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.
Answer 2: The color or wavelength of light does affect photosynthesis, which is how plants can basically create their own food.Essentially, the reason why plants are green is they are absorbing the other wavelengths of light but reflecting back the green. The wikipedia page on photosynthesis goes into a lot more detail.