Question 1

Which of the following best describes the role of acetyl-CoA in cellular metabolism?

Accepted Answer

It is the two-carbon molecule that enters the citric acid cycle for further oxidation.

Question 2

During glycolysis, what is the net gain of ATP molecules per molecule of glucose?

Accepted Answer

$$2$$

Question 3

Which enzyme catalyzes the conversion of glucose to glucose 6-phosphate, and what is the significance of this step?

Accepted Answer

Hexokinase; it traps glucose inside the cell by phosphorylation.

Question 4

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

Accepted Answer

It uses the energy from electrons to pump protons, creating a gradient used to synthesize ATP.

Question 5

Which hormone is released when blood glucose levels are high, and what is its primary effect?

Accepted Answer

Insulin; stimulates glucose uptake by cells.

Question 6

What is the main fate of pyruvate under anaerobic conditions in human muscle cells?

Accepted Answer

It is reduced to lactate to regenerate NAD$$^+.$$

Question 7

Which pathway is responsible for the synthesis of glucose from noncarbohydrate precursors such as amino acids and glycerol?

Accepted Answer

Gluconeogenesis

Question 8

How many molecules of carbon dioxide are produced from the complete oxidation of one molecule of glucose, and during which stages are they released?

Accepted Answer

$$6$$; during pyruvate oxidation and the citric acid cycle

Question 9

Which of the following best explains why glucose 6-phosphate cannot leave the cell once it is formed?

Accepted Answer

The phosphate group is charged, preventing it from crossing the cell membrane unaided.

Question 10

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

Accepted Answer

It is the process by which lactate produced in muscles is transported to the liver and converted back to glucose.

Question 11

Which of the following is the correct net equation for glycolysis?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 2\,\mathrm{NAD}^+ + 2\,\mathrm{ADP} + 2\,\mathrm{P_i} \rightarrow 2\,\mathrm{C_3H_4O_3} + 2\,\mathrm{NADH} + 2\,\mathrm{ATP} + 2\,\mathrm{H_2O}$$

Question 12

Which of the following best describes the function of the pentose phosphate pathway?

Accepted Answer

It produces NADPH and ribose 5-phosphate for biosynthetic reactions.

Question 13

A patient is experiencing hypoglycemia. Which hormone would you expect to be elevated in their blood, and what is its effect?

Accepted Answer

Glucagon; stimulates glycogen breakdown and gluconeogenesis.

Question 14

Which of the following is a correct statement about the regulation of phosphofructokinase in glycolysis?

Accepted Answer

It is inhibited by ATP and citrate, and activated by ADP and AMP.

Question 15

Which of the following best explains why fats are not a direct source of glucose during starvation?

Accepted Answer

Fatty acids cannot be converted to glucose because there is no pathway to convert acetyl-CoA to pyruvate or other gluconeogenic intermediates.

Question 16

Which of the following is the correct sequence of events for the complete aerobic oxidation of glucose?

Accepted Answer

Glycolysis → Pyruvate Oxidation → Citric Acid Cycle → Electron Transport Chain

Question 17

What is the total ATP yield from the complete aerobic oxidation of one molecule of glucose?

Accepted Answer

$$38$$

Question 18

Which of the following best describes the fate of galactose after it is absorbed from the digestive tract?

Accepted Answer

It is converted to glucose 6-phosphate and enters glycolysis.

Question 19

Which of the following is a correct description of the role of NAD$$^+ in $$glycolysis?

Accepted Answer

It is reduced to NADH during the oxidation of glyceraldehyde 3-phosphate.

Carbohydrate Metabolism: Glycolysis, Gluconeogenesis, and Regulation

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