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Assertion (A) : Trichoderma… (Class 12 Biology 2026, Q15)

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BiologyCBSE Class 12 · Board exam 2026, set 57/5/1 · 1 mark · Assertion-reason

CBSE Class 12 Biology 2026: question 15

Set in the CBSE Class 12 board exam of 2026, paper 57/5/1, section A, question 15, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q15 · 1 mark · Assertion-reasonCompetency-basedMicrobes in Human Welfare

Assertion (A) : Trichoderma species are free living fungi that are very common in the root ecosystems.
Reason (R) : They are effective bio-control agents of several plant pathogens.

  1. (A)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
  2. (B)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
  3. (C)Assertion (A) is true, but Reason (R) is false.
  4. (D)Assertion (A) is false, but Reason (R) is true.

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

Check whether each statement is true by itself.

Hint 2

Does being a biocontrol agent explain its habitat?

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. Both statements are true: Trichoderma is a free-living fungus common in root ecosystems, and it is an effective biocontrol agent.

    ½ mark

  2. Its biocontrol role does not explain why it is free-living in root ecosystems, so R is not the correct explanation of A. The answer is (B).

    ½ mark

Answer: (B)

Where the marks are

  • Judges both statements true but R not the explanation (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Microbes in Human Welfare, 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.