In the 1700s,a French scientist,Antoine Lavoisier gained new experimental information about how chemistry works.He isolated chemicals that were reacting,including a metal and an acid.His observation of the results seemed to show that much of the metal had been lost in the chemical reaction.Yet,upon weighing the system,the total amounts of materials had not changed during the reaction.His resulting law of Conservation of Mass also applies to biology,because the materials we are made of are _________ that change forms,but aren't truly lost as we conduct life chemical reactions.