Question 1

Which of the following best describes the fate of pyruvate in a eukaryotic cell when oxygen is present?

Accepted Answer

It is transported into the mitochondrion and oxidized to acetyl-CoA.

Question 2

During the oxidation of one molecule of glucose, how many molecules of NADH are produced from the citric acid cycle alone (not including glycolysis or pyruvate oxidation)?

Accepted Answer

$$6$$

Question 3

Which structure within the mitochondrion is primarily responsible for increasing the surface area available for the electron transport chain?

Accepted Answer

Cristae

Question 4

A patient’s cells are unable to actively transport pyruvate into the mitochondria. Which process will be directly impaired as a result?

Accepted Answer

Citric acid cycle

Question 5

Which of the following is released as a waste product during both the oxidation of pyruvate and the citric acid cycle?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 6

If a cell is deprived of oxygen, which pathway will it most likely use to metabolize pyruvate?

Accepted Answer

Fermentation

Question 7

How many total ATP molecules are produced from one molecule of glucose after complete aerobic respiration (including glycolysis, citric acid cycle, and electron transport chain)?

Accepted Answer

$$34-36$$

Question 8

Which of the following best explains why the inner mitochondrial membrane is highly folded into cristae?

Accepted Answer

To provide more surface area for ATP synthase and electron transport chain proteins

Question 9

During the citric acid cycle, which molecule is regenerated at the end of each cycle to combine with acetyl-CoA and start the cycle again?

Accepted Answer

Oxaloacetate

Question 10

A mutation prevents the formation of NADH during the citric acid cycle. Which of the following would be the most immediate consequence?

Accepted Answer

The electron transport chain would receive fewer electrons.

Question 11

Which of the following equations correctly summarizes the decarboxylation of pyruvate during its oxidation?

Accepted Answer

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

Question 12

If a toxin specifically destroyed the mitochondrial matrix, which process would be directly inhibited?

Accepted Answer

Citric acid cycle

Question 13

Which of the following is NOT a product of the citric acid cycle per acetyl-CoA molecule?

Accepted Answer

$$2$$ ATP

Question 14

A researcher measures the amount of CO$$_2$$ released from a cell and finds it is much lower than expected. Which process is most likely impaired?

Accepted Answer

Citric acid cycle

Question 15

Which of the following best explains why fermentation is less efficient than aerobic respiration?

Accepted Answer

Fermentation produces less ATP because it does not fully oxidize glucose to CO$$_2$$ and H$$_2O.$$

Question 16

In a metabolic experiment, a scientist blocks the active transport of pyruvate into the mitochondria. Which of the following would you expect to accumulate in the cytoplasm?

Accepted Answer

Pyruvate

Question 17

Which of the following is a correct sequence of events for the complete aerobic breakdown of glucose?

Accepted Answer

Glycolysis $$\rightarrow$$ Oxidation of Pyruvate $$\rightarrow$$ Citric Acid Cycle $$\rightarrow$$ Electron Transport Chain

Question 18

Which of the following statements about the intermembrane space of the mitochondrion is correct?

Accepted Answer

It is the space between the outer and inner mitochondrial membranes.

Question 19

If a cell is unable to regenerate NAD$$^+$$, which process will be directly affected first?

Accepted Answer

Glycolysis

Question 20

A genetic mutation causes a defect in the enzyme that converts pyruvate to acetyl-CoA. Which of the following would you expect to decrease as a direct result?

Accepted Answer

Entry of carbon into the citric acid cycle

Cellular Respiration: Oxidation of Pyruvate & Citric Acid Cycle

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