During the light reactions of photosynthesis, energy is stored in the compounds ATP and NADPH. A second set of reactions uses this stored energy to produce vital compounds such as glucose. This second set of reactions involves a biochemical pathway called

Explanation: The Calvin cycle involves the reduction of carbon( in this case CO2) to carbohydrates. This process requires reduction power and chemical energy which is provided by NADPH and ATP respectively, both generated from the light reaction. Thus, it is the Calvin cycle that produces sugar but it can do so only with the help of NADPH and ATP. The metabolic steps of the Calvin cycle are sometimes referred to as “dark reaction” because none of the steps requires light directly. Nevertheless, the Calvin cycle in most plants occurs during daylight, for only then can the light reaction regenerate NADPH and ATP spent in the reduction of CO2 to sugar.