Carbon in the environment form the carbon cycle. For example, photosynthetic plants draw carbon dioxide from the atmosphere (or seawater) and build it into biomass, as in the Calvin cycle, a process of carbon fixation. Some of this biomass is eaten by animals, while some carbon is exhaled by animals as carbon dioxide. The carbon cycle is considerably more complicated than this short loop; for example, some carbon dioxide is dissolved in the oceans; if bacteria do not consume it, dead plant or animal matter may become petroleum or coal, which releases carbon when burned. Carbon can form very long chains
Supercritical carbon dioxide selectively dissolve organic compounds and assist the functioning of enzymes, s has been suggested as a potential solvent to support biological activity on Venus- or super-Earth-type planets. Environmentally beneficial, low-cost substitutes for rigid thermoplastic and fired ceramic are made using s as a chemical reagent. The s in these processes is reacted with the alkaline components of fully hardened hydraulic cement or gypsum plaster to form various carbonates. The primary byproduct is water. Supercritical carbon dioxide is used in the foaming of polymers. Supercritical carbon dioxide can saturate the polymer with solvent. Upon depressurization and heating the carbon dioxide rapidly