Indicate the flow of energy in an ecosystem. Why is it unidirectional? Justify.
The general flow of energy in an ecosystem is:
Sun → Producer → Herbivore → Carnivore
Energy flows progressively from one trophic level to another and does not revert back. Hence, it is said to be unidirectional.
Available energy decreases at higher trophic levels, making it impossible for energy to flow in the reverse direction.
What are decomposers? What will be the consequence of their absence in an ecosystem?
Decomposers break down complex organic substances of garbage, dead animals and plants into simpler inorganic substances. These substances go into the soil and are reused by plants.
In the absence of decomposers, recycling of material in the biosphere will not take place.
Suggest any four activities in daily life which are eco-friendly.
(i) Separation of biodegradable and non-biodegradable substances
(ii) Gardening
(iii) Use of gunny bags/paper bags instead of polythene/plastic bags
(iv) Use of compost and vermicompost in place of fertilisers
(v) Harvesting rainwater
Give two differences between food chain and food web.
| Food Chain | Food Web |
|---|---|
| (a) Food chain is a series of organisms feeding on one another. | (a) Food web consists of a number of interlinked food chains. |
| (b) Members of higher trophic level feed upon a single type of organism of the lower trophic level. | (b) Members of higher trophic level can feed upon organisms of the lower trophic levels of other food chains. |
Name the wastes which are generated in your house daily. What measures would you take for their disposal?
Household wastes include:
(a) Kitchen wastes
(b) Paper wastes like newspapers, bags, envelopes
(c) Plastic bags
(d) Vegetable/fruit peels/rinds
Measures for disposal:
(a) Segregation of biodegradable and non-biodegradable wastes
(b) Safe disposal of plastic bags
(c) Vegetable/fruit peels can be placed near trees/plants; on decomposition they enrich the soil with nutrients
(d) Give paper wastes for recycling
(e) Prepare a compost pit for kitchen wastes
Suggest suitable mechanism(s) for waste management in fertiliser industries.
(a) Control of air pollution
(b) The effluent should be treated before discharge into the surrounding environment
What are the by-products of fertiliser industries? How do they affect the environment?
The harmful by-products are gases such as SO2 and NO. They cause extensive air pollution and are responsible for acid rain.
Explain some harmful effects of agricultural practices on the environment.
(a) Excessive use of fertilisers changes the chemistry of soil and kills useful microbes.
(b) Excessive use of non-biodegradable chemical pesticides leads to biological magnification.
(c) Extensive cropping causes loss of soil fertility.
(d) Excess use of groundwater for agriculture lowers the water table.
(e) Damage to natural ecosystem/habitat.