Question 1

Which statement best describes the first law of thermodynamics as it applies to biological systems?

Accepted Answer

Energy can be transformed but not created or destroyed.

Question 2

Which of the following is NOT one of the five major classes of metabolic reactions?

Accepted Answer

Hydrogen Bonding

Question 3

A cell is performing a reaction with a standard free energy change $\Delta G^\circ = -20$ kJ/mol. If the concentrations of reactants and products are such that $\Delta G = -30$ kJ/mol, what does this indicate about the reaction?

Accepted Answer

The reaction is more favorable under cellular conditions than under standard conditions.

Question 4

Which equation correctly relates Gibbs free energy change to enthalpy and entropy?

Accepted Answer

$\Delta G = \Delta H - T\Delta S$

Question 5

ATP hydrolysis is highly exergonic because:

Accepted Answer

It breaks high-energy anhydride bonds, releasing energy.

Question 6

Which compound has the highest standard free energy of hydrolysis among the following?

Accepted Answer

Phosphoenolpyruvate (PEP)

Question 7

The Nernst equation is used to calculate:

Accepted Answer

The standard reduction potential ($E^\circ$) under non-standard conditions.

Question 8

Which of the following best describes the role of NAD+/NADH in metabolism?

Accepted Answer

NAD+ is the oxidized form that accepts electrons during redox reactions.

Question 9

Which statement about entropy ($S$) in biological systems is correct?

Accepted Answer

Entropy is a measure of the randomness or disorder of a system.

Question 10

A reaction has $\Delta G^\circ = +5$ kcal/mol. Which of the following strategies could a cell use to make this reaction proceed?

Accepted Answer

Couple the reaction to ATP hydrolysis.

Question 11

Which of the following is true regarding thioesters such as acetyl-CoA?

Accepted Answer

Thioesters contain a sulfur atom instead of an oxygen in the ester linkage.

Question 12

Which of the following equations correctly relates the change in free energy to the reduction potential?

Accepted Answer

$\Delta G = -nF\Delta E^\circ$

Question 13

During the oxidation of glucose, which molecule acts as an electron shuttle to facilitate ATP synthesis?

Accepted Answer

NAD+/NADH

Question 14

Which of the following best explains why phosphoenolpyruvate (PEP) has a very high negative $\Delta G$ of hydrolysis?

Accepted Answer

The product of PEP hydrolysis is stabilized by isomerization.

Question 15

Which of the following is NOT a mechanism by which biological systems transfer electrons?

Accepted Answer

Transfer as sodium ions

Question 16

If a redox reaction has a positive standard reduction potential ($E^\circ$), what does this indicate?

Accepted Answer

The acceptor has a high affinity for electrons.

Question 17

Which of the following statements about the relationship between $\Delta G$ and $K_{eq}$ is correct?

Accepted Answer

$\Delta G^\circ = -RT \ln K_{eq}$

Question 18

Which of the following is a correct description of catabolism?

Accepted Answer

Catabolism is a series of reactions involved in breaking down nutrients into smaller, usable building blocks.

Question 19

Which of the following statements about ATP is FALSE?

Accepted Answer

ATP is the only molecule in cells that can transfer phosphate groups.

Question 20

Which of the following best describes the role of FAD/FMN in cellular metabolism?

Accepted Answer

They act as electron shuttles in redox reactions.

Bioenergetics: Principles and Mechanisms in Biochemistry

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