Question 1

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

Accepted Answer

It lowers the activation energy ($$E_A) $$required for the reaction to proceed.

Question 2

A scientist is studying the breakdown of sucrose into glucose and fructose. Which enzyme is most likely involved in this reaction?

Accepted Answer

Sucrase

Question 3

Which of the following statements about the enzyme-substrate complex is correct?

Accepted Answer

The enzyme-substrate complex is formed when the substrate binds to the enzyme's active site.

Question 4

Which of the following best explains the induced fit model of enzyme activity?

Accepted Answer

The enzyme's active site changes shape to fit snugly around the substrate when it binds.

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 patient is prescribed a drug that acts as a competitive inhibitor for a bacterial enzyme. Which of the following best describes how this drug works?

Accepted Answer

It binds to the active site, preventing the substrate from binding.

Question 7

Which of the following is an example of a coenzyme?

Accepted Answer

NAD (derived from niacin, vitamin B3)

Question 8

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

Accepted Answer

The enzyme would denature, causing the reaction rate to decrease.

Question 9

Which of the following best describes feedback inhibition in a metabolic pathway?

Accepted Answer

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

Question 10

A researcher adds a non-competitive inhibitor to an enzyme reaction. What is the most likely effect?

Accepted Answer

The inhibitor binds to a site other than the active site, causing a conformational change.

Question 11

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

Accepted Answer

A graph where the activation energy with enzyme is lower than without enzyme.

Question 12

Which of the following statements about cofactors is correct?

Accepted Answer

Cofactors are non-protein, small, inorganic compounds or ions that help enzymes function.

Question 13

Which of the following scenarios best illustrates irreversible inhibition?

Accepted Answer

A nerve gas binds permanently to an enzyme, preventing its function.

Question 14

Which of the following is true about allosteric regulation?

Accepted Answer

Allosteric regulators bind to a site other than the active site, causing conformational changes.

Question 15

A patient is taking a medication that acts as a non-competitive inhibitor for an enzyme involved in DNA synthesis. What is the most likely effect on the enzyme's activity?

Accepted Answer

The enzyme's shape is altered, reducing its activity regardless of substrate concentration.

Question 16

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

Accepted Answer

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

Question 17

Which of the following would most likely result if feedback inhibition in a metabolic pathway failed?

Accepted Answer

There would be an unnecessary accumulation of the final product, leading to chemical chaos.

Question 18

Which of the following is a real-life example of an enzyme and its substrate?

Accepted Answer

Lactase breaking down lactose in the human digestive system.

Question 19

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

Accepted Answer

Enzyme activity is highest at the enzyme's optimal pH and decreases at higher or lower pH values.

Question 20

A metabolic pathway consists of five steps, each catalyzed by a different enzyme. The final product inhibits the first enzyme in the pathway. What is this an example of?

Accepted Answer

Feedback inhibition

Enzymes: Structure, Function, and Regulation

Study Guide - Practice Questions

Study Guide - Flashcards