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Answer the following. (Class 12 Biology 2024, Q28)

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BiologyCBSE Class 12 · Board exam 2024, set 57/1/1 · 3 marks · Short answer

CBSE Class 12 Biology 2024: question 28

Set in the CBSE Class 12 board exam of 2024, paper 57/1/1, section C, question 28, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q28 · 3 marks · Short answerEvolution

Answer the following.

  1. (a)

    Explain how it is ensured that the orchid Ophrys is pollinated by a specific species of bee.

    2 marks
  2. (b)

    Describe co-evolution with the help of this example.

    1 mark

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 57/1/1.

Hints

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

Hint 1

The flower pretends to be something the male bee is looking for.

Hint 2

What would happen to pollination if the real female bees started to look different?

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. (a) The Mediterranean orchid Ophrys uses sexual deceit to get pollinated by one specific species of bee.

    ½ mark

  2. (a) One petal of its flower closely resembles the female bee of that species in size, colour and markings.

    ½ mark

  3. (a) The male bee is attracted to what it takes to be a female and pseudocopulates with the flower. In doing so, it gets dusted with pollen.

    ½ mark

  4. (a) When the same bee pseudocopulates with another flower, it transfers the pollen to it and pollinates it.

    ½ mark

  5. (b) Co-evolution: the flower and its pollinator evolve together. If the colour pattern of the female bee changes even slightly during evolution, pollination success falls unless the orchid's petal also evolves to keep resembling the female bee.

    1 mark

Answer: (a) Ophrys petal mimics female bee, so male bee pseudocopulates, picks up pollen and transfers it to another flower; (b) if female bee's pattern changes, the flower must co-evolve to keep resembling her

Where the marks are

  • Sexual deceit (½ mark)
  • Petal resembles female bee (½ mark)
  • Male bee pseudocopulates and gets dusted with pollen (½ mark)
  • Transfers pollen to another flower (½ mark)
  • Co-evolution: flower must change along with female bee's pattern (1 mark)

Revise the chapter

  • Chapter: Evolution (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Evolution, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 57/1/1: 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.