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Air-The Breath of Life


AIR-THE BREATH OF LIFE


  • Air that surrounds the earth constitutes the atmosphere. It is defined as a mixture of various gases in their appropriate concentration as required for the survival of living organisms.

Composition of air

S.No.

Gas

Percentage (%)

1

Nitrogen

78

2

Oxygen

21

3

Carbon dioxide

0.03

4

Water vapours

Varies

5

Other gases

Traces (overall 0.1% )

  • In planets such as Venus and Mars, where no life is known to exist the major component of the atmosphere is found to be carbon dioxide (95-97%).
  • Life is possible on earth because the level of oxygen and carbon dioxide is maintained by various processes.
  • Oxygen is a respiratory gas and is inhaled by aerobic organisms for the oxidation of glucose. It is also consumed in the processes like combustion. During these processes, carbon dioxide is released in air.
  • This carbon dioxide is used/fixed by the plants in photosynthesis for synthesizing glucose and during this the oxygen is released in air which is further consumed by living organisms. Carbon dioxide is also used by many organisms to synthesize their shells (Calcium carbonate).
  • Similarly the level of other gases is also balanced in environment by the interaction between living and non living things.