Complex sentence: It is the substrate used by the enzyme RuBisCO to fix carbon dioxide to create two molecules of glycerate 3-phosphate (G3P), this is then reduced in the Calvin-Benson cycle.
Split into simpler sentences: It is the substrate used by the enzyme RuBisCO to fix carbon dioxide to create two molecules of glycerate 3-phosphate (G3P). This is then reduced in the Calvin-Benson cycle.