Biodiversity and Conservation – Class 12 Biology notes, important questions and MCQs

Chapter overview

Biodiversity is the variety of life at genetic, species and ecosystem levels. It is being lost due to human activities, and is conserved in situ and ex situ.

Patterns and loss

• Diversity is highest in the tropics and decreases towards the poles.
• Species–area relationship: log S = log C + Z log A (Z ≈ 0.1–0.2).
• Causes of loss ("evil quartet"): habitat loss and fragmentation, over-exploitation, alien species invasion, co-extinctions.

Conservation

• In situ: biosphere reserves, national parks, wildlife sanctuaries, sacred groves; biodiversity hotspots (India has parts of Western Ghats–Sri Lanka, Himalaya, Indo-Burma, Sundaland).
• Ex situ: zoos, botanical gardens, seed banks, cryopreservation.
• India has about 8% of recorded global species; Earth Summit (Rio, 1992) led to the Convention on Biological Diversity.

Key terms

Hotspot

region with very high species richness and endemism under threat

Endemic species

species found only in one region

Co-extinction

extinction of one species causing loss of a dependent species

Formulas

• log S = log C + Z log A

Important questions with answers

Quick revision

• Tropics have the highest diversity.
• Sacred groves = in situ.
• Seed banks = ex situ.

Exam tips

• Remember the evil quartet: HOAC – Habitat loss, Over-exploitation, Alien species, Co-extinction.
• Remember the three levels of biodiversity (genetic, species, ecological) with one Indian example each — e.g. over 50,000 rice varieties and 1,000 mango varieties for genetic diversity.

Practice MCQs

1. National parks are an example of

   1. ex situ conservation
   2. in situ conservation
   3. cryopreservation
   4. seed banks
   Show answer

   Answer: (b) in situ conservation. In natural habitat.

2. Biodiversity is highest near the

   1. equator (tropics)
   2. poles
   3. deserts
   4. tundra
   Show answer

   Answer: (a) equator (tropics). Tropics.

3. Which is NOT a part of the 'evil quartet'

   1. habitat loss
   2. afforestation
   3. alien species
   4. over-exploitation
   Show answer

   Answer: (b) afforestation. Afforestation helps.

4. Zoos and seed banks are examples of

   1. in situ
   2. biosphere reserve
   3. hotspot
   4. ex situ
   Show answer

   Answer: (d) ex situ. Outside habitat.

5. The Western Ghats have more amphibian species than the Eastern Ghats. This shows

   1. genetic diversity
   2. species diversity
   3. ecological diversity
   4. extinction
   Show answer

   Answer: (b) species diversity. Number of species.

6. In log S = log C + Z log A, Z for small areas usually lies between

   1. 0.6 and 1.2
   2. 0 and 0.01
   3. 1 and 2
   4. 0.1 and 0.2
   Show answer

   Answer: (d) 0.1 and 0.2. Regression slope.

7. The Convention on Biological Diversity came out of the

   1. Stockholm Conference 1972
   2. Kyoto 1997
   3. Earth Summit, Rio 1992
   4. Paris 2015
   Show answer

   Answer: (c) Earth Summit, Rio 1992. Rio 1992.

8. The extinction of the Steller's sea cow and passenger pigeon was mainly due to

   1. over-exploitation by humans
   2. alien species
   3. co-extinction
   4. climate only
   Show answer

   Answer: (a) over-exploitation by humans. Overhunting.