Question 1

Which component of the mitochondrion is primarily responsible for the generation of the electrochemical proton gradient during aerobic respiration?

Accepted Answer

The inner mitochondrial membrane

Question 2

The endosymbiotic hypothesis is supported by which feature of mitochondria?

Accepted Answer

Presence of a double membrane and circular DNA

Question 3

Which equation correctly describes the relationship between free energy change ($$\Delta G^\circ) $$and the change in reduction potential ($$\Delta E) $$during electron transport?

Accepted Answer

$$\Delta G^\circ = (-nF \Delta E)$$

Question 4

Which molecule acts as the final electron acceptor in the mitochondrial electron transport chain?

Accepted Answer

O$$_2$$

Question 5

A patient takes 2,4-dinitrophenol (DNP), which uncouples the electron transport chain. What is the most likely physiological consequence?

Accepted Answer

Increased heat production

Question 6

Which complex in the electron transport chain does NOT pump protons into the intermembrane space?

Accepted Answer

Complex II

Question 7

Cytochrome c is best described as:

Accepted Answer

A peripheral membrane protein that transfers electrons only

Question 8

Which of the following best explains why the electron transport chain transfers electrons in small steps?

Accepted Answer

To increase the efficiency of energy conversion and reduce energy loss as heat

Question 9

If the reduction potential ($$E^\$$prime_0$$) of NADH is -0.32 V and that of O_2$ is +0.82 V, what is the change in reduction potential ($$\Delta E$$) for the transfer of electrons from NADH to O_2$?

Accepted Answer

$$\Delta E = +1.14\ 	ext{V}$$

Question 10

Which of the following is TRUE regarding the F$$_1F$_0$$ ATP synthase complex?

Accepted Answer

The F$$_1$$ subunit contains catalytic sites for ATP synthesis and is attached to the F$$_0$$ subunit

Question 11

During aerobic respiration, how many ATP molecules are produced per NADH molecule via the electron transport chain?

Accepted Answer

3 ATP

Question 12

Which of the following best describes the role of Coenzyme Q (ubiquinone) in the electron transport chain?

Accepted Answer

It is a non-protein carrier that transfers both electrons and protons

Question 13

Which of the following statements about chemiosmosis is correct?

Accepted Answer

Chemiosmosis is the movement of H$$^+$$ ions down their electrochemical gradient, driving ATP synthesis

Question 14

A mutation causes the F$$_1$$ β subunits of ATP synthase to lose their ability to change conformation. What is the most likely effect?

Accepted Answer

ATP synthesis will decrease because ADP and P cannot be converted to ATP

Question 15

Which of the following best describes the function of the Fe-S proteins in the electron transport chain?

Accepted Answer

They transfer electrons only

Question 16

In the electron transport chain, which complex receives electrons from succinate and passes them to CoQ?

Accepted Answer

Complex II

Question 17

Which of the following is a consequence of inhibiting H$$^+$$ diffusion through the inner mitochondrial membrane?

Accepted Answer

The electrochemical gradient is maintained but ATP synthesis stops

Question 18

Which of the following best explains why mitochondria in sperm cells are concentrated in the midpiece?

Accepted Answer

To provide energy for movement via ATP production

Question 19

Which of the following is TRUE regarding the lateral movement of electron transport chain complexes within the inner mitochondrial membrane?

Accepted Answer

It allows for efficient electron transfer between complexes

Question 20

Which of the following is the correct sequence of electron flow in the mitochondrial electron transport chain?

Accepted Answer

NADH → Complex I → CoQ → Complex III → Cytochrome c → Complex IV → O$$_2$$

Electron Transport Chain and ATP Synthesis in Mitochondria

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