OUR ENVIRONMENTMADE BY-Shayan Hashmi

10th

class

1. Effect of adding waste to

the environment :-

Human activities produce a lot of waste materials which

are thrown away into the environment. These wastes cause

pollution of air, water and soil.

The waste materials produced are of two main types. They

are biodegradable wastes and non biodegradable wastes.

1) Biodegradable wastes :- are wastes which are

decomposed into harmless substances by microorganisms.

Ex :- vegetables, fruits, pulses, cereals, cotton, jute, wool,

wood, leather, paper, animal dung, animal bones etc.

ii) Non biodegradable wastes :- are wastes which are not

decomposed by microorganisms.

Ex :- polythene bags, plastics, synthetic fibers, glass,

metals, synthetic rubber, insecticides, pesticides etc.

EXAMPLE OF

BIODEGRADEABLE WASTE EXAMPLE OF NONBIODEGRADEABLE WASTE

2. Ecosystem and its components :-

a) Ecosystem :- An ecosystem consists of all the living organisms in an

area along with the non living components and their interaction.

There are different types of ecosystems. They are :-

i) Natural ecosystems :- like forests, deserts, grass lands, mountains,

ponds, lakes, rivers, oceans etc.

ii) Artificial ecosystems :- like gardens, parks, crop fields, aquarium, zoo etc.

b) Components of an ecosystem :-An ecosystem consists of two main components. They are

biotic and abiotic

components.

i) Biotic components :- are the living components like plants, animals and

microorganisms. They consist of producers, consumers and decomposers.

Producers :- are green plants which produce food by photosynthesis.

Consumers :- are herbivores which get their food directly from plants,

carnivores which get their food indirectly from plants and omnivores which

get their food directly or indirectly from plants.i)Decomposers :- are microorganisms which decompose dead plants and

animals. They decompose complex organic substances into simple inorganic

substances in the soil which are again used by plants.

ii) Abiotic components :- are the non living components like air, water, soil,

minerals, sunlight , temperature, wind etc.

Food chain :-A food chain is the flow of food energy from one organism to the next and to the next and

so on. They usually start with a producer (plants) and end with a carnivore. In a food

chain an organism gets food from one group of organisms.

eaten by eaten by

Eg:- Grass Deer Lion

(producer) (primary consumer) (secondary consumer)

eaten by eaten by eaten by

Grass Insects Frog Snake

(producer) (primary consumer) (secondary consumer) (tertiary consumer)

eaten by eaten by eaten by eaten by

Grass Moth Frog Snake Hawk

(producer) (primary consumer) (secondary consumer) (tertiary consumer) (quarternary

consumer)

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Food web is a group of several interconnected food chains. In a food web

an organism gets food from more than one group of organisms.

Food web :-

4) Tropic levels :-Each step in a food chain where transfer of food energy takes place is called tropic level.

The first tropic level consists of producers.

The second tropic level consists of primary consumers.

The third tropic level consists of secondary consumers.

The fourth tropic level consists of tertiary consumers.

Since the transfer of food energy decreases at every tropic level, the number of tropic levels

are limited and do not exceed four or five.

Green plants (producers) absorb about 1% of solar energy falling on the leaves and stores it as food energy

during photosynthesis.

During the transfer of food energy from one tropic level to the next, 90% of the energy is lost to the

environment and only 10% is transferred to the next tropic level. So there is a decrease in the amount of food

energy transferred at every tropic level by 10%. This is known as the 10% law.

Energy flow in tropic levels :-

Biological magnification

Harmful chemicals like insecticides and pesticides which are used to protect crops from insects

and pests are absorbed by plants and enter the food chain. Since these chemicals are non

biodegradable, they get accumulated at every tropic level and their concentration increases. Since

human beings occupy the highest tropic level, the concentration of these harmful chemicals is

maximum in our bodies.

The increase in concentration of harmful chemicals in the bodies of organisms at higher tropic

levels is called biological magnification.

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Human activities affect the environment :-a) Depletion of ozone layer in the atmosphere :-

Ozone molecule contains three oxygen atoms (O3). At higher levels in the atmosphere the UV

radiation splits some oxygen molecules (O2) into free oxygen atoms which combines with oxygen

molecules (O2) to form ozone. It is highly poisonous.

UV radiation

O2 O + O

O2 + O O3

The ozone layer present in the higher layer of the atmosphere protects the earth from the

harmful UV radiation from the sun. UV radiation causes skin cancer in humans.

The ozone layer is being damaged by the use of chemicals like chloro fluoro carbons (CFCs)

used in refrigerators and fire extinguishers. So the use of CFCs is now being reduced to protect

the ozone layer.

THE END