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STD . 5th Sub:Science, 1 . The Environment and us, Summative Evaluation, Question and Answer, Q. 1. Fill in the blanks :, (1) The population of the world is now close to six hundred crore., (2) Marshy or low-lying areas are filled to reclaim the land., (3) due to pollution, number of living things reduce and some become extinct, (4) In Industries and factories, fuel is used in great quantities., (5) Tremendous quantities of carbon dioxide enter the air due to burning of fuels., (6) Due to human intervention in nature, large scale changes are taking place in the air, water and land., (7) We should make all possible efforts for conservation of the living world., (8) Forest areas reserved for the protection and conservation of a particular animal or plant is called a sanctuary., (9) Flamingos from Siberia region in Northern Asia migrate to Mayani., (10) Devrais or Sharanavanas can be called the sanctuaries of ancient times., Q. 2. State whether the following statements are True or False :, (1) Dead plants and animals are abiotic components. True, (2) is necessary to conserve biodiversity. True, (3) Man is not using up more and more land and water resources. False, (4) Soil becomes fertile, if polluted water seeps into it. False, (5) The temperature of the earth rises when the proportion of carbon dioxide rises. True, (6) The process of living things becoming extinct is at a very slow rate. False, (7) People visiting biodiversity park enjoy being close to nature. True, (8) Deer are found in the grasslands of Nannaj. True, 3. Match the columns :, 9. Classify the following as natural or man-made :, (Soll, horse, stone, water hyacinth, book, sunlight, dolphin, pen, chair, water, cotton wool, table, trees, brick.), (1) Natural: Soil, horse, stone, water hyacinth. sunlight, dolphin, water. Cotton wool, trees,, (2) Man-made: Book, pen, chair, table, brick., Q. 5. Answer the following questions:, (1) What is meant by migration?, Ans. When animals move temporarily or permanently from one place to another for feeding or breeding it is called migration., (2) Describe the life cycle of birds., Ans. Birds prefer to stay in natural environment of thick vegetation. Birds dwelling in cities also build their nests on the trees. Both the parents build the nest for laying eggs. The female bird lays the eggs in the nest. She incubates the eggs for some time till the young ones hatch out of the eggs. The hatchlings are cared for by both the parents. They are fed by mother as well as father. When the young ones develop wings and are able to fly, they leave the nest and go away from the parents., (3) Give two causes of air pollution., Ans. (1) Industries and factories burn fuel and this causes smoke and pollutant gases (2) Vehicles during transport emit poisonous gases and particles. The slow burning of fuels produce lots of carbon dioxide., (4) For what purpose do we use the land obtained by clearing forests ?, Ans. After clearing the forest, the land which is obtained is used for either building roads, bridges, housing colonies. Even farms were made after clearing the forests in the past. Since the world human population is rising, therefore, more and more land is required for all such activities., (5) What should all of us resolve about environment?, Ans. We should resolve that no action should be done that will cause pollution or cause harm to living things. All the possible efforts should be done to conserve nature and the living world., • Use your brain power!, (8) What would happen if no kites (birds) are left in a particular region? Which living things would increase in number ? Which would decrease ?, Ans. Kite is the bird of prey. They kill the smaller rodents and birds. They also ex dead and decaying matter. If kites are not present in nature, then these smaller roden like animals will increase in their numbers. Kite is a top predator and hence it is not the food for others. Thus even if kite's number falls, there will be little difference in any other animals population., What's the solution ?, (9) Rivers and lakes are filled with water hyacinth., Ans. If organic substances mix with water, there is growth of water plants like water hyacinth. But when they grow excessively. It causes problems for other aquatic organisms., During daytime, water hyacinth release oxygen but at night time they too require oxygen. This causes depletion of dissolved oxygen in water and hence many other organisms die due to lack of oxygen. Their dead remains act as fertilizers and they help the hyacinth to grow more. Such water body gets filled with water hyacinth. In order to save the environment of such water body, first of all the water hyacinth should be removed. This is also called eutrophication. Care should be taken that no organic pollutants enter this water body. Bund may be constructed around a lake or a river so that the land pollutants will not be let out in them. This will arrest the growth of water hyacinth., Q. 6. Give reasons, (1) It is important to conserve the living components of the environment., Ans. If the living components of the environment do not exist, then the food chall and food web will not function. Some species will get extinct. Living things were produced on earth many million years back. It is not possible to get them back by man-made processes. If the balance in nature is disturbed it will affect human beings too. Therefore, is important to conserve the living components of the environment., (2) The numbers of wild animals are falling day by day., Ans. Due to human interventions, many food chains and food webs are disturbed. forests are cleared for making land available. Due to loss of forest, wild animals are displaced. Due to climate change and global warming, natural cycles are also disturbed causing survival of wild animals difficult. Hunting and poaching of wild animals have also reduced their numbers significantly. All these factors have led to fall in the number of wild animals., (3) Many aquatic animals are becoming extinct., Ans. Soil and water is polluted to a great extent due to human intervention. The chemical fertilizers and insecticides used in farming practices also find their way into water. Waste water from industries, factories and households also find their way into water. All these may have poisonous and harmful substances in them. Therefore, many aquatic animals living in such water are becoming extinct., • Use your brain power!, (1) If a dam is built at a particular place, what changes will be seen in the environment?, Ans. When a large dam is constructed, we get ample water. In some parts there will be growth of vegetation. But the natural environment which was there previously will be completely lost. The plant cover, trees, etc. which were there will be totally lost. Some animals would be completely displaced. Some will be extinct. Human beings residents of those areas will be displaced and they will have to migrate to some other place. The local environment will be changed for ever.