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.
Full sunlight on a clear summer day has an intensity of about 10,000 foot-candles. A classroom will have an intensity of about 100-foot candles. Photosynthesis and hence rate of plant growth will increase linearly with increases in light intensity from about 100 foot-candles to about 2500 foot candles. A large number of plants are more efficient in use of sunlight and will increase in their rates f photosynthesis up to 10,000 foot-candles.