Class 11 NEET Biology Photosynthesis in Higher Plants

(c) : The C ‌4 plants have a characteristic leaf anatomy called kranz anatomy. Here two types of chloroplasts are present - bundle sheath chloroplasts and mesophyll chloroplasts. In C4 plants, there are two carboxylation reactions which occur first in mesophyll chloroplasts and then in bundle sheath chloroplasts. CO2 acceptor molecule in mesophyll chloroplasts is PEP (Phospho-enol pyruvate) and not Ribulose 1 , 5-biphosphate. Further it has enzyme PEPcarboxylase for initial CO2 fixation. RuBP carboxylase is absent in mesophyll chloroplasts but is present in bundle sheath chloroplasts. The first product formed is oxaloacetic acid and hence it is known as C4 cycle. Bundle sheath cells fix CO2 through C3 cycle.