Thursday, 18 April 2013

Ch7 Sci Class 8

Question 1. Fill in the blanks:
(a) A place where animals are protected in their natural habitat is called wildlife sanctuaries .
(b) Species found only in a particular area is known as Endemic species .
(c) Migratory birds fly to far away places because of  climatic changes.

Question 2. Differentiate between the following:
(a) Wildlife sanctuary and biosphere reserve
(b) Zoo and wildlife sanctuary
(c) Endangered and extinct species
(d) Flora and fauna

Answer :
 (a) Wildlife sanctuary and biosphere reserve :
Wildlife sanctuaryBiosphere reserve
Wildlife sanctuary are are areas where animals are protected from any disturbance to them and their habitat wildlife sanctuaries provide protection and suitable living conditions to wild animals. Here  killing (poaching) or capturing of animals is strictly prohibited.Biosphere reserve are large areas of protected land for conservation of wild life, plant and animal resources and traditional life of the tribals living in the area. Biosphere reserves like a complete ecosystem  take care of biodiversity comprising plants, animals and microorganisms generally found in an area.

(b) Zoo and wildlife sanctuary
ZooWildlife sanctuary
Zoo is man made places where animals
kept in artificial setting instead of their
natural habitat  and provided protection .
Zoo can be in the middle of a urbanised city
Wildlife sanctuary provide protection and suitable living
conditions to wild animals just like in theirs natural habitat

(c) Endangered and extinct species
Endangered SpeciesExtinct species
Animals Species whose numbers are diminishing to a level that they might face extinction are known as the endangered speciesExtinct species are those animal species which became extinct a long time ago due to sudden climatic changes . The dinosaurs are the extinct species, which were very large sized animals and were in plenty but vanished from this earth due to their inability to adjust to changes around.
(d) Flora and fauna
The plants found in a particular area are termed
flora of that area. They are naturally occurring and have a indigenous plant life cycle
The animals found in a particular area are termed fauna of that area

Question 3. Discuss the effects of deforestation on the following:
(a) Wild animals
(b) Environment
(c) Villages (Rural areas)
(d) Cities (Urban areas)
(e) Earth
(f) The next generation

Answer :
(a) Wild animals : Deforestation  deprives wild animals  of their natural habitat as result of which they may migrate to other areas or may face extinction.
(b) Environment : Deforestation is  disturbing the whole set of our eco-system , leading to major enviromental changes like Glabal warming.
(c) Villages (Rural areas) : Deforestation results in less rain fall, which means less water for human and crop irrigation. Domestic cattle will have no fodder. Floods  and soil erosion caused by deforestion will further adversly effect the rural economy and they may resort to migration to cities in great numbers.
(d) Cities (Urban areas) : Deforestation is making water scacity a major problem in cities. In the absence of a eco-system for recycling and over grown  urban areas and industries, cities are already facing air pollution and scarcity of resources obtained from forests. Rural migration caused by the depleted resources there, is adding further burden. In future cities may face water scacity, inadequate supplies of food grains, vegitables and other products like milk
(e) Earth : Deforestation is changing earth temerature due to Global Warming. This may endanger the the complete eco-system comprising of land, living beings, water, air and other resources.
(f) The next generation : Deforestation will offer great challenges to the next generation in the form of scarcity of water due to less rain fall, air pollution,  lesser food, lesser organic raw materials, increased temperature,   natural calamities or disasters floods, droughts and storms due to climatic changes.

Question 4. What will happen if:
(a) we go on cutting trees.
(b) the habitat of an animal is disturbed.
(c) the top layer of soil is exposed.

Answer :
(a) we go on cutting trees : Trees are the most important part of our eco-system directly responsible for recycling of polluted air we breath, rainfall augumenting our water reserves which are used for drinking as well as crop production, supply of organic raw materials in the form of food, wood and medicine, providing food and shelter to animals and birds. Trees also prevent soil erosion and floods. Cutting of trees in a longer run will result in catastrophic consequences for the existence of mankind along with whole spectrum of diversity envolvng living being and plants on this planet earth.

(b) the habitat of an animal is disturbed: Each species of a animal is part of a eco-system  chain with diverse elements in the form of land, air, water, flora and fauna.. Each part  essentially  play its role as a team member to support the co-existence of natural diversty in a wholistic and balanced term. If the habitat of an animal is disturbed, it will resort to migrate to some other place for food and shelter. This will disturb the ecosystem of that particular area resulting in long term consequences.

(c) the top layer of soil is exposed : If  the top layer of soil is exposed , rain water will directly hit the ground and impact of this will cause further loosening of humus rich top soil layer. First, this will result in soil erosion in the form of mud flush and reduced soil fertility, secondly it will deprive ground water reserves from recharging as water will flow down without any seapage or percolation. 

Question 5. Answer in brief:
(a) Why should we conserve biodiversity?
Answer : We should conserve biodiversity, because biodiversity represent whole eco-system comprising land, water, air, fauna and flora. Each component of this biodiversity chain is inter dependent on each other for a sustainability.
(b) Protected forests are also not completely safe for wild animals. Why?
Answer : Even protected forests are not safe for wild animals because people living in the neighbourhood encroach upon them and destroy them.
(c) Some tribals depend on the jungle. How?
 Answer : Some tribals depend on the jungle as  they live  in the deep forest like primitive people had lived in anciant time.They are still away from the basic amenities of modern life   Forest provide them food items like seed grains, fruit, raw vegetables and other products like honey, meat of hunted wild animals for themselves, fodder for theirs animals, wood fuel for heating and cooking even clothing using natural fibres, leaves and animal skins.
(d) What are the causes and consequences of deforestation?
Answer : The main causes of deforestation are exploitation of forest resources by the human being   to meet the ever growing requirements of an increasing population, rapid urbanization, industrialization. The consequences of deforestation will result in putting in danger, the whole existence  of human being along with biodiversity on the planet earth.
(e) What is Red Data Book?
Answer : Red Data Book is the source book which keeps a record of all the endangered animals and plants
(f) What do you understand by the term migration?
Answer : Migration is the phenomenon of movement of a species from its own habitat to some other habitat for a particular time period every year for a specific purpose like breeding.

Question 6. In order to meet the ever-increasing demand in factories and for shelter, trees are being continually cut. Is it justified to cut trees for such projects?
Discuss and prepare a brief report.
Answer : It is not justified to cut the trees at present rate for such project. Trees as a part of  forest are the most important part of our eco-system.Word wide, reduced forest cover have already started showing its devastating effects in terms of climatic changes. We must reduce our dependency on our forest resources to meet the ever-increasing demand in factories and for shelter. We should look for some other alternatives for the same. We have to start reforestation at much larger scale taking it as a top priority.

Question 7. How can you contribute to the maintenance of green wealth of your locality?
Make a list of actions to be taken by you.

Answer :
  • We can plant trees in open spaces, park, along the side of road and motivate others.
  • We can make use of roof water or water from kitchen for water harvesting to recharge the ground water table.
  • We can recycle our organic waste from kitchen for making  compost and use it in our kitchen garden or plants.
  • We can reduce use of paper .We can save it, reuse used paper and recycle it.

Question 8. Explain how deforestation leads to reduced rainfall.
Answer : Deforestation increases the temperature and pollution level on the earth. It increases the level of carbon dioxide in the atmosphere. Ground water level also gets lowered. Deforestation disturbs the whole eco-system. As we know, plants need carbon dioxide for photosynthesis. Fewer trees would mean that less carbon dioxide will be used up resulting in its increased amount in the atmosphere. This will lead to global warming as carbon dioxide traps the heat rays reflected by the earth. The increase in temperature on the earth disturbs the water cycle and may reduce rainfall.

Question 9. Find out the information about the national parks in your state. Identify and show their location on the outline map of India.
 Answer : Our state Punjab has just one national park.
Harike Wetland also known as "Hari-ke-Pattan", with the Harike Lake in the deeper part of it, is the largest wetland in northern India in the Ferozepur district of the Punjab state in India. The wetland and the lake were formed by constructing the head works across the Sutlej river, in 1953. The headworks is located downstream of the confluence of theBeas and Sutlej rivers. The rich biodiversity of the wetland which plays a vital role in maintaining the precious hydrological balance in the catchment with its vast concentration of migratory fauna of waterfowls including a number of globally threatened species (stated to be next only to the Keoladeo National Park near Bharatpur) has been responsible for the recognition accorded to this wetland in 1990, by the Ramsar Convention, as one of the Ramasar sites in India, for conservation, development and preservation of the ecosystem
(Source :
Question 10. Why should paper be saved? Prepare a list of ways by which you can save paper.
Answer : It takes 17 full grown trees to make one tonne of paper. Therefore, we should save paper. Paper can be recycled five to seven times for use. If each student saves at least one sheet of paper in a day, we can save many trees in a year. We should save, reuse used paper and recycle it. By this we not only save trees but also save energy and water needed for manufacturing paper. Moreover, the amount of harmful chemicals used in paper making will also be reduced.
We can also save paper by using Information technology for storage of printed data, books in  digital form.

Question 11. Complete the word puzzle:
1. Species on the verge of extinction.
2. A book carrying information about endangered species.
5. Consequence of deforestation.
1. Species which have vanished.
3. Species found only in a particular habitat.
4. Variety of plants, animals and microorganisms found in an area.

Answer :  

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