Question

Which of the following is NOT a character of plants having CAM (Crassulacean Acid Metabolism) cycle?

• A. CAM plants are mostly succulents living in xerophytic conditions
• B. CAM plants use PEP carboxylase during daytime and RUBISCO during the night
• C. In CAM plants, stomata open during the night and close during daytime
• D. CAM plants lack Kranz anatomy

Answer 1

The correct option is B

CAM plants use PEP carboxylase during daytime and RUBISCO during the night

All statements except B are correct. In CAM plants, since the stomata open only during the night, $C{O}_2$ can be absorbed only at that time and malic acid is formed. PEP (phosphoenolpyruvate) carboxylase first fixes $C{O}_2$ as OAA (oxaloacetic acid) which is then converted to malic acid and stored. During daytime, malic acids break into pyruvic acid and $C{O}_2$ which is fixed by RUBISCO in $C_3$ cycle.