When photolysis occurs, for example photolysis of an oxygen molecule occurs to form two separate oxygen atoms, is the photon that started the reaction absorbed to provide the energy needed for the reaction?
Directly from the Wikipedia article on photosynthesis:
In the light-dependent reactions, one molecule of the pigment chlorophyll absorbs one photon and loses one electron.
So, yes, in photosynthesis, during the creation of necessary NADPH + H$^+$ and ATP molecules, chlorophyll molecule starts the reaction chain by absorbing a photon. Actually, this mechanism absorbs 2 photons per cycle and produces 2 NADPH as well as 2 protons to be pumped back while creating ATP.