(a) What is a sensory cell?

(b) State one function each for the following parts of mammalian eye: (i) lens; (ii) vitreous humour; (iii) optic nerve.

(c) (i) List four structures which protect the eye from injury.
(ii)Explain briefly how each of these structures performs its function.

(d) Explain why a person in a dark room is dazzled for some seconds when he is suddenly exposed to bright sunlight.