Question 1

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

Accepted Answer

To pump protons across the inner mitochondrial membrane, creating an electrochemical gradient.

Question 2

Which of the following statements about chemiosmotic coupling is CORRECT?

Accepted Answer

It links the movement of electrons through the electron transport chain to the synthesis of ATP via a proton gradient.

Question 3

A mutation causes the inner mitochondrial membrane to become permeable to protons. What is the most likely consequence?

Accepted Answer

ATP synthesis by ATP synthase will decrease significantly.

Question 4

Which of the following equations correctly represents the overall reaction catalyzed by cytochrome c oxidase in the electron transport chain?

Accepted Answer

$$4e^- + 4H^+ + O_2$ \rightarrow 2H_2O$$

Question 5

Which feature is shared by mitochondria, chloroplasts, and bacteria, supporting the endosymbiotic theory?

Accepted Answer

Presence of circular DNA genomes.

Question 6

What is the primary role of NADH and FADH2 in cellular respiration?

Accepted Answer

To donate high-energy electrons to the electron transport chain.

Question 7

Which compartment of the mitochondrion contains the enzymes for the citric acid cycle?

Accepted Answer

Matrix

Question 8

If a cell's demand for ATP increases, what is a likely response of its mitochondria?

Accepted Answer

Increase in number and/or elongation to form networks.

Question 9

Which of the following best explains why FADH2 produces fewer ATP molecules than NADH during oxidative phosphorylation?

Accepted Answer

FADH2 donates electrons further down the electron transport chain, bypassing the first proton pump.

Question 10

Which of the following is a direct consequence of the proton gradient across the inner mitochondrial membrane?

Accepted Answer

Synthesis of ATP from ADP and Pi by ATP synthase.

Question 11

A scientist adds an uncoupling agent to isolated mitochondria. What is the most immediate effect?

Accepted Answer

ATP synthesis decreases while electron transport continues.

Question 12

Which of the following best describes the role of ATP synthase?

Accepted Answer

It uses the energy of the proton gradient to catalyze the formation of ATP from ADP and Pi.

Question 13

Which of the following statements about the inner mitochondrial membrane is TRUE?

Accepted Answer

It is impermeable to most ions and contains the proteins of the electron transport chain.

Question 14

Which of the following is a function of the cristae in mitochondria?

Accepted Answer

Increase the surface area for oxidative phosphorylation.

Question 15

Which of the following best explains why the chemiosmotic mechanism is considered ancient and fundamental to life?

Accepted Answer

It is found in mitochondria, chloroplasts, and many bacteria, indicating an early evolutionary origin.

Question 16

Which of the following is a correct description of a redox pair in the context of the electron transport chain?

Accepted Answer

$$NADH \rightleftharpoons NAD^+ + H^+ + 2e^-$$

Question 17

Which of the following is a property of transition metal ions that makes them suitable as electron carriers in the electron transport chain?

Accepted Answer

They can exist in multiple oxidation states with closely spaced redox potentials.

Question 18

Which of the following best describes the path of electrons from NADH through the respiratory chain?

Accepted Answer

NADH → NADH dehydrogenase complex → ubiquinone → cytochrome c reductase complex → cytochrome c → cytochrome c oxidase complex → O2

Question 19

Which of the following is a direct result of the stepwise movement of electrons through the electron transport chain?

Accepted Answer

Protons are pumped from the mitochondrial matrix to the intermembrane space.

Question 20

Which of the following best explains why oxygen is essential for aerobic respiration?

Accepted Answer

It serves as the final electron acceptor in the electron transport chain, allowing the chain to continue functioning.

Membrane-Based Energy Generation and Mitochondrial Function: Study Notes for Genetics Students

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