CBSE Class 10 Science 2017 · Paper 31/1/C · Question 6

Decomposers are micro-organisms, mainly bacteria and fungi, that break down the complex organic substances present in the dead remains and waste products of plants and animals into simple inorganic substances. Role in the environment: 1. They break down dead remains and wastes, so these do not pile up; they act as the cleaners of the environment. 2. The simple inorganic substances they release go into the soil and are taken up again by plants, so nutrients are returned to the soil and recycled, which keeps the soil fertile.