ADP to ATP
Food production of plants occurs in the chloroplasts. Its overall process can be understood as two closely linked reaction sets. The light-independent reactions take place in the thylakoid membranes whereby NADPH is produced from electron transport and hydrogen ion gradient is formed across the membrane of thylakoid which drives ATP synthesis by the process called chemiosmosis. Light- independent reactions use ATP and NADPH. The driving force of photosynthesis is light absorption. The wavelengths only of light absorbed by the photosystems can be used to drive photosynthesis.