Question

Why are some substances biodegradable and some non-biodegradable?

Answer 1

Hint: Breakdown of substances naturally with the help of microorganisms is known as the Biodegradation. The degrading microorganisms may be fungi, bacteria or other biological organisms.

Complete answer:
Biodegradable substances are those which can be easily broken down through various biological activities. Decomposers like fungi and bacteria have specific enzymes for carrying out such degradation activities in the environment. On the other hand, non-biodegradable substances are those which cannot be broken down through a natural degradation process carried out via bacteria and fungi. These substances, therefore, exist in an environment for a longer duration of time. Physical processes involving pressure and high temperature are employed for such substances.
Classification of substances into biodegradable and non-biodegradable substances is based on their ability to get decomposed by microorganisms. Biodegradable substances are often broken down into simpler substances that are soluble while non-biodegradable substances cannot be broken down into harmless components via help of the microbes because they do not have enzymes required for degrading such substances. Moreover, biodegradable substances are organic in nature. Hence, decomposers (microorganisms) can utilize such substances present in the environment for their growth. But non-biodegradable are synthetic in origin so decomposers cannot degrade them and they may remain in the environment for an unknown period of time. The degradation time varies for different substances. Plastic gets decomposed in millions of years.

Note: Waste materials including waste from garden, dead animal and plant material, fruit and vegetable peels, egg shells, etc. are the biodegradable substances. However, tyres, paints, aluminum cans, plastics, metals, polystyrene, etc. are non-biodegradable substances.