Q. What effect does a competitive inhibitor have on enzyme activity?
-
A.
Increases Vmax
-
B.
Decreases Km
-
C.
Increases Km
-
D.
Decreases Vmax
Solution
A competitive inhibitor increases the Km of the enzyme, indicating a higher substrate concentration is needed to reach half-maximal velocity.
Correct Answer:
C
— Increases Km
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Q. What is the effect of increasing temperature on enzyme activity up to a certain point?
-
A.
Decreases activity
-
B.
Increases activity
-
C.
No effect
-
D.
Denatures the enzyme
Solution
Increasing temperature generally increases enzyme activity up to an optimal point, beyond which denaturation occurs.
Correct Answer:
B
— Increases activity
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Q. What is the primary function of zymogens?
-
A.
To activate enzymes
-
B.
To inhibit enzyme activity
-
C.
To serve as substrates
-
D.
To protect enzymes from degradation
Solution
Zymogens are inactive enzyme precursors that require a biochemical change to become active.
Correct Answer:
A
— To activate enzymes
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Q. What is the primary mechanism by which allosteric enzymes are regulated?
-
A.
Covalent modification
-
B.
Allosteric site binding
-
C.
Substrate concentration
-
D.
Temperature changes
Solution
Allosteric enzymes are regulated by the binding of molecules at sites other than the active site, which alters their activity.
Correct Answer:
B
— Allosteric site binding
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Q. What is the role of a coenzyme in enzyme activity?
-
A.
To provide structural support
-
B.
To act as a substrate
-
C.
To assist in enzyme-substrate binding
-
D.
To participate in the reaction as a transient carrier
Solution
Coenzymes are organic molecules that assist enzymes by carrying chemical groups during reactions.
Correct Answer:
D
— To participate in the reaction as a transient carrier
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Q. Which of the following is an example of a covalent modification that regulates enzyme activity?
-
A.
Phosphorylation
-
B.
Competitive inhibition
-
C.
Feedback inhibition
-
D.
Allosteric activation
Solution
Phosphorylation is a common covalent modification that can activate or deactivate enzymes.
Correct Answer:
A
— Phosphorylation
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Q. Which of the following is NOT a method of enzyme regulation?
-
A.
Allosteric modulation
-
B.
Covalent modification
-
C.
Substrate saturation
-
D.
Gene expression regulation
Solution
Substrate saturation refers to the concentration of substrate and is not a regulatory mechanism itself.
Correct Answer:
C
— Substrate saturation
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Q. Which of the following statements about enzyme inhibitors is true?
-
A.
They always permanently inactivate enzymes.
-
B.
They can be reversible or irreversible.
-
C.
They only affect allosteric enzymes.
-
D.
They increase the rate of reaction.
Solution
Enzyme inhibitors can be either reversible or irreversible, affecting enzyme activity in different ways.
Correct Answer:
B
— They can be reversible or irreversible.
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Q. Which type of enzyme regulation involves the end product of a metabolic pathway inhibiting an earlier step?
-
A.
Allosteric regulation
-
B.
Feedback inhibition
-
C.
Covalent modification
-
D.
Proteolytic activation
Solution
Feedback inhibition is a regulatory mechanism where the end product inhibits an earlier step in the pathway.
Correct Answer:
B
— Feedback inhibition
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