Pentose phosphate pathway: transketolase: 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: transketolase

Sample item

Why is erythrocyte transketolase activity used in suspected thiamine deficiency?

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

The answer and the reasoning

A. Transketolase requires thiamine pyrophosphate as a cofactor

Transketolase is a thiamine-dependent enzyme in the nonoxidative pentose phosphate pathway. Reduced activity that improves after thiamine addition supports deficient thiamine status.

Option by option

  • A. Transketolase requires thiamine pyrophosphate as a cofactor (correct)

    Correct. TPP is required for transketolase function.

  • B. It is a marker of iron absorption

    Iron absorption does not depend on transketolase.

  • C. It detects folate-dependent DNA synthesis

    Folate supports one-carbon metabolism, not this assay.

  • D. It directly measures vitamin B12 stores

    Vitamin B12 status is assessed differently.

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 A, Transketolase requires thiamine pyrophosphate as a cofactor. Transketolase is a thiamine-dependent enzyme in the nonoxidative pentose phosphate pathway.

Why is "It is a marker of iron absorption" not the answer?

Iron absorption does not depend on transketolase.

Why is "It detects folate-dependent DNA synthesis" not the answer?

Folate supports one-carbon metabolism, not this assay.

Why is "It directly measures vitamin B12 stores" not the answer?

Vitamin B12 status is assessed differently.

What concept does this question test?

It tests Pentose phosphate pathway: transketolase in Biochemistry. Reduced activity that improves after thiamine addition supports deficient thiamine status.

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: transketolase?

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.