Q: Which of the following best describes the role of the electron transport chain in cellular respiration?

It uses the energy from electrons to pump H\textsuperscript{+} ions across a membrane, creating a proton gradient.

Q: During chemiosmosis, what is the immediate energy source that drives ATP synthesis by ATP synthase?

The flow of H\textsuperscript{+} ions down their concentration gradient across the mitochondrial membrane.

Question 1

Which of the following best describes the role of the electron transport chain in cellular respiration?

Accepted Answer

It uses the energy from electrons to pump H	extsuperscript{+} ions across a membrane, creating a proton gradient.

Question 2

During chemiosmosis, what is the immediate energy source that drives ATP synthesis by ATP synthase?

Accepted Answer

The flow of H	extsuperscript{+} ions down their concentration gradient across the mitochondrial membrane.

Question 3

Which equation correctly summarizes the overall process of 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 4

Why is oxygen required for aerobic cellular respiration?

Accepted Answer

Oxygen acts as the final electron acceptor in the electron transport chain.

Question 5

If a cell is deprived of oxygen, which process will continue to function?

Accepted Answer

Glycolysis

Question 6

Which of the following is a direct product of glycolysis?

Accepted Answer

Pyruvate

Question 7

In the context of yogurt production, which metabolic process is primarily responsible for the conversion of lactose to lactic acid by Lactobacillus?

Accepted Answer

Lactic acid fermentation

Question 8

Which of the following statements about ATP synthase is correct?

Accepted Answer

ATP synthase is embedded in the inner mitochondrial membrane and synthesizes ATP as H	extsuperscript{+} ions flow through it.

Question 9

Which of the following best explains why the electron transport chain is considered a series of redox reactions?

Accepted Answer

Electrons are transferred from one molecule to another, with each transfer involving oxidation and reduction.

Question 10

A patient has a genetic defect that prevents the formation of FADH	extsubscript{2}. Which stage of cellular respiration would be most directly affected?

Accepted Answer

Citric acid cycle

Question 11

Which of the following is the correct sequence of events in aerobic cellular respiration?

Accepted Answer

Glycolysis $$ \rightarrow $$ Citric acid cycle $$ \rightarrow $$ Electron transport chain

Question 12

Which of the following best describes the fate of NADH produced during glycolysis under anaerobic conditions in human muscle cells?

Accepted Answer

NADH is used to reduce pyruvate to lactate, regenerating NAD	extsuperscript{+}.

Question 13

Which of the following is a real-life consequence of a defect in the electron transport chain in human mitochondria?

Accepted Answer

Increased production of lactic acid in muscle cells during exercise

Question 14

Which of the following statements about the proton gradient in mitochondria is correct?

Accepted Answer

The proton gradient is established by the flow of protons from the mitochondrial matrix to the intermembrane space.

Question 15

A scientist adds a chemical that makes the inner mitochondrial membrane permeable to H	extsuperscript{+} ions. What is the most likely effect on ATP production?

Accepted Answer

ATP production by ATP synthase will decrease because the proton gradient is dissipated.

Question 16

Which of the following best explains why fermentation is less efficient than aerobic respiration?

Accepted Answer

Fermentation does not use the electron transport chain, so less ATP is produced per glucose molecule.

Question 17

Which of the following is a correct statement about the role of NAD	extsuperscript{+} in cellular respiration?

Accepted Answer

NAD	extsuperscript{+} acts as an electron acceptor during glycolysis and the citric acid cycle.

Question 18

Which of the following best describes the function of the citric acid cycle in cellular respiration?

Accepted Answer

It generates NADH and FADH	extsubscript{2} for use in the electron transport chain.

Question 19

A person is on a high-protein, low-carbohydrate diet. Which pathway allows amino acids to be used for ATP production?

Accepted Answer

Amino acids are converted to intermediates that enter the citric acid cycle.

Cellular Respiration: How Life on Earth Makes ATP

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