Photosynthesis is a unique mechanism to plants by which they synthesize organic matter using light energy, absorbing carbon dioxide from the air and releasing oxygen.
Figure 1 : Absorption spectrum of carotenoids and chlorophylls
Plants harvest, store and use light energy through chlorophyll photoreceptors and carotenoids. These are located on the plant surface and mainly in the leaves.
Chlorophylls A & B transform photons into energy.
Carotenoids are the regulators of photosynthesis. They act as a buffer by storing uncaptured photons when the light intensity is high and transmitting photons to the chlorophyll when the light intensity is lower. It thus ensures a constant and maximum output of photosynthesis.
However, light serves another mechanism used by plants. Apart from its energy use, plants also use it for signage.