The production of glyceraldehyde 3-phosphate (G3P) in the Calvin cycle requires six molecules each of ATP and NADPH. Another three molecules of ATP are then used in the cycle. What is the purpose of the three additional ATP molecules?

Calvin cycle is the metabolic process used by the plant to obtain food or carbohydrates from the carbon dioxide molecules. The Calvin cycle was first explained by the scientist Dr. Melvin Calvin.

The four sequential steps of the Calvin cycle are carbon fixation, reduction phase, carbohydrate formation, and regeneration phase. The extra three ATP molecules in calving cycle is required for the fourth step of the Calvin cycle. The ATP molecule is used for the generation of RuBP (ribulose 5 phosphate) molecule.