Q: Which of the following best describes the overall chemical equation for aerobic cellular respiration?

$$\text{C}_6\text{H}_{12}\text{O}_6 + 6 \text{O}_2 \rightarrow 6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{ATP} + \text{heat}$$

Question 1

Which of the following best describes the overall chemical equation for aerobic cellular respiration?

Accepted Answer

$$	ext{C}_6	ext{H}_{12}	ext{O}_6 + 6 	ext{O}_2 ightarrow 6 	ext{CO}_2 + 6 	ext{H}_2	ext{O} + 	ext{ATP} + 	ext{heat}$$

Question 2

During which stage of cellular respiration is the majority of ATP produced?

Accepted Answer

Oxidative phosphorylation (electron transport chain and chemiosmosis)

Question 3

Which molecule acts as the final electron acceptor in the electron transport chain during aerobic respiration?

Accepted Answer

$$	ext{O}_2$$

Question 4

What is the main purpose of redox reactions in cellular respiration?

Accepted Answer

To transfer electrons and energy from glucose to electron carriers

Question 5

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

Direct transfer of a phosphate group to ADP from a phosphorylated intermediate

Question 6

Where does glycolysis occur within the cell?

Accepted Answer

Cytosol

Question 7

Which of the following is a product of the citric acid cycle for each acetyl-CoA that enters?

Accepted Answer

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

Question 8

What is the role of NAD$$^+ in $$cellular respiration?

Accepted Answer

It acts as an electron carrier, accepting electrons during redox reactions.

Question 9

Which process regenerates NAD$$^+ in $$the absence of oxygen, allowing glycolysis to continue?

Accepted Answer

Fermentation

Question 10

A mutation disables Complex IV of the electron transport chain. What is the most immediate consequence for the cell?

Accepted Answer

Oxygen will not be reduced to water, halting ATP production by oxidative phosphorylation.

Question 11

Which of the following best explains why fats yield more ATP per gram than carbohydrates?

Accepted Answer

Fats are more reduced and thus have more electrons to donate to the electron transport chain.

Question 12

Which enzyme is a key regulatory point in glycolysis and is inhibited by high levels of ATP?

Accepted Answer

Phosphofructokinase

Question 13

In the context of chemiosmosis, what is the direct energy source that drives ATP synthesis by ATP synthase?

Accepted Answer

The flow of protons (H$$^+) $$down their electrochemical gradient across the inner mitochondrial membrane

Question 14

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation regenerates NAD$$^+ so $$glycolysis can continue in the absence of oxygen.

Question 15

If a cell is exposed to cyanide, which blocks electron transfer to O$$_2$$, what will happen to the NADH/NAD$$^+$$ ratio?

Accepted Answer

The ratio will increase because NADH cannot be oxidized in the electron transport chain.

Question 16

Which of the following is NOT a product of glycolysis?

Accepted Answer

FADH$$_2$$

Question 17

What is the efficiency of cellular respiration in converting the energy stored in glucose to ATP, given the following values: $$\Delta G$$ for glucose oxidation is $$-2870 kJ/$$mol and $$\Delta G$$ for ATP synthesis is $$30.5 kJ/$$mol, with 32 ATP produced per glucose?

Accepted Answer

$$\frac{30.5 	imes 32}{2870} = 0.34 or 34$$%

Question 18

Which of the following best describes the fate of the carbons from glucose during aerobic respiration?

Accepted Answer

They are released as CO$$_2$$ during pyruvate oxidation and the citric acid cycle.

Question 19

Which of the following is a key difference between aerobic respiration and fermentation?

Accepted Answer

Aerobic respiration uses an electron transport chain, fermentation does not.

Question 20

A patient has a genetic defect that prevents the formation of mitochondrial supercomplexes. Which of the following is a likely consequence?

Accepted Answer

Disrupted electron transport chain function, possibly leading to neurodegenerative disorders

Topic 5 Cellular Respiration: Pathways, Mechanisms, and Regulation

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