8.'Bile does not contain any enzyme but it is essential for digestion' Explain the statement .
9.(a)Name the substances that get reabsirbed by the tubules .
(b)How are the lungs designed in human beings to maximize the area for the exchange of gases ?
10.(a) What will happen if ...Mucus is not secreted by the gastric glands .
(b) What will happen if ....Leaves of plants are covered with vaseline .