- #1
Delong
- 400
- 17
Hi I was thinking about photosynthesis recently and I know that it first evolved in cyanobacteria like organisms to convert sunlight into chemical energy. It also produced oxygen from water (not CO2) to oxidize the atmosphere. I read that many Eukaryotic organisms need oxygen in order to live and so the increase of oxygen in the atmosphere, called the Great Oxygenic catastrophe, allowed for a greater diversification of life and eventually multicellularity. Anyways I am wondering if photosynthesis was at first sustainable because it seems to create oxygen faster than cellular respiration can use it which explains why oxygen levels increased. Assuming that this is correct, if heterotrophic organisms did not increase as a result of this change would all the carbon dioxide have been used up by photosynthesis before it was produced back by cellular respiration? I think that would be the case and so I wonder why photosynthesis evolved if it was not sustainable or if heterotrophic organisms increased diversity out of necessity to make photosynthesis sustainable.
My own answer is that photosynthesis evolved because it was much more efficient for the cyanobacteria then the axoxygenic photosynthesis that took place before hand because it used water as the reducing agent which was more abundant. It probably produced an excess of glucose since it was so efficient (or did it?) which allowed for greater diversity of autrophic organisms. Meanwhile, the heterotrophic organisms responded to the ecological niche of more oxygen by increasing in diversity. And so the mechanism responsible for making photosynthesis sustainable in the first place was the ecological niche part.
Does this sound correct? Otherwise how could photosynthesis have evolved if it produced oxygen faster than it consumed it and would be unsustainable?
My own answer is that photosynthesis evolved because it was much more efficient for the cyanobacteria then the axoxygenic photosynthesis that took place before hand because it used water as the reducing agent which was more abundant. It probably produced an excess of glucose since it was so efficient (or did it?) which allowed for greater diversity of autrophic organisms. Meanwhile, the heterotrophic organisms responded to the ecological niche of more oxygen by increasing in diversity. And so the mechanism responsible for making photosynthesis sustainable in the first place was the ecological niche part.
Does this sound correct? Otherwise how could photosynthesis have evolved if it produced oxygen faster than it consumed it and would be unsustainable?