In light reactions, a molecule of chlorophyll absorbs one photon of light, causing a chlorophyll electron to transfer to a higher energy level. The energized electrons from the chlorophyll molecules flow down a transportation chain to a compound called nicotinamide adenine dinucleotide phosphate or NADP.
One reason is for an animal to come along and eat it's fruit, so that it can excrete the seeds somewhere else allowing that type of flower/plant to spread over distances :)
