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The respiration in the photosynthetic (green) cells in presence of light resulting in the surplus release of carbon dioxide is called as photorespiration. It is also known as photosynthetic carbon oxidation cycle or C2 cycle. Photorespiration occurs in the peroxisomes. Under conditions of high light & oxygen concentration and low concentration of CO2 Rubisco catalyse photorespiration thereby protecting the plant from photo oxidative damages. As a result the excess carbon dioxide produced is utilized with the high light so that the excess light energy damage is reduced. Under high oxygen concentration Rubisco catalyse the conversion of RuBP into PGA (phosphoglyceric acid) and to phosphoglycolate. Then phosphoglycolate is converted into glycolate. From the chloroplast glycolate moves to peroxisome, it is the primary substrate for photorespiration. Then the glycolate is converted to glycine, and glycine to serine and carbon dioxide. Here ATP or NADPH is not produced. This is known as photorespiration.

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