Q. The enzymes ribulose biphosphate carboxylase-oxygenase(RuBisCO) and PEP-carboxylase are activated by :

Q. The enzymes ribulose biphosphate carboxylase-oxygenase(RuBisCO) and PEP-carboxylase are activated by :

(a) Mg

(b) Zn

(c) Mo

(d) Mn

Solution :

Correct option : A Both RUBisCO and PEP carboxylase are important enzymes of dark reaction of photosynthesis. RUBisCO catalyzes carboxylation in C₃ plants. In the presence of magnesium activated RUBISCO, carbon dioxide combines with ribulose bis phosphate to form phosphoglyceric acid. In C₄ plants, mesophyll cells fix carbon dioxide with the help of phospho enol pyruvate in the presence of magnesium activated phospho-enol pyruvate carboxylase.