NCERT 7th Class (CBSE) Social Science: Our Environment

Question: Explain the following terms- Environment, Lithosphere, Biosphere, Ecosystem, Pollution and Urbanization. Answer: Definitions are as follows: Environment - It refers to all external conditions in which an organism lives. It comes from the french word 'environ' which means to surround. It is used to describe everything, such as places, things, People, nature etc. It also includes thing created by human beings. Lithosphere - The rocky outermost layer of the earth is called the lithosphere. The term lithosphere means. Rocky crust it includes the crust and upper part of the mantle. The average thickness of the lithosphere is about 100 km. It is made up of rocks and minerals. The uppermost part of the lithosphere forms a thin layer of soil. Biosphere - The narrow zone where the lithosphere. Hydrosphere,and atmosphere meet and interact is called the biosphere. The word biosphere comes from the Greek word 'BIOS' meaning life and Latin word 'sphere' which means the total rang. The is sphere supports life and is this called the 'living world'. The biosphere consists of the plant and animal kingdom. Ecosystem - The complex system of interactions between the organisms and their physical environment in a particular area is referred to as an ecosystem the size of the ecosystem varies greatly. It can be as large as rain forests, grasslands, desserts, lakes, rivers or as small as a pond. Pollution - The disturbances caused to the environment due to excessive exploitation of nature, unplanned and use of technology, overpopulation, and Industrialization is called pollution. Urbanization - Number of People living in urban areas as compares to the total population of the country. Question: Why did the Chipko movement take place? Answer: In 1973 the villagers in the Alaknada river valley of Uttarakhand protested against the indiscriminate cutting down of trees. They did so by hugging the trees in order to save them from being cut down. This movement became famous as the Chipko movement. Question: What are the reasons for environmental be managed properly? Answer: The reasons for environmental pollution are unplanned and unwise use of technology. Question: How can natural environment be managed properly? Answer: A perfect balance is needed between the natural and human environment. A number of organization with the help of scientists, technologists and planners are working to solve the environmental problems facing the world. Question: Explain the relationship between geography and environment? Answer: Environment refers to the external conditions in which an organism lives. Geography studies the interrelationship between human beings and their environment. The relationship between geography and environment is very close. Question: How have human needs undergone changes with the passage of time and technological development? Answer: Early humans adjusted themselves with the surrounding in which they lived. Most of their needs were fulfilled from the environmental resources. Thus with time, the quality and quantity of human needs changed and they started developing techniques and new ways to use the environment. Humans settled in the fertile plains of the river valleys to cultivate land. They domesticated animals and learnt to use fire and invented wheel and it let to surplus food production and exchange of surplus goods. Question: What is the importance of ecosystem? Answer: The importance of an ecosystem is that it provides space to plants and animals to interact with each other as well as their physical environment. Through interactions they are interdependent on each other for their environment. Question: The earth would have been a barren planet without the atmosphere do you agree? Why? Answer: Yes, earth would have been a barren planet without the atmosphere because atmosphere is required for survival otherwise plants, animals and human beings will die. Question: Why do plants and animals depend on each other? Answer: Plants and animals depend on each other because plants need carbon dioxide which is given by animals and animals need food and oxygen which is given by planets. Question: Describe the main features of natural and human made environment. Answer: The natural elements, such as mountains, rivers, vegetation, animals etc. are created by nature. This is called natural environment. It includes the biotic and abiotic components. The human-made elements, such as agriculture, industries, settlements, means of transportation etc. are created by human beings. Therefore, it is called human-made environment. Human being develop features to live comfortably in their environment. Question: Distinguish between biotic and abiotic environment with examples. Answer: Following are the differences: Question: Give an account of atmosphere. Answer: Atmosphere is the thin layer of air that surrounds the earth. It is made up of various gases such as oxygen, nitrogen, carbon dioxide, dust particles and water vapour. The gravitational force of the earth holds the atmosphere around it. It protects us from harmful rays and scorching heat of the sun. The changes in atmosphere produce changes in the weather and climate. Question: Give an account of various domains of the environment. Answer: Various domains of the environment are: Lithosphere Atmosphere Hydrosphere Biosphere It is the solid crust or the hard top layer of the earth. It is made up of rocks and minerals and covered by a thin layer of soil. It provides us forests, grasslands and land. It is a source of mineral wealth. It is the thin layer of air that surrounds the earth. The gravitational force of the earth holds the atmosphere around it. It protects us from harmful rays and scorching heat of the sun. It consists of various gases, dust and water vapour. It refers to various water bodies such as rivers, lakes, seas, oceans, etc. that exist on the earth. Biosphere or the living world is comprised of plant and animal kingdom. It is a narrow zone of the earth where land, water and air interact with each other to support life. Question: How have human beings adapted to the environment to fulfill their needs? Answer: Human beings from the early times have been interacting with the environment and modifying it according to their needs. Early humans adapted themselves to the natural surroundings. They led a simple life and fulfilled their requirements from the nature around them. But their needs kept on increasing. They became varied also. To fulfill these varied needs, humans learnt to grow crops, tamed animals and began a settled life. The wheel was invented, surplus food was produced, barter system emerged, trade started and commerce developed. Industrial revolution made possible large scale production. By and by transportation became faster. Information revolution made communication easier and speedy across the world. In this way human beings adapted to the environment in order to fulfill their needs. Question: Define environment. How can you classify the environment? Answer: The environment is the sum of all the conditions that surround and influence a human beings at any given point of time and space. Environment consist of the natural environment and the human-made environment. Question: Distinguish between Physical and Biological environment. Answer: Difference is as follows: Question: How do human adapt themselves to the environment. Give examples. Answer: They adapt themselves to natural environment by making modifications in their shelter, food and clothing. They also modify the natural environment to suit their social, biological, economic and cultural needs. For example - People who live in hot, wet coastal areas like Kerala or Coastal Odisha traditionally eat rice and fish. They also wear cotton clothes which keep them cool and live in houses with sloping roofs so that rain can run off easily. Question: List some environmental issues. Answer: Some issues are: Over-population. Pollution - air, water, land and noise pollution. Deforestation Poaching Question: What factors lead to environmental degradation? Answer: With a passage of time, humans started changing the natural environment to their advantage with the help of varied skills and technologies. They started building houses to live in. They discovered minerals and invented machines, the growing population and increasing demand for goods resulted in rapid industrialization and mass production. To satisfy their increasing wants, natural environment is being exploited indiscriminately by humans. This is leading to environmental degradation. Question: Everything in the biosphere is interconnected and interdependent. how? Answer: Everything in the biosphere is interconnected and interdependent on each other: Forest provide products like timber, fruits, nuts, raisins, lac and medicinal herbs. They also provide a natural habitat for various plants and animals. Forests help moderate atmospheric temperature by absorbing carbon dioxide and adding moisture to the air through transpiration. Many animals depend on forests and grasslands for their food. Humans, in turn, depends on animals as a source of food. Some people also use animals as a mean of transport and to carry heavy loads.

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