A phyloGENETIC tree is not the same thing as a taxonomic tree, which is what Cal described. rRNA and molecular studies are used in phylogenetics to determine relations between species.
1 As the light intensity increases, the rate of photosynthesis increases. 2  However, the rate will not increase beyond a certain level of light intensity. 3  At high light intensities the rate becomes constant, even with further increases in light intensity, there are no increases in the rate.
Photosynthesis is responsive to certain wave lengths of light energy (see Fig. 7.3, 7.4 & 7.5, Pg. 110-111 in text). The visible spectrum, from Red to Violet light is effective in photosynthesis The most effective colors of light energy are in the Red and Blue/Violet range of the color spectrum.