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Class 12th Biology 2016 Set3 Delhi Board Paper Solution

Question 25

(a) Why should we conserve biodiversity ? How can we do it ?
(b) Explain the importance of biodiversity hot-spots and sacred groves.


                                                  OR


(a) Represent diagrammatically three kinds of age pyramids for human populations.
(b) How does an age pyramid for human population at given point of time helps the policy-makers in planning for future.

Answer

(a) (i) Narrowly utilitarian : We derive economic benefits from nature food (cereals/pulses/fruits). We also get firewood, fibre, construction material, industrial products (tannins, lubricants, dyes, resins, perfumes), products of medicinal importance etc.

Broadly utilitarian : We get 20% of the total O2 from the Amazon rain forests. Pollination is also achieved. We derive several aesthetic pleasures from them.
Ethical Argument : Millions of species of plants, animals and microbes share this planet with us. We need to realise that every species has an intrinsic value. We have a moral duty to care for their well being and pass on our biological legacy to future generations.



 

(ii) In situ conservation in biosphere reserves, national parks, sanctuaries, sacred groves etc.
Ex situe conservation in zoological parks, botanical gardens, safari parks, cryoprese-rvation, seed banks, tissue culture etc.

 

(b) Three of these hotspots are Western Ghats and Sri lanka, Indo-Burma and Himalaya-cover our country’s exceptionally high biodiversity regions.
Sacred Groves : They are tracts of forests containing wild life which are venerated and given total protection. Such sacred groves are found in Khasi and Jaintia Hills in Meghalaya, Aravalli hills of Rajasthan, Chand and Baster areas of Madhya Pradesh. In Meghalaya, the sacred groves are the last refuges for Meghalaya, for a large number of rare and threatened plants.
 

 

                                                                                                  OR

 

(a)
Post-reproductive Reproductive Pre-reproductive Expanding

(b) Age pyramid analysis of a population helps in planning and health, education, transport, infrastructure, finance, food or employment.