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.
The input of energy through photosynthesis generates biomass with an energy equivalent 10-30 times that involved in all anthropogenic processes. Since photosynthesis operates with a low efficiency (1-10%), the energy flux through photosynthesis is 100-1000 times all that associated with human activity.