CBSE Class 10 Science 2020 · Paper 31/2/3 · Question 18(b)

Decomposers are micro-organisms, mainly bacteria and fungi, that break down the complex organic substances of the dead remains and waste products of organisms into simple inorganic substances, which go into the soil and are used again by plants. Two consequences of their absence in the ecosystem: (i) Nutrients would not be recycled: the minerals locked in dead bodies and wastes would not return to the soil, so the soil would not be replenished and plants would lack nutrients. (ii) The natural cleaning of the environment would stop: dead plants, dead animals and wastes would not be broken down and would pile up.