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“Cattle and goats do not… (Class 12 Biology 2023, Q18)

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BiologyCBSE Class 12 · Board exam 2023, set 57/5/1 · 2 marks · Very short answer

CBSE Class 12 Biology 2023: question 18

Set in the CBSE Class 12 board exam of 2023, paper 57/5/1, section B, question 18, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q18 · 2 marks · Very short answerOrganisms and Populations

“Cattle and goats do not browse the Calotropis plant.” Justify the statement giving reasons.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 57/5/1.

Hints

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

Hint 1

Think about how plants defend themselves against grazing animals when they cannot run away.

Hint 2

Calotropis makes a specific poisonous chemical. Name its class.

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. Calotropis produces highly poisonous cardiac glycosides, which are chemicals that affect the heart.

    1 mark

  2. This is a chemical defence against herbivores. Cattle and goats that ate the plant could be poisoned or killed, so they have learnt to avoid browsing it.

    1 mark

Answer: Calotropis produces highly poisonous cardiac glycosides (a chemical defence against herbivores), so cattle and goats avoid it.

Where the marks are

  • Names the chemical produced as highly poisonous cardiac glycosides (1 mark)
  • Explains this as a defence against herbivores: grazing animals avoid the plant because it is toxic (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Organisms and Populations, one at a time, marked against the answer key and marking points.Back to the full paper2023 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.