Question 1

Which enzyme catalyzes the conversion of pyruvate to acetyl CoA in the mitochondria, and what are the products of this reaction?

Accepted Answer

Pyruvate dehydrogenase; produces acetyl CoA, CO$$_2$$, and NADH

Question 2

During glycolysis, which step is inhibited by its product, glucose-6-phosphate, and what is the enzyme responsible?

Accepted Answer

Step 1; hexokinase

Question 3

Which molecule is regenerated at the end of the citric acid cycle, allowing the cycle to continue?

Accepted Answer

Oxaloacetate

Question 4

How many NADH molecules are produced per glucose molecule during the citric acid cycle?

Accepted Answer

6

Question 5

Which enzyme in gluconeogenesis catalyzes the conversion of fructose-1,6-bisphosphate to fructose-6-phosphate?

Accepted Answer

Fructose-1,6-bisphosphatase (FBPase)

Question 6

Which of the following statements about the regulation of pyruvate dehydrogenase is correct?

Accepted Answer

It is inhibited by ATP, NADH, and acetyl CoA

Question 7

In the absence of oxygen, what is the fate of pyruvate in human muscle cells?

Accepted Answer

It is converted to lactate by lactate dehydrogenase

Question 8

Which step in the citric acid cycle produces GTP (which can be converted to ATP)?

Accepted Answer

Succinyl CoA to succinate

Question 9

What is the main function of coenzyme A in cellular respiration?

Accepted Answer

It forms a high-energy thioester bond with acetyl groups

Question 10

Which molecule is a B vitamin derivative and is essential for the formation of acetyl CoA?

Accepted Answer

Coenzyme A (pantothenic acid)

Question 11

If a cell is running gluconeogenesis, which of the following is NOT a reactant?

Accepted Answer

Fructose-1,6-bisphosphate

Question 12

Which enzyme catalyzes the conversion of succinate to fumarate in the citric acid cycle, and what is produced?

Accepted Answer

Succinate dehydrogenase; produces FADH$$_2$$

Question 13

Which of the following best describes the energy yield from one glucose molecule during aerobic respiration?

Accepted Answer

2 ATP from glycolysis, up to 36 ATP total

Question 14

Which molecule is produced during the conversion of isocitrate to α-ketoglutarate in the citric acid cycle?

Accepted Answer

CO$$_2$$ and NADH

Question 15

Which of the following is a logical reason why ATP inhibits pyruvate dehydrogenase?

Accepted Answer

High ATP indicates sufficient energy, so further breakdown of pyruvate is unnecessary

Question 16

Which compartment of the mitochondrion does the citric acid cycle occur in?

Accepted Answer

Matrix

Question 17

A patient with a deficiency in phosphoenolpyruvate carboxykinase (PEPCK) would have difficulty with which metabolic pathway?

Accepted Answer

Gluconeogenesis

Question 18

Which step in glycolysis is promoted by fructose-2,6-bisphosphate (F2,6BP) and AMP?

Accepted Answer

Step 3; phosphofructokinase

Question 19

Which of the following reactions is exergonic and provides energy for the formation of a thioester bond in acetyl CoA?

Accepted Answer

Pyruvate + CoA + NAD$$^+$$ → Acetyl CoA + CO$$_2 + $$NADH

Question 20

Which enzyme is responsible for the conversion of malate to oxaloacetate in the citric acid cycle, and what is produced?

Accepted Answer

Malate dehydrogenase; produces NADH

Cellular Respiration: Glycolysis, Gluconeogenesis, and the Citric Acid Cycle

Study Guide - Practice Questions