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Answer the following. (Class 12 Biology 2025, Q24)

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BiologyCBSE Class 12 · Board exam 2025, set 57/1/1 · 3 marks · Short answer

CBSE Class 12 Biology 2025: question 24

Set in the CBSE Class 12 board exam of 2025, paper 57/1/1, section C, question 24, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q24 · 3 marks · Short answerBiodiversity and Conservation

Answer the following.

  1. (a)

    Indiscriminate human activities such as alien species invasion, fragmentation and habitat loss have accelerated the loss of biodiversity. Justify by taking one example for each.

    0 marks
  2. (b)

    State the importance of the following :
    (i) IUCN Red data list
    (ii) Hot spots in conservation of biodiversity

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 57/1/1.

Hints

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

Hint 1

Recall a famous fish introduced into an African lake.

Hint 2

Think of the largest rainforest being cleared for farming.

Hint 3

What does a list of threatened species help conservationists decide? What two features define a hotspot?

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) Alien species invasion: Nile perch introduced into Lake Victoria (East Africa) caused the extinction of more than 200 species of cichlid fish. Other examples include Parthenium, Lantana and water hyacinth, and the African catfish Clarias gariepinus, which threatens native catfish.

    1 mark

  2. Habitat loss and fragmentation: The Amazon rainforest, home to millions of species, is being cleared to grow soybeans and to make grasslands for cattle. When large habitats are broken into small fragments, mammals and birds that need large territories decline badly.

    1 mark

  3. (b)(i) IUCN Red List: It documents species facing a high risk of extinction (threatened species). It therefore helps identify which species need protection and guides conservation planning.

    ½ mark

  4. (ii) Hotspots: They are regions with very high species richness and a high degree of endemism. Protecting these small areas saves a large share of global biodiversity.

    ½ mark

Answer: (a) Nile perch in Lake Victoria → extinction of 200+ cichlids; clearing of the Amazon rainforest/fragmentation → decline of species. (b)(i) Red List identifies threatened species for protection; (ii) hotspots have high species richness and endemism, so they are priority areas for conservation.

Where the marks are

  • Correct example of alien species invasion (1 mark)
  • Correct example of habitat loss/fragmentation (1 mark)
  • Importance of the IUCN Red List (½ mark)
  • Importance of hotspots: high richness and endemism (½ 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 paper2025 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.