Question 1

Which of the following statements best describes the main function of oxidative phosphorylation in mitochondria?

Accepted Answer

To use redox reactions and chemical gradients to produce ATP

Question 2

Which electron carrier is membrane-soluble and shuttles electrons between larger, less mobile membrane-bound proteins in the electron transport chain?

Accepted Answer

Ubiquinone (Coenzyme Q)

Question 3

What is the correct sequence of electron flow through the mitochondrial electron transport chain complexes?

Accepted Answer

Complex I → Complex III → Complex IV

Question 4

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

Accepted Answer

Complex II

Question 5

The proton motive force (PMF) generated by the electron transport chain creates potential energy in two forms. Which equation best represents the free energy change associated with PMF?

Accepted Answer

$$\Delta G = 2.3RT\Delta pH + ZFD\psi$$

Question 6

Which of the following statements about ATP synthase is TRUE?

Accepted Answer

ATP synthase uses the energy from the proton gradient to synthesize ATP from ADP and Pi

Question 7

During oxidative phosphorylation, which molecule acts as the final electron acceptor?

Accepted Answer

O$$_2$$

Question 8

Which of the following best explains why the electron transport chain does not directly produce ATP?

Accepted Answer

It creates a proton gradient that is used by ATP synthase to produce ATP

Question 9

A mutation causes the F$$_0$$ subunit of ATP synthase to lose its ability to rotate. What is the most likely consequence?

Accepted Answer

ATP synthesis will be severely impaired because rotational catalysis is required for ATP release

Question 10

Which of the following is a key regulatory mechanism of oxidative phosphorylation?

Accepted Answer

Acceptor control by levels of free ADP and Pi

Question 11

Which statement about the role of cytochromes in the electron transport chain is CORRECT?

Accepted Answer

Cytochromes are proteins with heme groups that shuttle electrons via changes in the oxidation state of iron

Question 12

Which of the following best describes the function of iron-sulfur proteins in the electron transport chain?

Accepted Answer

They transfer electrons via iron coordinated by cysteine, histidine, or inorganic sulfur

Question 13

In the context of the electron transport chain, what is the main role of Complex II (succinate dehydrogenase)?

Accepted Answer

To transfer electrons from succinate to ubiquinone

Question 14

Which of the following is TRUE regarding the movement of ADP and ATP across the mitochondrial membrane?

Accepted Answer

ADP (-3 charge) is pumped into the matrix while ATP (-4 charge) is pumped out

Question 15

Which of the following best describes the chemiosmotic model of ATP synthesis?

Accepted Answer

ATP is synthesized using the energy from the proton gradient across the inner mitochondrial membrane

Question 16

Which of the following is a consequence of inhibiting Complex IV (cytochrome c oxidase) in the electron transport chain?

Accepted Answer

Accumulation of NADH and FADH$$_2$$ and cessation of ATP synthesis

Question 17

Which of the following is TRUE about the structure and function of chloroplasts in photosynthesis?

Accepted Answer

Chloroplasts contain thylakoid membranes where photosynthetic pigments and ATP synthesis machinery are located

Question 18

Which of the following statements about the light-dependent reactions of photosynthesis is CORRECT?

Accepted Answer

They use light energy to generate ATP and reduce NADP$$^+ to $$NADPH

Question 19

Which of the following is a shared feature between oxidative phosphorylation in mitochondria and photosynthesis in chloroplasts?

Accepted Answer

Both use a proton gradient across a membrane to drive ATP synthesis

Question 20

A patient is diagnosed with a defect in the phosphate translocase of mitochondria. Which process would be most directly affected?

Accepted Answer

Import of H$$_2PO$_4^-$$ and H$$^+$$ into the matrix for ATP synthesis

Oxidative Phosphorylation and Photophosphorylation: Structure, Mechanism, and Regulation

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