Question 1

Which of the following best describes the primary function of the citric acid cycle in cellular respiration?

Accepted Answer

To generate high-energy electron carriers (NADH and FADH2) for use in the electron transport system

Question 2

During the citric acid cycle, what is the fate of the carbons from the original acetyl group?

Accepted Answer

They are released as $$CO_2$$

Question 3

Which coenzyme is reduced to FADH2 during the citric acid cycle, and at which step does this occur?

Accepted Answer

FAD; during the conversion of succinate to fumarate

Question 4

What is the total net gain of ATP molecules from one molecule of glucose after all stages of aerobic cellular respiration are complete?

Accepted Answer

$$36$$

Question 5

Which process is responsible for the majority of ATP production during cellular respiration?

Accepted Answer

Electron transport system (oxidative phosphorylation)

Question 6

What is the role of oxygen in the electron transport system?

Accepted Answer

It accepts electrons and hydrogen ions to form water

Question 7

If a poison blocks the function of ATP synthase, what would be the immediate effect on cellular respiration?

Accepted Answer

ATP production by oxidative phosphorylation would cease

Question 8

Which of the following best explains why fats yield more ATP per gram than carbohydrates?

Accepted Answer

Fatty acids generate more acetyl CoA units, leading to more turns of the citric acid cycle

Question 9

During anaerobic respiration in humans, what is the end product of glycolysis, and what happens to it?

Accepted Answer

Lactic acid; it is produced from pyruvate in the cytoplasm

Question 10

Which of the following equations correctly represents the formation of water at the end of the electron transport system?

Accepted Answer

$$\frac{1}{2}O_2$ + 2H^+ + 2e^- \rightarrow H_2O$$

Question 11

Which of the following statements about protein catabolism is correct?

Accepted Answer

Amino acids are deaminated, and the remaining carbon backbone enters the citric acid cycle

Question 12

What is the main reason why lactic acid builds up in muscle tissue during intense exercise?

Accepted Answer

Oxygen is not available, so pyruvate is converted to lactic acid

Question 13

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

ATP is produced directly by transferring a phosphate group to ADP from a high-energy intermediate

Question 14

How many NADH molecules are produced from one glucose molecule during the citric acid cycle (including both acetyl groups)?

Accepted Answer

$$6$$

Question 15

Which of the following is a waste product of the complete aerobic breakdown of one glucose molecule?

Accepted Answer

Carbon dioxide ($$CO_2)$$

Question 16

A patient is suffering from a genetic disorder that impairs the function of NAD+. Which stage of cellular respiration would be most directly affected?

Accepted Answer

Glycolysis and the citric acid cycle

Question 17

Which of the following best explains why the net gain of ATP from one glucose molecule is 36 and not 38?

Accepted Answer

Two ATP are used to shuttle NADH from the cytoplasm into the mitochondria

Question 18

Which of the following is TRUE regarding the fate of FADH2 in the electron transport system?

Accepted Answer

It donates electrons at a later point than NADH, resulting in fewer ATP produced per FADH2

Question 19

Which of the following best describes the process of oxidative phosphorylation?

Accepted Answer

The production of ATP using energy derived from the redox reactions of the electron transport chain

Question 20

Which of the following statements about the catabolism of fats is correct?

Accepted Answer

Glycerol can be converted into pyruvate or glucose, while fatty acids are converted into acetyl groups

Cellular Respiration: Citric Acid Cycle & Electron Transport System

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