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I think that they're hawt!!!

Overview of cycle between autotrophs and heterotrophs. Photosynthesis is the main means by which plants, algae and many bacteria produce organic compounds and oxygen from carbon dioxide and water (green arrow).

An autotroph [α] is an organism that produces complex organic compounds (carbohydrates, fats, and proteins) from simple inorganic molecules using energy from light (by photosynthesis) or inorganic chemical reactions. They are able to make their own food and can fix carbon dioxide. Therefore, they do not utilize organic compounds as an an energy source or a carbon source. Autotrophs can reduce carbon dioxide (add hydrogen to it) to make organic compounds. The reduction of carbon dioxide, a low-energy compound, creates a store of chemical energy. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide.

Autotrophs are the producers in a food chain, such as plants on land or algae in water. Bacteria which derive energy from oxidizing inorganic compounds (such as hydrogen sulfide, elemental sulfur, ammonium and ferrous iron) are chemoautotrophs, and include the lithotrophs.



Green fronds of a maidenhair fern, a photoautotroph

Autotrophs are fundamental to the food chains of all ecosystems in the world. They take energy from the environment in the form of sunlight or inorganic chemicals and use it to create energy-rich molecules such as carbohydrates. This mechanism is called primary production. Other organisms, called heterotrophs, take in autotrophs as food to carry out functions necessary for their life. Thus, heterotrophs — all animals, almost all fungi, as well as most bacteria and protozoa — depend on autotrophs for the energy and raw materials they need. Heterotrophs obtain energy by breaking down organic molecules (carbohydrates, fats, and proteins) obtained in food. Carnivorous organisms ultimately rely on autotrophs because the nutrients obtained from their heterotroph prey come from autotrophs they consumed.


Some organisms rely on 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 or chemolithoheterotroph.

Evidence suggests that some fungi may also obtain energy from radiation. Such radiotrophic fungi were found growing inside a reactor of the Chernobyl nuclear power plant.[1]


Flowchart to determine if a species is autotroph, heterotroph, or a subtype
  • Autotroph
    • Chemoautotroph
    • Photoautotroph
  • Heterotroph
    • Chemoheterotroph
    • Photoheterotroph

Autotrophs are the producers in an ecosystem

Cultural Reference

See also



α. ^  The word autotroph comes from the Greek autos = self and trophe = nutrition, related to trephein = to make solid, congeal, thicken

Simple English

[[File:|thumb|200px|right|Green (from chlorophyll) fronds of a maidenhair fern: a photoautotroph]]


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


Autotrophs are needed in every food chains of all ecosystems. They take energy from the environment (sun light or inorganic sources) and use it to make other organic molecules that are used to carry out various biological functions such as cell growth or repairing broken tissue.


Plants and other organisms that carry out photosynthesis are phototrophs (or photoautotrophs). Bacteria that use inorganic compounds like hydrogen sulfide, phosphorus or iron are called chemoautotrophs. Other organisms, called heterotrophs, eat autotrophs.

There are some species that need organic compounds as a source of food, but are able to use light as a source of energy. These are not autotrophic, but heterotrophic. A mixotroph is a (micro)organism that can use a mix of different sources of energy and carbon.

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