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Question
C4 photosynthetic pathway is more efficient than C3 pathway because
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Solution
The correct option is C C4 pathway minimizes photorespiration
In C3 cycle, RuBisCO enzyme which is present in the mesophyll cells is used for fixing CO2. In C4 pathway, the initial carbon dioxide fixation is done by the PEP carboxylase enzyme which is present in the mesophyll cells followed by the RuBisCO enzyme present in the bundle sheath cells.
As RuBisCO has a bifunctional activity, it can oxidise RuBP and lose the already fixed CO2.
But PEP carboxylase doesn't have such dual roles and hence, its activity is not dependent on the carbon dioxide and oxygen concentration. PEP carboxylase has a higher efficiency to take up CO2 when compared to the enzyme RuBisCO.
C4 pathway concentrates CO2 in the region where RuBisCO is present in high quantity to prevent the oxygenase activity and hence, prevents photorespiration. In C4 plants, the rate of photosynthesis remains the same even in low CO2 concentrations and high temperature.
In C3 cycle, RuBisCO enzyme which is present in the mesophyll cells is used for fixing CO2. In C4 pathway, the initial carbon dioxide fixation is done by the PEP carboxylase enzyme which is present in the mesophyll cells followed by the RuBisCO enzyme present in the bundle sheath cells.
As RuBisCO has a bifunctional activity, it can oxidise RuBP and lose the already fixed CO2.
But PEP carboxylase doesn't have such dual roles and hence, its activity is not dependent on the carbon dioxide and oxygen concentration. PEP carboxylase has a higher efficiency to take up CO2 when compared to the enzyme RuBisCO.
C4 pathway concentrates CO2 in the region where RuBisCO is present in high quantity to prevent the oxygenase activity and hence, prevents photorespiration. In C4 plants, the rate of photosynthesis remains the same even in low CO2 concentrations and high temperature.