Ans. Specific enzymes are needed for degradation of substances. A single enzyme cannot degrade many substances. Different types of microorganisms like bacteria and fungi secrete different types of enzymes. But degradation of different substances requires different types of enzymes. There are some substances that cannot be degraded by microorganisms. This is the reason why some substances are biodegradable and other substances are non-biodegradable.
- Suggest any two ways in which biodegradable substances would affect the environment.
Ans.(i) Biodegradable substances release bad smell and harmful gases while their decomposition. This condition affects the community health adversely.
(ii) Biodegradable substances promote reproduction and development of germs of various diseases that are very dangerous to the community health.
- Mention any two ways through which non-biodegradable substances would affect the environment.
Ans. (i) Non- biodegradable substances create problem of disposal due to their non- biodegradable nature and spoil the landscape.
(ii) These substances usually emit very dangerous gaseous pollutants that are very harmful to health.
- What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
Ans. Steps of food-chain are called as trophic levels. The living organisms associated with these different steps have different modes of nutrition.
In the above food-chain producer and consumers of different order are different trophic levels. After the death of top consumer decomposers decompose its dead body and get their nutrition. Thus saprophytic microorganisms too make an important trophic level.
- What is the role of decomposers in the ecosystem?
Ans. Decomposers play important role in the cycling of materials in the ecosystem. If there were no decomposers the whole land scape would appear like a big heap of wastes. All the bio-geo-chemical cycles would get interrupted and the natural balance of nature would be misbalanced forever.
- What is ozone and how does it affect any ecosystem?
Ans. Ozone is an isotope of oxygen. Its single molecule has three atoms. The molecule of oxygen gets broken into its atoms due to ultraviolet radiation and each atom combines with molecules of oxygen to form ozone.
Ozone can absorb the harmful ultraviolet radiation that comes to earth from the sun. Ultra violet radiation can cause many harmful effects if it reaches to earth. Skin cancer, cataract, death of microorganisms, and harms to plants are some of its bad impacts.
- How can you help in reducing the problem of waste disposal? Give any two methods.
Ans. We can take up many different measures for the disposal of waste. Recycling of useful substances, composting of degradable substances, selling metal pieces to kabariwala etc. are some of the methods of solid waste disposal. (Describe any two methods from the book)