Q26 of 29 Page 1

Explain, giving one example, how co-extinction is one of the causes of loss of biodiversity. List the three other causes also (without description).

OR


Eutrophication is the natural aging of a lake. Explain.


When a species become extinct, the plant and animal species associated with it in an obligatory way also become extinct.


For example, when a host fish species extinct, its unique assemblage of parasites also meets the same fate as they don’t get a host body to exploit for their own needs.


Other causes of loss of biodiversity –


• Habitat loss and fragmentation


• Over exploitation


• Alien species invasion


OR


• Eutrophication is the natural aging of a lake by nutrient enrichment of its water.


• In a young lake, the water is cold and clear, supporting little life but with time, streams draining into the lake introduce nutrients such as Nitrogen and phosphorus.


• The nutrient enrichment encourages the growth of aquatic organisms like plants and animals and organic matter begin to be deposited on the lake bottom and keep on depositing for centuries.


• The lake thus becomes shallower with time. Eventually, lake gives way to large masses of floating plants, finally converting into land.


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