Q: What is the balanced chemical equation for the complete aerobic catabolism of glucose?

$$C_6H_{12}O_6$ + 6\ \mathrm{O}_2 \rightarrow 6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2\mathrm{O} + \text{energy (ATP + heat)}$$

Question 1

Which of the following statements best distinguishes aerobic respiration from fermentation?

Accepted Answer

Aerobic respiration requires oxygen as the final electron acceptor, whereas fermentation does not use an electron transport chain.

Question 2

What is the balanced chemical equation for the complete aerobic catabolism of glucose?

Accepted Answer

$$C_6H_{12}O_6$ + 6\ \mathrm{O}_2 ightarrow 6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2\mathrm{O} + 	ext{energy (ATP + heat)}$$

Question 3

During the redox reactions of cellular respiration, which molecule is oxidized and which is reduced?

Accepted Answer

Glucose is oxidized; oxygen is reduced.

Question 4

Which of the following best describes the function of NAD+ in cellular respiration?

Accepted Answer

NAD+ is a coenzyme that temporarily stores high-energy electrons removed from organic molecules.

Question 5

Why is the transfer of electrons to oxygen in the electron transport chain performed in a stepwise manner rather than a single reaction?

Accepted Answer

Stepwise transfer allows controlled release of energy, which can be harnessed to pump protons and synthesize ATP.

Question 6

Which of the following enzymes is responsible for catalyzing substrate-level phosphorylation during glycolysis?

Accepted Answer

Pyruvate kinase

Question 7

What is the net energy yield (ATP and NADH) from glycolysis per molecule of glucose?

Accepted Answer

2 ATP, 2 NADH

Question 8

During pyruvate oxidation, what are the products generated from one molecule of pyruvate?

Accepted Answer

Acetyl-CoA, CO$$_2$$, NADH

Question 9

Which of the following statements about the citric acid cycle is correct?

Accepted Answer

The cycle regenerates oxaloacetate, allowing the process to continue with new acetyl-CoA.

Question 10

How many NADH molecules are produced by the citric acid cycle for each glucose molecule that enters cellular respiration?

Accepted Answer

6

Question 11

Which complex in the mitochondrial electron transport chain does NOT pump protons (H$$^+) $$across the inner mitochondrial membrane?

Accepted Answer

Complex II

Question 12

What is the role of ATP synthase in oxidative phosphorylation?

Accepted Answer

It uses the proton-motive force to synthesize ATP from ADP and inorganic phosphate.

Question 13

Why is the exact number of ATP molecules generated from one glucose molecule during cellular respiration not always known?

Accepted Answer

Some protons leak across the mitochondrial membrane, and NADH shuttling can vary between cells.

Question 14

Which of the following best describes the main difference between substrate-level phosphorylation and oxidative phosphorylation?

Accepted Answer

Substrate-level phosphorylation directly transfers a phosphate group to ADP from a substrate, while oxidative phosphorylation uses a proton gradient to drive ATP synthesis.

Question 15

In lactic acid fermentation, what is the primary purpose of reducing pyruvate to lactate?

Accepted Answer

To regenerate NAD$$^+ so $$glycolysis can continue

Question 16

Which of the following organisms is most likely to use anaerobic respiration?

Accepted Answer

Obligate anaerobic bacteria in deep soil

Question 17

Fatty acids produce more ATP per molecule than glucose because:

Accepted Answer

They are broken down into acetyl-CoA units that enter the citric acid cycle, generating more NADH and FADH$$_2.$$

Question 18

Which metabolic pathway is considered to be the most ancient and is found in nearly all living organisms?

Accepted Answer

Glycolysis

Question 19

A patient with a genetic defect in the enzyme triose phosphate isomerase would most likely experience which of the following?

Accepted Answer

Impaired conversion of glyceraldehyde-3-phosphate to dihydroxyacetone phosphate, reducing glycolytic ATP yield

Question 20

Which of the following best explains why proteins must be deaminated before entering cellular respiration?

Accepted Answer

Deamination removes the amino group, producing ammonia, which is toxic and must be processed into urea.

Cellular Respiration and Fermentation: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards