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A. Diagram given below… (Class 12 Biology SQP 2024-25, Q28)

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BiologyCBSE Class 12 · Sample paper, session 2024-25 · 3 marks · Short answer

CBSE Class 12 Biology sample paper 2024-25: question 28

From the official CBSE sample question paper for 2024-25, section C, question 28, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q28 · 3 marks · Short answerCompetency-basedOrganisms and Populations

A. Diagram given below depicts different species of Warbler birds feeding on different regions on a Spruce tree. Explain the mechanism which helps them to co-exist.
B. What does Gause‘s exclusion principle state? Does it apply in the case shown above? Explain.

Figure in the paper: Spruce tree with feeding height scale (0 to 18 m). Cape May Warbler feeds at the tips of branches near the top of the tree; Bay-Breasted Warbler feeds in the middle part of the tree; Yellow-Rumped Warbler feeds in the lower part of the tree and at the bases of the middle branches. See it in the official paper.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2024-25.

Hints

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

Hint 1

Look at where each warbler feeds on the tree.

Hint 2

Dividing up a shared resource has a specific ecological name.

Hint 3

Gause's principle concerns competition for exactly the same resource.

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 warblers co-exist by resource partitioning.

    ½ mark

  2. A. Species competing for the same resource avoid competition by using different foraging patterns: they feed at different times or in different zones of the same tree.

    ½ mark

  3. A. MacArthur showed that five closely related warbler species on the same spruce tree avoided competition through behavioural differences in foraging. For example, the Cape May warbler feeds at the top branch tips, the Bay-breasted in the middle and the Yellow-rumped in the lower part.

    ½ mark

  4. B. Gause's Competitive Exclusion Principle states that two closely related species competing for the same resources cannot co-exist indefinitely,

    ½ mark

  5. B. ...and the competitively inferior species will eventually be eliminated.

    ½ mark

  6. B. No, it does not apply here. The warblers partition the resource by feeding in different regions of the tree, so they are not competing for exactly the same resource and can co-exist.

    ½ mark

Answer: A. Resource partitioning: different foraging zones on the tree (MacArthur's warblers). B. Two closely related species competing for the same resource cannot co-exist indefinitely and the inferior one is eliminated; No, it does not apply because of resource partitioning.

Where the marks are

  • Names resource partitioning (0.5 mark)
  • Explains different foraging patterns to avoid competition (0.5 mark)
  • Cites MacArthur's warbler study (0.5 mark)
  • States that closely related species competing for the same resource cannot co-exist indefinitely (0.5 mark)
  • States that the inferior competitor is eliminated (0.5 mark)
  • Says No, with reason (0.5 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 paperSample paper 2024-25: 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.