Question

How does the C4 pathway limit photorespiration?

Answer 1

Photorespiration:

1. Respiration is the process of the metabolism of oxygen that results in the generation of carbon dioxide.
2. Photorespiration is a negative term since it refers to the process of photosynthetic organisms utilizing light energy to fix carbon for later carbohydrates.

Process of limiting photorespiration by C₄ plant:

1. Photorespiration is a phenomenon observed in C₃ plants such as oats and wheat, in which the carbon dioxide content rises as photosynthesis decreases.
2. C₄ photosynthesis produces a four-carbon molecule, which concentrates carbon dioxide in the Rubisco's bundle sheath cells.
3. These bundle sheaths assist in delivering carbon dioxide directly to Rubisco, removing the requirement for photorespiration and removing its contact with oxygen.
4. Rubisco requires the availability of carbon dioxide for C₄ plants. As a result, these are given in their leaf compartment.
5. C₄ plants do not experience photorespiration because they have a mechanism that raises the carbon dioxide content at the enzyme site.
6. When the mesophyll C₄ acid is broken down in bundle sheath cells, carbon dioxide is released, resulting in a high intracellular carbon dioxide concentration, ensuring that Rubisco operates as a carboxylase, reducing oxygenase activity.
7. Because they have the enzyme PEP during the initial step of carbon fixation, C₄ plants avoid photorespiration. As a result, the carbon dioxide produced during photorespiration is recycled via PEP.
8. Sugarcane, corn, and other plants suited to tropical dry climates contain C₄ pathways.