Class 7 Social Science Notes Chapter 1 (Environment) – Our Environment Book

Alright class, let's focus on Chapter 1, 'Environment', from your Class 7 NCERT textbook 'Our Environment'. This chapter lays the foundation for understanding our surroundings and is quite important for various competitive exams as well. Pay close attention to the definitions and components.

Chapter 1: Environment - Detailed Notes for Exam Preparation

1. What is Environment?

• Definition: Everything that surrounds any living organism is called the environment. It includes places, people, things, and nature.
• Origin: The word 'Environment' originates from the French word 'environer'/environner', meaning 'neighbourhood'.
• Combination: It is a combination of natural and human-made phenomena.

2. Components of Environment

The environment has two main components:

• A. Natural Environment:

  • Comprises biotic and abiotic conditions existing naturally on Earth.
  • Biotic: The world of living organisms.
    • Examples: Plants, Animals, Fungi, Bacteria.
  • Abiotic: The world of non-living elements.
    • Examples: Land (Rocks, Soil, Mountains), Water (Oceans, Rivers, Lakes), Air (Gases, Dust, Water Vapour), Temperature, Sunlight.

• B. Human-Made Environment:

  • Includes creations, activities, and interactions among human beings.
  • Examples: Buildings, Parks, Bridges, Roads, Industries, Monuments.
  • Also includes social structures like Family, Community, Religion, Educational institutions, Economic systems, Political situations.

3. Natural Environment: The Four Domains (Realms) of the Earth

The natural environment can be broadly classified into four major domains:

• a) Lithosphere:

  • Definition: The solid crust or the hard top layer of the Earth. It's made up of rocks and minerals and covered by a thin layer of soil.
  • Characteristics: It is an irregular surface with various landforms like mountains, plateaus, plains, valleys, etc.
  • Importance: Provides forests, grasslands for grazing, land for agriculture, human settlements, and is a source of mineral wealth.

• b) Hydrosphere:

  • Definition: The domain of water.
  • Components: Comprises various sources of water and different types of water bodies like rivers, lakes, seas, oceans, glaciers, groundwater, water vapour in the atmosphere.
  • Importance: Essential for all living organisms.

• c) Atmosphere:

  • Definition: The thin layer of air that surrounds the Earth.
  • Characteristics: Held to the Earth by gravitational force. Consists of a number of gases (Nitrogen - 78%, Oxygen - 21%, Carbon Dioxide, Argon, others - 1%), dust particles, and water vapour.
  • Importance: Protects us from the harmful ultraviolet (UV) rays and scorching heat of the sun. Changes in the atmosphere produce changes in weather and climate.

• d) Biosphere:

  • Definition: The narrow zone of the Earth where land (Lithosphere), water (Hydrosphere), and air (Atmosphere) interact with each other to support life.
  • Components: Plant and animal kingdom together make the biosphere or the living world.
  • Significance: It is the zone where life exists.

4. Ecosystem

• Definition: An ecosystem is a system formed by the interaction of all living organisms with each other and with the physical and chemical factors of the environment in which they live, all linked by the transfer of energy and material.
• Interdependence: All plants, animals, and human beings depend on their immediate surroundings and are often interdependent.
• Components: Includes biotic (producers, consumers, decomposers) and abiotic components.
• Variety: Ecosystems can be as large as a vast rainforest, grassland, desert, mountain, or ocean, and as small as a small pond or lake.
• Energy Flow: There is a continuous flow of energy within an ecosystem (e.g., sun -> plants -> herbivores -> carnivores).

5. Human Environment

• Interaction: Human beings interact with the environment and modify it according to their needs.
• Adaptation: Early humans adapted themselves to their natural surroundings. They led a simple life and fulfilled their requirements from the nature around them.
• Modification: With time, needs grew and became more varied. Humans learned new ways to use and change the environment:
  • Learned to grow crops (Agriculture).
  • Domesticated animals.
  • Led a settled life.
  • The wheel was invented.
  • Surplus food was produced.
• Barter System: A trade system in which goods were exchanged without the use of money. Emerged with surplus production.
• Trade and Commerce: Developed further with the advent of currency.
• Industrial Revolution: Enabled large-scale production.
• Transportation: Became faster.
• Information Revolution: Made communication easier and speedy across the world.
• Need for Balance: While modification is necessary, humans must learn to live and use their environment in a harmonious way. A perfect balance is necessary between the natural and human environment.

Key Terms to Remember:

• Environment: Our basic life support system; the surroundings or conditions in which a person, animal, or plant lives or operates.
• Biotic: Relating to or resulting from living things.
• Abiotic: Physical rather than biological; not derived from living organisms.
• Lithosphere: The rigid outer part of the earth, consisting of the crust and upper mantle.
• Hydrosphere: All the waters on the earth's surface, such as lakes and seas, and sometimes including water over the earth's surface, such as clouds.
• Atmosphere: The envelope of gases surrounding the earth or another planet.
• Biosphere: The regions of the surface, atmosphere, and hydrosphere of the earth occupied by living organisms.
• Ecosystem: A biological community of interacting organisms and their physical environment.
• Barter System: Exchange of goods for goods without the use of money.

Multiple Choice Questions (MCQs)

Here are 10 MCQs based on Chapter 1 to test your understanding:

1. Which of the following is NOT a component of the human-made environment?
a) Bridge
b) Mountain
c) Park
d) Building

2. The domain of water is referred to as the:
a) Lithosphere
b) Atmosphere
c) Hydrosphere
d) Biosphere

3. Which gas protects us from the harmful ultraviolet rays of the sun?
a) Carbon Dioxide
b) Nitrogen
c) Ozone (While not explicitly detailed in Ch1, the protective layer is in the atmosphere, making this the best fit in context, though Ozone is the specific gas - this tests application/prior knowledge slightly)
d) Oxygen

4. What does the 'Biotic' component of the environment refer to?
a) The world of non-living elements
b) The world of living organisms
c) The domain of air
d) The solid crust of the Earth

5. An ecosystem is formed by the interaction between:
a) Only living organisms
b) Only non-living elements
c) All living organisms and non-living elements in an area
d) Human beings and their creations

6. The term 'Lithosphere' refers to:
a) The thin layer of air surrounding the Earth
b) The water bodies on the Earth's surface
c) The narrow zone where life exists
d) The solid crust or hard top layer of the Earth

7. Which of these is an example of an Abiotic component of the environment?
a) Plants
b) Animals
c) Land
d) Fungi

8. The 'Barter System', mentioned in the context of human-environment interaction, refers to:
a) Trade using currency
b) Large scale production in industries
c) Exchange of goods without using money
d) Growing crops for self-consumption

9. The narrow zone where land, water, and air interact to support life is called:
a) Ecosystem
b) Biosphere
c) Atmosphere
d) Lithosphere

10. Which of the following represents human modification of the environment?
a) A flowing river
b) Growth of wild forests
c) Building a dam
d) Formation of mountains

Answer Key for MCQs:

1. b) Mountain
2. c) Hydrosphere
3. c) Ozone (within the Atmosphere)
4. b) The world of living organisms
5. c) All living organisms and non-living elements in an area
6. d) The solid crust or hard top layer of the Earth
7. c) Land
8. c) Exchange of goods without using money
9. b) Biosphere
10. c) Building a dam

Study these notes thoroughly. Understanding these basic concepts is crucial for building knowledge in Geography and Environmental Science. Let me know if any part needs further clarification.