Autotroph

autotroph Any organism capable of making its own food. It synthesizes its own organic food sub­stances from inorganic compounds using sources such as carbon dioxide, ammonia, and nitrates. Most plants and many protists and bacteria are autotrophs. Photoautotrophs can use light energy to make their food (photosynthesis). Chemoautotrophs use chemical energy to make their food by oxidizing compounds such as hydrogen sulfide (H₂S). Heterotrophs are organisms that must obtain their energy from organic compounds.