Carbohydrate metabolism: gluconeogenesis: 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 · Carbohydrate metabolism: gluconeogenesis

Sample item

Which enzyme bypasses the irreversible phosphofructokinase-1 step during gluconeogenesis?

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

The answer and the reasoning

D. Fructose-1,6-bisphosphatase

Fructose-1,6-bisphosphatase hydrolyses fructose-1,6-bisphosphate to fructose-6-phosphate. It is inhibited by AMP and fructose-2,6-bisphosphate.

Option by option

  • A. Glycogen phosphorylase

    Glycogen phosphorylase releases glucose-1-phosphate from glycogen.

  • B. Hexokinase

    Hexokinase uses ATP to trap glucose in cells.

  • C. Pyruvate dehydrogenase

    Pyruvate dehydrogenase links glycolysis to the TCA cycle and is irreversible.

  • D. Fructose-1,6-bisphosphatase (correct)

    Correct. It bypasses the PFK-1 step.

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.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is D, Fructose-1,6-bisphosphatase. Fructose-1,6-bisphosphatase hydrolyses fructose-1,6-bisphosphate to fructose-6-phosphate.

Why is "Glycogen phosphorylase" not the answer?

Glycogen phosphorylase releases glucose-1-phosphate from glycogen.

Why is "Hexokinase" not the answer?

Hexokinase uses ATP to trap glucose in cells.

Why is "Pyruvate dehydrogenase" not the answer?

Pyruvate dehydrogenase links glycolysis to the TCA cycle and is irreversible.

What concept does this question test?

It tests Carbohydrate metabolism: gluconeogenesis in Biochemistry. It is inhibited by AMP and fructose-2,6-bisphosphate.

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: gluconeogenesis?

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.