Question 1

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

Accepted Answer

An enzyme lowers the activation energy, allowing the reaction to proceed faster.

Question 2

During the process of enzyme catalysis, which step involves the substrate binding to the enzyme's active site?

Accepted Answer

Initiation

Question 3

A scientist is studying an enzyme that requires a zinc ion to function. What is the zinc ion classified as?

Accepted Answer

A cofactor

Question 4

Which of the following graphs best represents the effect of increasing substrate concentration on the rate of an enzyme-catalyzed reaction?

Accepted Answer

A curve that rises quickly and then plateaus at high substrate concentration.

Question 5

If an enzyme is exposed to a temperature much higher than its optimal range, what is the most likely effect?

Accepted Answer

The enzyme will denature, losing its shape and function.

Question 6

Which of the following statements about pH and enzyme activity is correct?

Accepted Answer

Enzymes from different organisms may have different optimal pH values.

Question 7

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 8

Which type of enzyme regulation involves a molecule binding to a site other than the active site, potentially increasing or decreasing enzyme activity?

Accepted Answer

Allosteric regulation

Question 9

Phosphorylation is an example of which type of enzyme regulation?

Accepted Answer

Covalent modification

Question 10

Feedback inhibition in metabolic pathways is best described as:

Accepted Answer

The product of a pathway inhibits an enzyme that functions early in the pathway.

Question 11

Which of the following changes to an enzyme would most likely result in a loss of function?

Accepted Answer

A change in the primary structure due to a mutation in the gene encoding the enzyme.

Question 12

A patient is given a drug that acts as a non-competitive inhibitor of an enzyme involved in blood clotting. What is the most likely effect of this drug?

Accepted Answer

It will bind to a site other than the active site and decrease enzyme activity.

Question 13

Which equation best describes the relationship between enzyme activity and substrate concentration at low substrate levels?

Accepted Answer

$v = k[S]$

Question 14

A mutation causes an enzyme to lose its ability to bind a required cofactor. What is the most likely consequence?

Accepted Answer

The enzyme will lose its catalytic activity.

Question 15

Which of the following is true regarding the effect of enzyme concentration on reaction rate?

Accepted Answer

Increasing enzyme concentration increases reaction rate only if substrate is not limiting.

Question 16

Which of the following scenarios best illustrates feedback inhibition?

Accepted Answer

A metabolic pathway produces ATP, which then inhibits the first enzyme in the pathway.

Question 17

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzyme specificity is determined by the shape of the active site.

Question 18

A researcher finds that an enzyme is active only when a phosphate group is attached to a specific amino acid. What type of regulation is this?

Accepted Answer

Covalent modification

Question 19

Which of the following is a consequence of competitive inhibition on enzyme kinetics?

Accepted Answer

The $K_m$ increases while $V_{max}$ remains unchanged.

Energy and Enzymes: Structure, Function, and Regulation

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