The given bar graph represents the utilization of ATP and NADPH molecules per CO₂ fixed during the three main stages (I, II, and III) of the Calvin cycle. Identify the stages I, II, and III respectively.

Step-by-step solution

The Calvin cycle consists of three main stages: Carboxylation, Reduction, and Regeneration. 1. Carboxylation (Stage I) : In this step, CO₂ combines with Ribulose-1,5-bisphosphate (RuBP) to form two molecules of 3-phosphoglycerate (3-PGA). This step does not utilize any ATP or NADPH. This matches the graph for Stage I, where the utilization is zero. 2. Reduction (Stage II) : The two molecules of 3-PGA are reduced to form triose phosphate. This process requires 2 molecules of ATP (for phosphorylation) and 2 molecules