Cell injury and adaptation: peroxynitrite: practice question

A Pathology 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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Pathology · Cell injury and adaptation: peroxynitrite

Sample item

In injured and inflamed tissue, nitric oxide reacts with another reactive species to form a powerful oxidant that damages lipids, proteins and DNA. Which species combines with nitric oxide?

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

The answer and the reasoning

A. Superoxide anion

Nitric oxide combines with the superoxide anion to form peroxynitrite, a highly reactive nitrogen species that injures cells and contributes to tissue damage in inflammation and reperfusion. Hydrogen peroxide and hypochlorous acid are formed by separate steps of the oxidative burst.

Option by option

  • A. Superoxide anion (correct)

    Correct. Nitric oxide plus superoxide gives peroxynitrite.

  • B. Hydroxyl radical

    The hydroxyl radical arises from hydrogen peroxide by the Fenton reaction.

  • C. Hydrogen peroxide

    Hydrogen peroxide is generated by dismutation of superoxide and does not form peroxynitrite with nitric oxide.

  • D. Hypochlorous acid

    Hypochlorous acid is generated from hydrogen peroxide and chloride by myeloperoxidase.

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 Pathology question

What is the answer to this Pathology question?

The best answer is A, Superoxide anion. Nitric oxide combines with the superoxide anion to form peroxynitrite, a highly reactive nitrogen species that injures cells and contributes to tissue damage in inflammation and reperfusion.

Why is "Hydroxyl radical" not the answer?

The hydroxyl radical arises from hydrogen peroxide by the Fenton reaction.

Why is "Hydrogen peroxide" not the answer?

Hydrogen peroxide is generated by dismutation of superoxide and does not form peroxynitrite with nitric oxide.

Why is "Hypochlorous acid" not the answer?

Hypochlorous acid is generated from hydrogen peroxide and chloride by myeloperoxidase.

What concept does this question test?

It tests Cell injury and adaptation: peroxynitrite in Pathology. Hydrogen peroxide and hypochlorous acid are formed by separate steps of the oxidative burst.

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 Cell injury and adaptation: peroxynitrite?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.