(a)[4]
Finish the sentences about features of the human gas exchange system. Gas exchange surfaces have a [BLANK] surface area. The distance across the gas exchange surfaces is very [BLANK]. The gas exchange system has a [BLANK] blood supply and good [BLANK] with air.
(b(i))[1]
State the name given to structure W in Fig. 5.1.
(b(ii))[2]
State the letters in Fig. 5.1 that show where the concentration of carbon dioxide in the blood is highest and where the concentration of oxygen in the blood is highest.
(b(iii))[1]
State the name of the process in which molecules move down a concentration gradient.