(a(i))[2]
State the letter in Fig. 4.1 that identifies: the structure that keeps oxygenated and deoxygenated blood separate; an atrioventricular valve.
(a(ii))[2]
Explain why the heart wall at H is thicker than the heart wall at D in Fig. 4.1.
(a(iii))[2]
Complete Table 4.1 by numbering the descriptions so that they are in the right order.
(b(i))[5]
Explain the effect of exercise on heart rate shown in Fig. 4.2.
(b(ii))[3]
State three other factors that can increase the risk of coronary heart disease.