Question 1

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

Accepted Answer

It lowers the activation energy ($$\Delta G$$^{\ddagger}$$) required for the reaction.

Question 2

Which statement about enzyme specificity is correct?

Accepted Answer

Enzyme specificity is due to the unique 3D structure of the active site.

Question 3

A reaction has a $$\Delta G of -5 kJ/$$mol. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will proceed spontaneously.

Question 4

Which of the following is true regarding the effect of enzymes on chemical equilibrium?

Accepted Answer

Enzymes do not affect the position of equilibrium; they only affect the rate.

Question 5

Which of the following best describes a holoenzyme?

Accepted Answer

An enzyme with its cofactor, forming the active complex.

Question 6

Which of the following is an example of a prosthetic group?

Accepted Answer

A covalently attached cofactor.

Question 7

Which of the following mechanisms is NOT a way enzymes catalyze reactions?

Accepted Answer

Catalysis by increasing activation energy.

Question 8

Which statement about lysozyme is correct?

Accepted Answer

Lysozyme cleaves the $$\beta(1-4)$$ glycosidic bonds between N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG).

Question 9

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

Accepted Answer

The enzyme changes shape upon substrate binding to enhance catalysis.

Question 10

Which of the following is the correct definition of the turnover number ($$k_{cat}) of an $$enzyme?

Accepted Answer

The number of substrate molecules converted to product per enzyme molecule per unit time.

Question 11

Which of the following is NOT a characteristic of enzymes?

Accepted Answer

They are consumed during the reaction.

Question 12

Which of the following statements about enzyme classification (EC numbers) is correct?

Accepted Answer

The first digit refers to the main class of reaction catalyzed.

Question 13

Which of the following is a real-world application of enzymes?

Accepted Answer

Using proteases and amylases to remove stains from clothing.

Question 14

In the lysozyme mechanism, which amino acid acts as a general acid catalyst at optimal pH?

Accepted Answer

Glutamate 35

Question 15

Which of the following best explains why enzymes are not consumed in reactions?

Accepted Answer

They are regenerated after each catalytic cycle.

Question 16

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

Accepted Answer

Enzyme activity is highest at the enzyme's optimal pH.

Question 17

Which of the following is a correct statement about the role of cofactors in enzyme activity?

Accepted Answer

Cofactors can be either inorganic ions or organic molecules.

Question 18

A competitive inhibitor of an enzyme:

Accepted Answer

Binds to the active site and prevents substrate binding.

Question 19

Which of the following best describes the main function of lysozyme in human tears?

Accepted Answer

It acts as a natural antibiotic by breaking down bacterial cell walls.

Question 20

Which of the following is the most abundant product when lysozyme hydrolyzes a 6-unit peptidoglycan substrate (ABCDEF)?

Accepted Answer

(ABCD)$$_4$$ and (EF)$$_2$$

Enzymes: Structure, Function, and Mechanism (with Lysozyme Case Study)

Study Guide - Practice Questions