Bacteriology: 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 · Bacteriology

Sample item

What stain differentiates bacteria by cell-wall structure?

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

The answer and the reasoning

C. Gram stain

Gram staining classifies bacteria based on cell-wall properties, with gram-positive organisms retaining crystal violet and gram-negative organisms counterstaining pink.

Option by option

  • A. Giemsa stain

    Giemsa is used for blood parasites and some cells.

  • B. Wright stain

    Wright stain is used for blood-film examination.

  • C. Gram stain (correct)

    Correct: Gram stain differentiates bacteria by cell-wall characteristics.

  • D. India ink

    India ink can demonstrate capsules in selected fungi.

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 Microbiology question

What is the answer to this Microbiology question?

The best answer is C, Gram stain. Gram staining classifies bacteria based on cell-wall properties, with gram-positive organisms retaining crystal violet and gram-negative organisms counterstaining pink.

Why is "Giemsa stain" not the answer?

Giemsa is used for blood parasites and some cells.

Why is "Wright stain" not the answer?

Wright stain is used for blood-film examination.

Why is "India ink" not the answer?

India ink can demonstrate capsules in selected fungi.

What concept does this question test?

It tests Bacteriology in Microbiology. The correct option holds because: Correct: Gram stain differentiates bacteria by cell-wall characteristics.

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 Bacteriology?

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.