Chapter 1. Environment

Overview
• The place, people, things & nature that surround any living organism is known as environment.
• It is a combination of natural and human made phenomena. The natural environment refers to both biotic and abiotic conditions existing on Earth.
• The Tropic of Cancer (23°30’N) divides India into two almost equal parts.

Natural Environment
• Natural environment comprises land, water, air, plants & animals.
• Lithosphere: Lithosphere is solid crust or hard top layer of Earth. Landforms are found over continents and on ocean floors.
• Environment provides:
1. Basic life support system
2. The air
3. The water
4. The food
5. The land

Hydrosphere
• The domain of water is referred to as hydrosphere.
• It comprises various sources of water and different types of water bodies like rivers, lakes, seas, oceans, etc.
• It is essential for all living organisms.

Lithosphere
• Lithosphere is solid crust or hard top layer of earth. It is made up of rocks and minerals and covered by a thin layer of soil.
• It is an irregular surface with various landforms such as mountains, plateaus, plains, valleys, etc.
• Landforms are found over continents and on ocean floors such as mountains, plateaus, plains, valleys, etc.
• Lithosphere is domain that provides us with forests, grasslands for grazing, land for agriculture and human settlements. It is a source of mineral wealth.

Atmosphere
• The atmosphere is thin layer of air that surrounds Earth.
• The gravitational force of earth holds atmosphere around it.
• It protects us from harmful rays and scorching heat of Sun.
• It consists of a number of gases, dust & water vapour.
• The changes in atmosphere produce changes in weather and climate.

Biosphere
• Plant and animal kingdoms together make biosphere or living world.
• It is a narrow zone of Earth where land, water & air interact with each other to support life.

Ecosystem
• It is a system formed by interaction of all living organisms with each other
• It includes physical and chemical factors of environment in which all living beings live and all are linked by transfer of energy and material.
• All plants, animals & human beings depend on their immediate surroundings.
• These relations between living organisms, as well as relation between organisms and their surroundings, form an ecosystem.
• There could be an ecosystem of any large rain forest, grassland, desert, mountain, lake, river, ocean & even a small pond.

Human Environment
• Human beings interact with environment and modify it according to their needs.
• Early humans adapted themselves to their natural surroundings.
• Humans learn new ways to use and change environment.
• They learn to grow crops, domesticate animals and lead a settled life.
• The wheel was invented, surplus food was produced, barter system emerged, trade started and commerce developed.
• The industrial revolution enabled large scale production.
• Transportation became faster. Information revolution made communication easier and speedy across world.

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