Question

Select correct statement concerning plants that utilise C4 photosynthesis.

• A. They only open their stomata in the day
• B. They use bundle sheath cells to separate the Calvin cycle from the atmosphere
• C. They use RuBisCO (ribulose bisphosphate carboxylase oxygenase) to capture carbon dioxide from the atmosphere
• D. They use lenticels exclusively for gaseous exchange in order to conserve water
• E. All of the above are true

Answer 1

The correct option is B They use bundle sheath cells to separate the Calvin cycle from the atmosphere

CAM plants exhibit temporal separation of photosynthesis and open stomata during night only. In C4 plants, spatial separation of carbon dioxide fixation and RUBISCO activity in mesophyll and bundle sheath cells of $C_4$ plants respectively avoids photorespiration by concentrating $C{O}_2$ in bundle sheath cells to scale down the oxygenase activity of RUBISCO and increase the RUBISCO efficiency. PEP carboxylase enzyme of mesophyll cells fixes carbon dioxide and malate enters Calvin cycle in bundle sheath cells only. Thus, the correct answer is B.