Final answer:
The Calvin reactions of photosynthesis cannot proceed without carbon dioxide, which is necessary for the production of glucose and other carbohydrate molecules.
Step-by-step explanation:
The Calvin reactions of photosynthesis cannot proceed without carbon dioxide. In the Calvin cycle, an enzyme called ribulose biphosphate carboxylase (RuBisCO) catalyzes a reaction with CO₂ and another molecule called ribulose biphosphate (RuBP), which is regenerated from a previous Calvin cycle. Carbon dioxide is essential for the production of glucose and other carbohydrate molecules.