11. Uric acid is the chief nitrogenous wasters in(A) frog(B) birds(C) fishes(D) man

18. During the propagate ion of a nerve ion of a nerve impulse, the action potential results from the movement of(A) K+ ions from intracellular fluid to extracellular fluid(B) K+ ios from extracellular fluid to intracellular fluid(C) Na+ ions from extracellular fluid to intracellular fluid(D) Na+ ions from intracellular fluid to extracellular fluid