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Biology

Class 12 · Science & Environment

Ch 13 · Biodiversity and Conservation

Real UPSC Prelims questions from 2016–2026, linked to this book. Try each one first, then open the answer. 2026 answers follow UPSC's provisional answer key.

Prelims 2018 · Q60

The term "sixth mass extinction/sixth extinction" is often mentioned in the news in the context of the discussion of

  1. (a)Widespread monoculture practices in agriculture and large-scale commercial farming with indiscriminate use of chemicals in many parts of the world that may result in the loss of good native ecosystems.
  2. (b)Fears of a possible collision of a meteorite with the Earth in the near future in the manner it happened 65 million years ago that caused the mass extinction of many species including those of dinosaurs.
  3. (c)Large scale cultivation of genetically modified crops in many parts of the world and promoting their cultivation in other parts of the world which may cause the disappearance of good native crop plants and the loss of food biodiversity.
  4. (d)Mankind's over-exploitation/misuse of natural resources, fragmentation/loss of natural habitats, destruction of ecosystems, pollution and global climate change.
Show answer

UPSC's answer: (d)

NCERT answers it: Class 12 Biology, Ch 13 (Biodiversity and Conservation).

Class 12 Biology, ch 13: the 'Sixth Extinction' now in progress differs from earlier ones in its rate. Species are vanishing 100 to 1,000 times faster than in pre-human times, and our activities are responsible. Answer (d).

Hindi version: UPSC's official question paper (2018), question 60 ↗

Prelims 2018 · Q86

Why is a plant called Prosopis juliflora often mentioned in news?

  1. (a)Its extract is widely used in cosmetics.
  2. (b)It tends to reduce the biodiversity in the area in which it grows.
  3. (c)Its extract is used in the synthesis of pesticides.
  4. (d)None of the above
Show answer

UPSC's answer: (b)

NCERT answers it: Class 11 Understanding Society, Ch 3 (Environment and Society); Class 12 Biology, Ch 13 (Biodiversity and Conservation).

How to solve it with NCERT: Class 11 Understanding Society, ch 3: Prosopis juliflora (vilayati kikar) came from South America and has spread all over north India. Class 12 Biology, ch 13: such alien species can turn invasive and push out native species. Answer (b).

Hindi version: UPSC's official question paper (2018), question 86 ↗

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