Class 10th Science Notes

Our Environment

Table of Contents

Q. Environment:

Everything that surround us is environment. It includes both biotic and abiotic components. Interaction between these biotic and abiotic component form an ecosystem.

Q. Components of ecosystem:

Biotic components: It includes three types of organisms

Producers: All green plants blue green algae can produce their food from inorganic substances using light energy (photosynthes) therefore are green plants are called producers.

Consumers: They are organisms which consume other organisms or their product as their food . All animal belongs to this category. The consumers depend upon producers for their food directly or indirectly.

Decomposers: Fungi and bacteria which breaks down (decompose) dead plants, animals complex compounds into the simpler one and clean the environment. Decomposers are also called reducers.

Importance of Decomposers: The composers help in disposing of wastes and dead bodiesbof plants and animals . Therefore they clean the environment and create space for living organisms

Abiotic components: These are non living components of an ecosystem. These include the physical environment such as water, Air,land,Light, Temperature etc.

Food chain: The sequence of living organisms in a community in which one organism consumes another organism to transfer food energy is called a food chain. Eg

Grass—> Insect—–> Frog—–> Eagle

Q. Food web: The interconnected food chains operating in an ecosystem which establishs a network of relation between various species are called a food web.

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

Q. Flow of energy between tropic levels:

*Green plants capture 1% of sunlight and convert it into food energy.

*10% Law : Only 10% of energy is transferred to the next tropic level the remaining 90% energy is used in life processes ( Digestion, growth, reproduction etc) by present tropic level.

*Due to this gradual decrease in energy, food chains contain 3-4 tropic levels.

Q. Biological magnification:

The concentration of harmful chemicals increases with every next topic level in a food chain. This is called biological magnification.

Q. Ozone layer:

Ozone layer is a protective blanket around the earth which absorbs most of the UV (ultraviolet) radiations of the sunlight, Thus protecting living beings from many health hazards such as skin cancer, cataract, destruction of plants etc.

*Ozone layer is present at the higher levels of atmosphere that is (Stratosphere) it is a deadly poison 8 ground level.

Formation of ozone molecule:

*The high energy (ultraviolet) UV radiations breakdown the O2 molecule into free oxygen atoms.

*These oxygen atoms then combine with oxygen O2 molecule to form the ozone molecule.

Q. Depletion of ozone layer:

*The decrease in the thickness of ozone layer over Antarctica was first observed in 1985 and was termed as ozone hole.

*This decrease was linked to excessive use of synthetic chemical like chlorofluorocarbons (CFC,s) which are used in refrigerators,AC’s, fire extinguishers etc.

*United nations environmental program (UNEP) succeeded in forging an agreement to stop CFC production at 1986 levels (Kyoto protocol) by all countries.

Q.Biodegradable Substances:

Substances which can be decomposed by the action of microorganisms are called biodegradable wastes eg vegetables, peels, fruits, cotton, jute, Dung, paper etc.

Non biodegradable substances:

Substances which cannot be decomposed by the action of microorganism are called non biodegradable substances/ polythene, glass, metals, plastic, synthetic fibre, pesticides etc.


Class 1oth Science Notes,
Class 1oth Science Our Environment Question Asnwers

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