Question 1

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

Accepted Answer

Oxygen acts as the final electron acceptor in the electron transport chain, allowing electrons to fall and form water.

Question 2

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

Accepted Answer

2 ATP and 2 NADH

Question 3

Which stage of cellular respiration releases the first carbon dioxide (CO₂) from glucose?

Accepted Answer

Pyruvate oxidation

Question 4

If a toxin blocks the citric acid cycle, which of the following would you expect to accumulate?

Accepted Answer

Acetyl-CoA

Question 5

Which of the following statements about enzyme inhibition is correct?

Accepted Answer

Competitive inhibitors bind to the active site and can be outcompeted by increasing substrate concentration.

Question 6

What is the main function of NAD⁺ in cellular respiration?

Accepted Answer

To act as an electron shuttle, accepting electrons and becoming NADH.

Question 7

Which of the following best explains why most of the mass lost during fat metabolism leaves the body as CO₂?

Accepted Answer

The carbon atoms in fat are oxidized and released as CO₂ during respiration, which is exhaled through the lungs.

Question 8

Which of the following equations correctly represents the overall reaction for aerobic cellular respiration?

Accepted Answer

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

Question 9

Which of the following is an example of feedback inhibition in cellular respiration?

Accepted Answer

ATP binding to an allosteric site on phosphofructokinase, slowing glycolysis when ATP is abundant.

Question 10

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

An enzyme transfers a phosphate group directly from a substrate to ADP, forming ATP.

Question 11

A patient is given a drug that blocks the transport protein for pyruvate into the mitochondrion. Which of the following would most likely occur?

Accepted Answer

Glycolysis would continue, but pyruvate would accumulate in the cytosol.

Question 12

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

Accepted Answer

It completes the oxidation of glucose by releasing the remaining carbons as CO₂.

Question 13

Which of the following best explains why enzymes are sensitive to temperature and pH?

Accepted Answer

Changes in temperature or pH can denature the enzyme, altering the shape of the active site and preventing substrate binding.

Question 14

Which of the following is true regarding the fate of the carbons from glucose during cellular respiration?

Accepted Answer

All six carbons are released as CO₂ by the end of the citric acid cycle.

Question 15

Which of the following best describes the role of coenzyme A in cellular respiration?

Accepted Answer

It carries the acetyl group into the citric acid cycle as acetyl-CoA.

Question 16

Which of the following statements about the energy yield of cellular respiration is correct?

Accepted Answer

Most of the ATP is produced during oxidative phosphorylation, not during glycolysis or the citric acid cycle.

Question 17

Which of the following best describes the process of beta oxidation?

Accepted Answer

Fatty acids are broken down into two-carbon units that enter the citric acid cycle as acetyl-CoA.

Question 18

Which of the following is a correct statement about the location of the stages of cellular respiration?

Accepted Answer

Glycolysis occurs in the cytosol, while pyruvate oxidation and the citric acid cycle occur in the mitochondrial matrix.

Cellular Respiration: The Fate of Carbons and Energy Flow

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