(N/A) $\Rightarrow$ 'Kranz' anatomy is observed in $C_{4}$ plants. The leaves of these plants exhibit two types of chloroplasts.
$\Rightarrow$ Grana-containing chloroplasts: These are present in mesophyll cells. These chloroplasts contain well-developed grana. They are capable of fixing $CO_{2}$ even at low concentrations. They contain the enzyme $PEP$ carboxylase,which fixes $CO_{2}$ to form a $C_{4}$ compound called $OAA$ (Oxaloacetic Acid).
$\Rightarrow$ Agranul chloroplasts: These are found in bundle sheath cells,where the $C_{3}$ pathway and the enzyme $RuBisCO$ are present.
$\Rightarrow$ $C_{4}$ plants can efficiently absorb $CO_{2}$ even when its atmospheric concentration is low.
$\Rightarrow$ Consequently,the rate of photosynthesis is higher in $C_{4}$ plants. Even when stomata are closed or water is scarce,they can continue photosynthesis by utilizing stored water and efficient $CO_{2}$ fixation.
$\Rightarrow$ Furthermore,$PEP$ carboxylase is insensitive to $O_{2}$,meaning photorespiration does not occur in $C_{4}$ plants.
$\Rightarrow$ Thus,$C_{4}$ plants are better adapted to tropical and arid (desert) regions.