28 October 2011

10th physics Chapter - 15 Our Environment POINTS TO REMEMBER


POINTS TO REMEMBER:
1) ECOLOGY – The study of the interaction of living organisms with each other and their surroundings is called ecology.

2) ENVIRONMENT – Everything that surrounds organisms and influences its life.

a) Biotic components of environment --- The living organisms .e.g. Plants and animals.

b) Abiotic components of environment --- The nonliving components  like water, air, light, etc.
It is the sum total of all external conditions and influences that affect the life and the development of organisms i.e.,it includes all the biotic and abiotic factors.

3) ECOSYSTEM – All interacting organisms in an area together with the nonliving constituents of environment. (Functional unit of an environment)
Functions of ecosystem:-
a) Flow of energy         b) Cycling of nutrients(bio-geo chemical cycles).

4) PRODUCERS --- They make the energy from sunlight available to the rest of the ecosystem.

5) CONSUMERS --- Animals can not manufacture their own food. They are called consumers.

6) BIODEGRABLE ---- Substances that are broken down by the action of bacteria or other saprophytes. e.g. – Paper.

7) NONBIODEGRABLE --- Substances that are not broken down by the action of bacteria or saprophytes. e. g. Plastic.

8) FOOD CHAIN -The process of one organism eating the other. 
GRASS-- > GRASSHOPPER-- >; FROG -> SNAKE
Importance of food chain
1.It helps in transfer of food energy from one organism to another.
2.It is a pathway for the flow of energy.
3. It helps in understanding the interdependence amongst different organisms.
Trophic levels are the various steps in the food chain .
Producers --- first trophic level                   Herbivores --- second trophic levels
Carnivores --- third trophic level               Top carnivores --- fourth trophic level

9) FOODWEB ----- It is a network of food links between populations in a community.

10) FLOW OF ENERGY -Ten percent law Energy available at each successive trophic level is 10 % of the previous level. (Lindeman 1942)
The law states that, “ only a 10 % amount of the total available energy is transferred from one trophic level to the next. The rest 90% of energy is used up or lost to the surrounding.”

11) BIOLOGICAL MAGNIFICATION --- Progressive accumulation of non- biodegradable waste at various trophic levels of food chain.

12. Differences between food chain & food web 
Food chain
1. The process of eating & being eaten to transfer food energy.  2. It forms a part of food web.
3. It has limited populations.

Food web

1. It is a system of interconnected food chains. 2. It contains many food chains.
3. It has several populations of different species.
13. HOW DO OUR ACTIVITIES AFFECT THE ENVIRONMENT?

Two major problems:-
a) Depletion of ozone layer
b) Disposal of waste

Good ozone and bad ozone
The thick blanket of ozone layer in the atmosphere which forms a protective cover & prevents UV radiation from reaching the earth‘s surface. This is called good ozone and is found in the stratosphere.

Ozone when present in the troposphere act as a pollutant . This harmful ozone is called bad ozone.
14. Depletion of ozone layer : The ozone layer protects all the organisms from the harmful ultra violet rays.
Ozone depleting substances: CFCs, N2O, CH4 , CCl4
These chlorine containing compounds are used in:  Aerosols, solvents, refrigerants and fire extinguishers.  Ozone hole developed over Antarctica.

15. Effects of ozone depletion on human health- Due to depletion of ozone layer UV radiations reaches the earth and cause:
i) skin cancer            ii) increased chances of cataract 
 iii) suppression of immune system . Managing the garbage we produce

16. Reasons for large production of garbage
i) Improvement in life style
ii) Changes in attitude (more things become disposable)
iii) Population explosion
iv) Changes in packaging (non -biodegradable)
10th Science – Chapter: Our Environment (Physics)
10th Science - Our Environment: Summative assignments
10th Chapter: Our Environment Questions Paper for FA-III
10th Science: Chapter: Our Environment HOTS Questions
10th Chapter: Our Environment: Gist of Lesson

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