Question 1

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

Accepted Answer

An enzyme decreases the activation energy required for the reaction.

Question 2

A patient is diagnosed with a deficiency in a coenzyme required for a redox reaction. Which class of enzyme activity will be most directly affected?

Accepted Answer

Oxidoreductases

Question 3

Which of the following reactions is catalyzed by a kinase?

Accepted Answer

The transfer of a phosphoryl group ($$-PO_3$^{2-}) $$from ATP to a substrate

Question 4

Which subclass of hydrolases is responsible for breaking down DNA during apoptosis?

Accepted Answer

Nucleases

Question 5

A reaction catalyzed by pyruvate carboxylase requires ATP hydrolysis. Which enzyme class does this belong to?

Accepted Answer

Ligases

Question 6

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Highly specific enzymes catalyze one type of reaction for a single substrate.

Question 7

Why does the induced fit model more accurately describe substrate binding than the lock-and-key model?

Accepted Answer

The induced fit model proposes that substrate binding triggers a conformational change in the enzyme.

Question 8

Which of the following factors will NOT increase the rate of an enzyme-catalyzed reaction if the enzyme is already saturated with substrate?

Accepted Answer

Increasing substrate concentration

Question 9

A scientist is studying an enzyme that catalyzes the hydrolysis of triglycerides. Which subclass does this enzyme belong to?

Accepted Answer

Lipases

Question 10

Which of the following best explains why human trypsin is not active in a thermophilic organism living at 75 $$^\circC$$?

Accepted Answer

The enzyme is denatured at high temperatures, losing its functional shape.

Question 11

Which of the following is a correct statement about the effect of enzyme concentration on reaction rate, assuming excess substrate is present?

Accepted Answer

The reaction rate increases linearly with increasing enzyme concentration.

Question 12

A mutation in the active site of an enzyme prevents it from binding its substrate. Which property of the enzyme is most directly affected?

Accepted Answer

Specificity

Question 13

Which of the following best describes the function of a coenzyme in an oxidoreductase-catalyzed reaction?

Accepted Answer

It acts as a carrier of electrons or hydrogen atoms.

Question 14

Which of the following is an example of a transferase reaction?

Accepted Answer

Transfer of a phosphoryl group from ATP to fructose-6-phosphate

Question 15

Which of the following statements about enzyme-catalyzed reactions is true?

Accepted Answer

Enzymes return to their original state after the reaction is complete.

Question 16

A patient is unable to digest starch due to a deficiency in a specific enzyme. Which enzyme subclass is most likely deficient?

Accepted Answer

Amylases

Question 17

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.

Question 18

Which of the following is a correct statement about the relationship between substrate concentration and reaction rate for an enzyme-catalyzed reaction (at constant enzyme concentration)?

Accepted Answer

The reaction rate increases and then levels off at a maximum value.

Question 19

Which of the following best explains why enzymes are considered highly efficient catalysts?

Accepted Answer

They lower the activation energy and are not consumed in the reaction.

Question 20

A researcher observes that an enzyme catalyzes the same reaction for several different but structurally similar substrates. This enzyme is best described as:

Accepted Answer

Nonspecific

Enzyme Classification and Regulation: GOB Chemistry Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards