Carbohydrate metabolism: glycolysis: 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.

Try it

Biochemistry · Carbohydrate metabolism: glycolysis

Sample item

Which glycolytic enzyme is the principal rate-limiting regulatory enzyme in most tissues?

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

The answer and the reasoning

C. Phosphofructokinase-1

Phosphofructokinase-1 catalyzes the committed step from fructose-6-phosphate to fructose-1,6-bisphosphate and is strongly regulated by cellular energy status. ATP and citrate inhibit it, whereas AMP and fructose-2,6-bisphosphate activate it.

Option by option

  • A. Pyruvate kinase

    Pyruvate kinase catalyzes the final ATP-generating step.

  • B. Lactate dehydrogenase

    Lactate dehydrogenase interconverts pyruvate and lactate.

  • C. Phosphofructokinase-1 (correct)

    Correct. PFK-1 controls the committed rate-limiting glycolytic step.

  • D. Hexokinase

    Hexokinase traps glucose in cells but is not the principal rate-limiting enzyme.

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, Phosphofructokinase-1. Phosphofructokinase-1 catalyzes the committed step from fructose-6-phosphate to fructose-1,6-bisphosphate and is strongly regulated by cellular energy status.

Why is "Pyruvate kinase" not the answer?

Pyruvate kinase catalyzes the final ATP-generating step.

Why is "Lactate dehydrogenase" not the answer?

Lactate dehydrogenase interconverts pyruvate and lactate.

Why is "Hexokinase" not the answer?

Hexokinase traps glucose in cells but is not the principal rate-limiting enzyme.

What concept does this question test?

It tests Carbohydrate metabolism: glycolysis in Biochemistry. ATP and citrate inhibit it, whereas AMP and fructose-2,6-bisphosphate activate it.

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 Carbohydrate metabolism: glycolysis?

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.