The Carbon Cycle
The carbon cycle is based upon carbon dioxide. Most of the carbon is found in the atmosphere ( about 0.03% ). The carbon cycle has a very fast rate of recycle because many organism have a high demand for the carbon. These organism are plants, bacteria, and algae ( phototrophs and lithotrophs ). The reason for this need is their photosynthetic activities of these organism. It is these photosynthetics activities that results in carbon fixation. The organism that do this fixation are the photoautotrophs like cyanobacteria, green plants, and algae, and green and purple sulfur bacteria.
All heterotropic organism; some bacteria, protists, fungi, and animals do not have the ability to photosynthesize. It is for this reason they must obtain their carbon indirectly from organism that can fix it. The heterotrophs consume these photoautotrophs the organic compounds are digested and resynthesized. The carbon atoms are transferred from organism to organism,up the food chain.
Carbon compounds are able to be broken down due to respiration and fermentation. This will then recycle the carbon dixoide into the atmosphere. Some carbon may be held for a longer period of time in the bodies of organism. But when the organism dies and decomposition occures the carbon is again released into the atmosphere. Carbon is also stored in rocks, like limestone and is dissolved in the oceans as carbonate ions. Carbon is also stored in minerals as coal and petroleum. Burning these minerals releases the carbon dioxide. There is evidence of an increase of carbon dioxide as the result of burning of carbon dioxide as the result of burning fossil fuels. This is one reason some scientists believe that the warming of the earth is caused by carbon dioxide of the earth is caused by carbon dioxide acting as a greenhouse around the earth.
Definitions:
* Carbon fixation or Calvin Cycle: The cycle of incorporating carbon dioxide from the air into organic molecules present in chloroplasts. The initial incorpation of carbon into organic compounds ( carbon fixation ). The Calvin cycle then reduce fixed carbon to carbohydrate by addition of electrons. This reducing power is needed to energized electron in the light reaction.
* Light reaction: This is photophosphorylation the production of ATP by photosynthesis.