Question 1

Which of the following best describes the main function of glycolysis in cellular metabolism?

Accepted Answer

To split glucose into two molecules of pyruvic acid, producing ATP and NADH

Question 2

What determines whether pyruvic acid produced in glycolysis will enter the citric acid cycle or be converted to lactic acid?

Accepted Answer

The presence of oxygen in the cell

Question 3

During anaerobic metabolism in muscle cells, what is the fate of NADH produced in glycolysis?

Accepted Answer

It is oxidized by transferring electrons to pyruvic acid, forming lactic acid

Question 4

Why is lactic acid fermentation not favored by the body for long-term ATP production?

Accepted Answer

It yields very little ATP and can lead to cellular acidity

Question 5

Which enzyme is responsible for converting lactic acid back to pyruvic acid in the liver?

Accepted Answer

Lactic acid dehydrogenase

Question 6

What is the main purpose of the transition step between glycolysis and the citric acid cycle?

Accepted Answer

To convert pyruvic acid into acetyl CoA and release CO2

Question 7

Where does the citric acid (Krebs) cycle occur within the cell?

Accepted Answer

Mitochondrial matrix

Question 8

Which of the following is the correct balanced equation for aerobic respiration of glucose?

Accepted Answer

$$6O_2 + C_6H_{12}O_6$ + 38ADP \rightarrow 38ATP + 6CO_2 + 6H_2O$$

Question 9

What is the final electron acceptor in the electron transport chain?

Accepted Answer

Oxygen ($$O_2)$$

Question 10

If a cell produces 2 NADH molecules, how many ATP are theoretically generated from them in the electron transport chain?

Accepted Answer

6 ATP

Question 11

Why can only the liver release glucose into the bloodstream after glycogenolysis?

Accepted Answer

Only the liver contains the enzyme glucose 6-phosphatase

Question 12

Which process describes the formation of glucose from non-carbohydrate sources such as amino acids or lactic acid?

Accepted Answer

Gluconeogenesis

Question 13

What is the main function of coenzymes such as NAD+ and FAD in cellular respiration?

Accepted Answer

To transfer electrons during oxidation-reduction reactions

Question 14

Which of the following best explains why glucose cannot be stored as free glucose in cells?

Accepted Answer

Glucose attracts water via osmosis, causing cells to swell and lyse

Question 15

Which of the following is a correct description of the Cori cycle?

Accepted Answer

It recycles lactic acid from muscles to the liver, where it is converted to glucose

Question 16

What is the process called when triglycerides are broken down into fatty acids and glycerol for energy?

Accepted Answer

Lipolysis

Question 17

A 16-carbon fatty acid can theoretically yield how many ATP molecules after complete oxidation?

Accepted Answer

108 ATP

Question 18

What is the main reason ketone bodies are produced in the liver?

Accepted Answer

When the rate of lipolysis exceeds fatty acid utilization

Question 19

Which of the following is NOT a product of the citric acid cycle?

Accepted Answer

Lactic acid

Question 20

Which of the following statements about the electron transport chain is TRUE?

Accepted Answer

It uses the energy from electrons to pump H+ ions across the inner mitochondrial membrane

Respiration and Metabolism: Biochemical Pathways in Human Physiology

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