1. Chlorophyll: Green plants contain a pigment called chlorophyll, which is found within organelles called chloroplasts. Chlorophyll absorbs light energy, primarily in the red and blue wavelengths, while reflecting green light (which is why plants appear green).
2. Light-Dependent Reactions: The absorbed light energy is used to split water molecules (H₂O) into hydrogen ions (H+), electrons, and oxygen (O₂). This process also produces ATP (adenosine triphosphate), a molecule that stores chemical energy.
3. Light-Independent Reactions (Calvin Cycle): The hydrogen ions and electrons, along with carbon dioxide (CO₂) from the air, are used to create glucose (C₆H₁₂O₆), a sugar that stores chemical energy. This process also regenerates the molecules needed for the light-dependent reactions to continue.
In summary:
* Light energy is absorbed by chlorophyll.
* Water molecules are split, releasing oxygen and providing electrons and hydrogen ions.
* ATP is produced as a form of chemical energy.
* Carbon dioxide is combined with the electrons and hydrogen ions to create glucose.
This glucose can then be used by the plant for growth, reproduction, and other vital processes. The chemical energy stored in glucose is essentially a captured form of the light energy that was originally absorbed.
