Nutrition: net protein utilisation: practice question

A PSM 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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PSM · Nutrition: net protein utilisation

Sample item

A food protein has a biological value of 80% and a digestibility coefficient of 90%. What is its net protein utilisation?

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

The answer and the reasoning

C. 72%

Net protein utilisation (NPU) is the proportion of ingested nitrogen that is retained in the body. It equals biological value multiplied by digestibility: 0.80 x 0.90 = 0.72, or 72%. Biological value alone measures only how much of the absorbed nitrogen is retained.

Option by option

  • A. 85%

    85% is the arithmetic mean, which is not how NPU is derived.

  • B. 90%

    90% is only the digestibility coefficient.

  • C. 72% (correct)

    NPU = BV x digestibility = 0.8 x 0.9 = 72%.

  • D. 80%

    80% is the biological value, which does not account for incomplete digestion.

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 PSM question

What is the answer to this PSM question?

The best answer is C, 72%. Net protein utilisation (NPU) is the proportion of ingested nitrogen that is retained in the body.

Why is "85%" not the answer?

85% is the arithmetic mean, which is not how NPU is derived.

Why is "90%" not the answer?

90% is only the digestibility coefficient.

Why is "80%" not the answer?

80% is the biological value, which does not account for incomplete digestion.

What concept does this question test?

It tests Nutrition: net protein utilisation in PSM. It equals biological value multiplied by digestibility: 0.80 x 0.90 = 0.72, or 72%. Biological value alone measures only how much of the absorbed nitrogen is retained.

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 Nutrition: net protein utilisation?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM 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.