All life depends on photosynthesis. Light consists of packets of energy called photons which vibrate over discreet distances called wavelengths. The wavelength range of visible light is 390 to 760 nanometers. Visible light contains the energy required for biochemical reactions.
Pigments transmit light.
These pigments absorb different wavelengths. When pigments are produced and destroyed at different rates, different colors are produced. This is where the actions take place. In photosynthesis, photon energy is passed to neighboring molecules. These require light to produce the energy to drive the light-independent reactions.