Question

Taking the example of a lake as a simple aquatic ecosystem, interpret how various functions of this ecosystem are carried out. Make a food chain that is functional in this ecosystem.?


class 12th CBSE Biology sample paper

Answer 1

i) Productivity - conversion of inorganic into organic material with the help of solar energy by the autotrophs                                                              

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ii) Energy flow - unidirectional movement of energy towards higher trophic level (and its dissipation and loss as heat to the environment)                           

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iii) Decomposition - fragmentation, leaching, catabolism, humification, mineralization by bacteria, fungi and flagellates (abundant at the bottom of lake)

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iv) Nutrient cycling - decomposition of dead matter to release the nutrients back to be re-used by the autotrophs.

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Food chain in aquatic ecosystem (lake)                                                          

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Phytoplanktons ----->Zooplanktons------>Small fish------>Big fish  (Any other appropriate example) .

Answer 2

PHYTOPLANKTON ZOOPLANKTON NYMPHON SMALL FISH LARGE FISH