Longman Panorma Geography Solutions for Class 7 Social science Chapter 1 - Our Environment

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The physical environment comprises of non-living components.

Explanation: Land, air and water are the non-living or abiotic components that form the physical environment of an organism. The physical environment is the habitat of an organism.

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The environment is dynamic in nature.

Explanation: The physical and biological environments of an organism interact with each other through transfer of energy and matter. Change in either of the components, biotic or abiotic, causes change in the other. Therefore, the environment is dynamic in nature.

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29% of the lithosphere is occupied by land.

Explanation: The lithosphere is the outermost layer of the Earth. Twenty-nine per cent of this layer is occupied by land and the remaining seventy-one per cent is occupied by water.

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Ozone protects us from the harmful ultraviolet rays of the Sun.

Explanation: Ozone, a pale blue gas, is a component of the atmosphere. This gas provides protection from the harmful ultra-violet rays of the Sun, benefiting both plants and animals.

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The great variety of life is on Earth is called biodiversity.

Explanation: The variety of living beings that constitutes the biosphere is collectively known as biodiversity. Biodiversity includes livings beings ranging from micro-organisms, herbs, plants, trees and animals to humans.

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All energy of life comes from the Sun.

Explanation: The Sun is at the centre of the solar system. It provides solar energy in the form of heat and light, which sustains all forms of life on Earth.

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Environment is the sum total of the surroundings and conditions within which a living organism exists. Land, water, air, plants and other living organisms constitute the environment.The components of environment can be divided into two groups: natural and human.The biological and physical environments of an organism form the natural environment. Human beings and their creations, such as bridges, roads and farms and the political, social and economic order in which they live, form the human environment.

Answer:

Lithosphere, also known as the crust, is the outermost solid layer of the Earth. It is a reservoir of resources that helps us in following ways:

i) It provides minerals and rocks that are used in construction and other industries.
ii) It is a source of fuels such as petroleum and natural gas.
iii) The lithosphere provides land for agriculture. This acts as a source of income as well as supply of food for human beings.
iv) The hydrosphere and the land provide nutrients to plants and animals. It helps in their growth.

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Hydrosphere is the total mass of water found on the surface of the Earth. Its components include ice sheets found in the mountainous regions and all the water bodies such as lakes, ponds, rivers, seas, oceans, underground water and the water vapour present in atmosphere.

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Earth's gravitational pull holds the atmosphere around the Earth and prevents it from escaping into outer space. The force of the Earth's surface, which pulls things towards itself, is known as gravitational force. This force is strong enough to hold the molecules of gases present in atmosphere close to the Earth.

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The sum total of land, water and air present on Earth is the called biosphere. It is the sum of all ecosystems in which living organisms are present.

The biosphere is important due to the following reasons:

i)  Biosphere provides all living beings the necessary conditions for life such as  suitable climate, water and air.
ii)  Air is necessary for humans and animals to breathe and for plants to produce energy through photosynthesis.
iii) Water is also essential for sustaining life.
iv) Land provides with minerals and fuels and also helps in the survival of plants and trees.

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A distinct zone in the biosphere within which a community of living as well as non-living components exist and survive by mutual interaction is an called an ecosystem. The biotic or living components are human beings, plants, animals, trees and the abiotic components are land, water and air. Energy from the Sun is recycled by transferring matter as well as energy among the components. The process of change and transfer of energy makes an ecosystem dynamic.

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Human beings have adjusted their surroundings according to their needs. However, with the increase in population at an alarming rate, the demand of basic requirements such as food, houses and roads has also increased. Therefore, human beings have started altering the environment for the fulfilment of their requirements. Farming, grazing, construction of bridges, houses and roads and building industries and transport systems have helped human beings survive and lead a life of convenience.

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The physical environment consists of all the abiotic elements of nature, that is, all the non living elements of nature, such as land, water and air. Physical environment derives most of its energy from the Sun. The biological environment, on the other hand, consists of all the living beings, such as humans, animals and micro-organisms. Elements of biological environment derive their energy from the physical environment. The biological and physical environments create a natural environment where they are interdependent.


1. Changes in physical environment affecting the biological environment: The physical environment can generate changes in the biological environment. For example, in case of a natural disaster in the physical environment, like landslide, the whole biotic environment of that place is affected. The ecosystem suffers in terms of its supply of food and relocation of inhabitants of an area. Another example emphasising changes in physical environment affecting the biological environment is the change in seasons and weather conditions . Due to the changes in the physical environment like increase or decrease in temperature or heavy or less rainfall, the biological elements of the ecosystem have to adapt themselves accordingly. For example, some animals go into hibernation during winters and humans change their clothing according to the change in climate.

2. Biological environment affecting the physical environment: The biotic environment can also generate changes in the physical environment. For example, hills are cut into steps for step farming, irrigation is done and the soil is loosened. Such changes are brought by the biological environment to the physical environment. Beavers build artificial dams out of wood to create a homes for themselves by blocking the rivers and changing the physical environment around them.

Hence, it can be seen that both the physical and the biological environments are in a constant state of interaction with each other.

Answer:

The organisms in an ecosystem have their own physical environment. The living components interact with each other, transferring matter and energy among themselves as well as to the abiotic elements. The Sun is the source of energy for all life forms. Therefore, the ecosystem goes through constant change and the energy is recycled. Maintenance of an equilibrium in the transfer of energy and matter is known as ecological balance. This balance helps to keep the ecosystem stable.

When there is more emission of energy and matter out of the ecosystem, an imbalance is created. This causes disruption in the proper functioning of the ecosystem. With the passage of time, the needs of human beings are increasing. This is leading to deforestation, loss of habitat of animals, increase in construction and transportation and industrialisation,  which, in turn, is resulting into depletion of the ecosystem.

The ecological balance can be maintained in the following ways:

i)   Controlling air and water pollution
ii)  Preventing deforestation
iii) Stopping the hunting and poaching of animals to conserve the endangered species. 
iv) Management of natural resources: Minerals, fossil fuels and other natural resources are being depleted very fast. These should be used carefully. This would ensure a better future with stable supply of natural resources.
v) Reuse and recycle: Water and other resources can be reused and recycled to prevent over consumption.

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Atmosphere is the layer of air that surrounds the Earth. The molecules of the gases are held close to the surface by the gravitational pull of the Earth. The atmosphere comprises the following components:

1. Gases
i)  Nitrogen,which is the most abundant gas in the atmosphere and constitutes 78% of the air.
ii) Oxygen constitutes 21% of the air.
iii) Ozone, Hydrogen, Argon and Helium constitute 1% of the air.

2. Water vapour

3. Dust particles

The uses of the above mentioned constituent gases are as follows:

i) Nitrogen: It is used to make fertilisers and dyes. It is also used as a refrigerant as well as to store food. 
ii) Oxygen: All living organisms use oxygen for breathing and hence, it is important for the survival of all life forms on Earth.
iii) Carbon dioxide: It is used by plants for producing energy through photosynthesis.
iii) Hydrogen helps in the formation of water.
iv) Ozone protects the Earth from the harmful ultraviolet rays of the Sun.
v) Argon is used for arc welding.
vi) Helium is used as a light weight aircraft fuel.

Answer:

Environment includes the conditions and surroundings in which all life forms, humans, animals and plants live in. Land, water, air and all the components around us are a part of the environment. These help us to survive and nourish ourselves and help in our growth as well. We need to protect our environment because of the following reasons:

i)   Increasing needs and demands are disrupting the balance in the environment.
ii)  Increasing deforestation is causing loss of habitat as well loss of supply of food. 
iii) Excessive construction is leading to the excessive use of natural resources like minerals and fuels.
iv) Increasing vehicles are depleting the resources of oil at an alarming rate.
v)  Excessive farming and grazing is causing harm to the productivity of land, which, in turn causes, is creating a scarcity of resources to sustain life.
vi) The necessity to maintain and protect our environment emerges from the need for a healthy survival. Maintaining a clean and healthy environment not only increases aesthetic beauty of the surroundings but also contributes in maintaining good health.

Answer:

Some of the environmental issues that the people are facing nowadays are created by themselves. People are disregarding the environmental needs for their own convenience. This has led to a polluted environment. Some of the key problems that my neighbourhood faces due to the ignorance of people are listed below along with their suitable solutions:

1. Excessive garbage on the streets: Some people do not put any effort in keeping the roads and the streets clean. They throw away garbage wherever they find it convenient. They litter the streets and do not use the dustbins that are provided for garbage disposal.

Solution: The solution to this problem is very simple; people only need to make the effort to throw the garbage in the nearest dustbin and not on the street. If a dustbin is not available nearby, then they can keep the waste that is to be disposed with them and throw it in the garbage bin at home.

2. Urinating in public: Some people do not have basic decency and pollute the environment by urinating wherever they please. This leads to spreading of diseases and a general unhygienic atmosphere.

Solution: People should have a sense of not polluting public places by urinating in public and should avoid such acts as they are unhygienic and harmful for the environment.

3. Improper drainage system: Some of the localities nearby have open drains that sometimes overflow on the streets. This leads to dirty water overflowing on the streets and transmission of diseases.

Solution: The drains should be covered, as it is not hygienic to come in contact with germs that breed in the drains and cause diseases and pollute the air around us.