Vitamins: thiamine: 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 · Vitamins: thiamine

Sample item

Which enzyme requires thiamine pyrophosphate as a cofactor and is impaired in Wernicke encephalopathy?

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

The answer and the reasoning

C. Transketolase

Thiamine is required by transketolase, pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and branched-chain alpha-ketoacid dehydrogenase. Erythrocyte transketolase activity helps assess deficiency.

Option by option

  • A. Gamma-glutamyl carboxylase

    Gamma-carboxylation of clotting factors requires vitamin K.

  • B. Homocysteine methyltransferase

    Methionine synthase requires cobalamin and folate pathways.

  • C. Transketolase (correct)

    Correct. Transketolase is a classic thiamine-dependent enzyme.

  • D. Pyruvate carboxylase

    Pyruvate carboxylase requires biotin.

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 C, Transketolase. Thiamine is required by transketolase, pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and branched-chain alpha-ketoacid dehydrogenase.

Why is "Gamma-glutamyl carboxylase" not the answer?

Gamma-carboxylation of clotting factors requires vitamin K.

Why is "Homocysteine methyltransferase" not the answer?

Methionine synthase requires cobalamin and folate pathways.

Why is "Pyruvate carboxylase" not the answer?

Pyruvate carboxylase requires biotin.

What concept does this question test?

It tests Vitamins: thiamine in Biochemistry. Erythrocyte transketolase activity helps assess deficiency.

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 Vitamins: thiamine?

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.