∞ generated and posted on 2016.01.29 ∞
Substance taken up by organisms from which organic molecules are primarily built in the course of anabolism.
Figure legend: For building up macromolecules, organisms need a source of organic carbon, which comes from carbon dioxide with autotrophs – which is an inorganic form of carbon that must be converted to an organic form prior to use – and organic molecules derived from other organisms for heterotrophs.