Question 1

Which of the following statements best describes the role of NADH in the electron transport chain (ETC)?

Accepted Answer

NADH donates electron pairs to Complex I, initiating the transfer of electrons through the ETC.

Question 2

What is the standard free energy change ($\Delta G^\prime$) for the oxidation of FADH$_2$ in the electron transport chain?

Accepted Answer

$\Delta G^\prime = -45.9$ kcal/mol

Question 3

Which electron carrier in the ETC is a nonprotein molecule that is freely mobile and accepts both electrons and protons?

Accepted Answer

Coenzyme Q (Ubiquinone)

Question 4

What is the main function of cytochromes in the electron transport chain?

Accepted Answer

To act as one-electron carriers using heme groups

Question 5

Which complex in the ETC is responsible for pumping protons into the intermembrane space when NADH is oxidized?

Accepted Answer

Complex I

Question 6

Why does electron flow in the ETC proceed from NADH to oxygen?

Accepted Answer

Because oxygen has a higher affinity for electrons, indicated by a more positive standard reduction potential ($E^\prime$)

Question 7

Which of the following best describes the role of ATP synthase in oxidative phosphorylation?

Accepted Answer

It uses the proton motive force to synthesize ATP from ADP and $P_i$.

Question 8

What is the effect of low ADP levels on the electron transport chain and oxidative phosphorylation?

Accepted Answer

ETC and oxidative phosphorylation are inhibited.

Question 9

Which of the following is TRUE about iron-sulfur proteins in the ETC?

Accepted Answer

Iron is the actual electron carrier, and they transfer one electron at a time.

Question 10

During the process of chemiosmosis, what drives the synthesis of ATP?

Accepted Answer

The diffusion of protons down their concentration gradient through ATP synthase

Question 11

Which of the following best explains the binding change model of ATP synthase?

Accepted Answer

ATP synthase binds ADP and $P_i$ loosely, tightly, and then releases ATP as the rod rotates through three conformations.

Question 12

How many ATP molecules are produced from one molecule of glucose during aerobic respiration, according to the study materials?

Accepted Answer

36-38 ATP

Question 13

Which ETC component keeps oxygen bound until it is reduced to water?

Accepted Answer

Copper-containing cytochromes (cytochromes a and a$_3$)

Question 14

Which of the following is a real-world consequence of a defect in Complex IV of the ETC?

Accepted Answer

Reduced ATP synthesis due to impaired reduction of oxygen to water

Question 15

Which molecule is the final electron acceptor in the mitochondrial electron transport chain?

Accepted Answer

O$_2$

Question 16

What is the main reason for the high fluidity of the inner mitochondrial membrane?

Accepted Answer

High unsaturated lipid content and absence of cholesterol

Question 17

Which of the following best describes the function of Coenzyme Q (Ubiquinone) in the ETC?

Accepted Answer

It is a nonprotein molecule that is freely mobile and transfers both electrons and protons.

Question 18

Which process is directly coupled to the electron transport chain to produce ATP?

Accepted Answer

Oxidative phosphorylation

Question 19

What is the effect of adding oxygen to suspended mitochondria in an experimental setup?

Accepted Answer

The pH of the solution declines rapidly due to unidirectional pumping of protons.

Question 20

Which of the following is TRUE regarding the movement of protons in the ETC?

Accepted Answer

Protons are pumped into the intermembrane space, creating a concentration gradient.

Electron Transport Chain and Oxidative Phosphorylation: Structure, Function, and Mechanisms

Study Guide - Practice Questions