Oxidative phosphorylation: uncoupling: 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 · Oxidative phosphorylation: uncoupling

Sample item

What is the effect of an uncoupling agent on oxygen consumption and heat production?

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

The answer and the reasoning

B. Increases both oxygen consumption and heat production

Uncouplers dissipate the proton gradient across the inner mitochondrial membrane, so electron transport and oxygen use continue or increase while energy is released as heat rather than captured as ATP.

Option by option

  • A. Blocks electron transfer at complex IV

    Complex IV blockade is a different mechanism, as in cyanide toxicity.

  • B. Increases both oxygen consumption and heat production (correct)

    Correct. Proton leak drives heat generation and increased respiration.

  • C. Increases ATP synthesis only

    ATP synthesis falls because the gradient is dissipated.

  • D. Decreases oxygen consumption and stops heat production

    Electron transport is not stopped by uncoupling.

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 B, Increases both oxygen consumption and heat production. Uncouplers dissipate the proton gradient across the inner mitochondrial membrane, so electron transport and oxygen use continue or increase while energy is released as heat rather than captured as ATP.

Why is "Blocks electron transfer at complex IV" not the answer?

Complex IV blockade is a different mechanism, as in cyanide toxicity.

Why is "Increases ATP synthesis only" not the answer?

ATP synthesis falls because the gradient is dissipated.

Why is "Decreases oxygen consumption and stops heat production" not the answer?

Electron transport is not stopped by uncoupling.

What concept does this question test?

It tests Oxidative phosphorylation: uncoupling in Biochemistry. The correct option holds because: Correct. Proton leak drives heat generation and increased respiration.

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 Oxidative phosphorylation: uncoupling?

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.