Question 1

Which of the following best describes the role of an enzyme in a biological reaction?

Accepted Answer

It lowers the activation energy required for the reaction to proceed.

Question 2

Which of the following is an example of an inorganic cofactor required by some enzymes?

Accepted Answer

$$Fe^{2+}$$

Question 3

A patient is diagnosed with liver damage. Which enzyme class is most likely to be elevated in their blood test results?

Accepted Answer

Transferases

Question 4

Which enzyme class catalyzes the hydrolysis of peptide bonds in proteins?

Accepted Answer

Hydrolases

Question 5

Which of the following reactions is catalyzed by a dehydrogenase?

Accepted Answer

$$\mathrm{CH_3CH(OH)COO^-} + \mathrm{NAD^+} \rightarrow \mathrm{CH_3COCOO^-} + \mathrm{NADH} + \mathrm{H^+}$$

Question 6

Which statement best explains why enzymes are highly specific for their substrates?

Accepted Answer

The active site of an enzyme has a unique shape that matches only specific substrates.

Question 7

Which of the following best describes the difference between the lock-and-key and induced-fit models of enzyme action?

Accepted Answer

The lock-and-key model suggests a rigid active site, while the induced-fit model allows for flexibility in the active site.

Question 8

Which of the following is an example of a competitive inhibitor?

Accepted Answer

A molecule that binds to the active site, preventing substrate binding.

Question 9

Which enzyme class catalyzes the transfer of a phosphate group from ATP to a substrate?

Accepted Answer

Kinases

Question 10

A patient is prescribed a drug that acts as a noncompetitive inhibitor of a key metabolic enzyme. What is the most likely effect of this drug?

Accepted Answer

It binds to a site other than the active site, altering enzyme shape and reducing activity.

Question 11

Which of the following best describes a zymogen (proenzyme)?

Accepted Answer

An enzyme that is produced in an inactive form and activated when needed.

Question 12

Which of the following is a reason why zymogens are necessary in the human body?

Accepted Answer

To ensure enzymes are active only when and where needed, preventing tissue damage.

Question 13

Which enzyme class catalyzes the conversion of one isomer to another, such as in glycolysis?

Accepted Answer

Isomerases

Question 14

Which of the following statements about allosteric control is correct?

Accepted Answer

Allosteric control involves a regulator binding to a site other than the active site, which can increase or decrease enzyme activity.

Question 15

Which of the following best describes the effect of temperature on enzyme activity?

Accepted Answer

Enzyme activity increases with temperature up to an optimum, then rapidly decreases due to denaturation.

Question 16

Which of the following is the correct way to name an enzyme that catalyzes the transfer of an amino group from phenylalanine?

Accepted Answer

Phenylalanine transaminase

Question 17

Which enzyme class catalyzes the joining of two molecules, often using energy from ATP hydrolysis?

Accepted Answer

Ligases

Question 18

Which of the following is an example of a redox reaction catalyzed by an oxidoreductase?

Accepted Answer

$$\mathrm{CH_3CH(OH)COO^-} + \mathrm{NAD^+} \rightarrow \mathrm{CH_3COCOO^-} + \mathrm{NADH} + \mathrm{H^+}$$

Question 19

Which of the following best describes the effect of pH on enzyme activity?

Accepted Answer

Each enzyme has an optimal pH at which its activity is maximal.

Enzymes: Classification, Naming, and Kinetics – A Biochemistry Study Guide

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