(a) Describe the route of blood through the heart, from the vena cava to the aorta. In your answer name the chambers, the blood vessels and the valves. [6]
(b) Explain why the wall of the left ventricle is thicker than the wall of the right ventricle. [2]
- (a) vena cava → right atrium(1)
- (a) right atrium → right ventricle(1)
- (a) right ventricle → pulmonary artery → lungs(1)
- (a) (lungs →) pulmonary vein → left atrium(1)
- (a) left atrium → left ventricle → aorta(1)
- (a) valves named in the correct places: atrioventricular / tricuspid (right) and bicuspid / mitral (left) valves between atria and ventricles AND semilunar valves at the exits to the pulmonary artery and aorta; accept pulmonary valve / aortic valve for semilunar valves(1)
- (b) left ventricle pumps blood to the whole body / further / right ventricle only pumps to lungs; reject 'pumps more blood' (both ventricles pump the same volume)(1)
- (b) so needs (more muscle to contract more strongly) to produce a higher pressure(1)
- Answer: (a) vena cava, RA, tricuspid valve, RV, semilunar valve, pulmonary artery, lungs, pulmonary vein, LA, bicuspid valve, LV, semilunar valve, aorta (b) pumps to whole body at higher pressure
- Examiner tip: The pulmonary ARTERY carries blood away from the heart to the lungs — swapping pulmonary artery and vein can cost you two marks.