Energy Source


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•  Most ecosystems rely on a supply of energy from sunlight

•  Light energy is converted to chemical energy in carbon compounds by photosynthesis

All green plants, and some bacteria, are photoautotrophic – they use sunlight as a source of energy

  • This makes light the initial source of energy for almost all communities
  • In a few ecosystems the producers are chemoautotrophic bacteria, which use energy derived from chemical processes

Light energy is absorbed by photoautotrophs and is converted into chemical energy via photosynthesis

  • This light energy is used to make organic compounds (e.g. sugars) from inorganic sources (e.g. CO2)
  • Heterotrophs ingest these organic compounds in order to derive their chemical energy (ATP)
  • When organic compounds are broken down via cell respiration, ATP is produced to fuel metabolic processes

Overview of Photosynthesis

photosynthesis overview