Immunology: practice question

A Microbiology 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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Microbiology · Immunology

Sample item

Which complement component is key opsonin?

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

The answer and the reasoning

D. C3b

This item reviews Immunology; C3b is the best answer because it directly matches the pharmacologic or microbiologic principle described.

Option by option

  • A. C5a

    C5a does not fit the stated mechanism or pattern.

  • B. C9 only

    C9 only is plausible but not the best answer.

  • C. IgM

    IgM is unsupported by the key finding.

  • D. C3b (correct)

    Correct. C3b fits the defining feature.

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 Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is D, C3b. This item reviews Immunology; C3b is the best answer because it directly matches the pharmacologic or microbiologic principle described.

Why is "C5a" not the answer?

C5a does not fit the stated mechanism or pattern.

Why is "C9 only" not the answer?

C9 only is plausible but not the best answer.

Why is "IgM" not the answer?

IgM is unsupported by the key finding.

What concept does this question test?

It tests Immunology in Microbiology. The correct option holds because: Correct. C3b fits the defining feature.

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 Immunology?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology 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.