Evolutionary Implications of Photosynthesis with and without Oxygen

4 Evolutionary Implications of Photosynthesis with and without Oxygen 

Is it possible to have photosynthesis without producing oxygen  

It is also possible for the hydrogen acceptor to be N02 or NOg , in which case NHg is a product. Photosynthesis linked to oxygen with carbon dioxide as the ultimate hydrogen acceptor is a special case of a far more general process that is widely distributed among many different organisms. 

Gyanobacteiia were apparently the first organisms that developed the ability to use water as the ultimate reducing agent in photosynthesis. As we have seen, this feat required the development of a second photosystem as well as a new variety of chlorophyll, chlorophyll a rather than bacteiiochlorophyll in this case. Ghlorophyll b had not yet appeared on the scene, as it occurs only in eukaryotes. The basic system of aerobic photosynthesis was in place with cyanobacteria. As a result of aerobic photosynthesis by cyanobacteria, the Earth 

When photosynthesis first evolved, it was most likely to have been carried out by organisms that used compounds other than water as the primary electron source. Cyanobacteria were the first organisms to use water as the source of electrons, giving rise to the present oxygen-containing atmosphere. 

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