Oxidative Phosphorylation: The Powerhouse of the Cell

Question 1

In the electron transport chain, which enzyme complex serves as the initial entry point for electrons?

Accepted Answer

Complex I (NADH dehydrogenase)

Answer

Complex II (succinate dehydrogenase)

Answer

Complex III (cytochrome bc1 complex)

Answer

Complex IV (cytochrome c oxidase)

Question 2

Which molecule serves as the terminal electron acceptor in the electron transport chain?

Accepted Answer

Oxygen

Answer

Hydrogen

Answer

Carbon dioxide

Answer

Water

Question 3

What is the primary role of the proton gradient generated during oxidative phosphorylation?

Accepted Answer

To drive the synthesis of ATP

Answer

To generate reducing equivalents

Answer

To regulate electron transport

Answer

To pump ions across the mitochondrial membrane

Question 4

In eukaryotic cells, which mechanism accounts for the majority of ATP production?

Accepted Answer

Oxidative phosphorylation

Answer

Substrate-level phosphorylation

Answer

Photophosphorylation

Answer

Anaerobic respiration

Question 5

In oxidative phosphorylation, what is the role of ATP synthase?

Accepted Answer

To synthesize ATP from ADP and inorganic phosphate

Answer

To pump protons across the mitochondrial membrane

Answer

To bind oxygen and reduce it to water

Answer

To regulate electron flow through the electron transport chain

Question 6

Which inhibitor specifically targets Complex III in the electron transport chain?

Accepted Answer

Antimycin A

Answer

Rotenone

Answer

Malonate

Answer

Carbon monoxide

Question 7

Which substance functions as an electron carrier between Complex II and Complex III in the electron transport chain?

Accepted Answer

Ubiquinone

Answer

Cytochrome c

Answer

Cytochrome b

Answer

Flavoprotein

Question 8

In the electron transport chain, the final electron acceptor is:

Accepted Answer

Oxygen

Answer

NADH

Answer

FADH2

Answer

ATP

Question 9

The chemiosmotic hypothesis explains:

Accepted Answer

How ATP is synthesized in mitochondria

Answer

How electrons pass through the electron transport chain

Answer

How NADH and FADH2 are reduced

Answer

How oxygen is used to produce water

Question 10

Uncoupling agents:

Accepted Answer

Decrease the proton gradient across the inner mitochondrial membrane

Answer

Increase the efficiency of oxidative phosphorylation

Answer

Inhibit ATP synthesis

Answer

Stimulate oxidative stress

Question 11

Which of the following is NOT a component of ATP synthase?

Accepted Answer

Cytochrome c

Answer

F0 complex

Answer

F1 complex

Answer

Fo complex

Question 12

In the electron transport chain, what serves as the ultimate electron recipient?

Accepted Answer

Oxygen

Answer

NADH

Question 13

Which enzyme complex in the electron transport chain is responsible for pumping protons across the inner mitochondrial membrane?

Accepted Answer

Complex III (cytochrome bc1)

Answer

Complex II (succinate dehydrogenase)

Question 14

ATP synthase plays a crucial role in oxidative phosphorylation by:

Accepted Answer

Synthesizing ATP from ADP and inorganic phosphate

Question 15

Which of the following substances is known to disrupt oxidative phosphorylation by acting as an uncoupler?

Accepted Answer

Carbonyl cyanide m-chlorophenylhydrazone (CCCP)

Question 16

During the complete oxidation of glucose via oxidative phosphorylation, approximately how many ATP molecules are generated?

Accepted Answer

32-34

Question 17

What is the primary electron acceptor in complex IV of the electron transport chain?

Accepted Answer

Oxygen

Answer

NADH

Answer

FAD

Answer

Cytochrome c

Question 18

Which of the following is NOT a mechanism of ATP synthesis?

Accepted Answer

Glycolysis

Answer

Substrate-level phosphorylation

Answer

Oxidative phosphorylation

Answer

Photophosphorylation

Question 19

What is the primary function of ATP synthase in oxidative phosphorylation?

Accepted Answer

To convert ADP into ATP

Answer

To pump protons across the inner mitochondrial membrane

Answer

To transfer electrons between complexes

Answer

To generate a proton gradient

Question 20

What is the significance of the F0F1 complex in oxidative phosphorylation?

Accepted Answer

It couples electron transfer to proton pumping

Answer

It generates the proton gradient

Answer

It synthesizes ATP

Answer

It regulates the electron transport chain

Question 21

Which of the following is a key difference between oxidative phosphorylation in prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes use the F0F1 complex while prokaryotes use a different ATP synthase

Answer

Prokaryotes have more complexes in the electron transport chain

Answer

Eukaryotes use NADH as the primary electron donor

Answer

Prokaryotes have a lower efficiency of ATP synthesis

Question 22

Which of the following respiratory chain inhibitors targets complex III?

Accepted Answer

Antimycin A

Answer

Rotenone

Answer

Oligomycin

Answer

Cyanide

Question 23

What is the role of ubiquinone in oxidative phosphorylation?

Accepted Answer

To transfer electrons between complexes II and III

Answer

To transfer electrons between complexes I and II

Answer

To transfer electrons between complexes III and IV

Answer

To transfer protons across the inner mitochondrial membrane