IMAT - International Medical Admissions Bioenergetics and Metabolism Questions and Answers

Question 1

Which of the following correctly identifies the net products of glycolysis starting from one molecule of glucose?

Accepted Answer

2 Pyruvate, 2 NADH, 2 ATP

Answer

1 Pyruvate, 1 NADH, 1 ATP

Answer

2 Acetyl-CoA, 2 CO2, 2 ATP

Answer

6 CO2, 6 H2O, ~32 ATP

Question 2

A patient is exposed to a toxin that specifically inhibits Complex IV (cytochrome c oxidase) of the electron transport chain. Which of the following metabolic consequences would be most likely to occur?

Accepted Answer

Accumulation of NADH and FADH2.

Answer

Increased ATP production via oxidative phosphorylation.

Answer

Oxygen consumption would increase to compensate.

Answer

The proton gradient across the inner mitochondrial membrane would become steeper.

Question 3

The process of chemiosmosis, which is essential for ATP production during oxidative phosphorylation, is directly driven by:

Accepted Answer

The flow of protons down their electrochemical gradient through ATP synthase.

Answer

The direct transfer of a phosphate group from a substrate to ADP.

Answer

The movement of electrons between protein complexes.

Answer

The reduction of NAD+ to NADH in the mitochondrial matrix.

Question 4

What is the primary role of the Krebs cycle (citric acid cycle) in cellular respiration?

Accepted Answer

To generate reduced electron carriers (NADH and FADH2) for the electron transport chain.

Answer

To directly produce the majority of the cell's ATP.

Answer

To break down glucose into two molecules of pyruvate.

Answer

To consume oxygen and produce water.

Question 5

A key distinction between aerobic respiration and anaerobic respiration is the identity of the final electron acceptor. In aerobic respiration, the final electron acceptor is oxygen. In anaerobic respiration, the final electron acceptor is:

Accepted Answer

An inorganic molecule other than oxygen, such as nitrate or sulfate.

Answer

Pyruvate or a derivative of pyruvate.

Answer

Another organic molecule, such as ethanol.

Answer

Water.

Question 6

How do enzymes catalyze metabolic reactions within a cell?

Accepted Answer

By decreasing the activation energy required for the reaction to proceed.

Answer

By increasing the overall free energy change (ΔG) of the reaction.

Answer

By providing the necessary reactant molecules for the reaction.

Answer

By shifting the equilibrium of the reaction to favor the products.