Indicate the flow of energy in an ecosystem.

Indicate the flow of energy in an ecosystem. Why is it undirectional ? Justify. (CCE 2014)


An ecosystem does not have its own source of energy. It receives the same from sun. Green plants or producers trap the solar energy and

change it into chemical form during synthesis of food. Herbivores obtain energy from the food they take. A lot of energy dissipates during transfer

and utilization of food energy by herbivores (10% law). From herbivores the food energy passes to primary carnivores. However, only about 10%

of herbivore energy is passed into body mass of primary carnivores.

The rest is dissipated. From primary carnivores the energy passes into secondary carnivores (10%), etc. It is ultimately lost as heat.

Since energy available decreases at every tophic level, very little of it is available at higher trophic levels. There is dissipation of energy at every s

tep of its transfer and transformation. Hence it cannot flow in the reverse direction i.e., energy flow is unidirectional from sun to plants, plants to

animals, animals to animals, organic remains to decomposers and dissipation as heat.


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