Question 1

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

Accepted Answer

It lowers the activation energy, allowing the reaction to proceed faster.

Question 2

A patient is prescribed a drug that acts as a competitive inhibitor for a key metabolic enzyme. Which of the following best explains how this drug works?

Accepted Answer

It competes with the substrate for binding at the active site of the enzyme.

Question 3

Which enzyme class is responsible for catalyzing the transfer of a phosphate group from ATP to another molecule?

Accepted Answer

Transferases

Question 4

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzyme specificity is determined by the shape and chemical environment of the active site.

Question 5

A scientist observes that increasing the substrate concentration increases the reaction rate, but only up to a certain point. What is the most likely explanation for this observation?

Accepted Answer

The enzyme has reached saturation; all active sites are occupied.

Question 6

Which of the following is an example of an irreversible inhibitor?

Accepted Answer

A heavy metal ion that binds covalently to the active site of an enzyme.

Question 7

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

Accepted Answer

The active site changes shape to accommodate the substrate upon binding.

Question 8

Which of the following is NOT a function of enzyme cofactors?

Accepted Answer

Acting as the main substrate for the enzyme.

Question 9

A certain enzyme catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate. To which enzyme class does this enzyme most likely belong?

Accepted Answer

Isomerases

Question 10

Which of the following best explains why enzymes are sensitive to changes in pH?

Accepted Answer

pH changes can denature the enzyme by disrupting ionic and hydrogen bonds in the active site.

Question 11

Which of the following is an example of feedback inhibition in metabolic pathways?

Accepted Answer

A product at the end of a pathway inhibits an enzyme that acts early in the pathway.

Question 12

Which of the following statements about vitamins is correct?

Accepted Answer

Vitamins are organic molecules that often serve as enzyme cofactors.

Question 13

A patient is exposed to a poison that binds covalently to the active site of acetylcholinesterase, preventing nerve signal transmission. What type of inhibition is this?

Accepted Answer

Irreversible inhibition

Question 14

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

Accepted Answer

Enzyme activity is highest at an optimal temperature, but decreases if the temperature is too high or too low.

Question 15

Which of the following is a correct description of a zymogen?

Accepted Answer

An inactive precursor of an enzyme that requires modification to become active.

Question 16

Which of the following is a function of antioxidants in the body?

Accepted Answer

They prevent oxidation by neutralizing free radicals.

Question 17

Which of the following best describes allosteric regulation of an enzyme?

Accepted Answer

A molecule binds to a site other than the active site, changing enzyme activity.

Question 18

Which of the following equations best represents the effect of an enzyme on the activation energy ($$E_a) of a $$reaction?

Accepted Answer

$$E_{a,\ enzyme} \u003c E_{a,\ uncatalyzed}$$

Question 19

Which of the following is a correct example of a hydrolase enzyme and its function?

Accepted Answer

Lipase, which breaks down fats into glycerol and fatty acids.

Question 20

A genetic mutation reduces the synthesis of a key enzyme in a metabolic pathway. Which type of enzyme regulation does this illustrate?

Accepted Answer

Genetic control

Enzymes and Vitamins: Structure, Function, and Regulation

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