Question 1

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

Accepted Answer

Enzymes lower the activation energy ($$E_A) $$required for a reaction, acting as a catalyst.

Question 2

A patient is given a drug that binds to the active site of an enzyme, preventing the substrate from binding. What type of inhibition is this?

Accepted Answer

Competitive inhibition

Question 3

Which of the following statements about the induced fit model of enzyme action is correct?

Accepted Answer

The enzyme changes shape to fit snugly around the substrate when it enters the active site.

Question 4

Which equation best represents the hydrolysis of sucrose by sucrase?

Accepted Answer

Question 5

Which of the following is NOT a way that enzymes lower activation energy ($$E_A$$)?

Accepted Answer

Increasing the temperature of the reaction

Question 6

A scientist is studying an enzyme that requires magnesium ions to function. What is magnesium in this context?

Accepted Answer

A cofactor

Question 7

Which of the following best explains why enzymes are specific to their substrates?

Accepted Answer

The active site of the enzyme has a unique shape that only fits specific substrates.

Question 8

What would happen to the rate of an enzyme-catalyzed reaction if the temperature is increased above the enzyme's optimal range?

Accepted Answer

The enzyme would denature, causing the rate to decrease.

Question 9

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

Accepted Answer

The final product of a pathway acts as an allosteric inhibitor of an earlier enzyme.

Question 10

A patient is exposed to sarin gas, which irreversibly binds to an enzyme involved in nerve function. What is the effect of this type of inhibition?

Accepted Answer

The enzyme is permanently inactivated, leading to loss of function.

Question 11

Which of the following best describes the effect of a non-competitive inhibitor on an enzyme?

Accepted Answer

It binds to a site other than the active site, causing a conformational change that reduces enzyme activity.

Question 12

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

Accepted Answer

A curve that rises and then plateaus as the enzyme becomes saturated

Question 13

Which of the following is a correct statement about coenzymes?

Accepted Answer

Coenzymes are large, organic molecules that often contain carbon and bind near the active site.

Question 14

If the pH of the environment changes drastically from the optimal pH for an enzyme, what is most likely to occur?

Accepted Answer

The enzyme will denature, losing its functional shape.

Question 15

Which of the following is a real-world example of a competitive inhibitor?

Accepted Answer

Penicillin blocking the enzyme bacteria use to build cell walls.

Question 16

Which of the following best describes allosteric regulation?

Accepted Answer

Regulatory molecules bind to a site other than the active site, causing conformational changes that lock the enzyme in either an active or inactive form.

Question 17

Which of the following is true about the enzyme-substrate complex?

Accepted Answer

It is held together by weak interactions such as hydrogen bonds and ionic bonds.

Question 18

A metabolic pathway is not regulated and continues to produce its final product without inhibition. What is the most likely outcome?

Accepted Answer

Chemical chaos will occur due to unnecessary accumulation of product.

Question 19

Which of the following is NOT a property of enzymes?

Accepted Answer

Enzymes are consumed during the reaction.

Enzymes: Structure, Function, and Regulation

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