The Process of Photosynthesis and the Organisms That Perform It
- Photosynthesis is the process where energy from sunlight is harnessed to fix carbon dioxide into organic compounds.
- This includes sugars, amino acids, and other carbon-based molecules that form the basis of life.
This process supports almost all life on Earth by fueling food chains and producing oxygen.
The Three Groups of Photosynthetic Organisms
- Plants
- Includes mosses, ferns, conifers, and flowering plants.
- Plants are the dominant terrestrial photosynthesizers, playing a crucial role in capturing solar energy and converting it into chemical energy.
- Eukaryotic Algae
- Includes seaweeds that grow along rocky shores and unicellular algae like Chlorella.
- These photosynthesizers dominate aquatic environments, producing significant amounts of oxygen and forming the base of marine ecosystems.
- Photosynthetic Bacteria
- Includes cyanobacteria (commonly called blue-green bacteria) and purple bacteria.
- Cyanobacteria are especially important because they are believed to be responsible for the Great Oxygenation Event, which made Earth’s atmosphere habitable for aerobic organisms.
Photosynthesis Across the Domains of Life
- Photosynthesis occurs in two out of the three domains of life:
- Eukaryotes (plants and algae).
- Bacteria (cyanobacteria and purple bacteria).
- Archaea, the third domain, do not perform photosynthesis, highlighting the diverse strategies organisms use to survive.
- In which domains of life does photosynthesis occur, and why is it absent in archaea?
- Why are cyanobacteria significant in the history of life on Earth?
