Question 1

Which of the following statements best describes the First Law of Thermodynamics as it applies to biological systems?

Accepted Answer

Energy cannot be created or destroyed, only transferred or transformed.

Question 2

A chemical reaction has a negative $$\Delta G. $$What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will proceed spontaneously.

Question 3

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

Accepted Answer

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

Question 4

Which of the following best explains why enzymes are necessary for life?

Accepted Answer

Enzymes allow reactions to occur at rates sufficient to sustain life by lowering activation energy.

Question 5

Which of the following is true about the effect of temperature on enzyme activity?

Accepted Answer

Enzyme activity increases with temperature up to an optimal point, then decreases as the enzyme denatures.

Question 6

In a metabolic pathway, feedback inhibition most likely occurs when:

Accepted Answer

The final product of the pathway binds to and inhibits an enzyme early in the pathway.

Question 7

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP provides energy for cellular activities by transferring a phosphate group to target molecules.

Question 8

During a redox reaction, what happens to the molecule that is oxidized?

Accepted Answer

It loses electrons and often loses protons.

Question 9

Which of the following is an example of an anabolic pathway?

Accepted Answer

The synthesis of proteins from amino acids.

Question 10

A scientist adds a molecule that binds to the active site of an enzyme, preventing substrate binding. This is an example of:

Accepted Answer

Competitive inhibition

Question 11

Which of the following statements about enzyme saturation kinetics is correct?

Accepted Answer

At high substrate concentrations, the reaction rate plateaus because all enzyme active sites are occupied.

Question 12

Which of the following best describes the induced fit model of enzyme function?

Accepted Answer

The enzyme changes shape slightly to better fit the substrate upon binding.

Question 13

Which of the following is a correct statement about the effect of pH on enzyme activity?

Accepted Answer

Changes in pH can alter the charge and shape of the enzyme, affecting its activity.

Question 14

Which of the following molecules is an electron carrier that is reduced during cellular respiration?

Accepted Answer

NAD+

Question 15

A reaction has $$\Delta H = -50 kJ/$$mol and $$\Delta S = +0.1 kJ/($$mol·K). At $$T = 300 K$$, what is $$\Delta G$$ for the reaction?

Accepted Answer

$$\Delta G = -50 - (300 	imes 0.1) = -80 kJ/$$mol

Question 16

Which of the following is NOT a way that enzymes can be regulated?

Accepted Answer

Permanent destruction of the enzyme's active site by substrate binding

Question 17

Which of the following best describes the difference between catabolic and anabolic pathways?

Accepted Answer

Catabolic pathways release energy; anabolic pathways require energy input.

Question 18

Which of the following is true about the role of cofactors, coenzymes, and prosthetic groups in enzyme function?

Accepted Answer

Prosthetic groups are non-amino acid molecules permanently attached to enzymes.

Question 19

Which of the following scenarios best illustrates energetic coupling in a cell?

Accepted Answer

The energy released from ATP hydrolysis is used to drive an endergonic reaction.

Question 20

Which of the following is a likely result if a mutation causes an enzyme's active site to change shape?

Accepted Answer

The enzyme may lose its ability to bind its substrate and become nonfunctional.

Energy and Enzymes: An Introduction to Metabolism (Chapter 8 Study Notes)

Study Guide - Practice Questions