a) Substrate compulsory to hexokinase causes large conformational variations which forms the binding site for ATP
and eliminates water from active site. This averts ATP from binding in the absenteeism of the other substrate,
which would endorse hydrolysis in its place of phosphate transfer.
b) Opposing anabolic and catabolic pathways have diverse enzymes that catalyze opposite irreparable
reactions. These are differentially regulated when one is stimulated the other is reserved to guarantee that
only one pathway is efficient at a time.