Chapter 8 Test Left Side Activity Identify the choice that best completes the statement or answers the question. 1. Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ____ is to ____. a. exergonic; spontaneous
d. work; energy
b. exergonic; endergonic
e. entropy; enthalpy
c. free energy; entropy 2. Which of the following statements regarding enzymes is true? a. Enzymes decrease the free energy change of a reaction. b. Enzymes increase the rate of a reaction. c. Enzymes change the direction of chemical reactions. d. Enzymes are permanently altered by the reactions they catalyze. e. Enzymes prevent changes in substrate concentrations. 3. A chemical reaction that has a positive G is correctly described as a. endergonic. b. endothermic. c. enthalpic. d. spontaneous. e. exothermic. 4. Which of these statements regarding enzymes is false? a. Enzymes are proteins that function as catalysts. b. Enzymes display specificity for certain molecules with which they interact. c. Enzymes provide activation energy for the reactions they catalyze. d. The activity of enzymes can be regulated by other molecules. e. An enzyme may be used many times over for a specific reaction. 5. What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways? a. feedback regulation
d. entropy
b. bioenergetics
e. cooperativity
c. energy coupling 6. The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as a. metabolic inhibition.
d. noncooperative inhibition.
b. feedback inhibition.
e. reversible inhibition.
c. allosteric inhibition.
7. Which of the following types of reactions would decrease the entropy within a cell? a. dehydration reactions
d. digestion
b. hydrolysis
e. catabolism
c. respiration 8. If an enzyme has been inhibited noncompetitively, a. the G for the reaction it catalyzes will always be negative. b. the active site will be occupied by the inhibitor molecule. c. raising substrate concentration will increase the inhibition. d. more energy will be necessary to initiate the reaction. e. the inhibitor molecule may be chemically unrelated to the substrate. 9. If an enzyme is added to a solution where its substrates and products are in equilibrium, what would occur? a. Additional product would be formed. b. Additional substrate would be formed. c. The reaction would change from endergonic to exergonic. d. The free energy of the system would change. e. Nothing; the reaction would stay at equilibrium 10. How does a non-competitive inhibitor decrease the rate of an enzyme reaction? a. by binding at the active site of the enzyme b. by changing the structure of the enzyme c. by changing the free energy change of the reaction d. by acting as a coenzyme for the reaction e. by decreasing the activation energy of the reaction 11. What are enzymes? What is the importance of enzymes for living beings? 12. An experiment to measure the rate of respiration in crickets and mice at 10oC and 25o C was performed using a respirometer, an apparatus that measures changes in gas volume. Respiration was measured in mL of O2 consumed per gram of organism over several five-minute trials and the following data were obtained. a. Which organism at which temperature had the fastest metabolic rate (produced the most ATP) during its trials? Explain how you know. b. According to the data, the mice at 10oC demonstrated greater oxygen consumption per gram of tissue than did the mice at 25oC. Propose an explanation for why this is.
AP Biology Chapter 8 Study Test Question Answers 1. b. exergonic, spontaneous 2. e. catabolism 3. c. they consume energy to build up polymers from monomers 4. a. energy cannot be created or destroyed. 5. a. dehydration synthesis 6. b. the organism ultimately must obtain energy for life from its environment 7. a. an organism (exchanging material with environment always.) 8. a. is consistent with the second law of thermodynamics 9. d. metabolism is a property of all organismal life 10. d. entropy of the universe. 11. Enzymes are proteins that are catalysts of chemical reactions. Chemistry shows us that catalysts are non-consumable substances that reduce the activation energy necessary for a chemical reaction to occur. Enzymes are highly specific to the reactions they catalyze. They are of vital importance for life because most of the chemical reactions in cells and tissues are catalyzed by enzymes. Without enzyme action, those reactions would not occur or would not happen with the required speed for the biological processes in which they are involved. 12a. The mouse at 10oC had the fastest metabolic rate because its average respiration was the highest. This means it was taking in the greatest amount of O2 and therefore production the greatest amount of ATP via oxidative phosphorylation. 12b. Mice at 10oC demonstrated greater oxygen consumption because they were colder. Mice are endotherms, meaning they regulate their body temperature, keeping it at a constant value. When their environmental temperature decreases, mice need to produce greater amounts of ATP maintain their internal temperature. They therefore have to take in greater amounts of oxygen to perform cellular respiration.
EQ: What role do enzymes play in metabolism? Enzymes are chemicals in saliva, or spit, that break down your food so that you can digest it. Without enzymes, you wouldn't be able to digest your food. Enzymes are known as biological catalysts as they lower the energy barrier and so speed up the reaction without being used up in that reaction. Enzymes are made up of proteins and the effectiveness of their actions is changed by changing temperature or pH or by chemically changing the molecule. Metabolic pathways are how the body makes many of the things it needs, they involve many breakdowns and rebuilding of substances. These changes are made possible because of the presence of enzymes.