Oxidative stress: 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 stress

Sample item

What is a free radical?

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

The answer and the reasoning

B. A molecule with an unpaired electron

Free radicals contain unpaired electrons and can damage lipids, proteins, and DNA unless controlled by antioxidant systems.

Option by option

  • A. A saturated fatty acid only

    Saturation does not define radical chemistry.

  • B. A molecule with an unpaired electron (correct)

    Correct: unpaired electrons make radicals reactive.

  • C. A protein with no amino acids

    Proteins are made from amino acids.

  • D. A carbohydrate with two phosphate groups

    Phosphate groups do not define a radical.

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, A molecule with an unpaired electron. Free radicals contain unpaired electrons and can damage lipids, proteins, and DNA unless controlled by antioxidant systems.

Why is "A saturated fatty acid only" not the answer?

Saturation does not define radical chemistry.

Why is "A protein with no amino acids" not the answer?

Proteins are made from amino acids.

Why is "A carbohydrate with two phosphate groups" not the answer?

Phosphate groups do not define a radical.

What concept does this question test?

It tests Oxidative stress in Biochemistry. The correct option holds because: Correct: unpaired electrons make radicals reactive.

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 stress?

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.