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Expand ELISA. On what… (Class 12 Biology SQP 2025-26, Q27)

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BiologyCBSE Class 12 · Sample paper, session 2025-26 · 3 marks · Short answer

CBSE Class 12 Biology sample paper 2025-26: question 27

From the official CBSE sample question paper for 2025-26, section C, question 27, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q27 · 3 marks · Short answerHuman Health and Disease

Expand ELISA. On what principle is the ELISA test based? List two ways by which an infection can be detected by this test.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2025-26.

Hints

Open one hint at a time and try again before the next.

Hint 1

The 'I' and 'S' in ELISA stand for 'Immunosorbent'.

Hint 2

Infection can be detected either by the pathogen's molecules or by the body's response to them.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. ELISA = Enzyme Linked Immunosorbent Assay.

    1 mark

  2. Principle: ELISA is based on the specific antigen–antibody interaction.

    1 mark

  3. An infection can be detected in two ways:
    (a) by detecting antigens of the pathogen (proteins, glycoproteins, etc.) in the sample;
    (b) by detecting antibodies the body has made against the pathogen.

    1 mark

Answer: Enzyme Linked Immunosorbent Assay; antigen–antibody interaction; detects pathogen antigens or antibodies produced against the pathogen.

Where the marks are

  • Correct expansion of ELISA (1 mark)
  • Principle – antigen–antibody interaction (1 mark)
  • Two ways – detection of antigens and of antibodies (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Human Health and Disease, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2025-26: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.