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Our Environment

Chapter: Our Environment

Environment is defined as the natural world or in particular a geographical area, especially as affected by human activity.We create so much waste in our daily lives which is disturbing our environment. These wastes are classified as:

  1. Biodegradable wastes
  2. Non-biodegradable wastes

1. Biodegradable Substances:

Biodegradable substances are those which are broken down by biological processes. These substances are decomposed by the actions of bacteria, fungi and other leaving organisms. Factors like temperature and sunlight play a predominant role in this decomposition.

Some examples of biodegradable substances are food leftovers, cow-dung, urine, paper, wood, cloth etc.

2. Non-Biodegradable Substances:

Non- biodegradable substances are those substances which are not broken down by biological processes. These substances may be in solid, liquid or gaseous form. They simply persist in the environment and may harm eco system.

Some examples of non-degradable substances are plastics, polythene bags, glass, radioactive wastes etc.


Biodegradable Wastes

Non-biodegradable Wastes

1 - They are broken down naturally

1 - They are not broken down

2 - They form harmless and non poisonous products

2 - No such action is possible

3 - They release raw materials back to the nature

3 - They do not release raw materials

4 - They pollute environment only when produced in larger quantities

4 - They pollute environment though produced in small quantity

5 - Recycling is possible

5 - Human efforts are required for recycling

6 - They rarely accumulate

6 - They accumulate continuously


Ecosystem — what are its components?

Ecosystem is a unit of biosphere comprising of living beings and the physical environment. Energy and matter are continuously exchanged in an ecosystem

An ecosystem can be natural or man-made. Forest, sea, rivers etc come under natural ecosystem. Garden, aquarium etc come under artificial or man-made ecosystem.

Every ecosystem has two main components:

1. Abiotic components

Abiotic components are the non-living components of an ecosystem. Rainfall, temperature, wind, soil, carbon dioxide, nitrogen, proteins, carbohydrates, sunlight etc come under these components.

2. Biotic components

Biotic components are the living components of an eco system. Plants, animals, microbes come under these components.

These are further classified as

a. Producers

Producers are such organisms which can synthesize their food. Green plants come under this category. They use sun light and make food which is carbohydrates. This process is called photosynthesis.

b. Consumers

Consumers are such organisms which consume other organisms as food. All animals come under this category. Man, goat, deer, lion, cow etc are common consumers.

Consumers can be sub classified as

i. Herbivores:

These are organisms which get food by eating producers.

E.g. deer, rat, cattle etc

ii. Carnivores

These are organisms which consume other animals.

E.g. snake, cat, frog etc

iii. Omnivores

The organisms which feed on both plants and animals. Human beings come under this category.

c. Decomposers

Decomposers are organisms which feed on dead bodies of plants and animals. Micro organisms such as bacteria and fungi come under this category. They break down the complex organic compounds into a simpler substance. Hence they are also called as reducers.

Uses of Decomposers

  1. They help in decomposing the wastes and dead bodies of plants and animals.
  2. They help to maintain the fertility of the soil.
  3. They help in recycling the materials in the biosphere

Food Chains and Webs

Food Chains

Each and every living organism interacts with another organism for the preparation of food. Some organisms consume other organisms and they are in turn consumed by others, thereby forming a chain. This is called food chains.

Food chain is sequential process which represents “who eats whom”.

Simple food chain can be shown as

Grass      →       Deer      →      Lion

      (Producer)       (Herbivore)        (Carnivore)

Food web

Food web is defined as the network of various food chains which are interconnected at various tropic levels.

In a food web, one organism may occupy position is more than one food chain. An organism can obtain its food from different sources and in turn may be eaten up by different types of organisms.

Tropic levels

Tropic levels are the various levels or steps in a food chain at which the transfer of energy/ food takes place from one generation to another.



Flow of Energy

Energy is transferred from one tropic level to another. This is called flow of energy. Plants capture sunlight and some amount of this is used in performing their metabolic activities and some is released as heat into the atmosphere. The remaining energy is stored in plants which is called carbohydrates. When herbivores eat plants, carbohydrates stored in plants are transferred to herbivores and they use this to perform their metabolic activities and leaving the remaining energy as heat into the atmosphere.

How Do Our Activities Affect the Environment?

Any changes in environment affect us and our activities do affect environment around us. Depletion of ozone layer and waste disposal are such effects.

Ozone Layer and how it is Getting Depleted

The ozone layer protects life by hindering sun rays to fall directly on earth. Sun rays contain ultra violet rays which are harmful to life.

Ozone molecule is made up of three atoms of oxygen. Ozone is getting attacked by chlorine and an atom of oxygen combines with chlorine to form chlorine monoxide. The oxygen molecules left over cannot stop harmful ultra violet rays to reach earth.

Diseases like skin cancer and cataract are caused by exposure of ultra violet rays.

Managing the Garbage we produce

  1. The disposal of waste should be done scientifically. We need to implement different techniques of waste disposal, which depends upon the nature of the waste.
  2. Generally most solid wastes are buried in urban areas as landfills.
  3. Some solid wastes like plastics, metals, papers are recycled.
  4. Industrial wastes are treated in special plants and valuable wastes are recycled.
  5. Domestic wastes are used as manure for plants, including trees after compositing.
  6. Waste coming out of industries, such as metals can be melted and recycled into solid metal once again.