Respiration vs Photorespiration
Difference between Respiration and Photorespiration: Photorespiration is a type of respiration process occurs in plants in presence of light and at higher concentrations of oxygen. The photorespiration is also called C2 cycle or glycolate metabolism since the first stable product of the photorespiration reaction is a 2 carbon compound called glycolate.
The respiration (also called normal respiration or dark respiration) is a metabolic pathway which releases energy-rich molecules by the breakdown of sugar molecules such as glucose. Even though the photorespiration and the normal respiration occur in the presence of oxygen, the two pathways are independent process and show considerable differences. The photorespiration is not universally present in all plants; rather it usually occurs in C3 plants. The process of photorespiration is essentially absent in C4 plants.
The present post discusses the similarities and differences between photorespiration and normal respiration with a comparison table.
Learn more: C3 vs C4 Cycle of Photosynthesis
Similarities between Photorespiration and Respiration
Ø Both photorespiration and respiration are catabolic processes.
Ø Both photorespiration and respiration occurs in green plants.
Ø Both uses oxygen.
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Ø Both processes produce CO2 in the end.
Ø Both are enzymatic reactions involves many enzymes.
Ø Both processes use ATP molecules.
Ø Both processes need mitochondria.
Difference between Respiration and Photorespiration
Sl. No. Photorespiration Respiration
1 Also called C2 cycle or glycolate cycle. Also called normal respiration or dark respiration.
2 Occurs only in green plants. Occurs in all aerobic and anaerobic organisms.
3 Commonly occurs in C3 plants Occurs in all plants.
4 A light dependent process, occurs in presence of light. A light-independent process, occurs both in presence and absence of light.
5 The substrate of photorespiration is Glycolate. The substrate of respiration is glucose.
6 Photorespiration does not involve glycolysis, Krebs cycle and ETS. Aerobic respiration is completed in glycolysis, Krebs cycle and ETS.
7 Photorespiration is completed in three organelles – Chloroplasts, Peroxisomes and Mitochondria. Respiration is completed in cytoplasm and Mitochondria.
8 Accept O2 at three places. Accept O2 only at one place – at the end of termination oxidation of ETS
9 Do not produce energy-rich molecules such as ATP. Produce energy-rich molecules such as ATP, GTP, NADH2 and FADH2.
10 No phosphorylation occurs. Substrate level and oxidative phosphorylation occur.
11 The end product of photorespiration is CO2 and PGA. The end product of respiration is CO2 and water.
12 Release CO2 only at the end of photorespiration. CO2 is released at several places.
13 The end products of photorespiration are recycled by photosynthesis. The end products of respiration may or may not recycle by photosynthesis.
14 One molecule of NH3 (ammonia) is produced. No NH3 is produced in respiration.
15 The saturation point is attained at high oxygen concentration. The saturation point is reached at relatively lower concentrations of oxygen.
16 Photorespiration maintains the carbon economy in plants. No such role in plants.
17 Photorespiration is an energy wastage process. Respiration is an energy producing process.
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