Sunday, December 16, 2012

CBSE _NCERT_ 10th Our Environments: Formative Assessments Questions with solution

1. In our country, there are attempts to increase the height of several existing dams like Tehri and Almati, dams across Narmada. What are the reasons behind it?

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 - Our Environment: Summative assignments
10th Chapter: Our Environment Questions Paper for FA-III
10th Science: Chapter: Our Environment HOTS Questions
10th Chapter: Our Environment: Gist of Lesson
10th Our Environment CBSE SOLVED GUESS PAPER 
10th Our Environment CBSE SOLVED GUESS PAPER
Our Environment Notes class X

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