Photosynthesis in `C_(4)` plants is relatively less limited by atmospheric `CO_(2)` levels because

Options

A. effectve pumping of `CO_(2)` into bundle sheath cells
B. RuBisCO in `C_(4)`-plants has higher affinity for `CO_(2)`
C. Four carbon acids are the primary initial `CO_(2)`-fixation products
D. The primary fixation of `CO_(2)` is mediated via PEP carboxylase

Answer

D

Explanation

The fixation of `CO_(2)` in `C_(4)`-plants takes place in two places and by two different organic compounds. Phosphoenol pyruvate (PEP) is found atmospheric `CO_(2)` into oxalo acetic acid (4C). RuBisCO is present in bundle sheath cells where final fixation of `CO_(2)` in hexose sugars takes place. `CO_(2)` is primarily fixed by PEP carboxylase because this enzyme has greater affinity to `CO_(2)` than RuBisCO.