(b) : During glycolysis pyruvic acid is produced from glucose and is oxidatively decarboxylated to form acetyl CoA. This formation of acetyl CoA from pyruvic acid needs a multienzyme complex and 5 essential cofactors, i.e., lipoic acid, CoA,Mg2+, NAD and TPP (thiamine pyrophosphate). It results in production of 2 molecules of CO2 and 2 molecules of NADH2. This acetyl CoA enters mitochondria and is completely oxidised during Krebs' cycle. Thus acetyl CoA acts as the linker of glycolysis and Krebs' cycle.