<prompt> All the following are biotin independent carboxylation reactions, EXCEPTAddition of CO2 to from C6 in purine ringConversion of pyruvate to malate by malic enzymeAcetyl CoA carboxylaseCarbamoyl phosphate synthetase  <response>: The conversion of pyruvate to oxaloacetate by biotin dependent pyruvate carboxylase is essential for the synthesis of glucose from many non-carbohydrate sources. 