General physiology: heat loss in water: practice question

A Physiology 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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Physiology · General physiology: heat loss in water

Sample item

A man falls into a lake at 20 degrees C and becomes hypothermic far sooner than he would have standing in still air at the same temperature. Which property of the medium best explains this?

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

The answer and the reasoning

B. Much higher thermal conductivity than air

Water conducts heat many times faster than air, and its large heat capacity carries heat away from the body surface. Conduction therefore dominates heat loss in immersion, and the trapped layer of warm air next to the skin is lost.

Option by option

  • A. Lower specific heat capacity than air

    Water has a higher, not lower, specific heat than air.

  • B. Much higher thermal conductivity than air (correct)

    Correct. Water's high thermal conductivity drains heat from the body rapidly.

  • C. Reflection of body radiant heat back to the skin

    Water does not reflect body radiation back; heat leaves by conduction instead.

  • D. Greater suppression of evaporation than in air

    Evaporation is irrelevant when the skin is already wet and does not explain the faster loss.

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 Physiology question

What is the answer to this Physiology question?

The best answer is B, Much higher thermal conductivity than air. Water conducts heat many times faster than air, and its large heat capacity carries heat away from the body surface.

Why is "Lower specific heat capacity than air" not the answer?

Water has a higher, not lower, specific heat than air.

Why is "Reflection of body radiant heat back to the skin" not the answer?

Water does not reflect body radiation back; heat leaves by conduction instead.

Why is "Greater suppression of evaporation than in air" not the answer?

Evaporation is irrelevant when the skin is already wet and does not explain the faster loss.

What concept does this question test?

It tests General physiology: heat loss in water in Physiology. Conduction therefore dominates heat loss in immersion, and the trapped layer of warm air next to the skin is lost.

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 General physiology: heat loss in water?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.