Pentose phosphate pathway: G6PD: 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 · Pentose phosphate pathway: G6PD

Sample item

A man develops jaundice and dark urine after receiving primaquine. Which product of the pentose phosphate pathway is deficient in his red cells?

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

The answer and the reasoning

B. NADPH

G6PD generates NADPH, which maintains glutathione in its reduced form. Without it, oxidant stress causes haemoglobin denaturation and haemolysis.

Option by option

  • A. FADH2

    FADH2 is produced in several oxidative pathways but does not maintain glutathione.

  • B. NADPH (correct)

    Correct. NADPH is needed to regenerate reduced glutathione.

  • C. Acetyl-CoA

    Acetyl-CoA is not a pentose phosphate pathway product.

  • D. NADH

    NADH is mainly generated in glycolysis and the TCA cycle.

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 B, NADPH. G6PD generates NADPH, which maintains glutathione in its reduced form.

Why is "FADH2" not the answer?

FADH2 is produced in several oxidative pathways but does not maintain glutathione.

Why is "Acetyl-CoA" not the answer?

Acetyl-CoA is not a pentose phosphate pathway product.

Why is "NADH" not the answer?

NADH is mainly generated in glycolysis and the TCA cycle.

What concept does this question test?

It tests Pentose phosphate pathway: G6PD in Biochemistry. Without it, oxidant stress causes haemoglobin denaturation and haemolysis.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Pentose phosphate pathway: G6PD?

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.