Pentose phosphate pathway: 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

Sample item

What is the principal product of the oxidative phase of the pentose phosphate pathway that protects red cells from oxidant injury?

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

The answer and the reasoning

D. NADPH

The oxidative pentose phosphate pathway generates NADPH, which keeps glutathione reduced and protects cells from oxidative stress. Red cells depend heavily on this pathway because they lack mitochondria.

Option by option

  • A. ATP only

    ATP is not the key protective output of this pathway.

  • B. NADH

    NADH is mainly generated in glycolysis and the TCA cycle.

  • C. FADH2

    FADH2 is generated in several oxidative pathways.

  • D. NADPH (correct)

    Correct. NADPH supports glutathione reduction.

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, NADPH. The oxidative pentose phosphate pathway generates NADPH, which keeps glutathione reduced and protects cells from oxidative stress.

Why is "ATP only" not the answer?

ATP is not the key protective output of this pathway.

Why is "NADH" not the answer?

NADH is mainly generated in glycolysis and the TCA cycle.

Why is "FADH2" not the answer?

FADH2 is generated in several oxidative pathways.

What concept does this question test?

It tests Pentose phosphate pathway in Biochemistry. Red cells depend heavily on this pathway because they lack mitochondria.

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 Pentose phosphate pathway?

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.