Some species of this phylum form filamentous hormogonia during reproduction.
Some species of this phylum form filamentous hormogonia during reproduction. During dormancy, they create thick structures called akinetes. Stromatoliths are primarily composed of these organisms, which form heterocysts in order to perform nitrogen fixation. The evolution of these organisms triggered the Great Oxygenation Event, in which the Earth's atmosphere became oxidizing and oxygen-intolerant organisms went extinct. These organisms express the dye (*) phycocyanin, and they are one of the most evolutionarily ancient organisms to contain photosystems I and II. These organisms are thought to be the precursors of modern chloroplasts in the endosymbiotic hypothesis. For 10 points, name this type of bacteria named for its blue-green appearance.
Some species of this phylum form filamentous hormogonia during reproduction.
cyanobacteria [or cyanophyta; accept blue-green algae or blue-green bacteria before "blue-green", prompt after; prompt on "algae" or "bacteria"]