Question 1

Which of the following best describes the fate of pyruvate under aerobic conditions in eukaryotic cells?

Accepted Answer

It is converted to acetyl CoA in the mitochondrial matrix.

Question 2

During aerobic respiration, what is the final external electron acceptor, and what is the main by-product of this process?

Accepted Answer

O$$_2$$; H$$_2O$$

Question 3

Which of the following equations correctly represents the oxidative decarboxylation of pyruvate?

Accepted Answer

$$\mathrm{Pyruvate + CoA{-}SH + NAD^+ \rightarrow Acetyl{-}CoA + CO_2$ + NADH + H^+}$$

Question 4

Which step in the citric acid cycle directly produces GTP (or ATP) by substrate-level phosphorylation?

Accepted Answer

Conversion of succinyl CoA to succinate

Question 5

How many NADH molecules are produced per turn of the citric acid cycle?

Accepted Answer

3

Question 6

Which enzyme in the citric acid cycle is allosterically activated by ADP and inhibited by NADH?

Accepted Answer

Isocitrate dehydrogenase

Question 7

A patient has a genetic defect that impairs the function of the TOM complex in mitochondria. Which process would be most directly affected?

Accepted Answer

Import of nuclear-encoded proteins into the mitochondrial matrix

Question 8

Which of the following best explains why FADH$$_2$$ yields less ATP than NADH during oxidative phosphorylation?

Accepted Answer

FADH$$_2$$ donates electrons to Complex II, which does not pump protons across the membrane.

Question 9

Which of the following is the correct calculation for the standard free energy change ($$\Delta G^\circ') $$for the transfer of electrons in the electron transport chain?

Accepted Answer

$$\Delta G^\circ' = -nF\Delta E^\circ'$$

Question 10

In the electron transport chain, which complex is responsible for reducing molecular oxygen to water?

Accepted Answer

Complex IV (cytochrome c oxidase)

Question 11

A mutation causes the ATP synthase F$$_0$$ subunit to lose its ability to rotate. What is the most likely consequence?

Accepted Answer

Protons will not flow through ATP synthase, and ATP synthesis will stop.

Question 12

Which of the following best describes the role of the proton motive force in mitochondria?

Accepted Answer

It drives the synthesis of ATP by ATP synthase.

Question 13

During beta-oxidation of fatty acids, which of the following is produced in each cycle?

Accepted Answer

1 NADH, 1 FADH$$_2$$, and 1 acetyl CoA

Question 14

Which of the following statements about the regulation of pyruvate dehydrogenase is correct?

Accepted Answer

It is inhibited by high levels of acetyl CoA and NADH.

Question 15

If a cell is deprived of oxygen, which of the following will most likely occur?

Accepted Answer

Pyruvate will be converted to lactate to regenerate NAD$$^+.$$

Question 16

Which of the following best explains why the citric acid cycle is considered amphibolic?

Accepted Answer

It functions in both catabolic and anabolic pathways.

Question 17

A patient is diagnosed with a deficiency in malate dehydrogenase. Which of the following would most likely be observed?

Accepted Answer

Decreased production of NADH in the citric acid cycle

Question 18

Which of the following best describes the function of coenzyme Q (ubiquinone) in the electron transport chain?

Accepted Answer

It transfers electrons from Complex I and II to Complex III.

Question 19

How many ATP molecules are produced from the complete aerobic oxidation of one molecule of glucose (including glycolysis, citric acid cycle, and oxidative phosphorylation)?

Accepted Answer

36-38 ATP

Question 20

Which of the following is a direct consequence of inhibiting Complex III of the electron transport chain?

Accepted Answer

A decrease in proton gradient across the inner mitochondrial membrane

Aerobic Respiration and Energy Metabolism in Eukaryotic Cells

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