35. NCERT Exemplar XVII

 

The percentage of gases like oxygen, nitrogen and carbon dioxide remains almost constant in the atmosphere. This constant percentage is maintained by their constant flow through photosynthesisnutrient cyclesnitrogen fixation.

Various nitrogen fixationphotosynthesisnutrient cycles like the oxygen, carbon and nitrogen cycle continuously operate in nature by constant interaction between biotic and abiotic components of the biosphere. This interaction consists of a transfer of matter and energy between different components of the mesospherelithospherebiosphere.

The environment acts as a reservoir for these gases and living organisms continuously take up gases from it. These gases are further returned to the environment by various processes like respiration, combustion, evaporationrespiration, evaporation, decompositionrespiration, combustion, decomposition, etc., thereby maintaining a constant percentage. Any major change in the percentage of these gases can disrupt the ecosystem and adversely affect the living components of the bio-systemeco-systemair-system.