Photorespiration

• It has been observed that light affects respiration and the rate of respiration in light may be three to five times higher than the respiration in darkness. Such type of respiration is called photorespiration.
• In photorespiration, temperature plays a very vital role, its rate being very high in between 25-35˚C. It also depends upon the concentration of oxygen and increases with increasing oxygen concentration.

Main features of P.R.

1. It takes place in the presence of light.

2. glycolate serves as substrate for photorespiration.

3.Photorespiration takes place in peroxisomes. Chloroplast and mitochondria are also involved in this process.

4. It occurs in some plants like Beet, Rice, Bean, etc.

5. Photorespiration increases with the availability of O2

6. It is pronounced in C3 plants and negligible in C4 plants.

7. Toxic H2O2 is formed during oxidation of the substrate

8. End-products are CO2.

9.It is wasteful method and does not produce energy.