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

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

Question 1

During one complete turn of the citric acid cycle, how many molecules of NADH and FADH$$_2$$ are produced, and how many molecules of CO$$_2$$ are released?

Accepted Answer

3 NADH, 1 FADH$$_2$$, and 2 CO$$_2$$

Question 2

Which molecule enters the citric acid cycle by combining with oxaloacetate to form citrate?

Accepted Answer

Acetyl CoA

Question 3

If a cell is deprived of oxygen, which process will be directly inhibited, and what alternative pathway may be activated to allow ATP production?

Accepted Answer

Electron Transport Chain; Fermentation

Question 4

In oxidative phosphorylation, what is the role of the electron transport chain and how does it contribute to ATP synthesis?

Accepted Answer

It pumps H$$^+$$ ions into the intermembrane space, creating a gradient that drives ATP synthesis via chemiosmosis.

Question 5

A yeast cell is moved from an aerobic to an anaerobic environment. To maintain the same rate of ATP production, how must its rate of glucose consumption change?

Accepted Answer

It must increase because fermentation yields less ATP per glucose.

Question 6

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

Accepted Answer

It takes place in the cytosol and does not require oxygen.

Question 7

Which of the following is a correct sequence of events in cellular respiration starting from glucose?

Accepted Answer

Glycolysis → Pyruvate Oxidation → Citric Acid Cycle → Electron Transport Chain

Question 8

Which of the following organic molecules can be used as fuel for cellular respiration?

Accepted Answer

Carbohydrates, fats, and proteins

Question 9

How can a person gain fat even when consuming a low-fat diet?

Accepted Answer

Carbohydrates and proteins can be converted into fat through metabolic pathways.

Question 10

Which process recycles NAD$$^+$$ from NADH by reducing pyruvate to lactate in muscle cells under anaerobic conditions?

Accepted Answer

Lactic acid fermentation

Question 11

What is the final electron acceptor in the electron transport chain of aerobic respiration?

Accepted Answer

O$$_2$$

Question 12

Which metabolic pathway is regulated by feedback inhibition to prevent the overproduction of intermediates?

Accepted Answer

Cellular respiration

Question 13

If a person eats a meal high in protein but low in carbohydrates, which pathway allows amino acids to be used for energy?

Accepted Answer

Amino acids are deaminated and their carbon skeletons enter the citric acid cycle.

Question 14

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

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 6\,\mathrm{O_2$} ightarrow 6\,\mathrm{CO_2$} + 6\,\mathrm{H_2O} + 	ext{energy}$$

Question 15

Which step in cellular respiration produces the most ATP?

Accepted Answer

Oxidative phosphorylation

Question 16

What is the main purpose of fermentation in cells under anaerobic conditions?

Accepted Answer

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

Question 17

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

Accepted Answer

It completes the breakdown of glucose by oxidizing acetyl CoA.

Question 18

If a cell uses only fats and proteins for energy, which metabolic pathway will be most active?

Accepted Answer

Citric acid cycle

Question 19

Which of the following is a product of alcohol fermentation?

Accepted Answer

Ethanol and CO$$_2$$

Question 20

A patient with a genetic defect in ATP synthase would have difficulty with which process?

Accepted Answer

Producing ATP via chemiosmosis

Cellular Respiration: The Citric Acid Cycle, Oxidative Phosphorylation, and Fermentation

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