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autotroph |
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autotroph (ôt`ətrōf'), in biology, an organism capable of synthesizing its own organic substances from inorganic compounds. Autotrophs produce their own sugars, lipids, and amino acids using carbon dioxide as a source of carbon, and ammonia or nitrates as a source of nitrogen. Organisms that use light for the energy to synthesize organic compounds are called photosynthetic autotrophs; organisms that oxidize such compounds as hydrogen sulfide (H2S) to obtain energy are called chemosynthetic autotrophs, or chemotrophs. Photosynthetic autotrophs include the green plants, certain algae, and the pigmented sulfur bacteria (see photosynthesis photosynthesis (fō'tōsĭn`thəsĭs) ..... Click the link for more information. ). Chemotrophs include the iron bacteria, the nitrifying bacteria, and the nonpigmented sulfur bacteria (see chemosynthesis chemosynthesis, process in which carbohydrates are manufactured from carbon dioxide and water using chemical nutrients as the energy source, rather than the sunlight used for energy in photosynthesis . Most life on earth is fueled directly or indirectly by sunlight. ..... Click the link for more information. ). Heterotrophs heterotroph (hĕt`ərətrōf'), living organism that obtains its energy from carbohydrates and other organic material. ..... Click the link for more information. are organisms that must obtain their energy from organic compounds. autotroph [′ȯd·ō‚träf] (biology) An organism capable of synthesizing organic nutrients directly from simple inorganic substances, such as carbon dioxide and inorganic nitrogen. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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There are at present two schools: one supporting a heterotrophic origin of life and the other supporting an autotrophic origin of life. 1998) and Hoffman and Schrag (2000) propose a runaway albedo mechanism for initiating Snowball glaciation, where extreme cold and thick sea ice shut down all hydrological activity and chemical weathering such that marine autotrophic activity and organic carbon burial would cease. These compounds, which form an essential link in the chemical chain reactions of life, are created by autotrophic organisms--plants--that gather carbon and energy from the environment, carbon from carbon dioxide, and energy from sunlight. |
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