The Three Stages of Photosynthesis

By Athena Hessong; Updated April 24, 2017
The Three Stages of Photosynthesis

The Plant Absorbs Light

Plants require CO2, water and light to produce sugar and oxygen.

Chlorophyll in the plant's cells absorbs light waves hitting the green portions of the plant. The capturing of the light energy allows the chlorophyll to pull electrons from water. This creates extra oxygen from the water to be released as waste from the process. The electrons set off the generation of ATP to create energy for the cell.

Electron Transport and ATP is Generated

An initial electron acceptor takes the electrons from the oxygen and passes them down the electron transport chain which ends with NADP+. The electrons reduce each NADP+ to NADPH. A movement of protons coincides with the electron transport. This proton movement, known as the proton motive force, creates ATP by combining ADP with a proton (P1-).

Carbon Dioxide is Fixed and Sugar is Produced

The NADPH contributes the electrons and the ATP brings the energy required for the plant cell to create sugars from carbon dioxide (CO2) and water. This stage requires no light to start or complete, but it often occurs when the plant has light available. (