The table shows pressures at three instants in the left side of the heart. The atrioventricular valve opens when atrial pressure exceeds ventricular pressure. The aortic valve opens when ventricular pressure exceeds aortic pressure.
Table
| Instant | Left atrium pressure in kPa | Left ventricle pressure in kPa | Aorta pressure in kPa |
|---|---|---|---|
| P | 1.2 | 0.8 | 10.0 |
| Q | 1.0 | 5.0 | 10.0 |
| R | 1.0 | 13.0 | 11.0 |
At which instant are both valves closed?
P only
Q only
R only
P and R
42 exam-style questions on Edexcel GCSE Biology 8.2 Blood and circulation, covering 8.2.1 Structure and function of the blood, 8.2.2 Structure of blood vessels, 8.2.3 Structure of the heart and circulatory system, and 8.2.4 Cardiac output. Each one has a worked solution and a mark scheme showing where the marks go.