Quiz

QUIZ

1. Which word does not describe the process of cellular respiration reactions?

a. Redox reactions b. Exothermic reactions c. Catabolic reactions d. Anabolic reactions

Answer: d. These reactions are all exothermic (giving off heat), catabolic (breakdown), redox reactions (involving the exchange of electrons and hydrogen ions). They are not anabolic.

2. Which aspect of aerobic biochemical reactions leads to the most ATP molecules?

a. Fermentation b. Glycolysis c. Electron transport d. Krebs cycle

Answer: c. Electron transport yields many more ATP molecules (about 34 theoretically) when compared to the other aspects of aerobic respiration.

3. Where in the cell does glycolysis take place?

a. Nucleus b. Rough endoplasmic reticulum c. Cytoplasm d. Mitochondria

Answer: c. Glycolysis specifically happens in the cytoplasm without the aid of any membranes. It delivers the pyruvate molecules to the mitochondria for the rest of the pathway leading to aerobic respiration.

4. Which molecule essentially starts and finishes the closed loop that is the

Krebs cycle?

a. Oxaloacetate b. Citrate c. Acetyl CoA d. Pyruvate

Answer: a. Oxaloacetate gets recycled over and over again in the Krebs cycle in order to further break down the glucose that started the entire process of cellular respiration.

5. Where in the cell does oxidative phosphorylation take place in eukaryotes?

a. Mitochondrial matrix b. Cell membrane c. Mitochondrial cristae d. Outer mitochondrial membrane

Answer: c. This must take place across a membrane in order to generate a pH or electrochemical gradient, which drives the reactions that make ATP from ADP. The mitochondrial cristae represent the inner membrane of the mitochondria.

6. Where do most of the ATP molecules come from in cellular respiration?

a. NADH b. FADH2 c. GTP d. Pyruvate decarboxylation

Answer: a. Most of the ATP comes from NADH. The yield is 2.5 ATP molecules per molecule of NADH and only 1.5 ATP molecules per molecule of FADH2. There are many more NADH molecules than FADH2 molecules made prior to oxidative phosphorylation, making these the greatest source of ATP in cellular respiration.

7. What is the beginning substrate in the fermentation process?

a. Glucose b. Acetate c. Carbon dioxide d. Oxaloacetate

Answer: a. All fermentation ultimately starts with glucose, leading into the glycolysis pathway and then leading to a variety of fermentation pathways.

8. What is the major downside of having lactic acid as an end product of fermentation?

a. It is not completely oxidized. b. It is acidic and blocks the growth of the organism. c. It is too volatile for the organism. d. It gives off CO2 gas.

Answer: b. The major downside of homolactic fermentation, in which only lactic acid is made, is that it is too acidic, adversely affecting the growth of the organism making the acid.

9. What is the most abundant photosynthetic pigment on earth?

a. Xanthophylls b. Phycoerythrin c. Fucoxanthin d. Chlorophyll

Answer: d. The most abundant photosynthetic pigment is chlorophyll, found in most photosynthetic plants. The others are pigments that are seen in some plants and algae but are less abundant.

10. What is the main waste product in the act of photosynthesis?

a. Water b. CO2 c. O2 d. Acetate

Answer: c. In photosynthesis, the actual waste product is O2 gas, which is given off after H2O is split to give an electron back to chlorophyll in the chloroplast.