| Abstract: | If the photosynthetic organisms assimilated only CO_2 in the Archean atmosphere,hydroxide ion in the Archean seawater would not increase.If plants would not consume bicarbonate as a direct substrate during photosynthesis,it is difficult to explain the evolution of Earth's environment.To date,it is generally accepted that photosynthetic O_2 evolution of plants come from water photolysis.However,it should be debated by evaluating the effect of bicarbonate in photosynthetic O_2 evolution,analyzing the role of carbonic anhydrase(CA) in photosynthetic O_2 evolution,and the relationship between thylakoid CA and photosynthetic O_2 evolution.In the paper,I propose that bicarbonate is directly used as substrate to participate in photosynthetic O_2 evolution.The rationality of bicarbonate photolysis of plants is discussed from the thermodynamics and evolution of Earth's environment.The isotopic evidence that bicarbonate is not the direct substrate of photosynthetic O_2 release is reexamined,and the new explanation of bicarbonate photolysis in photosynthetic O_2 evolution is proposed. |
