Q: Which of the following equations correctly represents the standard free energy change for electron transfer from NADH to O$$_2 in $$the respiratory chain?

$$\Delta G^\circ = -nF(E^\circ_{\text{acceptor}} - E^\circ_{\text{donor}})$$

Question 1

Which of the following best describes the primary function of the mitochondrion in eukaryotic cells?

Accepted Answer

Site of oxidative energy generation through electron transport and ATP synthesis

Question 2

During oxidative metabolism, which molecule is the final electron acceptor in the electron transport chain?

Accepted Answer

O$$_2$$

Question 3

Which of the following equations correctly represents the standard free energy change for electron transfer from NADH to O$$_2 in $$the respiratory chain?

Accepted Answer

$$\Delta G^\circ = -nF(E^\circ_{	ext{acceptor}} - E^\circ_{	ext{donor}})$$

Question 4

Which of the following statements about the electron transport chain is TRUE?

Accepted Answer

Electron transport is coupled to the pumping of protons from the matrix to the intermembrane space

Question 5

Which component of the electron transport chain acts as a mobile electron carrier between Complexes I/II and III?

Accepted Answer

Coenzyme Q (ubiquinone)

Question 6

What is the main role of iron-sulfur clusters in the electron transport chain?

Accepted Answer

To transfer single electrons between protein complexes

Question 7

Which of the following best explains the chemiosmotic theory of ATP synthesis?

Accepted Answer

ATP synthesis is driven by the dissipation of the proton gradient across the inner mitochondrial membrane

Question 8

The P/O ratio refers to:

Accepted Answer

The number of ATP molecules synthesized per pair of electrons transferred to oxygen

Question 9

If a mutation impairs the function of Complex IV (cytochrome c oxidase), which of the following would most likely occur?

Accepted Answer

Accumulation of NADH and FADH$$_2 in $$the matrix

Question 10

Which equation correctly describes the free energy change associated with the electrochemical gradient (protonmotive force) across the inner mitochondrial membrane?

Accepted Answer

$$\Delta G = RT \ln \left| \frac{C_2$}{C_1$} \right| + ZF \Delta \psi$$

Question 11

Which of the following is TRUE regarding ATP synthase (Complex V)?

Accepted Answer

It contains a rotor (c-ring) that rotates in response to proton flow

Question 12

Which of the following best describes the binding-change model for ATP synthase?

Accepted Answer

The three catalytic sites cycle through loose, tight, and open conformations as the gamma subunit rotates

Question 13

Which of the following statements about respiratory control is correct?

Accepted Answer

Electron transport and ATP synthesis are tightly coupled and regulated by ADP and Pi availability

Question 14

A patient is exposed to an uncoupler of oxidative phosphorylation. Which of the following would you expect to observe?

Accepted Answer

Increased oxygen consumption and decreased ATP synthesis

Question 15

Which of the following is a major source of reactive oxygen species (ROS) in the cell?

Accepted Answer

Electron leakage from the mitochondrial electron transport chain

Question 16

Which enzyme catalyzes the dismutation of superoxide radicals to hydrogen peroxide and oxygen?

Accepted Answer

Superoxide dismutase (SOD)

Question 17

Which of the following best explains why the total ATP yield per glucose oxidized is not always an integer?

Accepted Answer

The P/O ratios are not whole numbers due to variable coupling efficiency and transport processes

Question 18

Which of the following mitochondrial transport systems is responsible for exchanging ADP and ATP across the inner membrane?

Accepted Answer

Adenine nucleotide translocase

Question 19

A defect in mitochondrial DNA most commonly affects which of the following processes?

Accepted Answer

Electron transport and oxidative phosphorylation

Electron Transport, Oxidative Phosphorylation, and Oxygen Metabolism

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