Q.Explain 'Carbon cycle'.

Carbon cycles between the atmosphere and living organisms via photosynthesis (fixation) and respiration/decomposition/combustion (release).

The carbon cycle is the biogeochemical cycle describing the continuous movement of carbon through the atmosphere, biosphere and physical environment. Producers (green plants and algae) fix atmospheric CO2 into organic carbon compounds via photosynthesis. This carbon is transferred along the food chain as herbivores eat plants and carnivores eat herbivores. Respiration by plants, animals and microbes releases CO2 back into the atmosphere. When organisms die, decomposers (bacteria and fungi) break down their organic remains, releasing further CO2 into the atmosphere and soil. Combustion of wood, and of fossil fuels such as coal and petroleum (themselves formed from ancient buried organic carbon), is another major route by which carbon returns to the atmosphere. There is also a continuous two-way exchange of dissolved CO2 between the atmosphere and the oceans, where it may be taken up by aquatic producers or deposited as carbonate sediments. This cycl …

Carbon moves from the atmosphere into living organisms via photosynthesis and returns via respiration, decomposition and combustion.

The carbon cycle describes the continuous circulation of carbon between the atmosphere, living organisms and the physical environment. Producers (green plants) fix atmospheric CO2 into organic compounds through photosynthesis. This fixed carbon is transferred through the food chain as herbivores consume plants and carnivores consume herbivores. Carbon is returned to the atmosphere as CO2 through the respiration of plants, animals and microorganisms. When organisms die, decomposers (bacteria and fungi) break down the organic matter, releasing more CO2 back into the atmosphere as well as into the soil. Combustion of wood and fossil fuels (coal, petroleum, formed from ancient buried organic carbon) is another major pathway returning carbon to the atmosphere. Additionally, there is a continuous exchange of CO2 between the atmosphere and the oceans, …