Question 1

Which of the following best describes the role of oxygen in cellular respiration?

Accepted Answer

Oxygen is the terminal electron acceptor, allowing electrons to flow through the electron transport chain and form water.

Question 2

During glycolysis, ATP is invested in the early steps. Why is this initial investment necessary?

Accepted Answer

It provides the energy to split glucose into two three-carbon sugars, enabling subsequent energy harvest.

Question 3

Which of the following statements about NAD+ and NADH is correct?

Accepted Answer

NAD+ acts as an oxidizing agent, accepting electrons and becoming NADH, which then donates electrons to the electron transport chain.

Question 4

Why does moving electrons from C-H bonds toward oxygen release usable free energy?

Accepted Answer

Because electrons lose potential energy as they move to a more electronegative atom, and this energy can be harnessed for cellular work.

Question 5

In the citric acid cycle, why must oxaloacetate be regenerated rather than consumed?

Accepted Answer

Oxaloacetate acts as a catalyst, accepting acetyl groups each cycle, so it must be regenerated to keep the cycle running.

Question 6

Which of the following best explains why FADH2 yields less ATP than NADH when donating electrons to the electron transport chain?

Accepted Answer

FADH2 donates electrons at a later point in the chain, bypassing Complex I, resulting in fewer protons pumped and less ATP generated.

Question 7

A poison that makes the inner mitochondrial membrane permeable to protons would most directly inhibit which process?

Accepted Answer

The generation of proton-motive force required for ATP synthesis by ATP synthase.

Question 8

Which of the following is a correct description of substrate-level phosphorylation?

Accepted Answer

ATP is produced directly by transferring a phosphate group from a high-energy substrate to ADP.

Question 9

During anaerobic conditions, why must NAD+ be regenerated for glycolysis to continue?

Accepted Answer

NAD+ is needed to accept electrons during glycolysis; without regeneration, glycolysis would stop due to lack of electron acceptors.

Question 10

Which of the following best explains why stepwise electron transfer in the electron transport chain is advantageous for the cell?

Accepted Answer

It enables controlled release of free energy, which can be harnessed to pump protons and synthesize ATP, rather than releasing all energy as heat.

Question 11

Which molecule is both produced during glycolysis and required for the continuation of glycolysis under anaerobic conditions?

Accepted Answer

NAD+

Question 12

A mutation prevents the attachment of coenzyme A to the two-carbon fragment produced from pyruvate. What is the most immediate consequence?

Accepted Answer

The citric acid cycle cannot proceed because acetyl-CoA is not formed.

Question 13

Which of the following is a direct product of the citric acid cycle that is used in the electron transport chain?

Accepted Answer

NADH

Question 14

Which of the following best describes the mechanical action of ATP synthase during oxidative phosphorylation?

Accepted Answer

Proton flow through the channel causes rotation of the rotor, which drives conformational changes in the catalytic knob to synthesize ATP.

Question 15

Which of the following is the correct sequence of events during aerobic respiration?

Accepted Answer

Glycolysis → Pyruvate oxidation → Citric acid cycle → Electron transport chain → ATP synthesis

Question 16

If a cell is deprived of oxygen, which process will stop first?

Accepted Answer

Electron transport chain

Question 17

Which of the following is a correct statement about the fate of carbon atoms from glucose during aerobic respiration?

Accepted Answer

All carbon atoms are released as CO2 during pyruvate oxidation and the citric acid cycle.

Question 18

Which of the following best explains why fermentation yields less ATP than aerobic respiration?

Accepted Answer

Fermentation does not use the electron transport chain, so less energy is extracted from glucose.

Question 19

Which of the following is the correct redox description for the reaction: $$ \mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O} $$?

Accepted Answer

Methane is oxidized and oxygen is reduced.

Question 20

Which of the following best describes the role of the proton-motive force in oxidative phosphorylation?

Accepted Answer

It is the energy stored as a combination of a proton gradient and membrane potential, used to drive ATP synthesis.

Guided Study for BIO 1305 Chapter 9: Cellular Respiration and Redox Reactions

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