CBSE Class 10 Science 2023 · Paper 31/5/2 · Question 21
State two reasons why human-made materials like plastics persist for a long time in the environment.
Answer
Decomposers have no enzyme for plastics, and the ordinary temperature and pressure of the environment are too mild to break them down.
(i) Enzymes are specific in their action: a particular enzyme is needed to break down a particular substance. The common decomposers (bacteria and other saprophytes) have no enzymes that can act on plastics, so plastics are not broken down by biological processes; they are non-biodegradable.
(ii) Plastics can be acted upon by physical processes such as strong heat and high pressure, but the ambient conditions of our environment (the ordinary temperature and pressure of soil, water and air) are too mild to break them down.
So plastics are not removed from the environment and persist in it for a very long time.
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