CBSE Class 10 Science 2022 · Paper 31(B)/5 · Question 7(a)

Decomposers are micro-organisms, mainly bacteria and fungi, that break down the dead remains and waste products of plants and animals, converting the complex organic substances in them into simple inorganic substances. Two important roles in an ecosystem: 1. They break down the dead bodies and wastes of organisms, and so clean the environment; without them, dead remains and wastes would pile up. 2. They return nutrients to the soil: the simple inorganic substances they release go into the soil and are used up once more by plants, so nutrients are recycled and the soil is replenished.