What is Primary production?
[[File:Seawifs global biosphere.jpg|280px|thumb|Global oceanic and terrestrial photoautotroph abundance, from September 1997 to August 2000. As an estimate of [[autotroph]] biomass, it is only a rough indicator of primary-production potential. From the SeaWiFS Project, [[NASA]]/Goddard Space Flight Center and ORBIMAGE.]] '''Primary production''' is the synthesis of [[organic compound]]s from [[carbon dioxide]]. It occurs by [[photosynthesis]]. Light is its source of energy. It also occurs through [[chemosynthesis]], which uses the oxidation or reduction of inorganic [[chemical compound]]s as its source of energy. Almost all [[life]] on Earth relies directly or indirectly on primary production. The organisms responsible for primary production are known as ''primary producers'' or [[autotroph]]s. They form the base of the [[food chain]]. On land, these are mainly [[plant]]s; in the sea (or lakes) [[algae]] do this role. Also, there are shallow water oxygen primary producers like [[sea grass]]. By photosynthesis or chemosynthesis, energy is used to make complex organic molecules from simpler inorganic compounds (such as carbon dioxide (CO<sub>2</sub>) and water (H<sub>2</sub>O). The following are simplified equations of photosynthesis (top) and (one form of) chemosynthesis (bottom): ::: CO<sub>2</sub> + H<sub>2</sub>O + ''light'' → CH<sub>2</sub>O + O<sub>2</sub> ::: CO<sub>2</sub> + O<sub>2</sub> + 4 H<sub>2</sub>S → CH<sub>2</sub>O + 4 S + 3 H<sub>2</sub>O [[Category:Plants]] [[Category:Photosynthesis]]