$$\frac{1}{2} \text{O}_2 + 2e^- + 2\text{H}^+ \rightarrow \text{H}_2\text{O}$$

Question 1

Which of the following best describes the main function of the electron transport chain (ETC) in cellular respiration?

Accepted Answer

To transfer electrons from NADH and FADH₂ to oxygen, pumping protons to create a proton gradient

Question 2

During oxidative phosphorylation, what is the role of oxygen?

Accepted Answer

It is the final electron acceptor, forming water

Question 3

A poison blocks the function of cytochrome c oxidase (complex IV) in the ETC. What is the immediate effect on cellular respiration?

Accepted Answer

O₂ consumption stops, NADH accumulates, and ATP synthesis collapses

Question 4

Which equation correctly represents the formation of water at the end of the electron transport chain?

Accepted Answer

$$\frac{1}{2} 	ext{O}_2 + 2e^- + 2	ext{H}^+ ightarrow 	ext{H}_2	ext{O}$$

Question 5

What would happen if the inner mitochondrial membrane became leaky to protons (H⁺)?

Accepted Answer

Electron transport would continue, ATP synthesis would fall, and body temperature would rise

Question 6

Why do cells perform fermentation in the absence of oxygen?

Accepted Answer

To regenerate NAD⁺ so glycolysis can continue producing ATP

Question 7

Which of the following is a correct summary of the products generated per turn of the citric acid cycle?

Accepted Answer

2 CO₂, 3 NADH, 1 FADH₂, 1 ATP

Question 8

A yeast culture is switched from aerobic to anaerobic conditions with plenty of glucose. What happens to its rate of glucose consumption and why?

Accepted Answer

It increases because fermentation produces much less ATP per glucose

Question 9

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 to CO₂, which is exhaled

Question 10

What is the main purpose of the proton-motive force generated by the electron transport chain?

Accepted Answer

To drive the synthesis of ATP by ATP synthase

Question 11

Which of the following statements about ATP synthase is correct?

Accepted Answer

It is a rotary enzyme that uses the flow of H⁺ to synthesize ATP from ADP and Pᵢ

Question 12

Which of the following is NOT a product of lactic acid fermentation?

Accepted Answer

CO₂

Question 13

In the absence of oxygen, what is the main emergency for a cell?

Accepted Answer

Lack of NAD⁺ to accept electrons in glycolysis

Question 14

Which of the following best describes the evolutionary significance of glycolysis?

Accepted Answer

It is an ancient pathway present in nearly all living cells and does not require oxygen

Question 15

What did Jan Baptista van Helmont's willow tree experiment demonstrate?

Accepted Answer

That most of a tree's mass does not come from the soil

Question 16

Which of the following equations represents the overall process of aerobic cellular respiration?

Accepted Answer

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

Question 17

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

Accepted Answer

It completes the oxidation of glucose carbons to CO₂ without directly using O₂

Question 18

Which of the following best explains why FADH₂ yields less ATP than NADH during oxidative phosphorylation?

Accepted Answer

FADH₂ donates electrons at a lower energy level, so fewer protons are pumped across the membrane

Question 19

Which of the following is a correct description of chemiosmosis?

Accepted Answer

The use of a proton gradient to drive the synthesis of ATP

Cellular Respiration II: Electron Transport, Chemiosmosis, and Fermentation

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