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 enzyme facilitating the formation of the transition state?

Accepted Answer

Transition State facilitation

Question 3

A scientist is studying an enzyme that requires zinc ions to function. What is the role of zinc in this scenario?

Accepted Answer

Zinc is a cofactor necessary for enzyme activity.

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 levels off at a maximum rate ($V_{max}$).

Question 5

Why does enzyme activity typically decrease at temperatures above the enzyme's optimal range?

Accepted Answer

High temperatures cause denaturation, altering the enzyme's shape.

Question 6

A digestive enzyme from a human functions best at pH 7. What would likely happen if this enzyme is placed in a solution with pH 2?

Accepted Answer

The enzyme would be denatured and lose activity.

Question 7

Which of the following is an example of competitive inhibition?

Accepted Answer

A molecule binds to the enzyme's active site, preventing substrate binding.

Question 8

How does allosteric regulation differ from competitive inhibition?

Accepted Answer

Allosteric regulation involves binding at a site other than the active site, which can increase or decrease enzyme activity.

Question 9

Which of the following modifications can regulate enzyme activity by altering the enzyme's primary structure?

Accepted Answer

Phosphorylation of specific amino acids.

Question 10

A metabolic pathway is regulated by feedback inhibition. Which statement best describes this process?

Accepted Answer

The final product of the pathway inhibits an enzyme that acts early in the pathway.

Question 11

If an enzyme is regulated by phosphorylation, what effect does adding a phosphate group typically have?

Accepted Answer

It can either activate or deactivate the enzyme depending on the enzyme.

Question 12

Which of the following statements about enzyme specificity is correct?

Accepted Answer

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

Question 13

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?

Accepted Answer

The drug binds to an allosteric site, reducing enzyme activity regardless of substrate concentration.

Question 14

Which equation best represents the maximum rate of an enzyme-catalyzed reaction?

Accepted Answer

$V_{max}$

Question 15

A mutation changes a single amino acid in the active site of an enzyme. What is the most likely consequence?

Accepted Answer

The enzyme's substrate specificity may change or the enzyme may lose activity.

Question 16

Which of the following is NOT a way that cells regulate enzyme activity?

Accepted Answer

Increasing the temperature beyond the enzyme's optimal range.

Question 17

In a metabolic pathway, the accumulation of product X inhibits enzyme A, which catalyzes the first step. What type of regulation is this?

Accepted Answer

Feedback inhibition.

Question 18

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

Accepted Answer

Enzymes increase the rate of reaction by lowering the activation energy ($E_a$).

Question 19

A researcher observes that an enzyme is active only when a small molecule binds to a site other than the active site. What is this type of regulation called?

Accepted Answer

Allosteric regulation.

Energy and Enzymes: Structure, Function, and Regulation

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