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A Green Valley X… (Class 12 Biology SQP 2026-27, Q33A)

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BiologyCBSE Class 12 · Sample paper, session 2026-27 · 5 marks · Long answer

CBSE Class 12 Biology sample paper 2026-27: question 33(A)

From the official CBSE sample question paper for 2026-27, section E, question 33(A), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q33(A) · 5 marks · Long answerCompetency-basedBiodiversity and Conservation

A Green Valley , home to rare medicinal plants and several migratory bird species, is facing multiple environmental challenges.
I. A luxury brand of cosmetics with little regulation has been sourcing wild medicinal plants from the valley.
II. The company has introduced an ornamental grass species from another country, which has taken over large areas of native grassland.
III. There is also a reported drastic decline in the endemic trees.
IV. Large scale forest fire in a part of the valley.
a) From the above hypothetical case, identify and explain the four major biodiversity threats. (4)
b) Suggest one in-situ conservation practice that could help protect the biodiversity of Green Valley , and justify your choice. (1)

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

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

Hint 1

Recall the 'Evil Quartet' of biodiversity loss.

Hint 2

Match each case: harvesting wild plants, a foreign species, linked species declining together, and fire destroying habitat.

Hint 3

In-situ means conserving species where they naturally live.

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) I – Over-exploitation: The cosmetic brand is collecting wild medicinal plants unsustainably. Their populations fall faster than they can regenerate, which can push these rare species towards extinction.

    1 mark

  2. II – Invasion by alien species: The exotic ornamental grass spreads aggressively. It outcompetes native grasses and the species that depend on them, reducing local biodiversity. This is similar to Parthenium and Lantana in India.

    1 mark

  3. III – Co-extinction: When the endemic trees decline, the migratory birds that depend on them for nesting also decline sharply. Loss of one species therefore drags down an associated species and upsets the ecological balance.

    1 mark

  4. IV – Habitat loss and fragmentation: The forest fire destroys vegetation and breaks the continuous habitat into small, isolated patches. Species are forced to migrate, populations shrink, and local extinctions can follow.

    1 mark

  5. (b) In-situ practice: Declare Green Valley X a protected area, such as a national park, wildlife sanctuary or biosphere reserve. Justification: This protects the species in their natural habitat and keeps their ecological interactions intact, for example between trees and nesting birds. It also gives long-term protection to genetic, species and ecosystem diversity, and legally stops plant collection and habitat destruction.

    1 mark

Answer: (a) I – Over-exploitation; II – Alien species invasion; III – Co-extinction; IV – Habitat loss and fragmentation. (b) Declare the valley a protected area (national park/wildlife sanctuary/biosphere reserve), which conserves species in their natural habitat.

Where the marks are

  • Over-exploitation named and explained (1 mark)
  • Alien species invasion named and explained (1 mark)
  • Co-extinction named and explained (1 mark)
  • Habitat loss and fragmentation named and explained (1 mark)
  • Suggests an in-situ protected area with a justification (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Biodiversity and Conservation, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2026-27: 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.