Q: Which of the following is a correct summary of ATP yield from one molecule of glucose during aerobic cellular respiration in eukaryotes?

$$\text{2 ATP from glycolysis} + \text{2 ATP from citric acid cycle} + \text{about 28 ATP from oxidative phosphorylation} = \text{about 32 ATP}$$

Question 1

Which of the following best describes the role of oxygen in aerobic cellular respiration?

Accepted Answer

Oxygen is the final electron acceptor in the electron transport chain, forming water.

Question 2

During intense exercise, muscle cells switch to lactic acid fermentation. What is the primary reason for this metabolic shift?

Accepted Answer

To regenerate NAD$$ ^+  so $$glycolysis can continue in the absence of sufficient oxygen.

Question 3

Which of the following statements about chemiosmosis in mitochondria is correct?

Accepted Answer

Chemiosmosis uses the energy stored in a proton gradient to drive ATP synthesis via ATP synthase.

Question 4

A bacterium uses sulfate (SO$$_4^{2-}) as $$its final electron acceptor instead of oxygen. What type of respiration is this?

Accepted Answer

Anaerobic respiration

Question 5

Which of the following is a correct summary of ATP yield from one molecule of glucose during aerobic cellular respiration in eukaryotes?

Accepted Answer

$$	ext{2 ATP from glycolysis} + 	ext{2 ATP from citric acid cycle} + 	ext{about 28 ATP from oxidative phosphorylation} = 	ext{about 32 ATP}$$

Question 6

Which molecule is reduced during glycolysis?

Accepted Answer

NAD$$ ^+ $$

Question 7

What is the main difference between fermentation and anaerobic respiration?

Accepted Answer

Anaerobic respiration uses an electron transport chain with a final electron acceptor other than oxygen, while fermentation does not use an electron transport chain.

Question 8

Which of the following best explains why NAD$$ ^+ $$ regeneration is essential for glycolysis to continue?

Accepted Answer

NAD$$ ^+  is $$required to accept electrons during the oxidation of glucose.

Question 9

Which of the following is a product of alcohol fermentation but NOT lactic acid fermentation?

Accepted Answer

Ethanol

Question 10

If the proton-motive force generated by the electron transport chain is used for processes other than ATP synthesis, what is the likely effect on the cell's ATP yield?

Accepted Answer

ATP yield will decrease because fewer protons flow through ATP synthase.

Question 11

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

ATP is produced directly by transferring a phosphate group from a substrate to ADP.

Question 12

Which of the following statements about the connection between glycolysis, the citric acid cycle, and other metabolic pathways is correct?

Accepted Answer

Proteins, carbohydrates, and fats can all be broken down and enter glycolysis or the citric acid cycle at various points.

Question 13

Which of the following is a correct sequence of events in aerobic cellular respiration?

Accepted Answer

Glycolysis → Citric Acid Cycle → Electron Transport Chain → Chemiosmosis

Question 14

Which of the following is NOT a difference between obligate anaerobes and facultative anaerobes?

Accepted Answer

Obligate anaerobes can use both fermentation and aerobic respiration.

Question 15

Which of the following best explains why FADH$$_2$$ produces less ATP than NADH when donating electrons to the electron transport chain?

Accepted Answer

FADH$$_2$$ donates electrons at a lower energy level, bypassing the first proton-pumping complex.

Question 16

A patient has a genetic defect that prevents the formation of the proton gradient across the inner mitochondrial membrane. Which process would be most directly affected?

Accepted Answer

ATP synthesis by ATP synthase

Question 17

Which of the following is a direct result of the flow of protons through ATP synthase?

Accepted Answer

Phosphorylation of ADP to form ATP

Question 18

Which of the following is a correct equation for the net reaction of glycolysis?

Accepted Answer

$$	ext{Glucose} + 2\ 	ext{NAD}^+ + 2\ 	ext{ADP} + 2\ 	ext{P}_i ightarrow 2\ 	ext{Pyruvate} + 2\ 	ext{NADH} + 2\ 	ext{ATP} + 2\ 	ext{H}_2	ext{O} + 2\ 	ext{H}^+$$

Question 19

Which of the following best describes the fate of lactate produced in muscle cells during intense exercise?

Accepted Answer

It is transported to the liver, where it is converted back to pyruvate and can enter the citric acid cycle.

Metabolic Pathways: Catabolic Pathways and Cellular Respiration (Chapter 9: Concepts 9.1–9.6)

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