Question 1

Which of the following best describes the relationship between breathing and cellular respiration in humans?

Accepted Answer

Breathing supplies O$$_2$$ needed for cellular respiration and removes CO$$_2$$ produced as a waste product.

Question 2

What is the overall chemical equation for cellular respiration?

Accepted Answer

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

Question 3

During which stage of cellular respiration is the majority of ATP produced, and what is the main process responsible for this production?

Accepted Answer

Stage 3: Oxidative phosphorylation, primarily through chemiosmosis.

Question 4

Which of the following statements about glycolysis is correct?

Accepted Answer

Glycolysis occurs in the cytosol and produces a net gain of 2 ATP and 2 NADH per glucose molecule.

Question 5

A patient is found to have a genetic mutation that prevents the formation of NAD$$^+. $$Which stage of cellular respiration would be directly and immediately affected?

Accepted Answer

Glycolysis, because NAD$$^+ is $$required to accept electrons during the oxidation of glucose.

Question 6

Which of the following best explains why brown fat is able to generate heat instead of ATP?

Accepted Answer

Brown fat contains ion channels that allow H$$^+ to $$flow freely across the inner mitochondrial membrane, dissipating the proton gradient and releasing energy as heat.

Question 7

Which of the following is a correct comparison between lactic acid fermentation and alcohol fermentation?

Accepted Answer

Both recycle NAD$$^+$$ from NADH, but lactic acid fermentation produces lactate while alcohol fermentation produces ethanol and CO$$_2.$$

Question 8

A marathon runner's muscle cells switch to lactic acid fermentation during the final sprint. What is the primary reason for this metabolic shift?

Accepted Answer

Oxygen supply is insufficient for the rate of ATP demand, so cells rely on glycolysis and fermentation to regenerate NAD$$^+.$$

Question 9

Which of the following statements about the electron transport chain (ETC) in mitochondria is correct?

Accepted Answer

The ETC uses energy from electrons to pump H$$^+$$ into the intermembrane space, creating a gradient used by ATP synthase to make ATP.

Question 10

Which of the following best describes the role of dehydrogenase enzymes in cellular respiration?

Accepted Answer

They remove hydrogen atoms from substrates and transfer electrons to NAD$$^+ or $$FAD.

Question 11

A person is placed on a diet consisting almost entirely of fats and proteins, with minimal carbohydrates. Which of the following best explains how their cells can still produce ATP?

Accepted Answer

Fats and proteins can be broken down into intermediates that enter cellular respiration pathways, such as acetyl CoA.

Question 12

Which of the following is NOT a characteristic that suggests glycolysis is an ancient metabolic pathway?

Accepted Answer

It requires oxygen to function.

Question 13

During the citric acid cycle, for each acetyl CoA that enters, what are the main products generated?

Accepted Answer

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

Question 14

Which of the following best explains why the energy yield from cellular respiration is less than 100% efficient?

Accepted Answer

Some energy is lost as heat during the transfer of energy from glucose to ATP.

Question 15

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

Accepted Answer

It involves the direct transfer of a phosphate group from an organic molecule to ADP to form ATP.

Question 16

A cell is exposed to a toxin that blocks ATP synthase. Which of the following would be the most immediate effect on cellular respiration?

Accepted Answer

ATP production by oxidative phosphorylation would stop, but electron transport would continue for a short time.

Question 17

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

Accepted Answer

It acts as the final electron acceptor in the electron transport chain and is reduced to form water.

Question 18

Which of the following is true about facultative anaerobes?

Accepted Answer

They can survive using either fermentation or aerobic respiration, depending on oxygen availability.

Question 19

A scientist discovers a new organism that can survive in environments with or without oxygen, switching between fermentation and aerobic respiration. Which term best describes this organism?

Accepted Answer

Facultative anaerobe

Question 20

Which of the following best explains the role of feedback inhibition in cellular respiration?

Accepted Answer

It allows cells to regulate metabolic pathways by inhibiting enzymes when sufficient end products are present.

Cellular Respiration: How Cells Harvest Chemical Energy

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