Most food chains start with photosynthesizers. Photosynthesis has produced most of the oxygen in the atmosphere of our planet. Solar radiation is described in terms of its energy content and its wavelength. Photons are discrete packets of radiant energy that travel in waves. The electromagnetic spectrum is the range of types of solar radiation based on wavelength.
Radio waves have longest wavelength.
Higher energy wavelengths are screened out by ozone layer in upper atmosphere. Lower energy wavelengths are screened out by water vapor and CO 2 . Consequently, both the organic molecules within organisms and processes, such as vision and photosynthesis, are adapted to radiation that is most prevalent in the environment. Photosynthetic pigments use primarily the visible light portion of the electromagnetic spectrum. Carotinoids are yellow-orange pigments which absorb light in violet, blue, and green regions.