They are organized in highly efficient assemblies from 250 to 400 each called photosystems . All of the pigment molecules within a photosystem are capable of absorbing photons, but only one chlorophyll molecule per photosystem actually uses the energy in the photochemical reaction. The molecule that uses the energy has been designated the reaction center of the system. The other pigment molecules are termed antenna pigments. Electron flow is initiated and the work of photosynthesis has begun.
Carotene is also a pigment found in the chlorophyll.
It also functions to absorb light and transfer it to the reaction center. Carotene belongs to a group of pigments known as carotenoids. It gives the color to carrots, yellow squash etc. Biological Switches Plants contain a pigment that can function to germinate seed or delay flowering. This pigment is known as phytochrome.