Green plants, and therefore ultimately all other higher forms of life, depend upon organic carbon derived from carbon dioxide in processes driven by light energy. Central to every aspect of such photosynthetic carbon assimilation by leaves, lies the Benson-Calvin cycle. In this cyclic sequence of reactions, carbon dioxide is added to an acceptor molecule. The newly formed addition compound then undergoes a series of changes, including reduction, so that a stable product is formed and set aside. At the same time, the CO2-acceptor is regenerated and new molecules of acceptor formed so that the process might continue and grow.