(b) : Photosynthesis consists of light dependent phase and light independent phase or dark reaction. Light dependent phase occurs in grana fraction of chloroplast. It involves cyclic and non-cyclic photophosphorylation where assimilatory powers (ATP and NADPH ‌2 ) are produced. In dark reaction, which occurs in stroma fraction of chloroplast, actual reduction of CO2 to carbohydrates takes place using the assimilatory powers (ATP and NADPH ‌2 produced in the light dependent phase. It needs 18 ATP and 12 NADPH ‌2 molecules to produce one molecule of glucose.