Question

In case of $C_4$ pathway

• A. $C{O}_2$ combines with PGA
• B. $C{O}_2$ combines with PEP
• C. $C{O}_2$ first combines with RuBP
• D. $C{O}_2$ combines with RMP

Answer 1

The correct option is B $C{O}_2$ combines with PEP

In $C_4$ plants, $C{O}_2$ combines with PEP (phosphoenolpyruvate) in the presence of the enzyme PEP carboxylase to form OAA (oxaloacetate). This is the second step in the C4 pathway.
The fixation of $C{O}_2$ by the enzyme RuBisCO into PGA (3-phosphoglycerate) happens in the first step of the $C_3$ pathway.
The fixation of $C{O}_2$ into RuBP is observed in the CAM pathway.