Photorespiration – Definition, Diagram, Process, Significance

Photorespiration is a plant metabolic process, most precisely in the cells of the leaves. Photorespiration is a wasteful pathway that competes with photosynthesis and can have negative effects on plant growth and productivity. Photorespiration is triggered when the concentration of carbon dioxide (CO₂) in the leaf is low and the concentration of oxygen (O₂) is high.

What is Photorespiration?

Photorespiration is the metabolic process occurred during the Calvin cycle. Photorespiration is also known as C2 Cycle. RuBisCO is the major enzyme in photorespiration. Photorespiration mainly occurs in the C3 plants to take care of the wasteful activity of RuBisCO. 

During the Photorespiration mechanism, O₂ is needed and CO₂ is released in the presence of light.

Photorespiration is exactly the same as the respiration process because in both reactions O₂ is used and CO₂ is released. 

 

Organelles involved in Photorespiration

3 cell organelles are involved in photorespiration those are:

• Chloroplast
• Peroxisomes
• Mitochondria

Photorespiration is the Wasteful Product

When the concentration of CO₂ around the cell. 

Photorespiration is started by the oxygenation of ribulose-1,5-bisphosphate-carboxylase/oxygenase (RUBISCO), the very chemical that is additionally liable for CO₂ obsession in practically all photosynthetic creatures. Phosphoglycerate shaped by oxygen is reused in the Calvin cycle middle phosphoglycerate in the Photorespiratory pathway. This response overflow consumes energy and lessens the reciprocals and part of them in advance fixed carbon is again delivered as CO₂. Along these lines, photorespiration was much of the time seen as an inefficient interaction. In photorespiration, the O₂ binds with the enzyme Rubisco and gives the final product 3-Phosphoglycerate in a reduced environment and consumes high energy for the process

Factors influencing Photorespiration 

• In submerged, stress conditions, the higher the light concentration higher the photorespiration.
• Influenced by temperature

Benefits of Photorespiration 

• It upholds plant-resistant protections.
• It assists in keeping up with the redox equilibrium of the cell.

Significance of Photorespiration

• It is the converse of photosynthesis.
• It decreases the viability of photosynthesis.
• It is an inefficient cycle, as it doesn’t deliver ATP or NADPH.

FAQs on Photorespiration

Q1: Why is photorespiration also known as C2 Cycle?

Answer:

It is also known as C2 Cycle because the first product in this process is a 2C compound i.e., Phosphogylcolate.

Q2: Is photorespiration takes place in C4 plants?

Answer:

No, photorespiration doesn’t take place in C4 plants. It is because C4 plants have different mechanisms due to which the concentration of CO₂ increases around the enzyme.

Q3: Are the C4 cycle and photorespiration are same?

Answer:

No, C4 plants used different mechanisms i.e.., PEP for the carbon fixation.

Q4: How many ATP are used in photorespiration/

Answer:

During photorespiration 3.5 ATP is produced.