(a)[2]
Many of the allergens capable of triggering an asthma attack are breathed in during normal breathing. 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 perform its main function in the walls of blood vessels and airways.
(b(ii))[3]
Suggest why this type of asthma was very common in the population of Tristan da Cunha.