Question 1

Which molecule directly enters the citric acid cycle after the preparatory step in cellular respiration?

Accepted Answer

Acetyl CoA

Question 2

What is the primary role of NAD+ during the citric acid cycle?

Accepted Answer

To pick up hydrogen ions and electrons, becoming NADH

Question 3

How many molecules of ATP are produced by substrate-level phosphorylation during the citric acid cycle for each glucose molecule?

Accepted Answer

2

Question 4

Which of the following best describes the fate of the electrons carried by NADH and FADH2 in the electron transport system?

Accepted Answer

They are transferred to oxygen, forming water

Question 5

What is the main reason why fats yield more ATP than glycogen when metabolized?

Accepted Answer

Fats have longer carbon chains, producing more acetyl CoA

Question 6

During anaerobic respiration in humans, what is the end product of pyruvate metabolism?

Accepted Answer

Lactic acid

Question 7

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

Accepted Answer

Electron transport system

Question 8

What is the equation for the formation of water at the end of the electron transport system?

Accepted Answer

$$1/2\ \mathrm{O}_2 + 2\mathrm{H}^+ + 2\mathrm{e}^- \rightarrow \mathrm{H}_2\mathrm{O}$$

Question 9

If a person is starving and their body begins to break down muscle tissue for energy, which metabolic pathway is being utilized?

Accepted Answer

Protein catabolism

Question 10

Which of the following best explains why oxygen is essential for the electron transport system?

Accepted Answer

Oxygen acts as the final electron acceptor, allowing the chain to continue

Question 11

How many molecules of NADH are produced from one glucose molecule during the citric acid cycle?

Accepted Answer

6

Question 12

Which step in cellular respiration is responsible for the production of the most water molecules?

Accepted Answer

Electron transport system

Question 13

What is the net gain of ATP molecules from the complete aerobic catabolism of one glucose molecule, accounting for the cost of shuttling NADH into the mitochondria?

Accepted Answer

36

Question 14

Which of the following is a waste product of the citric acid cycle?

Accepted Answer

CO2

Question 15

What is the main function of ATP synthase in the mitochondria?

Accepted Answer

To catalyze the formation of ATP from ADP and Pi

Question 16

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

Accepted Answer

Glycerol can enter glycolysis or be converted to pyruvate

Question 17

Which process is responsible for the burning sensation in muscles during intense exercise when oxygen is limited?

Accepted Answer

Accumulation of lactic acid from anaerobic respiration

Question 18

What is the correct sequence of events for the complete aerobic breakdown of glucose?

Accepted Answer

Glycolysis → Preparatory Step → Citric Acid Cycle → Electron Transport System

Question 19

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

ATP is produced directly by the transfer of a phosphate group to ADP from a substrate molecule

Question 20

Which coenzyme is reduced to FADH2 during the citric acid cycle?

Accepted Answer

FAD

Cellular Respiration: Citric Acid Cycle & Electron Transport System

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