Free Enzyme Inhibitors MCQs with Answers
35 Enzyme Inhibitors MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Enzyme inhibitors reduce reaction rate by interfering with enzyme-substrate interaction or catalytic activity. Coverage includes reversible competitive, non-competitive and uncompetitive inhibition, the effects of inhibitor concentration on reaction rate, and why competitive inhibition can be reduced by increasing substrate concentration.
Last updated
35 questions · page 1 of 2
- A. binding the active site because it resembles the substrate
- B. binding a site away from the active site and distorting it
- C. permanently destroying the enzyme
- D. lowering the pH of the surroundings
Explanation: A competitive inhibitor is structurally similar to the substrate and occupies the active site, so substrate and inhibitor compete for the…
Correct answer: binding the active site because it resembles the substrate- A. a competitive inhibitor
- B. a non-competitive inhibitor
- C. a low enzyme concentration
- D. a substrate below the saturation point
Explanation: A non-competitive inhibitor binds at a site other than the active site and changes the enzyme's shape, so the substrate cannot compete it…
Correct answer: a non-competitive inhibitor- A. non-competitive inhibition
- B. competitive inhibition
- C. feedback inhibition
- D. denaturation
Explanation: Malonate is close enough in structure to succinate to occupy the same active site without being converted, which is the definition of…
Correct answer: competitive inhibition- A. compete with the substrate for the active site
- B. raise the pH of the solution
- C. supply the enzyme with excess energy
- D. bind to the sulphydryl groups of the protein and destroy its shape
Explanation: These ions attack the sulphur containing side chains, breaking disulphide bridges and permanently distorting the tertiary structure, so…
Correct answer: bind to the sulphydryl groups of the protein and destroy its shape- A. the final product inhibits an enzyme acting early in the pathway
- B. the first substrate inhibits the last enzyme
- C. the enzyme is destroyed after each reaction
- D. the pathway runs faster as product accumulates
Explanation: When enough product has been made it binds an allosteric site on an early enzyme and switches it off, so the cell stops spending resources…
Correct answer: the final product inhibits an enzyme acting early in the pathway- A. a second active site that binds the same substrate
- B. a site away from the active site where a regulatory molecule binds and changes the enzyme's shape
- C. the region that is denatured first by heat
- D. the point where the enzyme attaches to the cell membrane
Explanation: A molecule binding at an allosteric site alters the conformation of the whole enzyme, and therefore the shape of the active site, either…
Correct answer: a site away from the active site where a regulatory molecule binds and changes the enzyme's shape- A. raises Vmax and leaves Km unchanged
- B. raises both Vmax and Km
- C. lowers Km and leaves Vmax unchanged
- D. lowers Vmax and leaves Km unchanged
Explanation: Because the inhibitor binds elsewhere and cannot be displaced by substrate, a fraction of the enzyme is permanently out of action, so the…
Correct answer: lowers Vmax and leaves Km unchanged- A. Bind to allosteric site
- B. Cannot be overcome by increasing substrate
- C. Bind to active site
- D. Change Vmax but not Km
Explanation: Competitive inhibitors bind to the active site, competing with substrate. They can be overcome by increasing substrate concentration.
Correct answer: Bind to active site- A. Maximum reaction velocity
- B. Substrate concentration at half Vmax
- C. Enzyme concentration
- D. Inhibitor concentration
Explanation: Km is the substrate concentration at which the reaction velocity is half of Vmax. It indicates enzyme-substrate affinity.
Correct answer: Substrate concentration at half Vmax- A. Follow Michaelis-Menten kinetics strictly
- B. Have multiple subunits and regulatory sites
- C. Are not affected by feedback inhibition
- D. Always show competitive inhibition
Explanation: Allosteric enzymes have multiple subunits with regulatory (allosteric) sites where activators or inhibitors bind, affecting enzyme…
Correct answer: Have multiple subunits and regulatory sites11. Zymogens are
- A. Active enzymes
- B. Inactive enzyme precursors
- C. Coenzymes
- D. Enzyme inhibitors
Explanation: Zymogens (proenzymes) are inactive precursors that are activated by cleavage, e.g., pepsinogen → pepsin, trypsinogen → trypsin.
Correct answer: Inactive enzyme precursors- A. Bind permanently and cannot be removed
- B. Bind temporarily and can be removed
- C. Permanently inactivate the enzyme
- D. Change enzyme structure permanently
Explanation: A reversible inhibitor binds through weak interactions and detaches again, so activity returns when it is removed or outcompeted, which is…
Correct answer: Bind temporarily and can be removed- A. Co-enzyme
- B. Blocker
- C. Inhibitor
- D. Cofactor
Explanation: An inhibitor is a substance that reduces enzyme activity by binding to the enzyme; a competitive inhibitor can occupy the active site and…
Correct answer: Inhibitor- A. Irreversible inhibitor
- B. Reversible inhibitor
- C. Competitive inhibitor
- D. Non-competitive inhibitor
Explanation: A competitive inhibitor resembles the substrate and binds to the enzyme's active site, preventing the substrate from forming products.
Correct answer: Competitive inhibitor- A. Competitive inhibitors.
- B. Non-competitive inhibitors
- C. Irreversible inhibitors.
- D. Both a and b
Explanation: Weak, non-covalent bonds usually produce reversible inhibition, and both competitive and non-competitive inhibitors can act reversibly.
Correct answer: Both a and b- A. Irreversible inhibitor
- B. Reversible inhibitor
- C. Competitive inhibitor
- D. Non-competitive inhibitor
Explanation: Malonic acid resembles succinic acid and competes with it for the active site of succinate dehydrogenase, so it is a competitive…
Correct answer: Competitive inhibitor- A. Irreversible inhibitor
- B. Reversible inhibitor
- C. Competitive inhibitor
- D. Non-competitive inhibitor
Explanation: Irreversible inhibitors permanently alter an enzyme, often by forming strong covalent bonds with amino acids needed for its structure or…
Correct answer: Irreversible inhibitor- A. Substrate
- B. Co-factor
- C. Inhibitor
- D. Promotor
Explanation: An inhibitor binds to an enzyme without being converted into the normal product and can block the active site, preventing substrate…
Correct answer: Inhibitor- A. activate the enzymes
- B. alter the rate of reactions
- C. minimize the energy efficiency
- D. regulate the amount of product
Explanation: Feedback inhibition is a regulatory mechanism in which the end product of a metabolic pathway inhibits an enzyme involved early in the…
Correct answer: regulate the amount of product- A. allosteric inhibitor
- B. irreversible inhibitor
- C. competitive inhibitor
- D. non-competitive inhibitor
Explanation: Malonate is a competitive inhibitor, which means it competes with the substrate for the active site of the enzyme.
Correct answer: competitive inhibitorEnzyme Inhibitors MCQs: common questions
Are these Enzyme Inhibitors MCQs free?
Yes. All Enzyme Inhibitors MCQs from Biology are free on TestUstad, with unlimited attempts and no account needed. Nothing on this page is a sample or a trial.
How many Enzyme Inhibitors MCQs are on this page?
There are 35 Enzyme Inhibitors MCQs in the Biology bank, shown 20 to a page with the correct answer and an explanation on each.
Does every Enzyme Inhibitors MCQ have an explanation?
Yes. Each Enzyme Inhibitors question shows the correct option and a written explanation of why it is correct, so a wrong answer teaches you something rather than just being marked wrong.
Can I take a timed Enzyme Inhibitors test?
Yes. The practice button on this page starts a free Enzyme Inhibitors test drawn from the Biology bank. It marks each answer instantly, gives you a score at the end, and can be retaken as many times as you like.