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)
