Question 1

Which of the following best describes the main purpose of glycolysis in cellular respiration?

Accepted Answer

To convert glucose into two molecules of pyruvate, generating a small amount of ATP and NADH.

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 of the following equations correctly represents the overall process of aerobic glucose oxidation?

Accepted Answer

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

Question 4

What is the primary function of NAD+ and FAD in cellular respiration?

Accepted Answer

They act as electron carriers, temporarily storing energy as they are reduced to NADH and FADH$$_2.$$

Question 5

Which process occurs in the cytosol and does not require oxygen directly?

Accepted Answer

Glycolysis

Question 6

In the citric acid cycle, what is the fate of the two-carbon acetyl group from acetyl-CoA?

Accepted Answer

It is fully oxidized to two molecules of CO$$_2.$$

Question 7

Which of the following best explains why cells cannot maximize ATP production alone during metabolism?

Accepted Answer

Some citric acid cycle intermediates are withdrawn for biosynthesis, diverting carbon away from complete oxidation.

Question 8

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

Accepted Answer

It involves the direct transfer of a phosphate group from a substrate to ADP by an enzyme.

Question 9

A muscle cell is deprived of oxygen. Which pathway will allow it to continue producing ATP, and what is the main limitation of this pathway?

Accepted Answer

Glycolysis, but it produces much less ATP per glucose than aerobic respiration.

Question 10

Which of the following is a correct description of a redox reaction in cellular respiration?

Accepted Answer

Glucose is oxidized (loses electrons) and oxygen is reduced (gains electrons).

Question 11

During the energy investment phase of glycolysis, what is the role of ATP?

Accepted Answer

ATP phosphorylates glucose and its intermediates, making them more reactive.

Question 12

Which of the following best explains why the citric acid cycle is considered a cycle?

Accepted Answer

The four-carbon molecule oxaloacetate is regenerated at the end of each turn, allowing the cycle to repeat.

Question 13

If a cell withdraws oxaloacetate from the citric acid cycle for biosynthesis, what is a likely consequence?

Accepted Answer

The cycle will slow down or stop unless oxaloacetate is replenished.

Question 14

Which of the following is NOT a product of one turn of the citric acid cycle per acetyl-CoA?

Accepted Answer

2 ATP

Question 15

A researcher adds a chemical that blocks the reduction of NAD+ to NADH during glycolysis. What is the most immediate effect on the cell?

Accepted Answer

Glycolysis will stop because NAD+ is required to accept electrons.

Question 16

Which of the following best describes the fate of the six carbons in glucose after complete aerobic respiration?

Accepted Answer

All six carbons are released as CO$$_2.$$

Question 17

Which of the following statements about oxidative phosphorylation is correct?

Accepted Answer

It uses the energy from electrons carried by NADH and FADH$$_2 to $$create a proton gradient that drives ATP synthesis.

Question 18

A patient has a genetic defect that prevents the formation of FADH$$_2. $$Which stage of cellular respiration will be most directly affected?

Accepted Answer

Citric acid cycle

Question 19

Which of the following best explains why glycolysis is considered an ancient metabolic pathway?

Accepted Answer

It occurs in the cytosol and does not require oxygen, making it possible in early anaerobic environments.

Question 20

Which of the following is a real-world example of the importance of balancing ATP production and biosynthesis in a growing organism?

Accepted Answer

A pig with the same body mass as another may have different tissue composition depending on nutrient delivery and ATP demand.

Cellular Respiration: Harvesting Energy from Glucose

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