Class 7 Biology Forests: Our Lifeline Food chain

Food chain

  • A food chain is a series of organisms where all the organisms are dependent on next organism as a source of food.
  • All the components of forests are interrelated to one another.
  • Autotrophs, heterotrophs and saprotrophs in the forest are connected to each other.
  • Autotrophs prepare food by photosynthesis, heterotrophs depend on plants for food and saprophytes feed on heterotrophs and so the process goes on.

For example-  i) Grass àinsects àfrog à snakeà eagle

Grass is eaten by insects and frogs eat the insects which in turn is eaten by the snakes and eagles eat the snakes.


Fig. Food chain

  1. ii) sun à plant àdear à lion


Fig. Food chain 

iii) maizeà locust à lizard à snake


fig. a food chain

  • Many types of food chains can be found in the forest.
  • Food web is a network of food chains where all the chains are naturally interconnected.
  • In a food web nutrients and energy are passed on from one species of living organisms to another.
  • Sun is the ultimate source of energy and energy is absorbed by plants and then transferred through all other organism in a particular area, this transfer of energy is called a food web.
  • If any one component of the forest is removed, it affects all the food chains and ultimately the whole forest.

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