Complement: 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 · Complement

Sample item

Which complement component acts as an important opsonin for phagocytosis?

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

The answer and the reasoning

A. C3b

C3b coats microbial surfaces and is recognized by complement receptors on phagocytes, enhancing ingestion; other complement fragments contribute to chemotaxis, inflammation, or membrane attack complex formation.

Option by option

  • A. C3b (correct)

    Correct: C3b is a major opsonin that promotes phagocytosis.

  • B. C5a only

    C5a is a potent chemotactic and anaphylatoxic fragment.

  • C. C1q only

    C1q initiates the classical pathway but is not the principal opsonin described.

  • D. C9 only

    C9 forms part of the membrane attack complex.

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 Pathology questions

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is A, C3b. C3b coats microbial surfaces and is recognized by complement receptors on phagocytes, enhancing ingestion; other complement fragments contribute to chemotaxis, inflammation, or membrane attack complex formation.

Why is "C5a only" not the answer?

C5a is a potent chemotactic and anaphylatoxic fragment.

Why is "C1q only" not the answer?

C1q initiates the classical pathway but is not the principal opsonin described.

Why is "C9 only" not the answer?

C9 forms part of the membrane attack complex.

What concept does this question test?

It tests Complement in Pathology. The correct option holds because: Correct: C3b is a major opsonin that promotes phagocytosis.

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 Complement?

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.