissue and bone formation e. mimicking insulin 76. arsenic 77. boron 78. silicon 79. vanadium 80. fluoride
81. Describe the pharmacological effects of vanadium. 82. Although all produce symptoms of toxicity, not all of the important trace elements have a Tolerable Upper Intake
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals Level established. Give the UL and/or the toxicity symptoms of arsenic, boron, nickel, silicon, and vanadium. 83. How does nickel work in the human body? 84. What is different about cobalt as an ultratrace mineral as compared to the other ultratrace minerals in regard to human nutrition? 85. How does boron exert its effect on body functions? 86. Describe the mechanism by which boron is thought to bring about the beneficial effects of inhibiting inflammation and positively influencing bone composition, structure and strength. 87. Detail why children excrete less fluoride in their urine that do adults? How is fluoride absorbed? 88. Explain the physiological role of silicon in normal growth and bone development. 89. How might a type II diabetic or prediabetic benefit from taking vanadium supplements? 90. Discuss the paradox between the benefits versus the toxic effects of arsenic.
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals Answer Key 1. True 2. False 3. True 4. True 5. False 6. False 7. False 8. True 9. True 10. True 11. True 12. True 13. False 14. True 15. False 16. d 17. d 18. a 19. d 20. b 21. c 22. b 23. c 24. b 25. d
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals 26. c 27. d 28. a 29. d 30. b 31. a 32. a 33. c 34. b 35. b 36. b 37. c 38. a 39. d 40. c 41. a 42. a 43. b 44. a 45. c 46. c 47. a 48. d 49. c 50. b 51. a
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals 52. a 53. a 54. c 55. a 56. d 57. d 58. d 59. c 60. a 61. c 62. b 63. c 64. c 65. d 66. a 67. b 68. a 69. b 70. a 71. c 72. d 73. e 74. a 75. b 76. b
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals 77. c 78. d 79. e 80. a 81. Grading rubric – answer should include the following items: In pharmacological amounts, vanadium mimics the action of insulin by stimulating glucose uptake by moving GLUT4 transporters to the cell membrane, enhancing glucose uptake, and stimulating glycogen and lipid synthesis while it inhibits gluconeogenesis and lipolysis. Vanadium improves insulin sensitivity and reduces serum glucose concentrations and hemoglobin A1c. 82. Grading rubric – answer should include the following items: Arsenic – No UL. Acute toxicity: GI distress, dehydration, electrolyte imbalance, muscle cramping, numbness and tingling. Chronic toxicity: skin hyperpigmentation, hyperkeratosis, muscle weakness, peripheral neuropathy, excessive sweating, liver and kidney damage, delirium, encephalopathy, vascular changes, and cancers. Boron – UL is 20 mg/day. Acute toxicity: nausea, vomiting, diarrhea, dermatitis, and lethargy. Chronic toxicity: nausea, poor appetite, anemia, dermatitis, and seizures. Nickel – UL is 1 mg/day. Acute toxicity: headache, nausea, vomiting, insomnia, and irritability. Delayed symptoms, which may occur up to 5 days after ingestion: tightness of the chest, cough, difficulty breathing, tachycardia (rapid heart rate), palpitations, sweating, weakness, and possibly death. Chronic toxicity (from occupational exposure via inhalation): respiratory and other systemic disorders as well as cancer. Silicon – No UL. Toxicity from silicon has been associated with the formation of kidney stones; however, it is frequent, chronic (years) use of large amounts of silicon-containing antacids that appears to contribute to the rare development of kidney stones. Toxicity of silicon has also been associated with diminished activities of several enzymes that prevent free radical damage, including glutathione peroxidase, superoxide dismutase, and catalase. Silicosis occurs from the inhalation of dust high in silica; the condition is characterized by a progressive fibrosis of the lungs that leads to respiratory problems. Vanadium – UL is 1.8 mg/day. Mild toxicity: green tongue syndrome, diarrhea, and gastrointestinal cramps. Chronic toxicity (as seen in miners): hypertension, respiratory tract irritation neurological disorders, and hepatic, cardiac, and renal damage. 83. Grading rubric – answer should include the following items: Research has not been able to define a specific role for nickel in the human body. It is possible that it may be involved directly in the activity of cyclic nucleotide-gated (CNG) channels and/or with guanylate cyclase activity, which potentiates the action of CNG channels. These channels play a role in renal function and may be found in several other organ systems including the central nervous system, reproductive system and urogenital system. 84. Grading rubric – answer should include the following items: Because there is little evidence suggesting that cobalt itself is necessary in human nutrition, its importance is its inclusion in the vitamin B12 molecule. This vitamin is crucial to human survival and, therefore, without cobalt the vitamin would not exist. Studies have shown that ionic cobalt can substitute for other metals in metalloenzyme activity in vitro, but there is no evidence to show that this occurs in vivo. 85. Grading rubric – answer should include the following items: Boron most likely exerts its effect on several body functions by interacting with S-adenosylmethionine (SAM) and nicotinamide adenine dinucleotide (NAD+). An example is as boron binds to NAD+, intracellular signaling pathways are affected and may inhibit calcium release from the endoplasmic reticulum into the cell cytosol. It’s also possible that boron may form complexes with cell membrane components such as glycoproteins, glycolipids and phosphoinositides.
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Chapter_14_Nonessential_Trace_and_Ultratrace_Minerals These types of activities suggest that boron may alter the ability of some hormones to act on their target cells. 86. Grading rubric – answer should include the following items: Boron facilitates the production of anti-inflammatory cytokines and other molecules. Bone composition, structure and strength are positively influenced possibly through nodulation of osteoblast and or osteoclast activity. In addition, it enhances extracellular matrix turnover. 87. Grading rubric – answer should include the following items: Healthy children continue to grow during their childhood years. Fluoride is absorbed from the stomach and small intestine by passive diffusion. The absorption rate is nearly 100% and happens within 90 minutes of ingestion. Most fluoride, although distributed throughout the body and taken up by several different tissues, is more highly concentrated in the bones and teeth. Because the children’s bones are growing, they incorporate more fluoride into the skeleton and excrete less in the urine than do normal adults. 88. Grading rubric – answer should include the following items: Silicon likely plays a role in both metabolism and structure of bone. It influences both formation and growth, including mineralization, calcification and crystallization. It also enhances collagen synthesis. This aids in bone growth because collagen is present in high concentrations in bone. 89. Grading rubric – answer should include the following items: Insulin requires receptors on cells so that it may assist glucose to enter the cell. Vanadium mimics the action of insulin, but most likely not via the receptors, but through interactions with cytosolic and plasma membrane protein kinases to affect intracellular insulin signaling pathways. This activation of cytosolic protein kinases enhances glucose and lipid metabolism. Vanadate activates Akt signaling through inhibition of protein tyrosine phosphatases, which prolongs the activity of phosphorylated enzymes and enhances the insulin signaling pathway. These activities, by bypassing insulin receptors, will help to lower serum glucose levels without relying on the faulty relationship between insulin and its receptors. 90. Grading rubric – answer should include the following items: Small amounts of arsenic facilitate the beneficial use of methyl groups, whereas toxic amounts produce methylated intermediates that are carcinogenic. Arsenic can be used to treat cancer in controlled quantities, but chronic arsenic toxicity can cause cancer.