Autotroph

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Green (from chlorophyll) fronds of a maidenhair fern: a photoautotroph
Green (from chlorophyll) fronds of a maidenhair fern: a photoautotroph
Flowchart to determine if a species is autotroph, heterotroph, or a subtype
Flowchart to determine if a species is autotroph, heterotroph, or a subtype

An autotroph (from the Greek autos = self and trophe = nutrition) is an organism that produces complex organic compounds from simple molecules.

Autotrophs are a vital part of the food chains of all ecosystems. They take energy from the environment (sun light or inorganic sources) and use it to process carbon-based and other organic molecules that are used to carry out various biological functions such as cell growth.

Plants and other organisms that carry out photosynthesis are phototrophs (or photoautotrophs). Bacteria that utilize the oxidation of inorganic compounds such as hydrogen sulfide, ammonium or ferrous iron as an energy source are chemoautotrophs (some are known as lithotrophs). Other organisms, called heterotrophs, utilize autotrophs as food to carry out these same functions.

There are some species of organisms that require organic compounds as a source of carbon, but are able to use light or inorganic compounds as a source of energy. Such organisms are not defined as autotrophic, but rather as heterotrophic. An organism that obtains carbon from organic compounds but obtains energy from light is called a photoheterotroph, while an organism that obtains carbon from organic compounds but obtains energy from the oxidation of inorganic compounds is termed a chemoheterotroph.