Final answer:
In the Calvin cycle, three-carbon molecules can either contribute to the formation of carbohydrate molecules or regenerate RuBP. ATP is involved in the regeneration process.
Step-by-step explanation:
The three-carbon molecules made in the Calvin cycle can undergo several processes.
One of the molecules leaves the cycle to contribute to the formation of a carbohydrate molecule, such as glucose.
The remaining molecules regenerate the molecule called RuBP, which enables the cycle to continue.
ATP is used in the regeneration process.