Enzymes: practice question

A Biochemistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Biochemistry · Enzymes

Sample item

What is the usual effect of a competitive enzyme inhibitor?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Increases apparent Km without lowering Vmax

Competitive inhibitors compete at the active site and can be overcome by more substrate, increasing apparent Km while preserving Vmax.

Option by option

  • A. Irreversibly destroys all enzyme

    Competitive inhibition is usually reversible.

  • B. Increases product concentration immediately

    Product output does not immediately rise from inhibition.

  • C. Increases apparent Km without lowering Vmax (correct)

    Correct: extra substrate can overcome competitive binding.

  • D. Lowers Vmax without changing Km

    Lowered Vmax is more typical of noncompetitive inhibition.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More Biochemistry questions

Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is C, Increases apparent Km without lowering Vmax. Competitive inhibitors compete at the active site and can be overcome by more substrate, increasing apparent Km while preserving Vmax.

Why is "Irreversibly destroys all enzyme" not the answer?

Competitive inhibition is usually reversible.

Why is "Increases product concentration immediately" not the answer?

Product output does not immediately rise from inhibition.

Why is "Lowers Vmax without changing Km" not the answer?

Lowered Vmax is more typical of noncompetitive inhibition.

What concept does this question test?

It tests Enzymes in Biochemistry. The correct option holds because: Correct: extra substrate can overcome competitive binding.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Enzymes?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.