Question

after light excites electrons and they leave Photosystem II to travel down the first electron transport chain. How are these electrons replaced to Photosystem II?

Answer 1

Through the photolysis of water molecules

Step-by-step explanation:

When the electrons in photosystem II gets excited, released and travel down to the electron transport chain, the electrons are replaced by the electron released by the cleavage/photolysis of water.

Water molecule is cleaved resulting in the formation of hydrogen ion, oxygen gas and electrons. The electrons then replace those lost by photosystem II.