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Ecosystems — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYEcosystems5 Marks
Question
Citing lake as an example of a simple aquatic ecosystem, interpret how various functions of this ecosystem are carried out. Make a food chain that is functional in this ecosystem.
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Answer

  1. Productivity: Conversion of inorganic into organic material with the help of solar energy by the autotrophs.
  2. Energy flow: Unidirectional movement of energy towards higher trophic level (and its dissipation and loss as heat to the environment).
  3. Decomposition: Fragmentation, leaching, catabolism, humification, mineralization by bacteria, fungi and flagellates (abundant at the bottom of lake).
  4. Nutrient cycling: Decomposition of dead matter to release the nutrients back to be re-used by the autotrophs.
Food chain in aquatic ecosystem (lake):
Phytoplanktons → Zooplanktons → Small fish → Big fish (Any other appropriate example).

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