Here's why:
* Photosystem II (PSII): The process begins in Photosystem II. Light energy excites electrons in chlorophyll molecules within PSII.
* Water Splitting: To replace the excited electrons, PSII splits water molecules. This process releases oxygen as a byproduct, which is the oxygen we breathe.
* Electron Transfer: The electrons from water are passed along an electron transport chain, ultimately reaching Photosystem I (PSI).
In summary, water is the ultimate source of electrons for linear electron flow, providing the reducing power needed to generate ATP and NADPH, which are essential for carbon fixation.
