Question 1

Which of the following best describes the role of enzymes in biological systems?

Accepted Answer

Enzymes lower the activation energy, increasing the rate of reaction without altering the equilibrium position.

Question 2

Which class of enzyme catalyzes the transfer of functional groups from one molecule to another?

Accepted Answer

Transferases

Question 3

The equation $\Delta G = -RT \ln K_{eq}$ relates which two properties in enzyme-catalyzed reactions?

Accepted Answer

Standard free energy change and equilibrium constant

Question 4

Which of the following is NOT a mechanistic way enzymes enhance reaction rates?

Accepted Answer

Changing the overall thermodynamics ($\Delta G$) of the reaction

Question 5

Which metal ion is commonly found as a cofactor in carbonic anhydrase?

Accepted Answer

Zn$^{2+}$

Question 6

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzyme specificity is controlled by the unique fit of substrate with the enzyme's active site structure.

Question 7

Which of the following is an example of a biochemical nucleophile commonly involved in enzyme catalysis?

Accepted Answer

R-OH (hydroxyl group)

Question 8

Which enzyme class catalyzes the joining of two molecules together with ATP hydrolysis?

Accepted Answer

Ligases

Question 9

A patient presents with symptoms of acetylcholine accumulation. Which enzyme is most likely deficient?

Accepted Answer

Acetylcholinesterase

Question 10

Which of the following best explains why enzymes do not alter the equilibrium position of a reaction?

Accepted Answer

Enzymes only increase the rate at which equilibrium is reached by lowering activation energy.

Question 11

Which organic cofactor is responsible for transferring acyl groups in metabolic reactions?

Accepted Answer

Coenzyme A (CoA)

Question 12

Which of the following amino acid side chains is most likely to act as a nucleophile in enzyme catalysis?

Accepted Answer

Serine (R-OH)

Question 13

Which of the following factors can influence enzyme activity in vivo?

Accepted Answer

All of the above

Question 14

Which enzyme class catalyzes redox reactions?

Accepted Answer

Oxidoreductases

Question 15

The induced fit theory of enzyme specificity suggests that:

Accepted Answer

The enzyme and substrate both undergo conformational changes to achieve optimal binding.

Question 16

Which of the following is a plausible reason why metal ion cofactors are important for enzyme catalysis?

Accepted Answer

They increase the nucleophilicity of water by making it more acidic.

Question 17

Which of the following best describes the function of hydrolases?

Accepted Answer

Catalyze hydrolysis reactions, breaking bonds with water

Question 18

A mutation in the active site of an enzyme replaces a serine residue with alanine. What is the most likely effect on enzyme activity?

Accepted Answer

Decreased ability to form covalent intermediates

Question 19

Which of the following is true regarding the pH dependence of enzyme activity?

Accepted Answer

Enzyme activity can vary significantly with changes in pH due to ionization of active site residues.

Question 20

Which of the following is a real-world example of an enzyme-catalyzed reaction?

Accepted Answer

Conversion of glucose to glucose-6-phosphate by hexokinase

1. Enzymes

Study Guide - Practice Questions