ECOSYSTEM
It is a system of interaction between living and non-living components of environment.
It is of two types
Natural Ecosystem
❖ It is governed by natural conditions
❖ Terrestrial Natural Ecosystem : eg. Forest, grassland and desert.
❖ Aquatic Natural Ecosystem : eg. Freshwater (Pond, Pool, River, stream and Marine water Ocean and sea.)
Artificial Ecosystem
❖ It is governed by man.
❖ Also known as man made ecosystem.
❖ Eg. Cropland ecosystem and aquarium.
Components of an Ecosystem:-
(1) Biotic
-Living organisms are included.
-Biotic components can further be divided into:-
• Producers (Trophic level 1)
• Consumers
• Decomposers
(2) Abiotic
-Non living organisms are included.
PRODUCERS
❖ All green Plants that can prepare their own food and are called Producers.
❖ Also called as Autotrophs.
CONSUMERS
❖ They are organisms which consume other organisms or their products.
❖ They depend on producers for their food directly or indirectly.
❖ Consumers can be of 4 types:-
• Herbivores - E.g Deer, cow.
• Carnivores- E.g Tiger, Lion
• Parasite- E.g Plasmodium
• Omnivores- E.g Bear, Crow
HERBIVORES
❖ These are primary consumers
❖ They get their food by eating the producers directly.
❖ They are at 2nd trophic level.
CARNIVORES
❖ These are Secondary or Tertiary consumers.
❖ They eat the flesh of herbivores.
❖ Eg → Owl, Peacock, Tiger, Lion etc.
❖ The Carnivores which are not preyed upon further are called top carnivores eg. Lion.
PARASITE
❖ They live and feed on the host body.
❖ They depend on its host for survival and often harms it.
❖ Eg. Plasmodium, Tapeworm, etc.
OMNIVORES
❖ They feed on both plants and animals’ flesh.
❖ Eg. Humans, Crow, Bear, etc.
DECOMPOSERS
❖ They are also known as Saprotrophs.
❖ They feed on dead and decaying food.
❖ Fore eg. Microorganisms like fungi and bacteria which break down or decompose the dead plants & animals.
Importance of Decomposers
❖ They clean up the environment
❖ They add nutrients back to soil or water, so that producers can use them to grow and reproduce.
❖ The fix the nitrogen in the soil.
❖ They are ‘housekeeper’s of an ecosystem.
FOOD CHAIN
The chain of organisms which involves transfer of energy from one trophic level to next tropic level is called food chain. The flow of food or energy in an ecosystem is called food chain.
Trophic levels
• Those organisms which join the food chain are termed as Trophic levels.
• There are four trophic levels present in the ecosystem because level of energy decreases during the flow of energy from one trophic level to another trophic level.
First trophic level [T1] → Producers
Second trophic level [T2] → Primary Consumers.
Third trophic level [T3] → Secondary Consumers.
Fourth trophic level [T4] → Top Consumers.
Terrestrial Food chains :
❖ Plants → Rat → Snake → Hawk
❖ Plants → Frog → Snake → Peacock
Aquatic food chains :
❖ Phyto planktons → Zooplanktons → Small fish → Large fish
❖ Algae → Small fish → Large fish → Crocodile.
Difference between Food chain and Food Web
Food Chain
❖ A straight single path of transfer of food energy in the ecosystem.
❖ Consists of 3-4 trophic levels.
❖ Does not improve the adaptability and competitiveness of organisms.
Food web
❖ It consists of a large number of interconnected food chains
❖ Consists of numerous trophic levels.
❖ Improve the adaptability and competitiveness of organisms.
FLOW OF ENERGY
❖ Energy is used and then transferred to next trophic level in a food chain. This is called flow of energy.
❖ Only 1% of the solar energy is captured by green plants and they use some of it to perform photosynthesis and some is released as heat into the atmosphere.
❖ The remaining energy is chemical energy which is stored in the plants as ‘Carbohydrates.
❖ This stored energy is transferred to next trophic level when plants are eaten up by herbivores.
❖ Herbivores also store some of this energy, which will be transferred to carnivores.
Ten percent Law
According to Ten percent law, 90% of the captured energy is lost as heat. And only 10% is available for the next level.
ENVIRONMENTAL PROBLEMS
Pollution :
Pollution is one of the major environmental problem these days. The term ‘Pollution’ means an undesirable change in the physical, chemical or biological characteristics of our air, land & water that will harm fully affect the human life.
Green House Effect :
When there is increase in CO2 concentration, the deposition of CO2 gas presents the heat from
radiating out from the earth. This is called Green house effect which leads to global warming.
The average global temperature on earth has increased due to green house gases (CO2 & CH4).
OZONE LAYER DEPLETION
Ozone layer protects the earth from harmful UV rays. It is present in the stratosphere layer of atmosphere (15 to 30 km above the
Earth’s surface).
Formation of Ozone layer :
• When UV radiations from sun strike the O2 molecules, it causes splitting of O2.
• Oxygen molecules react with energy atoms in the upper atmosphere to form Ozone (O3).
• Most of ozone is formed at equator where there is maximum sunshine but with winds it travels at high altitude and gets accumulated in stratosphere.
Causes of Ozone layer Depletion
1. Chlorofluorocarbon : All ozone depleting chemicals contain chlorine and Bromine. CFCS are highly volatile and non combustible so they are very quickly evaporated can start depleting ozone layer.
2. Global Warming : Due to global warming and green house effect most of heat is trapped in troposphere.
3. Nitrogenous Compound : Nitrogenous compounds like NO, N2O and NO2 which are emitted by human activities are considered to
be responsible for the depletion of Ozone layer.
Effects of Ozone layer depletion :
❖ UV radiations can severely damage eye lens and cornea of eye. It can cause cataract and Blindness.
❖ Exposure to UV radiations can also cause Skin Cancer.
❖ Exposure to UV radiations can cause Breast Cancer and Leukemia.
❖ It can also result in suppression of immune response.
In 1989, the United Nation Programme (UNEP) succeeded in forging an agreement to freeze CFC production at 1986 levels.
Ban on the usage of synthetic chemicals like CFCs, aerosols (which are used in refrigerants and in fire extinguisher) can helps in saving
the ozone layer.
BIOLOGICAL MAGNIFICATION
Gathering of various harmful substances like pesticides, DDT and biphenyls at different levels of a food chain is called Biological Magnification.
It increases the concentration of toxic substances in organisms at higher trophic levels.
For eg. DDT was a pesticide which was consumed by many organisms of the lower trophic level in aquatic ecosystem (fish). Birds accumulated sufficient amounts of DDT that ate those fish. This caused fragility in the egg shell of these birds. There was increased egg breakage during nesting, which adversely affected birds population. The use of DDT was banned in US in the 1970 s.
Measures to control the changes in the environment include applying the R’s (Reuse, Recycle and Reduce), afforestation and saving
endangered animals.
Modes of waste Disposal
1. Recycling
2. Preparation of Compost
3. Incineration
4. Landfill
5. Sewage treatment
1. Recycling : It is the process of collecting waste materials and turning them into new products.
Example : Newspapers and paper towels, recovered plastic in carpenting and park benches.
2. Preparation of Compost : A pit is dug into the ground in which domestic or kitchen waste can be added and can be converted into compost.
3. Incineration : The burning of a substances at high temperature (more than 1000°C) to form ash is called incineration. It is used to destroy household waste, chemical waste and biological waste.
4. Landfill : The waste can also be disposed by putting it in low, lying areas of ground and covering it with earth is called landfill.
5. Sewage Treatment : The dirty drain water containing urine and faces which is carried from our homes by sewers or underground pipes is called sewage.
The treatment of sewage produces clean water which is discharged into the river.
MANAGING THE GARBAGE WE PRODUCE
Wates from household is called Garbage. This garbage includes left over food, fruits and vegetable peels, fallen leaves of plotted plants
waste paper, also unwanted plastic objects (such as plastic bottles, polythene bags, toys etc) glass articles like glass bottles, broken window planes etc) metal articles like aluminium foils, rusted iron grills etc.
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