. I think that bivalves have evolved to have smaller head regions because they have also evolved to have bigger shells or valves than cephalopod
Electrons in photosystem I are energized by electromagnetic radiation with a wavelength of about 690 nanometers(colour red). These electrons are received from plastocyanin to then be passed on to NADP to form NADPH+.
Plants use their roots to get water, they collect carbon dioxide through openings on their leaves called stomata.