Question

Phosphoenol pyruvate (PEP) is the primary ${\mathrm{CO}}_2$ acceptor in :

• A. $C_3$ plants
• B. $C_4$ plants
• C. $C_2$ plants
• D. $C_3$and $C_4$ plants

Answer 1

The correct option is B $C_4$ plants

In $C_4$plants, the primary
${\mathrm{CO}}_2$ acceptor is phosphoenol pyruvate (PEP). The enzyme responsible for this fixation is PEP carboxylase or PEPcase.

In $C_3$plants, ${\mathrm{CO}}_2$ is utilised for the carboxylation of ribulose-1,5-bisphosphate (RuBp) catalyzed by the enzyme RuBisCO.