Give reasons for the following : (a) Plants do not have an excretory system so how they excrete their wastes ? (b) Why…

(a) Some waste is stored in leaves that fall off/wastes may be stored in cellular vacuoles/other wastes are stored as resins and gums in old xylem/ may excrete some waste into soil via roots. (1 Mark)
(b) Mammals and birds have high energy needs to maintain their body temperature. Therefore, mixing of blood is prevented by separation of right and left side of heart and thus they have double circulation. (2 Marks)