Question 1

Which molecule acts as the final electron acceptor in the electron transport system during aerobic cellular respiration?

Accepted Answer

Oxygen ($$O_2)$$

Question 2

During the citric acid cycle, what is the fate of the carbons from the original glucose molecule?

Accepted Answer

They are released as carbon dioxide ($$CO_2)$$

Question 3

Which coenzyme is reduced to form FADH$$_2$$ during the citric acid cycle?

Accepted Answer

FAD

Question 4

What is the main purpose of the electron transport system in mitochondria?

Accepted Answer

To generate a proton gradient for ATP synthesis

Question 5

If a person is starving and has depleted their glycogen stores, which macromolecule will the body primarily catabolize next for energy?

Accepted Answer

Fats

Question 6

Which process is responsible for the net production of 34 ATP molecules during cellular respiration?

Accepted Answer

Electron transport system (oxidative phosphorylation)

Question 7

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

Accepted Answer

Glycolysis → Preparatory step → Citric acid cycle → Electron transport system

Question 8

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

Direct transfer of a phosphate group to ADP from a phosphorylated intermediate

Question 9

During anaerobic respiration in humans, what is the end product of glycolysis when oxygen is not available?

Accepted Answer

Lactic acid

Question 10

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

Accepted Answer

Glycerol can enter glycolysis or be converted to pyruvate

Question 11

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

Accepted Answer

6

Question 12

Which waste products are generated during the complete aerobic catabolism of one glucose molecule?

Accepted Answer

6 $$CO_2$$ and 6 $$H_2O$$

Question 13

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

Accepted Answer

Electron transport system

Question 14

What happens to the NAD+ and FAD coenzymes after they drop off their electrons in the electron transport system?

Accepted Answer

They are recycled and reused in earlier steps

Question 15

A patient with a mitochondrial disorder cannot efficiently use the electron transport system. Which of the following would most likely occur?

Accepted Answer

Increased production of lactic acid

Question 16

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 17

Which metabolic pathway is responsible for the burning sensation in muscles during intense exercise?

Accepted Answer

Anaerobic glycolysis

Question 18

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

Accepted Answer

Fatty acids have longer carbon chains, providing more acetyl groups for the citric acid cycle

Question 19

What is the primary reason why protein catabolism increases during starvation?

Accepted Answer

Glycogen and fat stores are depleted, so the body uses muscle protein for energy

Question 20

Which of the following is NOT a product of the citric acid cycle for each glucose molecule?

Accepted Answer

6 ATP

Cellular Respiration: Citric Acid Cycle & Electron Transport System

Study Guide - Practice Questions