ICSE Class 9 Answered

The sequential process of eating and being eaten is called a food chain.

All food chains begin with green plants or the producers. So, the plants or the producers constitute the first trophic level. E.g. Grass

The herbivores or primary consumers that feed on plants constitute the second trophic level. E.g. Grasshopper

The herbivores are next fed upon by the carnivores or secondary consumers. They constitute the third trophic level. E.g. Snake

Finally, the large carnivores, also called the top carnivores or tertiary consumers form the fourth trophic level. E.g. Hawk

The large carnivores die and form the feed of the decomposers.The decomposers feed on these dead animals and plants. E.g. Fungi

There is transfer of food from one organism to the other forming a chain.