(a(i))[1]
Name the epithelium type at N.
(a(ii))[1]
Name the structures at O.
(a(iii))[1]
Name the tissue labelled P.
(b)[2]
During strenuous exercise, smooth muscle in the trachea and bronchi relaxes. Suggest the advantages of this relaxation in such periods of strenuous exercise.
(c)[2]
The walls of the trachea and bronchi include elastic fibres. These elastic fibres are formed from bundles of the fibrous protein elastin. Describe two ways in which the structure of a collagen molecule is different from the structure of the elastin molecule described above.