Ans.
Dams are large water storing bodies
that are usually built by government agencies across the rivers to regulate the
flow of water and generate electricity. They store huge amount of water for
irrigation of fields throughout the year.
2. On
the banks of the river, there are several factories that are discharging
effluents into the river. The pH of water sample collected from the river is
found to be acidic in the range of 3.5–4.5. Name the effluents which is the
most likely to cause the lowering of pH of river water. What should be the
effect of pollution on the fishes of the river.
Ans.
Untreated sewage, garbage, some human
activities like bathing, washing of clothes and immersion of ashes or unburnt
corpses are the most likely causes of lowering of pH of river water. It makes
the water toxic and kills the aquatic organisms.
3. Despite good rains, we are not able
to meet the demand of water for all the people in our country. Explain, why?
Ans.
Despite good rains, we are not able to
meet the demand of water for all the people in our country.
The
main reasons are —
(i)
Rapidly increasing population.
(ii)
Lack of sufficient vegetation covered area.
(iii)
Cemented areas surrounding the houses do not enable the rain water to seep into
the ground.
(iv)
High yielding varieties need more water for irrigation.
(v)
Discharge of sewage and other wastes into the water bodies makes water unfit
for use.
(vi)
Consumption of water per person per day is continuously increasing in urban
areas.
4. Suggest two measures which could be
incorporated in daily life to become more environments friendly.
Ans.
We can become more environment-friendly by following the given changes in our
daily life :
(i)
Reusing articles : Some non-biodegradable wastes like carry bags, packing
paper, plastic containers, metallic cans, glass bottles, etc. can be reused.
(ii)
Recycling : We can separate the recyclable items from our daily wastes to which
we can give to the rag pickers to recycle. Paper, plastic, glass, cotton cloth,
metal, etc. are recyclable things.
(iii)
Reducing the consumption: We can reduce the consumption of :
a.
petroleum fuels by walking down to nearby places.
b.
electricity by switch off the unnecessary lights, fans and electrical
appliances.
c.
water by repair of leaky taps and reducing wastage.
5. What is Chipko movement? How did
this movement ultimately benefit the local population and the environment?
Ans.
The Chipko movement was a movement of
the local people to resist the deforestation attempt on the hill slopes. It was
started in early 1970s in village Reni in Garhwal. The women of Reni literally
clasped the trees, thus preventing the workers of the contractor to cut the
trees.
Benefits
of Chipko movement to the local population
(i)
The Chipko movement helped in the conservation of forests.
(ii)
The 'Chipko andolan' forced the government to whom the forest belongs, to
re-think their priorities in the use of forest produce.
(iii)
It helps to conserve forests, maintain ecological balance and prevent floods
and soil erosion.
(iv)
It also helps in the availability of forest materials for the future
generations.
6. Write any two ways of energy flow
through an ecosystem.
Ans: i) Unidirectional in a food chain.
ii) Multidirectional in food web.
7. Differentiate between biodegradable
and non biodegradable with respect to the effect of biological processes on
them and the way they affect our environment.
Ans:
Substances that can be broken down by biological processes are biodegradable.
Substances that are not broken down by biological processes are
non-biodegradable.
a)
Biodegradable wastes are decomposed by the micro-organisms. By this process,
mineral elements like C, N, O, P etc. are cycled back into the biosphere.
b) Biodegradable substances such as human wastes can pollute sources of water
and cause diseases like Cholera, Diarrhoea and Dysentery. Heaps of
biodegradable wastes become breeding sites of houseflies, mosquitoes and rats
which are causes of many diseases.
Non-biodegradable may enter the food chain and harm the organisms in the higher
trophic levels. e.g. Pesticides like DDT
Non-biodegradable substances like radioactive wastes, lead, mercury etc. affect
the health of all living organisms.
8. Why is a pond self sustaining unit
while an aquarium may not be?
Ans:
It is because pond is a natural ecosystem while an aquarium is created by man
and is artificial
9.
Why do you think there should be equitable distribution of resources? What
forces would be working against an equitable distribution of our resources?
Ans. The natural resources are living as well as
non-living components which provide food, fodder, shelter, water, energy,
articles of daily use and comforts. All human beings have the fundamental right
to use these resources. Equitable distribution of resources make this possible.
Forces
against equitable distribution :
(i) Excessive consumption by rich people.
(ii) Restricted availability of resources.
(iii) Profit-making by exploiting resources.
10.
What would be the advantages of exploiting resources with short-term aims?
Ans. It will provide short term advantages and the
comforts available in plenty. There will be rapid industrialization and
development.
10th Science – Chapter: Our
Environment (Physics)
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10th Science:
Chapter: Our Environment HOTS
Questions
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10th Chapter: Our Environment: Gist of Lesson
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