question_answer 22)

  The reaction that is responsible for the primary fixation of  is catalysed by (a) RuBP carboxylase                                                      (b) PEP carboxylase (c) RuBP carboxylase and PEP carboxylase            (d) PGA synthase

Answer:

                  (c) In  cycle RuBP carboxylase is used to fix atmospheric  whereas, in  plants PEP carboxylase is involved in primary  fixation. So, both are used in  fixation but in different cycles. Other options are incorrect because in (a) and (b) option is giving incomplete information and option (d) PGA synthase is not at all involved in  fixation.