Chloroplast: areas in the cells of green plants that use pigments, called chlorophyll and carotenoids, to convert light energy to chemical energy used by cells. Chloroplasts concentrate chlorophyll in the thylakoid membrane of the chloroplast. In part one of photosynthesis chlorophyll absorbs light energy to make ATP. The energy is used to split water, releasing oxygen. The hydrogen from the water combines with NADP+ to form NADPH + H⁺. In the second part of photosynthesis the energy of NADPH and ATP made in part one split carbon dioxide with the hydrogen from NADPH being used to make carbohydrates to be used as long term fuel storage for the cell. (Solomon & Berg & Martin & Villee, 1993)