Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Phototrophs are organisms that obtain energy from light to synthesize organic compounds. They play a crucial role in converting solar energy into chemical energy.
5 Must Know Facts For Your Next Test
Phototrophs use chlorophyll or similar pigments to capture light energy.
They can be found in both prokaryotic and eukaryotic forms, including cyanobacteria and plants.
Phototrophs are essential components of the biogeochemical cycles, particularly the carbon and oxygen cycles.
There are two main types: photoautotrophs and photoheterotrophs, differentiated by their sources of carbon.
Photosynthesis in phototrophs involves light-dependent reactions (producing ATP) and light-independent reactions (fixing CO2).
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Related terms
Photoautotroph: Organisms that use light as an energy source and carbon dioxide as a carbon source.
Photoheterotroph: Organisms that use light as an energy source but require organic compounds for their carbon.
Chemoautotroph: Organisms that obtain energy from chemical compounds rather than light.