Quiz: Mechanism of Enzyme Catalysis

1. What is the primary role of an enzyme in a chemical reaction?

• a) To act as a substrate

• b) To increase activation energy

• c) To decrease activation energy

• d) To change the reaction’s equilibrium

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

• a) It permanently binds to the substrate

• b) It is formed during the transition state

• c) It lowers the reaction rate

• d) It is an irreversible intermediate

3. Which model suggests that the enzyme changes shape to fit the substrate upon binding?

• a) Lock-and-key model

• b) Induced-fit model

• c) Transition-state model

• d) Enzyme-substrate model

4. What term describes the location on the enzyme where the substrate binds?

• a) Active site

• b) Catalytic site

• c) Binding pocket

• d) Reaction groove

5. Which of the following is an example of a coenzyme?

• a) Zinc ion

• b) ATP

• c) Water

• d) Oxygen

6. What is the role of the transition state in enzyme catalysis?

• a) It increases the energy required for the reaction

• b) It stabilizes the enzyme-substrate complex

• c) It represents the highest energy state of the reaction

• d) It permanently binds to the enzyme

7. Enzymes exhibit specificity. What does this mean?

• a) They bind to multiple substrates simultaneously

• b) They catalyze reactions for only a specific substrate

• c) They function at all pH levels

• d) They require high temperatures to work

8. Which of the following is a mechanism by which enzymes catalyze reactions?

• a) Lowering the free energy of the substrate

• b) Providing an alternate reaction pathway

• c) Increasing the equilibrium constant

• d) Raising the activation energy

9. What is competitive inhibition in enzymatic reactions?

• a) The inhibitor binds to an allosteric site

• b) The inhibitor binds to the substrate

• c) The inhibitor binds to the active site

• d) The inhibitor prevents coenzyme binding

10. What effect does increasing substrate concentration have on enzyme activity, assuming enzyme saturation is not yet reached?

• a) Decreases reaction rate

• b) Stops the reaction

• c) Increases reaction rate

• d) No effect on reaction rate