Final answer:
NADPH and ATP are metabolic intermediates produced in the light reactions of photosynthesis and used in the dark reactions to synthesize carbohydrates.
Step-by-step explanation:
NADPH and ATP are considered metabolic intermediates because they are products of the light reactions and are used as reactants in the dark reactions (also known as the Calvin cycle or light-independent reactions). These molecules are essential for synthesizing carbohydrates from carbon dioxide through a process called carbon dioxide fixation.
ATP provides the energy, while NADPH provides the reducing power needed to add electrons in the synthesis of glucose and other carbohydrates during the dark reactions. Therefore, they are crucial links between the energy captured by chlorophyll in the light reactions and the energy-consuming process of sugar production in the dark reactions of photosynthesis.