Vitamins and minerals: 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 and minerals

Sample item

Tryptophan can be converted to niacin in the body. About how many milligrams of dietary tryptophan are equivalent to 1 mg of niacin?

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

The answer and the reasoning

B. 60 mg

Sixty milligrams of tryptophan yield about one milligram of niacin, so diets rich in protein protect against pellagra. Maize-based diets are poor in available niacin and tryptophan. The conversion needs vitamin B6, riboflavin and iron.

Option by option

  • A. 30 mg

    30 mg understates the amount of tryptophan needed.

  • B. 60 mg (correct)

    Correct. The accepted conversion ratio is 60 mg tryptophan to 1 mg niacin.

  • C. 120 mg

    120 mg overstates the amount of tryptophan needed.

  • D. 6 mg

    6 mg is ten times too low.

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.

More Biochemistry questions

Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is B, 60 mg. Sixty milligrams of tryptophan yield about one milligram of niacin, so diets rich in protein protect against pellagra.

Why is "30 mg" not the answer?

30 mg understates the amount of tryptophan needed.

Why is "120 mg" not the answer?

120 mg overstates the amount of tryptophan needed.

Why is "6 mg" not the answer?

6 mg is ten times too low.

What concept does this question test?

It tests Vitamins and minerals in Biochemistry. Maize-based diets are poor in available niacin and tryptophan. The conversion needs vitamin B6, riboflavin and iron.

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 and minerals?

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.