What Are the Three Stages of Photosynthesis?

Photosynthesis has two main stages: light reactions and the Calvin cycle; the Calvin cycle has three stages called carbon fixation, reduction and regeneration of RuBP. Photosynthesis is a chemical process in plants which converts light energy to chemical energy. This energy is stored in the bonds of sugar.

Photosynthesis begins with the light reactions, in which light that is absorbed moves electrons to a higher energy level. From there, the electrons enter the electron transport chain. The light reactions produce the NADPH and ATP used in the Calvin cycle to reduce carbon dioxide into sugar.

The Calvin cycle produces energy in three stages:

  • Carbon fixation: CO2 is linked to a carbon skeleton (RuBP)
  • Reduction: Carbohydrates are formed from NADPH and ATP
  • Regeneration: RuBP is reformed from ATP