3) first two links on your Google search will give you some answer
4) what happens with the energy trapped by photosynthetic pigments if it is not passed to photosynthetic center?
5) look for biosynthesis of anthocyanins
Thanks, I’m making progress. Also – if one does an experiment where they put a plant under light stress then measure anthocyanin concentration (using absorption techniques), why might the light response take some time to become detectable?