are similar to repair enzymes, and are believed to be evolved modifications of the enzymes originally used to overcome DNA damages caused by UV. Photobiology Photobiology is the scientific study of the beneficial and harmful interactions of non-ionizing radiation in living organisms, conventionally demarcated around 10 eV, the first ionization energy of oxygen. UV ranges roughly from 3 to 30 eV in energy. Hence photobiology entertains some, but not all, of the UV spectrum. See also Biological effects of high-energy visible light Infrared Ultraviolet astronomy Ultraviolet catastrophe Ultraviolet index UV marker UV stabilizers in plastics Weather testing of polymers References Further reading External links Electromagnetic radiation Electromagnetic spectrum Ultraviolet radiation