The color spectrum of visible light falls smomewhere in the middle and is responsible for a wide range of biological activities.Radiation can also be defined as particles of energy.Light particles,called photons,are distinguished by their individual amounts of energy.the energy of a photon is inversely proportional to its wavelength,implying that radiation of a longer wavelength will possess photons of lower energy.light within the visible spectrum carries enough energy to initiate chemical changes in biological molecules without destroying melecular bonds.Biologists speculate that this is why visible light is quite effective in triggering life processes.