Solution

In C₄  plants, the initial step of the C₄  cycle involves the enzyme PEP carboxylase, which catalyzes the fixation of CO₂  to form oxaloacetate in the cytosol of mesophyll cells. After the initial fixation of CO₂  in the mesophyll cells, the C₄  compound (oxaloacetate) is transported to the bundle sheath cells, where it is decarboxylated to release CO₂ , which then enters the Calvin cycle. The C₄  cycle takes place in the chloroplasts of bundle sheath cells.