(a)[2]
Some allergens that can bring on an asthma attack are taken in while breathing normally. Suggest two examples of such allergens.
(b(i))[1]
Collagen is also present in the walls of blood vessels. State one property of collagen that allows it to carry out its main function in the walls of blood vessels and airways.
(b(ii))[3]
Suggest why this type of asthma was especially common in the population of Tristan da Cunha.