Which is not a function associated with the excretory system? A. removing urine
B. chemically breaking down glucose
C. reabsorbing water and salts
D. filtering blood for metabolic waste

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme

nucleus

would be most reasonable answer tbh