10 5 The cardiac cycle is the sequence of events in one heartbeat. In humans, the cardiac cycle can be divided into three stages. (a) In the ventricular systole stage of the cardiac cycle, the (1) A ventricles contract, atrioventricular valves close and semilunar valves open B ventricles contract, atrioventricular valves open and semilunar valves close C ventricles relax, atrioventricular valves close and semilunar valves open D ventricles relax, atrioventricular valves open and semilunar valves close (b) Caffeine is a stimulant found in coffee. The effect of different types of coffee on blood pressure was investigated. Decaffeinated coffee has most of the caffeine removed. Four groups of volunteers had their blood pressure measured before having a drink and again 30 minutes later. The results of this investigation are shown in the table. Drink provided to volunteers Mean systolic blood pressure / mm Hg Before the drink 30 minutes later Water 115 119 Decaffeinated coffee 120 118 Regular coffee 106 118 (i) Calculate the percentage increase in the mean systolic blood pressure after drinking regular coffee. (1) .............................................................. % Turn over 11 (ii) Daphnia can be used to investigate the effects of caffeine on heart rate. Devise a procedure to compare the effects of decaffeinated coffee and regular coffee on the heart rate of Daphnia. (4) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... 12 (c) Explain why high blood pressure can increase the risk of developing cardiovascular disease (CVD). (3) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 5 = 9 marks) Turn over 13 BLANK PAGE