Even though a very few cells in a $C_{4}$ plant carry out the biosynthetic-Calvin pathway,yet they are highly productive. Can you discuss why?

(N/A) The productivity of a plant is measured by the rate at which it photosynthesizes. The amount of carbon dioxide present in a plant is directly proportional to the rate of photosynthesis.
$C_{4}$ plants have a mechanism for increasing the concentration of carbon dioxide in the bundle-sheath cells.
In $C_{4}$ plants,the Calvin cycle occurs exclusively in the bundle-sheath cells.
The $C_{4}$ acid (malic acid or aspartic acid) formed in the mesophyll cells is transported to the bundle-sheath cells,where it is broken down to release $CO_{2}$.
This high concentration of $CO_{2}$ ensures that the enzyme $RuBisCO$ functions primarily as a carboxylase rather than an oxygenase.
This mechanism effectively prevents photorespiration,which would otherwise waste energy and carbon,thereby significantly increasing the overall rate of photosynthesis and productivity.