Class 11 Environment Chapter 1 Basic Concepts of Environment

Class 11 Environment Chapter 1 Basic Concepts of Environment The answer to each chapter is provided in the list so that you can easily browse through different chapters Assam Board HS 1st Year Environmental Studies Chapter 1 Basic Concepts of Environment Question Answer.

Class 11 Environment Chapter 1 Basic Concepts of Environment

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Also, you can read the SCERT book online in these sections Solutions by Expert Teachers as per SCERT (CBSE) Book guidelines. These solutions are part of SCERT All Subject Solutions. Here we have given Assam Board Class 11 Environment Chapter 1 Basic Concepts of Environment Notes for All Subjects, You can practice these here.


1. What is biological environment?

Ans: The biological environment is consisted of the plants, animals, insects and human beings. The existence of all living organisms is completely dependent upon biological environment.

2. What are the main causes of environmental degradation?

Ans: Increasing populations, industries, motorcars and destruction of forests are the main causes of environmental degradation.

3. What are the main elements of biosphere?

Ans: The plants, animals and all living organisms are the main elements of biosphere. There are about 10 lakh species of plants and 3 lakh species of animals including man in biosphere.

4. What is environmental studies?

Ans: Environmental studies means the study of human beings, the interrelations of man and environment and how to change and develops this relation.

5. What is environment?

Ans: All the physical, social and cultural factors and conditions which influence the existence, sustenance and development of living organisms is called environment.

6. Name the types of environment?

Ans: There are two types of environment:

(a) Physical environment.

(b) Biological environment.

7. What is ecology?

Ans: The scientific study of the interrelationship of various organisms and the physical environment under the domain of a subject is called ecology.

8. What is biosphere?

Ans: The part of the earth in which life forms and exists is called biosphere. It extends upto 6 km above the earth’s surface and 6 km below. the sea level.

9. Define the term ‘environment.

Ans: The term ‘environment’ literally means surroundings of an object. The surroundings which provide conditions for all the organisms live in harmony with one another is called ‘environment.

10. What does physical environment mean?

Ans: The environment which consists of air, water, land, solar radiation, rainfall, water vapour, humidity, temperature, wind velocity, wind direction and duration of sunshine is called physical environment.

11. Describe the biosphere.

Ans: The biosphere is a region of the earth in which life originates and exists. It is a biological envelope which supports life without the help of artificial systems. Biosphere extends upto 6 km above the earth’s surface and 6 km below the water surface (sea level). The number of plant and animal species in the biosphere are about 10,00,000 and 3,00,000 respectively. Plants and animals are interdependent. Man depends more on plants and animals. So, our existence depends upon proper handling of the biosphere.

12. Define and explain the term ‘ecology”?

Ans: The scientific study of the interrelation of various organisms and the physical environment under the domain of a subject is a called ecology.

The term ‘ecology’ was defined first by the German zoologist Earnest Haeckel, “the body of knowledge concerning the economy of nature, the investigations of the total relations of the animals to its inorganic and organic environment. The term “ecology’ is coined by the German zoologist Earnest Haeckel. The word ecology originally comes from the Greek word ‘oekologie’. The Greek word ‘oikos’ means ‘house’ and ‘logos” means ‘study of”. So the term ‘ecology” means “he study of house”.

13. Define and explain the term ‘ecosystem’. [2015] 

Ans: The study of a community of plants and animals together with their environment is called ecosystem or ecological system.

The ecosystem is the basic functional unit in ecology. It includes all the living organisms which interact with the physical environment.

An ecosystem has two components:

(i) Autotrophic and

(ii) Heterotrophic components.

14. Why are people concerned about the environment of the present day earth?

Ans: Increasing industry, populations, motorcars and destruction forests are the main causes of environmental deterioration and degradation. If the environment goes on deteriorating and degrading in that way it will be very difficult for lives to exist on earth. The scientist have noticed some irregular changes in climate and defective behaviour of plants and animals So they are very much concerned about the environmental degradation It is now a burning question for the all classes of people of the entire world.

15. What is atmosphere? Give an account of its composition?

Ans: Some physical factors influence the life of living organisms and plants. The mass of this physical factors is called atmosphere.

The atmosphere is composed of various gases and water vapour. It Ogos contains about 78% Nitrogen, 21 % oxygen, 0.03% carbon-di-oxide, 0.93% Argon and 0.02% other gases.

Besides the gases and water vapours, the atmosphere also contain dusts, smokes, some metals, harmful chemicals etc. The atmosphere is also composed of some layers. The atmosphere is divided into five layers in accordance with their heights and properties. These are-Troposphere, Stratosphere, Mesosphere, Ionosphere and Exosphere.

16. What is hydrosphere? 

Ans: The part of the earth covered by water is called hydrosphere. Hydrosphere contains 1,460,000 cubic km. of water. The oceans occupy 70.8% of the earth’s total surface area and hold 1445 million cubic km of water. Hydrosphere play a very important role in forming cloud and rains and thereby controlling weather and climate.

17. Write a note on lithosphere?

Ans: The outer cover of the earth is of hard rocks and soil is the lithosphere. The average thickness of lithosphere is 40 km.

The topmost portion of the earth composed of sand and soil. Rock turns into sand and then soil by weathering. When rocks are heated extremely by the sun and suddenly cooled by rain, they crack. When this process goes on for a long time, the rocks break into sand and soil. Frosts can also break down rock. In this way the rocks gradually turns into soil.

The lithosphere covered by soil is the reservoir of various minerals, coals and petroleum, Plants and crops are grown on the soils. But the lithosphere is not uniform is depth. Some natural factors like rivers, floods, rainfall, earthquakes, volcanoes and other climatic conditions gradually change the land forms.

18. What is biosphere? Describe its composition.

Ans: The part of the earth and atmosphere which supports the various forms of life is called biosphere. It is a biological envelope that surrounds the globe containing life and supporting life without the help of artificial systems.

The biosphere contains more than 3,50,000 species of plant including algae, fungi, mosses and other plants and more than 11 million living organisms including men. All the living organisms get all the essential substances like water, light, heat, food and living space from the biosphere.

19. Narrate how the plants and animals are dependent on each other?

Ans: Carbon-di-oxide is very necessary for the plants during photosynthesis. Because with the help of sun rays and carbon-di-oxide the plants produce their food in their green parts. All the animals exhales carbon-di-oxide and the plants absorb it.

On the other hand oxygen is the elixir of life. Without oxygen life cannot thrive. Plants supplies oxygen during the photosynthesis. But animals depend heavily on plants, because some animals eat plants, and man eat both plants and animals.

In this way the plans and animals are dependent on each other.

20. Write short notes on :

(a) Troposphere

(b) Stratosphere.

(c) Mesosphere.

(d) Ionosphere.

(e) Exosphere.

(f)Energy cycle.

(g) Nitrogen cycle.

(h) Carbon cycle.

Ans: (a)Troposphere: Troposphere is the nearest layer to the earth. It extends upto the height of 8 km to 18 km above the earth. It contains water vapour and dust. Clouds are found in this layer. It is the densest layer with 80% of the total air of the atmosphere and greatly influences our climate.

(b) Stratosphere: Stratosphere is the second nearest layer to the earth. It extends from 18 to 60 km. In this layer the temperature does not change. It is free from water vapour, clouds and dust. So it is the safest layer of the sky for the jet planes. This layer contains the ozone gas, which protects the earth from the ultra-violet rays of the sun. 

(c) Mesosphere: Mesosphere is just above stratosphere. Its range is from about 60 km to 80 km above the earth. It is very cold.

(d) Ionosphere : Ionosphere is just above the Mesosphere. This layer is composed of ions or atoms gases. The atoms carry both positive and negative changes.

(e) Exosphere: Exosphere exists above the ionosphere. Exosphere extends unlimited height above lanosphere.

(f) Energy cycle: The sun supplies almost 99 98% of the total energy to the biosphere. By photosynthesis the plant produces carbohydrate and oxygen. The herbivores get energy feeding on plants and carnivores feeding on herbivores and omnivores (man) get energy from both animals and plants.

The energy that is not spread out in the course of life is stored in dead objects. By the process of decomposing, bacteria breakup the dead object and produce humus, releasing carbon-di-oxide, water and heat into the atmosphere and nutrients are added to the soil. The soil supplies nutrients to plants. This process is called energy cycle.

(g) Carbon cycle: All living organisms respire and release carbon di-oxide. Bacteria also release carbon-di-oxide by decomposing dead objects. But plants absorb carbon-di-oxide during photosynthesis. The process of absorption and production of carbon in the form of carbon-di oxide is called carbon cycle.

(h) Nitrogen cycle : Nitrogen is a colourless gas which is found almost 98% in our atmosphere. But the higher organisms cannot use nitrogen directly. It can only absorbed as chemical compounds of nitrogen. These chemicals are ammonia or amino aside.

Some special bacteria store nitrogen and making it available to plant. The nature supplies nitrogen through various means. Man and plant-eating animal get nitrogen from plants. Animals die and decay and the nitrogen again goes to soil through bacteria. This process is called nitrogen cycle.

21. Describe the water cycle with the help of a diagram. 

Ans: Water plays a very vital role in the life of the living organisms on the Earth. Water cycle is divided into two branches-the atmosphere branch and the terrestrial branch. In the atmosphere water exists in vapours and on the earth surface in liquid and solid forms (ice). Water vapour evaporates from the water surface of the earth and rises above the atmosphere and is turned into clouds. Some clouds produce rain and fall on the earth. This circulation of water through hydrosphere, atmosphere and lithosphere is called water cycle.

22. How is the nitrogen in the atmosphere used by organisms?

Ans: Nitrogen is a colourless gas which occupies almost 98% of our atmosphere. But the higher organisms cannot consume nitrogen directly. It can only be absorbed as chemical compounds of nitrogen. The chemical compounds may be ammonia or amino acids.

Some special bacteria store up nitrogen and make it available to plants. Animals die and decay and the nitrogen again goes to the soil through bacteria. Man and plant-eating animals get nitrogen from plants.

23.Describe the problem of population explosion.

Ans: The population explosion badly affect the poor and underdeveloped countries. The rapidly growing population have caused the environmental deterioration, poverty and illiteracy.

In poor countries, cities are crowded because they provide more scopes for livelihood. As a result the cities face the problems of disposal of sewage, garbage and other kinds of pollution.

In rural area the rapid growth of population creates unhealthy situations and creates demands for more foods, accommodation and other facilities. As a result the forests are indiscriminately destroyed by people for agriculture and other necessities. The deforestation is a serious threat to our environmental balance. So population explosion is one of the major causes of environmental pollution.

24. Describe how the natural calamities affect the environment. 

Ans: Natural calamities also do a lot to pollute our environment.

Earthquake, cyclone, volcano, flood, drought, storm, erosion etc. are called natural calamities. Earthquake may change the forms of soil and courses of rivers. The smoke and ashes due to volcanic eruption may cover the sunlight and damage its nearby areas. The lava also destroy crop fields and forests. Floods and drought are equally harmful for man, animals and plants. So the natural calamities bring various environmental problems.

25. Describe briefly what are the problems of our environment?

Ans: Both the nature and human beings create problems for the environment. But human beings are more responsible than the nature.

Earthquake, volcano, cyclone, drought, flood, soil erosion storm etc. are the natural problems of our environment.

On the other hand human beings create many problems for our environment. The increasing population growth is the burning question for the world today. For the increasing population we need more food, more houses and other facilities. For our needs we cut down the trees and destroy the forest for more cultivable land and our environment slowly lose the ecological balance, which is threat to our environment.

The excessive use of natural resources also create problems to our environment. We use fossil fuels in factories and motor vehicles. As a result the factories and the motor vehicles release many poisonous gases and smoke to our atmosphere and pollute the environment. The industries also discharge the unused waste material to the rivers and crop field and pollute the water and soil.

In this way our environment has been facing many problems from the activities of biosphere. 

26. What is Ozone layer? Discuss the reasons behind the formation of holes in the Ozone layer.

Ans: Ozone is a light blue gas which is found in a large quantity in a layer in our atmosphere at a distance of 25 to 50 km from the earth surface. This layer is called Ozone layer.

The chlorofluorocarbons that are used in refrigerators, hair dyes, airconditioners, perfumes etc. are found to be very very harmful to the t ozone layer of the upper atmosphere. These compounds rise, upto 25 km to 50 km of the atmosphere, in which ozone layer exists. The chlorofluorocarbons not only reduce the thickness of the ozone layer, but also make some holes. The smokes and ashes emitted from various sources are very harmful for the ground layer of ozone. These are the reasons for which some holes are formed in the ozone layer.

27. What is acid rain? Describe how it can damage life and vegetation?

Ans: When the oxides of sulphur, nitrogen and carbon mix with the water vapour of the atmosphere, they form sulphuric acid, nitric acid and carbonic acid and incorporate into rain drops. When such drops of water fall onto the ground in the form of raindrops, it is called acid rain.

Acid rain is quite harmful. It increases acidity of the streams, rivers, and lakes and damages aquatic life. It also damages trees, forests etc Old buildings and monuments also suffer from corrosion due to acid rain. Some times the acid rain result in dwindling away of the forest regions.

28. Discuss the environmental problems caused by chemicals used in agriculture.

Ans: To increase the agricultural production we use more and ore chemical fertilizers and pesticides. These fertilizers and pesticides go into the soil and reach even the ground water, contaminating both with toxic chemical compounds. Some of the deadly chemical compounds carried by rain water is mixed with the river water. So this kind of chemical pollutes the water sources of the earth, which is now a very serious environmental problem.

29. What is radioactivity and isotope? How does radioactivity damage the environment?

Ans: Radioactivity: Radioactivity is the spontaneous emission of powerful radiations from some substances without any energy being supplied from outside. By this process the unstable nuclei get converted into stable nuclei.

Isotope: Radioactive materials are the by-products of the elements which produce nuclear energy. It may be heavy like Uranium or Plutonium. These two elements in the process of producing energy, transform themselves into different elements called isotope, Isotopes are nothing but atoms of same elements with a difference.

The radioactive nuclear wastes are harmful for a long period of time. Their harmful action not only affect the immediate generation, but also the later generations. The radioactivity may cause genetic anomaly resulting in the birth of abnormal babies who may be deformed. For the radioactivity action in Nagasaki and Hiroshima cities the abnormal children are still being born.

30. What is nuclear energy and how is it generated?

Ans: The atoms of Uranium or Plutonium splits into almost two equal halves and in this process the neutrons are emitted with a large amount of energy. This energy is called nuclear energy.

The atoms of Uranium or Plutonium are heavy, so they are used for generating nuclear energy. The atoms of Uranium or Plutonium split into almost two equal halves and in this process the neutrons are emitted with a large amount of energy. Neutron is a very small nuclear particle and is electrically neutral. To generate nuclear energy, the nucleus should be bombarded with neutrons.

31. What is global warming? Discuss its future effects.

Ans: We know the green house gases of the atmosphere keep the temperature of the earth at an average level of 15 C. But at present time, for the human activities the amount of green house gases has increased to large extent. As a result, there has been a rise in global temperature. This is called global warming.

The Antarctica is covered with almost two km thick ice, so we call it water reservoir. It the global warming increases, the ice of Antarctica will start to melt and as a result many countries will be submerged under the water and this will destroy human being, animals and plants. In short, the global warming is very very dangerous to the earth. So we should control it as quickly as possible.

32. Discuss the effects of nuclear wastes.

Ans: The nuclear wastes are radioactive. So their harmful effects may continue for many years. They do not affect the immediate generation only, they affect the later generations also. The radioactive elements spontaneously emit three types of rays. These are alpha, beta and gamma The gamma is most harmful to us. So the nuclear wastes are very harmful to us. They damage the plants and animals. They cause cancer in human body. They can affect human embryo also.

33. Justify the need of studying environment.

Ans: Environmental studies means the study of human being, the interrelations of man and environment. Following are the necessities of environmental studies.

(i) Environmental studies helps to give a general concept of environment to the people of all classes.

(ii) It helps to create an awareness among the people of the society about the environmental problems.

(iii) It also helps the Government and other organizations who are laking different schemes of stop the environmental degradation and for its development.

(iv) Through environmental studies the social units can able to acquire the knowledge of the environmental problems.

(v) It helps people to know about the techniques, their applications and so on, necessary for the environmental control and development and for the solution of environmental problems.

(vi) Environmental studies is necessary in cooperating in the scheme, taken to prevent air, water and sound pollution etc.

(vii) It also helps the people to understand the environmental problems. 

(viii) It also helps the people to emphasising the feeling like liberty, truth, justice, fraternity etc.

(x) It also helps to understand about the corelation between different stage of life and different problems related to environment.

34. Write on the necessities of environmental studies.

Ans: Following are the necessities of environmental studies:

(a) Environmental studies is necessary to help the Govt and other organisations who are taking different schemes to stop the environmental degradation, and for its development.

(b) It is necessary to keep clean the neighbouring places.

(c)It is necessary to create an awareness among different units of the society about the environmental problems

(d) Through environment studies each and every individual of the society can acquire the knowledge of the environmental problems.

(e) Through environment studies each and every individual of the society can able to ignorant concepts of the environment, natural wealths and the ways to preserve them.

(f) It is very essential in cooperating in the schemes, taken to prevent air, water and sound pollution.

(g) It also necessary to helps the people to know about different aspects, emphasising upon the cleanliness of the environment, admiring the nature’s contribution, instructing the tolerance in the field of religion and culture, emphasising the feelings like liberty,truth justice, fraternity etc.

(h) Environmental studies is necessary to helps to give a general concept of environment to the people of all classes.

(i) It is necessary to create the interest and feelings among the people to understand the environmental problems.

35. Write in brief on different types of Environment? 

Ans: Environment can be divided into three. 

These are discussed in brief as below:

(a) Natural Environment : Natural environment is the ecological conditions around us can be taken together such as climate, hills, mountains. oceans, sky, air, rivers, sun, moon, seas etc.

(b) Social Environment : Social environment means our parents, brothers and relatives to homes, families, social and international organisations together known as social environment.

(c) Mental Environment : Mental environment means social and physical aspects which increase the intellects, hobbies, attention and interest of human beings and help them to be guided in right direction.

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