CBSE Class 10 Science 2022 · Paper 31/3/3 · Question 10

(a) Decomposers are micro-organisms, such as bacteria and fungi, that break down the dead remains and waste products of plants and animals. They break the complex organic substances in them down into simple inorganic substances, which go into the soil and are absorbed again by plants. In this way the nutrients taken up from the soil are returned to it, and the soil is replenished naturally. (b) Decomposers break substances down with enzymes, and enzymes are specific in their action: a particular enzyme is needed to break down a particular substance. Decomposers have no enzymes that can act on plastics, which are human-made materials, so they cannot decompose plastic waste. Plastic is non-biodegradable and persists in the environment for a long time.