Distribution of excitation energy among photosystem I and photosystem II in red algae. I. Action spectra of light reactions I and II.

Action spectra of light reaction I and light reaction II from red algae (marine members of Florideae and Bangiales) were measured with 550 nm (light 2) or 699 nm light 1) background light, using a Teflon-covered platinum electrode for O2 measurement. Care was taken to ensure that maximum enhancement was reached by the background light. The action spectra of light reaction I, we found under these conditions, are very similar to the thallus absorption, whilst the action spectra of light reaction II show, besides strong bands of the phycobilins, only minor bands of chlorophyll a, which account for only 10-20% of the total chlorophyll.