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Suggest how a virus-free… (Class 12 Biology 2026, Q20a)

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BiologyCBSE Class 12 · Board exam 2026, set 57/5/1 · 2 marks · Very short answer

CBSE Class 12 Biology 2026: question 20(a)

Set in the CBSE Class 12 board exam of 2026, paper 57/5/1, section B, question 20(a), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q20(a) · 2 marks · Very short answerBiotechnology and its Applications

Suggest how a virus-free healthy plant can be obtained from a diseased sugarcane plant.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 57/5/1.

Hints

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

Hint 1

Even in an infected plant, one tissue usually remains free of virus.

Hint 2

Use the virus-free tip region as an explant in a technique that grows whole plants from small pieces of tissue.

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. Remove the meristem (apical or axillary) from the diseased sugarcane plant. The meristem stays free of virus even when the rest of the plant is infected.

    1 mark

  2. Grow this meristem in vitro by tissue culture on a suitable nutrient medium. The plantlets that regenerate are virus-free healthy plants.

    1 mark

Answer: Meristem culture: excise the virus-free apical/axillary meristem and grow it by tissue culture to get virus-free plants.

Where the marks are

  • States that the meristem is taken from the diseased plant because it is virus-free (1 mark)
  • States that it is grown in vitro by tissue culture to obtain virus-free plants (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Biotechnology and its Applications, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 57/5/1: 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.