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

1. What breaks them down: Biodegradable substances are broken down by biological processes, that is, by the action of decomposers such as bacteria and fungi. Non-biodegradable substances are not broken down by biological processes. 2. How long they last: Biodegradable substances are broken down into simpler substances and do not persist in the environment. Non-biodegradable substances persist in the environment for a long time. 3. Effect on the ecosystem: The materials of biodegradable substances return to the soil and are reused in natural cycles. Non-biodegradable substances may remain as inert waste or may harm members of the ecosystem; some, such as DDT, build up in food chains. Examples: biodegradable - vegetable peels (or paper, cotton cloth); non-biodegradable - polythene bags and other plastics (or glass, DDT).