Biology 5090 · Question 1[11 marks]
(a)[3]
Identify structure P and valve Q. State the vital function of structure P in maintaining the efficiency of the mammalian circulatory system.
(b)[3]
With reference to blood pressure changes shown in the graph:
(i)[2]
Explain why valve Q closes at Point X.
(ii)[1]
Explain why the aortic semilunar valve opens at Point Y.
(c)[5]
Coronary heart disease (CHD) is a major cause of mortality worldwide.
(i)[3]
Describe how the narrowing of a coronary artery by an atheroma (fatty deposit) can lead to a myocardial infarction (heart attack).
(ii)[2]
State two dietary or lifestyle modifications that reduce the risk of coronary heart disease.