Characteristics: Prokaryotic, but only distantly related to the other domain of prokaryotes, the Archaea
are photosynthetic organisms with both photosystems I and II, hence, evolves oxygen. Cyanobactera have chlorophyll a only, and store cyanophycean starch.
Link to Cyanobacteria image collection
(recognize heterocysts and know their function).
What photosystems are found n heterocysts and how does this relate to nitrogen fixation?
Recognize a stromatolite as a fossil of the Cyanobacteria