Even though a very few cells in a C4 plant carry out the biosynthetic – Calvin pathway, yet they are highly productive. Can you discuss why?
The productivity of plants can be measured by the rate at which plants perform photosynthesis. The rate of photosynthesis is directly proportional to the amount of carbon dioxide in plants. In C₄ plants, a few cells carry out photosynthesis, but their productivity is very high. C₄ plants possess a mechanism that increases the concentration of CO₂ at the enzyme site. RUBISCO mainly functions as carboxylase thus minimizing the oxygenase activitySince photorespiration is a wasteful process, and it is absent in C₄ plants, therefore C₄ plants are more efficient photosynthetically. Final Answer The C₄ cycle concentrates CO₂ in bundle sheath cells, keeping the CO₂ concentration in the bundle sheath cells high enough for RUBISCO to bind carbon dioxide rather than oxygen. In this way, C₄ minimizes the photorespiration and enhance carbohydrate production. In photorespiration, there is a release of CO₂ from 2 phosphoglycerates. The release of CO₂ in thus process decreases the photosynthetic output and limits the plant biomass production. In this pathway, there is no fixation of CO2 rather, and it results in the release of fixed carbon in the form of CO₂ with the utilization of ATP. Therefore, photorespiration is a wasteful process.
