CAIE A Level Biology 9700 · Transport in mammals
The table below shows the pressures (mmHg) in the left atrium, left ventricle and aorta at four stages of one cardiac cycle in a healthy adult.
| Stage | Left atrium | Left ventricle | Aorta |
|---|---|---|---|
| 1 | 8 | 2 | 80 |
| 2 | 6 | 80 | 80 |
| 3 | 5 | 120 | 120 |
| 4 | 4 | 5 | 95 |
Describe the changes in pressure in the left atrium, left ventricle and aorta during one cardiac cycle, and explain how these pressure changes cause the opening and closing of the atrioventricular and semilunar valves.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.