Question: 31 :- Indicate the flow of energy in an ecosystem. Why is it unidirectional? Justify.
Answer: The flow of energy in an ecosystem happens in following sequence:
Producer â†’ Primary Consumer â†’ Secondary Consumer â†’ Tertiary Consumer
The flow of energy is unidirectional in the food chain due to two reasons. A predator always eats its prey but other way round is not possible. Moreover, out of the total energy consumed by an organism at a particular trophic level; 90% is utilised for its own need and just 10% is left for the organism of next trophic level. Thus, the availability of energy gets reduced at subsequent trophic level. Due to this, the flow of energy is unidirectional in a food chain.
Question: 32 :- What are decomposers? What will be the consequence of their absence in an ecosystem?
Answer: Organisms which decompose the dead remains of plants and animals are called decomposers. Bacteria and fungi play the role of decomposers.
Decomposers decompose dead remains of plants and animals. By doing so, they serve two purposes. One; they reduce the burden on the environment by clearing dead remains. Two; they channelize the raw materials back to the environment.
Hence, if there were no decomposers in the environment it would lead to accumulation of dead plants and animals in the environment. Additionally, the environment would be finally sapped of all its resources which are needed to maintain and sustain life.
Question: 33 :- Suggest any four activities in daily life which are eco-friendly.
Answer: Four eco-friendly activities in daily life:
Question: 34 :- Give two differences between food chain and food web.
Question: 35 :- Name the wastes which are generated in your house daily. What measures would you take for their disposal?
Question: 36 :- Suggest suitable mechanism (s) for waste management in fertiliser industries.
Answer: Effluents and harmful gases are the main wastes which are produced in a fertiliser factory.
Treatment of Polluting Gases: For reducing the amount of gaseous pollutants, catalytic converters should be fitted in the chimneys.
Effluent Treatment: Effluent from the factory should be sent to effluent treatment plant. Sedimentation, flocculation, filtration and chlorination are the various steps of effluent treatment. Once effluent is treated, the clean water can then be sent to the nearest water bodies. The sludge can be allowed to decompose which can later be used as manure.
Question: 37 :- Explain some harmful effects of agricultural practices on the environment.
Answer: Some of the harmful effects of agricultural practices on the environment are as follows:
Climate Change: As farming means growing a selected number of species on a large tract of land, it promotes monoculture. Thus farming affects the biodiversity of a region in a negative way.
Deforestation: Clearing of forests for agriculture has resulted in loss of habitat to wildlife. Deforestation has also affected the natural recharge process of groundwater.
Soil degradation: Intensive farming robs off the soil of its nutrients. In the long run, it can lead to soil erosion and finally to desertification.
Water shortage: Overexploitation of groundwater for irrigation has resulted in acute water shortage at many places.
Pollution: Use of synthetic fertilisers and pesticides creates soil pollution, water pollution and air pollution.
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