Carbon source
In biology, carbon source refers to the molecules used by an organism as the source of carbon for building its biomass. A carbon source can be an organic compound or an inorganic compound. Heterotrophs needs organic compounds as source of carbon and source of energy, while autotrophs can use inorganic compounds as carbon source and an abiotic sources of energy, as light (photoautotrophs) or inorganic chemical energy (chemolithotrophs). The biological use of carbon is part carbon cycle, where it starts from an inorganic source of carbon, such as carbon dioxide, that passes through the process of carbon fixation