Question 1

Which structure in the mitochondrion is the site of the citric acid cycle?

Accepted Answer

Matrix

Question 2

During oxidative phosphorylation, protons are pumped into which compartment of the mitochondrion?

Accepted Answer

Intermembrane space

Question 3

Which of the following best describes the chemiosmotic coupling model?

Accepted Answer

Electron transport drives proton pumping into the intermembrane space, and the resulting gradient powers ATP synthesis.

Question 4

Which complexes of the electron transport chain pump protons into the intermembrane space?

Accepted Answer

Complexes I, III, and IV

Question 5

What is the order of reduction potential as electrons move along the electron transport chain?

Accepted Answer

Electrons move from carriers with more negative to more positive reduction potentials.

Question 6

Which electron carrier is found in Complex I and can accept 2 electrons and 2 protons?

Accepted Answer

FMN

Question 7

What is the P/O ratio for the oxidation of NADH?

Accepted Answer

$$2.5$$

Question 8

Why is the P/O ratio not an integer?

Accepted Answer

Because phosphorylation and oxidation are not directly coupled, and proton pumping does not divide evenly into protons needed per ATP.

Question 9

Which of the following is a property of Coenzyme Q (ubiquinone)?

Accepted Answer

It is lipid soluble and diffuses rapidly through the inner mitochondrial membrane.

Question 10

Which complex is also known as NADH-Coenzyme Q reductase?

Accepted Answer

Complex I

Question 11

How many moles of ATP are generated from the beginning of glycolysis through the end of the citric acid cycle?

Accepted Answer

$$4$$

Question 12

Which of the following statements about the structure of ATP synthase (Complex V) is correct?

Accepted Answer

The F1 portion is composed of α3β3γδε subunits.

Question 13

Which of the following best describes the mechanism by which protons drive the synthesis of ATP?

Accepted Answer

Rotation of the γ subunit, driven by proton flow through F0, causes conformational changes in αβ dimers, enabling ATP synthesis.

Question 14

Which of the following is NOT a class of electron carrier in the electron transport chain?

Accepted Answer

ATP synthase

Question 15

Which cytochrome acts as a shuttle between Complex III and IV?

Accepted Answer

Cytochrome c

Question 16

What is the total yield of ATP per mole of glucose oxidized in cellular respiration?

Accepted Answer

$$32$$

Question 17

Which of the following reactions is catalyzed by Complex II?

Accepted Answer

Electron transfer from succinate to CoQ

Question 18

Which of the following statements about iron-sulfur clusters is correct?

Accepted Answer

Each cluster carries just one electron.

Question 19

Which of the following best explains why the total ATP yield per glucose can vary between cells?

Accepted Answer

Some cells use the glycerol phosphate shuttle, which causes cytosolic NADH to enter the respiratory chain as FADH2, yielding less ATP.

Question 20

Which of the following is the correct sequence of electron flow through Complex I?

Accepted Answer

NADH → FMN → FeS → CoQ

Study Guide: Electron Transport, Oxidative Phosphorylation, and Mitochondrial Structure

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