Question 1

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

Accepted Answer

To convert glucose into two molecules of pyruvic acid, producing a net gain of 2 ATP and 2 NADH.

Question 2

During anaerobic conditions in skeletal muscle, what is the fate of pyruvic acid produced by glycolysis?

Accepted Answer

It is converted to lactic acid, regenerating NAD+ for continued glycolysis.

Question 3

What is the net ATP yield from glycolysis per molecule of glucose under anaerobic conditions?

Accepted Answer

$$2$$

Question 4

Which molecule determines whether pyruvic acid will enter the citric acid cycle or be converted to lactic acid?

Accepted Answer

Oxygen

Question 5

Why can only the liver release glucose into the bloodstream from its glycogen stores?

Accepted Answer

The liver contains glucose-6-phosphatase, which removes the phosphate group from glucose-6-phosphate, allowing free glucose to exit the cell.

Question 6

Which of the following is NOT a product of the citric acid (Krebs) cycle per turn?

Accepted Answer

$$2$$ ATP

Question 7

What is the primary role of oxygen in the electron transport chain?

Accepted Answer

It acts as the final electron acceptor, forming water.

Question 8

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

Accepted Answer

$$6$$ ATP

Question 9

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

Accepted Answer

Gluconeogenesis

Question 10

A patient with uncontrolled diabetes is found to have high levels of ketone bodies in their blood. Which metabolic process is responsible for this?

Accepted Answer

Ketogenesis

Question 11

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

Accepted Answer

Lactic acid dehydrogenase

Question 12

What is the main reason why glucose cannot be stored in its free form inside cells?

Accepted Answer

It would cause osmotic swelling and possible cell lysis.

Question 13

Which of the following best describes the process of lipolysis?

Accepted Answer

The breakdown of triglycerides into fatty acids and glycerol.

Question 14

How many acetyl CoA molecules are produced from the complete β-oxidation of a 16-carbon fatty acid?

Accepted Answer

$$8$$

Question 15

Which of the following statements about the Cori cycle is correct?

Accepted Answer

It involves the conversion of lactic acid from muscle to glucose in the liver.

Question 16

Which coenzymes are reduced during the citric acid cycle and later used in the electron transport chain?

Accepted Answer

NAD+ and FAD

Question 17

What is the theoretical maximum number of ATP molecules produced from the complete aerobic oxidation of one molecule of glucose?

Accepted Answer

$$36-38$$

Question 18

Which of the following is a direct (substrate-level) phosphorylation event?

Accepted Answer

ADP + Pi \rightarrow ATP during glycolysis

Question 19

Which of the following best explains why red blood cells rely exclusively on lactic acid fermentation for ATP production?

Accepted Answer

They lack mitochondria and cannot perform aerobic respiration.

Question 20

Which of the following is NOT a reason why lactic acid fermentation is not favored by the body for long-term energy production?

Accepted Answer

It requires oxygen to proceed.

Respiration and Metabolism: Biochemical Pathways in Human Physiology

Study Guide - Practice Questions