Carbon Cycle

Name:
Carbon Cycle
Detailed information:
(1) The progress of carbon from air (carbon dioxide) to plants by photosynthesis (sugar and starches), then through the metabolism of animals to decomposition products that ultimately return it to the atmosphere in the form of carbon dioxide. (2) One of the processes by which the sun and other self-luminous astronomical bodies are thought to derive their energy. The net process is the combination (fusion) of four hydrogen atoms to form helium. The carbon cycle involves successive additions of hydrogen atoms, followed by β decay, to an initial carbon-12 atom until a final step is reached in which the new nucleus breaks down to a helium atom and regenerated carbon-12. The carbon thus functions as a catalyst for the process. At the temperatures prevailing in the sun, all atoms are stripped of their electrons and the reaction is between the nuclei of the atoms (thermonuclear reaction). Symbolically the set of reactions is written ¹²C + ¹H → ¹³N, ¹³N → ¹³C + e; ¹³C + ¹H → ¹⁴N, ¹⁴N + ¹H → ¹⁵O. ¹⁵O→ ¹⁵N +e, ¹⁵N→ ¹²C + ⁴He.See Fusion.