$ \mathrm{C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}} $

Question 1

Which of the following best describes the overall chemical reaction for aerobic cellular respiration?

Accepted Answer

$ \mathrm{C_6H_{12}O_6 + 6O_2 ightarrow 6CO_2 + 6H_2O + 	ext{energy}} $

Question 2

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

Accepted Answer

2 ATP and 2 NADH

Question 3

Which enzyme is regulated by feedback inhibition during glycolysis, and what molecule acts as the inhibitor?

Accepted Answer

Phosphofructokinase; ATP

Question 4

Where does pyruvate processing occur in eukaryotic cells, and what are the main products?

Accepted Answer

Mitochondrial matrix; Acetyl CoA, NADH, CO$_2$

Question 5

What happens to the carbons from glucose during the citric acid cycle?

Accepted Answer

They are released as CO$_2$

Question 6

How is the citric acid cycle regulated?

Accepted Answer

By feedback inhibition at multiple points, especially when ATP and NADH are abundant

Question 7

Which process directly produces the most ATP during aerobic cellular respiration?

Accepted Answer

Oxidative phosphorylation

Question 8

What is the primary role of oxygen in cellular respiration?

Accepted Answer

It acts as the final electron acceptor in the electron transport chain

Question 9

Which of the following best explains why fermentation is less efficient than aerobic respiration?

Accepted Answer

Fermentation does not use the electron transport chain, so less ATP is produced per glucose

Question 10

A patient has a genetic defect that prevents the phosphorylation of pyruvate dehydrogenase. What is the most likely consequence?

Accepted Answer

Pyruvate dehydrogenase remains active, leading to continuous conversion of pyruvate to acetyl CoA

Question 11

Which of the following statements about substrate-level phosphorylation is correct?

Accepted Answer

It involves the direct transfer of a phosphate group to ADP from a phosphorylated substrate

Question 12

During the energy payoff phase of glycolysis, which molecules are produced?

Accepted Answer

ATP and NADH

Question 13

Which of the following best describes the fate of NADH produced during glycolysis under anaerobic conditions?

Accepted Answer

It donates electrons to pyruvate or its derivatives, regenerating NAD$^+$ for glycolysis

Question 14

If a toxin inhibits the enzyme ATP synthase, what would be the immediate effect on cellular respiration?

Accepted Answer

ATP production by oxidative phosphorylation would decrease dramatically

Question 15

Which of the following is a correct comparison between fermentation and aerobic respiration?

Accepted Answer

Fermentation produces less ATP per glucose molecule than aerobic respiration

Question 16

Which molecule is oxidized and which is reduced during the conversion of glucose to carbon dioxide and water?

Accepted Answer

Glucose is oxidized; oxygen is reduced

Question 17

Why is glycolysis considered a central metabolic pathway in cells?

Accepted Answer

It provides intermediates for other pathways and is used by nearly all organisms

Question 18

Which of the following best explains the coupling of electron transport to ATP synthesis in mitochondria?

Accepted Answer

The electron transport chain creates a proton gradient that drives ATP synthesis via chemiosmosis

Question 19

A muscle cell is deprived of oxygen. Which process will allow it to continue producing ATP?

Accepted Answer

Lactic acid fermentation

Question 20

Which of the following is a direct output of the citric acid cycle for each acetyl CoA that enters?

Accepted Answer

3 NADH, 1 FADH$_2$, 1 ATP (or GTP), and 2 CO$_2$

Cellular Respiration and Fermentation: Pathways and Regulation

Study Guide - Practice Questions