Topic 1 Mark Scheme

Explain why high blood pressure can increase the risk of developing cardiovascular disease (CVD). (3 marks)

• high blood pressure causes damage to the endothelium of the arteries (1 mark)

• inflammatory response/build up of cholesterol leads to the formation of an atheroma (1 mark)

• plaque develops and narrows the lumen of the artery (1 mark)

During the development of the mammalian heart, there is a hole between the left ventricle and the right ventricle. This hole usually becomes sealed before the mammal is born. If it is not sealed, the mammal will become easily tired due to a lack of energy. Explain why a mammal born with a hole between the two ventricles will have these symptoms. (3 marks)

• less oxygen available for aerobic respiration (1 mark)

• deoxygenated blood mixes with oxygenated blood (1 mark)

• therefore reducing the concentration of oxygen in the blood circulating in the body (1 mark)

• because some deoxygenated blood {does not leave right ventricle/is transferred to the left ventricle/does not go to the lungs/goes to the respiring tissues} (1 mark)

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