Define and Discuss on Carbon Cycle - QS Study
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Carbon cycle: The carbon cycle is the circulation and transformation of carbon back and forth between living things and the environment.

Description of carbon cycle.

Three main sources of carbon are –

  1. Atmosphere
  2. Carbonate rocks of the earth surface
  3. Coal and petroleum

Carbon from the sources stated above performs the carbon cycle by the following ways:

  • Atmospheric carbon dioxide (CO2) is synthesized by plants as chemical substance (Glucose). By photosynthesis plants use this glucose in preparing other chemical substances. Thus plants, through photosynthesis, convert CO2 gas from the biotic environment to organic compounds by photosy
  • Animals take plants as their food and gave out CO2 during respiration that goes back to atmosphere.
  • Plenty of carbon remains in the timbers as stored form. A great deal of carbon is present in natural gas and oils Coal, oil and natural gas are called fossil fuels. Atmospheric carbon has been depositing as fossil fuel in the form of coal, oil and natural gases for millions of years. This stored carbon again comes back to the atmosphere as carbon dioxide during combustion.
  • Atmospheric CO2 reacts with rain water to form carbonic acid and CO2 also converts CaO, CaCO3 to hard water. Towards the sea bottom thousand feet of lime stones are stored which may come up due to t earth surface as a result of geological uplift. This limestones gradually being depleted physically or chemically which come back to the atmosphere and again take part in the carbon cycle.

Therefore it is seen that photosynthesis brings up carbon from the abiotic environment and this carbon fixes in the organic molecules. Then cell respiration, combustion and erosion return this carbon to the abiotic environment again.