Science Mission by Jsunil Sir To better understand this chapter, follow these steps:
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Theoretical Questions
A. Short answer type questions. 1. Is it justified to cut trees for the construction of shelters and factories? Ans: No it is not justified to cut trees for shelters and factories as trees are natural habitat of wildlife. 2. What is Red Data Book? Ans: Red Data Book take record of endangered and threatened species of plants and animals and publish them. This book is designed specifically to recognize and preserve certain species that are on the brink of extinction. 3. In what way tribals depend upon the forests? Ans: Tribals living around forests depend on forest for wood for fuel, fruits for food etc. 4. Why do some birds migrate from one place to another? Ans: some birds migrate from one place to another to overcome the harsh and cold period of their habitat to a warmer place and to lay eggs 5. Saving paper is good for conservation of forests. Comment. Ans: Paper is made from the pulp from wood and wood comes from trees (mostly forest trees).Thus, Saving paper is good for conservation of forests 6. Name two 'Bird Sanctuaries' in India and their importance? Ans: Keoladeo National park, formerly known as Bharatpur Bird Sanctuary (For birds, especially migratory birds). Sultanpur Lake Bird Sanctuary, Haryana. To protect these birds and their species, bird sanctuaries are built 7. Why each one of us must plant at least one tree in our lifetime? Ans: Each one of us must plant at least one tree in our lifetime as it helps in conservation of forests. 8. List some of the natural disasters which are a danger to biodiversity. Ans: Some of the natural disasters which are a danger to biodiversity are forest fires, droughts, climate changes, earthquakes, storms and cyclones. 9. Why do we consider tiger an endangered species? Ans: Most tigers are being wiped out by poachers (hunters) killing them for their hide, bones, nails and teeth, which are being sold within India and also exported to outside world. B. Long answer type questions. 1. Differentiate between: a. 'Flora' and 'fauna'. Ans: The specific plants growing naturally in a particular area form the flora of that area. Similarly, the animals which by nature inhabit a particular area form the fauna of that area. b. Endangered species and extinct species. Endangered species of plants and animals are those which are exposed to danger of extinction. This is because their natural growth and multiplication has slowed down. Examples are tiger, lion, snow leopard, white bear etc Extinct species of plants and animals are those which existed upon the earth at one time and now they no longer exist anywhere. They have been lost forever. For examples : dinosaur, dodo c. Zoological Park (Zoo) and wildlife sanctuary. Ans: Zoological Park (zoo) is an artificial home for wild animals whereas wildlife sanctuary is a protected natural habitat for wild life. d. Wildlife sanctuary and biosphere reserve. Wildlife sanctuary is to provide protection and suitable living conditions to wild animals in their natural habitat. In a wild life sanctuary human activity is highly restricted and poaching is strictly prohibited. A biosphere reserve is an ecosystem with mostly wild plants and wild animals of natural and scientific interest. This includes the 'sustainable use of natural resources'. e. Deforestation and Reforestation Deforestation is the clearing or destruction of the forests by human activities and natural cause. Reforestation or afforestation is the re-growing of forests found in native place that have previously been cut down . 2. What is the importance of biodiversity? Ans: Biodiversity help us to sustain ecosystem. Biodiversity helps scientists understand how life functions and the role of each species in sustaining ecosystems 3. Describe the basic design of a biosphere Reserve. Ans: Biosphere reserves are the areas meant for conservation of biodiversity. It is divided into different zones with specified activities in each zone. Protected Zone: Human activity in this zone is totally prohibited. Buffer Zone: The protected zone to develop into a dense forest. Tourists are encouraged to visit this zone to educate them about the importance to save the environment Nursery Zone: this zone protected to prepare saplings for forest trees.. This is actually a zone where activities for the development and betterment of forest and wildlife are being undertaken. 4. What is the importance of forest for the preservation of wildlife? Ans: Forest keeps the natural cycle of water, oxygen and nutrients going on. Forest influences the climate and is a home for different life forms . Forest, not only preserves wildlife but also conserve the environment. 5. What are the possible reasons of destruction of forests? Ans: The possible reasons of destruction of forests are: (i) Forest fire (ii) Climate and weather changes (iii) Storms and cyclones (iv) Earthquake and land slides and flood 6. In what way deforestation harms biodiversity? Ans: Deforestation destroy natural home of wildlife. Without shelter and food wild animals die and get killed by the hunters . Some of the species of plants and animals become extinct . This is a great loss to biodiversity. 7. Explain "excessive exploitation of natural resources lead to degeneration of biodiversity". Ans: Excessive exploitation of natural resources reduce shelter and food for wild life forms. The natural growth and multiplication might slow down .The species of plants and animals become extinct. Thus, excessive exploitation of natural resources lead to degeneration of biodiversity. 8. What are the major causes of extinction of species? Ans: Extinction of species may be due to various reasons such as excessive cutting of forest trees, climatic changes, shortage of food and loss of habitats. 9. Which gas in the atmosphere is responsible for global warming and how? Ans: An increase in amount CO2 gas in the atmosphere is responsible for global warming. carbon dioxide gas trap s the heat rays being reflected by the earth . This increasing the average temperature of earth’s atmosphere. This leads to global warming 10. How ecosystem is the self-supporting system for an organism? Ans: Ecosystem includes all living and non-living objects in an area where they interact and help each other for survival. One organisms is the food for another. Food chain is a link-system of organisms starting from green plants, and each organism in the chain is important for the next link to maintain the continuity of life 11. In what way we can save the earth from global warming? Ans: we can save the earth from global warming by Saving forests, planting more trees and using cleaner fuel in vehicles. 12. What purpose is served by Biosphere Reserve?? Ans: Biosphere reserve helps conservation of forest and wild life; it also provide certain daily needs of the tribal people living around; and it is a good source of environmental education. 13. Why are 'biosphere reserves' or the 'reserve forests' the better way to conserve wildlife? Ans: Biosphere reserves and the reserve forests are protected from invasion by visitors, poachers and destroyers of trees and vegetation. This conserves the wild life. 14. Write a note on 'project tiger'. Ans: Most tigers are being wiped out by hunters as they kill them for their skin, bones, nails and teeth etc. The population of tiger reduces also due to clearing forest. Therefore, government of India launched project tiger program to save Tiger population. India is now a home to nearly 3000 tigers as against 2000 four years ago 15. What do you understand by 'migration' in respect to birds? Ans: Migration is to move from one place to another. Birds and animals migrate from one place to find favourable condition and food .Birds move to avoid harsh and extremely cold conditions on polar regions during winter to warmer places in plains and return to their original habitat after the winter is over. For example like Arctic tern and Siberian crane. 16. How recycling of paper and reforestation serve the same purpose in respect to wildlife. Ans: A major cause of deforestation is the cutting down of trees to obtain wood pulp for making paper. We can recycle the paper a number of times and use it again and again instead of cutting trees and destroying forest. Recycling paper not only saves trees but also save water and energy. Save paper to save forests and save wildlife. More additional study material Ch_11 Force and Pressure Answer (Science Mission class 08)
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1. What is ore? [1]
Ans: An ore is a naturally occurring mineral from which one or more metals can be profitably extracted. 2. What is metallurgy? [1] Ans: Metallurgy is the science of extracting metals from their ores and purifying them. 3. Differentiate between metal and non–metals on the basis of any one physical property. [1] Ans: Metals are ductile. It is the property that allows the metals to be drawn into wires. Non metals are not ductile. 4. Give the reaction of magnesium with water. [1] Ans: Mg + 2H2O -----------> Mg(OH)2 + H2 5. What is alloy? [1] Ans: An alloy is a homogeneous mixture of a metal with another metal(s) or non–metal(s). 6. Define: (i) Concentration of ore (ii) Reduction [2] Ans: (i) Concentration of ore: It is the preliminary treatment of an ore in which impurities are removed. (ii) Reduction: The metal compound is reduced to get free metal 7. What is metallic luster? Why metals are useful for jewellery and decoration. [2] Ans: Metals have shiny appearance. This property is known as metallic luster.The shiny appearance makes the metals useful for jewellery and decoration 8. Explain conductivity in case of metals and non metals. [2] Ans: Metals are good conductor of heat and electricity. Gold is the best conductor followed by silver, copper and aluminum. Non–metals are generally bad conductors of heat and electricity. 9. Discuss the reaction of metals and non–metals with oxygen. [3] Ans: In general, metals form oxides on combining with oxygen. The water solutions of these oxide are alkaline or basic in nature and changes red litmus into blue. 2Mg + O2 ---------> 2MgO MgO + H2O-----> Mg (OH)2 Non metals too combine with oxygen to form oxides. However, such oxides are acidic in nature 10. Discuss the reaction of metals with water. [3] Ans: Sodium reacts violently with water. Magnesium reacts mildly with cold water but vigorously with hot water or steam. Mg + 2H2O -----------> Mg(OH)2 + H2 Zinc and iron react very mildly with steam, whereas copper, silver and nickel do not react with water.Non–metals also do not react with water. 11. What happens when iron nails are put in copper sulphate solution? [3] Ans: When iron nails are put in copper sulphate solution, the blue colour of the solution starts fading gradually. At the same time, iron nails get a shiny coating of red brown copper metal on their surface.This change takes place as iron displaces copper from copper sulphate. 12. What is electroplating? [5] Ans: Electroplating: Iron and steel are protected from corrosion by coating them with a layer of tin or chromium metals which are resistant to corrosion. This can be done by electroplating. A thin layer of tin deposited on the inner surface of iron containers makes them safe, for storing food. Chromium plating protects steel furniture, taps and bicycle handles from corrosion. Coating of chromium not only giveslonger life to the coated objects but also gives a good shining appearance to them. 13. Discuss some common uses of metals and non–metals? [5] Ans: Metals are strong, hard and rigid. So they are used in making machinery. The automobiles, the aeroplanes, the trains, satellites, industrial gadgets all use metals in large amounts. Iron is the most commonly used metal.
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