alleryIn photosynthesis, the source of O2 released into the atmosphere is:
ACO2 (the carbon dioxide molecule)
BGlucose (from carbon fixation)
CH2O (via photolysis in PS II)
DOzone (O3) in the upper atmosphere
Answer & Solution
Correct answer: C. H2O (via photolysis in PS II)
**WATER is split (photolysis) by PSII:** 2H2O → 4H+ + O2 + 4e⁻.
This is the source of atmospheric O2 (proved by Ruben + Kamen using ¹⁸O isotope). NOT from CO2.
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