Answer question n

(a) Exchange and secretion of materials takes place by movement of molecules across the epithelium which is determined by the permeability of different types of epithelia.

(b) (i) Skin – Stratified squamous epithelium

(ii) Simple squamous.

(c) In the alimentary canal.

(d) The hair-like cilia allow movement pushing down of substances and tall columnar cells facilitate movement across the epithelial layer.