ABSTRACT
Over 99% of the 'free energy in the biosphere arises from the sun. The remaining free energy is obtained from the oxida tion of inorganic compounds such as hydrogen and sulphur by specialist microorganisms, the chemolithotrophs (see Chapter 4) . Photosynthesis is the process in which living organisms, phototrophs, convert the light energy from the sun into the chemical energy of bonding electrons.
