Difference Between Normal Respiration And Photorespiration






Normal respiration is a metabolic pathway which releases energy-rich molecules by the breakdown of sugar molecules such as glucose. Photorespiration is a type of respiration which occurs in plants in presence of light and at high oxygen concentration.
Alternative Names


Respiration can also be referred to as Normal respiration or dark respiration. Photorespiration can also be referred to as dark respiration.
Occurrence Normal respiration takes place in both in presence of light and dark. Photorespiration only takes place in the presence of light.
Substrate The substrate for normal respiration is commonly glucose though other food materials (fat, protein, organic acids) can also be used. The substrate for photorespiration is RuBP and its breakdown product is glycolate.
Organelles  of Occurrence Normal respiration is completed in cytoplasm and mitochondria. Photorespiration is completed in three organelles chloroplasts, Mitochondria and Peroxisomes.
Saturation Point The saturation point is atteined at relatively lower concentrations of oxygen. The saturation point is attained at relatively high oxygen concentration.
Involves Aerobic respiration is completed in Glycolysis, Krebs Cyle and Electron Transport System. Photorespiration does not involve Electron Transport System (ETS), Krebs cycle and Glycolysis.
Occurrence Normal respiration takes place in both green and non green cells. Photorespiration takes place only in green photosynthesizing cells.
Effect of Oxygen Concentration Respiration is not influenced by change in oxygen concentration between 10-25%. Beyond it there is a decline in the rate of respiration. Photorespiration increases with increase in availability of oxygen.
Production of Energy-Rich Molecules Normal respiration produces energy-rich molecules such as ATP, GTP, NADH2 and FADH2. Photorespiration does not produce energy-rich molecules such as ATP.
End Products


The end products of respiration are CO2 and water. The end products of photorespiration are CO2 and PGA.
Nature Respiration is an energy producing process. It produces usable energy in the form of ATP. Photorespiration is an energy wastage process. It does not produce any usable energy in the form of ATP.
Hydrogen Peroxide



During normal respiration hydrogen peroxide is not produced. Toxic hydrogen peroxide may be formed during oxidation of the substrate.
Importance Normal or dark respiration is essential for survival of organisms. Photorespiration is not essential to the survival of organisms.
End Product Recycling The end products of respiration may or may not be reutilized by photosynthesis. Both the end products of photorespiration are reutilized in photosynthesis.
Substrate Formation The substrate is already present in the cells. The substrate is formed at the time of utilization.
Phosphorylation Oxdative Phosphorylation takes place. Phosphorylation does not take place.
Ammonia Production


No single molecule of Ammonia (NH3) is produced. One molecule of ammonia (NH3) is produced.


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