Question: 133: What is the role of large bundle sheath cells found around the vascular bundles in \mathrm{C}_{4} plants?
(1) To enable the plant to tolerate high temperature
(2) To protect the vascular tissue from high light intensity
(3) To provide the site for photorespiratory
(4) To increase the number of chloroplast for the operation of Calvin cycle
Answer: Option (4)
Explanation:
\mathrm{C}_{4} plants show a special type of leaf anatomy known as Kranz anatomy.
In this anatomy, large bundle sheath cells surround the vascular bundles and contain numerous chloroplasts.
The Calvin cycle operates in the chloroplasts of bundle sheath cells in \mathrm{C}_{4} plants.
The increased number of chloroplasts in these cells ensures efficient fixation of \mathrm{CO}_{2} and minimizes photorespiration.
Photorespiration is reduced because bundle sheath cells have low oxygen concentration and high \mathrm{CO}_{2} concentration.
Therefore, the main role of large bundle sheath cells is to increase the number of chloroplasts for the operation of the Calvin cycle.
Hence, the correct answer is Option (4).