Short notes: Our environment

Ecosystem

This is a system of interdependencies among various living beings and non-living things in a given habitat.

 

Components of Ecosystem

An ecosystem has two types of components, viz. biotic component and abiotic component.

Abiotic Component

All the non-living things make the abiotic component of an ecosystem. Air, water and soil are the abiotic components.

  • Air provides oxygen (for respiration), carbon dioxide (for photosynthesis) and other gases for various needs of the living beings.
  • Water is essential for all living beings because all the metabolic activities happen in the presence of water.
  • Soil is the reservoir of various nutrients which are utilised by plants. Through plants, these nutrients reach other living beings.

Biotic Component

All living beings make the biotic component of an ecosystem.

  • Green plants play the role of producers; because they prepare the food by photosynthesis.
  • Animals and other living beings play the role of consumers; because they take food (directly or indirectly) from plants.
  • Bacteria and fungi play the role of decomposers; as they decompose dead remains of plants and animals so that raw materials of organisms can be channelized back to the environment.

 

Food Chain

A food chain is a simple representation of transfer of energy from the sun to different biotic components of an ecosystem. Sun is the ultimate source of energy. Green plants convert solar energy into chemical energy during photosynthesis. When an animal takes food, this energy is supplied to the animal and the process goes on. A simple food chain can be shown as follows:

Producer → Primary Consumer → Secondary Consumer

Food Web

Real life cannot be as simple as a food chain shown above. In any ecosystem, there can be many food chains which are interlinked at various levels. Thus, many food chains form a network which is called food web.

Transfer of Energy through a food chain

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Balance in the Ecosystem

  • There is a delicate balance in an ecosystem; as far as number of organisms at a particular trophic level is concerned.
  • An increase or decrease in population of any organism can disturb this balance.
  • Let us take a hypothetical example to understand this. If all the deer are killed in a jungle, the lions would be left with no food.
  • This would endanger the existence of lions. Once the lions and deer would be finished, it would result in population explosion of green plants.
  • If all the lions die in a jungle, it would create another problem.
  • Since no lion would be left to kill the deer, the population of deer would increase substantially.
  • This will finish off all the green plants and finally even the deer would be left with no food for them.

Biodegradable Substance

Substances which can be decomposed by microorganisms are called biodegradable substances. All the organic substances are biodegradable.

Non-biodegradable

Substances which cannot be decomposed by microorganisms are non-biodegradable. All inorganic substances are non-biodegradable. Many synthetic substances are also non-biodegradable.

Ozone Layer Depletion

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Ozone layer is also known as stratosphere. When ultraviolet radiations act on oxygen, the oxygen gets converted into ozone.

ozone oxygen conversion

Effect of CFCs

  • Emissions of CFCs to date have accounted for roughly 80% of total stratospheric depletion.
  •  Although CFC molecules are several times heavier than air, winds mix the atmosphere to altitudes far above the top of the stratosphere much faster than molecules can settle according to their weight.
  • CFCs are insoluble in water and relatively unreactive in the lower atmosphere but are quickly mixed and reach the stratosphere regardless of their weight.
  • When UV radiation hits a CFC molecule it causes one chlorine atom to break away.
  • The chlorine atom then hits an ozone molecule consisting of three oxygen atoms and takes one of the oxygen molecules, destroying the ozone molecule and turning it into oxygen.
  • When an oxygen molecule hits the molecule of chlorine monoxide, the two oxygen atoms join and form an oxygen molecule. When this happens, the chlorine atom is free and can continue to destroy ozone.
  • Naturally occurring chlorine has the same effect in the ozone layer, but has a shorter life span.

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Problems of Waste Disposal

  • During our day to day activities, we produce lot of waste. While some of the waste is biodegradable, a large chunk is composed of non-biodegradable substances.
  • Plastic waste is a serious concern because plastic is non-biodegradable. We need to respect our environment and find out ways to reduce the burden on our environment.

 

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