Photorespiration is the light dependent process in which utilization of oxygen and release of CO2 by the photosynthesis organs of a plant takes place. Normally, photosynthetic organs are reverse in the light, i.e., uptake, of CO2 and release of O2 . This process is pronounced in C3 plants and negligible in C4 plants. At high temperature RuBP carboxylase functions as oxygenase and instead of fixing CO2 , oxidizes ribulose 1, 5-biphosphate to produce phosphoglyceric acid and phosphoglycolate (starting product). On hydrolysing, it forms glycolate and then glyoxylate glycine and serine respectively.