Molecular diagnostics: 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 · Molecular diagnostics

Sample item

What is the central purpose of polymerase chain reaction in a diagnostic laboratory?

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

The answer and the reasoning

B. Amplify a selected DNA sequence

Polymerase chain reaction uses primers and repeated temperature cycling to amplify a selected DNA target, allowing very small amounts of genetic material to be detected or characterized.

Option by option

  • A. Separate blood cells by density

    Cell-density separation uses centrifugation rather than PCR.

  • B. Amplify a selected DNA sequence (correct)

    Correct: PCR makes many copies of a defined DNA target.

  • C. Visualize bone fractures

    Fractures are visualized with imaging modalities such as radiographs.

  • D. Measure serum sodium directly

    Serum sodium is measured with chemistry analyzers or electrodes.

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, Amplify a selected DNA sequence. Polymerase chain reaction uses primers and repeated temperature cycling to amplify a selected DNA target, allowing very small amounts of genetic material to be detected or characterized.

Why is "Separate blood cells by density" not the answer?

Cell-density separation uses centrifugation rather than PCR.

Why is "Visualize bone fractures" not the answer?

Fractures are visualized with imaging modalities such as radiographs.

Why is "Measure serum sodium directly" not the answer?

Serum sodium is measured with chemistry analyzers or electrodes.

What concept does this question test?

It tests Molecular diagnostics in Biochemistry. The correct option holds because: Correct: PCR makes many copies of a defined DNA target.

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 Molecular diagnostics?

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.