Question

The reaction that is responsible for the fixation of $C{O}_2$ is catalyzed by which of the following enzymes in $C_4$ plants?

• A. RuBP carboxylase
• B. PEP carboxylase
• C. RuBP carboxylase and PEP carboxylase
• D. PGA synthase

Answer 1

The correct option is B PEP carboxylase

During $C_4$ cycle, instead of RuBP carboxylase, a different enzyme, PEP carboxylase, is used to fix CO${}_2$. Carbon is taken up in the mesophyll cells of the leaf (by PEP carboxylase), added to other carbons to form a 4-C chemical called oxaloacetate, and the oxaloacetate is pumped into adjacent bundle sheath cells where the rest of the calvin cycle takes place.

So, the correct option is 'PEP carboxylase'.