Answer :
Final answer:
During the light-dependent reactions of photosynthesis, water molecules are split to provide electrons and produce oxygen. This reaction takes place in the thylakoid membranes of chloroplasts. Other processes mentioned, such as carbon fixation and RuBP regeneration, occur in the Calvin cycle, not in the light-dependent reactions.
Explanation:
Light-Dependent Reactions of Photosynthesis
The light-dependent reactions are the first stage of photosynthesis, occurring in the thylakoid membranes of chloroplasts. One of the crucial processes that occurs during these reactions is the splitting of water molecules (a process known as photolysis). This reaction provides the necessary electrons for the light-dependent reactions and produces oxygen as a byproduct.
To clarify further, the other options listed in the question pertain to the light-independent reactions (also known as the Calvin cycle), which occur in the stroma of the chloroplasts. For instance:
- Carbon fixation: This occurs during the Calvin cycle, where CO2 is incorporated into organic molecules.
- PGA reduction: This also happens in the Calvin cycle, where 3-phosphoglycerate (PGA) is reduced to glyceraldehyde-3-phosphate (G3P).
- RuBP regeneration: Another step of the Calvin cycle, where ribulose bisphosphate (RuBP) is regenerated to continue the cycle.
In summary, the correct answer to the question regarding what process occurs during the light-dependent reactions is the splitting of water molecules.
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