NCERT Solutions for Class 7 Social Science

Question 1. Answer the following questions briefly.

• What is an ecosystem?
• What do you mean by natural environment?
• Which are the major components of the environment?
• Give four examples of human-made environment.
• What is lithosphere?
• Which are the two major components of biotic environment?
• What is biosphere?

Answer: (i) All plants, animals and human beings depend on their immediate surroundings. They are also interdependent on each other. This relation between the living organisms as well as the relation between the organism and their surroundings form an ecosystem. (ii) Natural environment consists of land, water, air, plants and animals. Thus, natural environment refers to both biotic (plants and animals) and abiotic (land) conditions that exist on the earth.

• The major components of the environment are—natural (land, air, water, living things), human made (buildings, parks, bridges, roads, industries, monuments, etc.) and human (individual, family, community, religion, educational, economic, etc).
• Four examples of human-made environment—buildings, parks, bridges and roads. (v) Lithosphere 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 is an irregular surface with various land forms such as mountains, plateaus, plains, valleys, etc.
• Plants and animals are the two major components of biotic environment,
• Biosphere is a narrow zone of the earth where land, water and air interact with each other to support life. Thus, plant and animal kingdom together make biosphere, ie., the living world.

Question 2. Tick the correct answer.

(i) Which is not a natural ecosystem?

• Desert
• Aquarium (c) Forest.

(ii) Which is not a component of human environment?

• Land
• Religion
• Community.

(iii) Which is a human made environment?

• Mountain
• Sea
• Road.

(iv) Which is a threat to environment? (a) Growing plant              (b) Growing population (c) Growing crops.

Answer:    (i)—(b), (ii)—(a), (iii)—(c), (iv)—(b).

Question 3. Match the following:

• Biosphere              (a)    blanket of air which surrounds the earth
• Atmosphere          (b)   domain of water
• Hydrosphere       (c)    gravitational force of the earth
• Environment      (d)    our surroundings

(e) narrow zone where land, water and air interact Answer:    (i)—(e), (ii)—(a), (iii)—(b), (iv)—(d).

Question 4. Give reasons:

• Man modifies his environment
• Plants and animals depend on each other. .

Answer: (a) Man modifies his environment to fulfil his needs and make his life comfortable. He also modified his environment to adopt himself to the natural surroundings.

(b) Plants and animals depend on each other for their own sake. Plants release oxygen that animals breathe and absorb carbon dioxide that animals release.

Question 5. Activity

Imagine an ideal environment where you would love to live. Draw the picture of your ideal environment.

Answer: Students are expected to do this activity themselves. However, a sample is given below:

Very Short Answer Type Questions

Question 1. What is environment? ‘ [Imp.]

Answer: Everything that we see in our surroundings forms environment. It is our basic life support system. It provides us air, water, food and land—the basic needs of our life.

Question 2. Why is our environment changing?[V. Imp.]

Answer: Our environment is changing because our needs are increasing day by day. To fulfil these needs we often don’t think about the environment and start modifying it.

Question 3. What are the basic components of natural environment?

Answer: The basic components of natural environment are—land, water, air, plants and animals.

Question 4. What does lithosphere provide us? [Imp.]

Answer: Lithosphere provide us forests, grasslands for grazing land for agriculture and human settlements. It is a rich source of minerals.

Question 5. Name different types of water bodies.

Answer: Rivers, lakes, seas, oceans, etc.

Question 6. How is atmosphere important for us? [Imp.]

Answer: Atmosphere protects us from the harmful rays and scorching heat of the sun.

Question 7. What do you see in the deserts? Name some animals.

Answer: We see camels, snakes, lizards and insects.

Question 8. What is barter system?

Answer:  Barter system is a method of trade in which goods are exchanged without the use of money.

Question 9. Distinguish between biotic and abiotic environment with examples. Answer: The world of living organisms is known as biotic environment. Example: plants and animals.

The world of non-living element is known as abiotic environment. Example: land.

Question 10. How is environment important for us?

Answer: It is important for us because it is the provider of air, water, food and land— the basic necessities of life.

Short Answer Type Questions

Question 1. Write a note on lithosphere. [Imp.]

Answer:  Lithosphere is the solid crust or the hard top layer of the earth. It is made up of rocks and minerals. It is covered by a thin layer of soil. It is an irregular surface with various landforms such as mountains, plateaus, desert, plains, valleys etc. Lithosphere plays an important role in our life. It provides us forests, grassland for grazing , land for agriculture and human settlements. It is also a treasure of various minerals.

Question 2. 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, carbondioxids, 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 3. How do human beings modify natural environment?            [V. Imp.].

Answer:  The needs of human beings are increasing day and day. Hence, they modify natural environment to fulfil these needs. Sometimes they even destroy their environment Human beings have made cars for their convenience. These cars release fumeswhich pollute the air. They have established factories on land. These factoriesmanufacture various items such as containers. This is how they modify naturalenvironment.

Long Answer Type Questions

Question 1. Give an account of various domains of the environment.

Answer:  Various domains of the environment are:

1. Lithosphere
2. Atmosphere
3. Hydrosphere
4. Biosphere
5. 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.
6. 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.
7. It refers to various water bodies such as rivers, lakes, seas, oceans, etc. that exist on the earth.
8. 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 2. How have human beings adapted to the environment to fulfil 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 fulfil 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 fulfil their needs.