- the cycle by which plants through photosynthesis use atmospheric carbon dioxide to produce carbohydrates, which are in turn metabolized by animals to decomposition products that return carbon dioxide to the atmosphere
- a cyclic series of thermonuclear reactions in the interior of some stars, involving carbon as a catalyst and producing large quantities of energy by the transformation of hydrogen into heliumalso called car′bon-ni′trogen cycle
- A plant absorbs carbon dioxide, which is naturally found in the Earth’s atmosphere.
- The plant uses the carbon dioxide in order to grow – the process of photosynthesis is how the plant converts carbon dioxide into sugars, using the heat of the sun and water from the ground to help. A human may then harvest the plant and eat it.
- The human absorbs the carbon atoms in the plant into his own body as nutrition, and his body grows and thrives. It also breathes – and when he breathes out, the human releases carbon dioxide back into the atmosphere.
- If the human doesn’t harvest the plant and it dies in the first winter freeze, it will release carbon dioxide as it decomposes, just as the human will when one day he passes away.
The carbon cycle is defined as a series of naturally occurring processes where carbon is exchanged between organisms and the environment.
How the Carbon Cycle Works
Photosynthesis is an example of the carbon cycle.
- Physics See carbon-nitrogen-oxygen cycle.
- Ecology The combined processes, including photosynthesis, decomposition, and respiration, by which carbon as a component of various compounds cycles between its major reservoirs—the atmosphere, oceans, soil, rocks, and living organisms.
- The continuous process by which carbon is exchanged between organisms and the environment. Carbon dioxide is absorbed from the atmosphere by plants and algae and converted to carbohydrates by photosynthesis. Carbon is then passed into the food chain and returned to the atmosphere by the respiration and decay of animals, plants, and other organisms. The burning of fossil fuels also releases carbon dioxide into the atmosphere.
- A cycle of thermonuclear reactions caused by the absorption of protons by the nucleus of a carbon-12 atom, in which helium and isotopes of nitrogen, carbon, and oxygen are produced, and resulting in the regeneration of a carbon-12 atom so that the process can begin again. The carbon cycle is thought to be the source of significant amounts of energy in the Sun and other stars. Also called Bethe cycle
See also proton-proton chain