(b) : In Calvin cycle, CO2 is accepted by Ribulose -1,5 - diphosphate (RuDP) already present in the cells and a 6 -carbon addition compound is formed which is unstable. It soon gets converted into 2 molecules of 3 -phosphoglyceric acid due to hydrolysis and dismutation. Phosphoenol pyruvate (PEP) and Phosphoglyceric acid (PGA) are formed in glycolysis.