Pressure sensors recorded the pressure on each side of the left atrioventricular valve at two moments during one heartbeat.
| Moment | Pressure in left atrium (kPa) | Pressure in left ventricle (kPa) |
|---|---|---|
| P | 1.2 | 0.5 |
| Q | 0.8 | 16.0 |
State whether the left atrioventricular valve is open or closed at each moment.
In one person, the left atrioventricular valve does not close completely.
Explain why this fault reduces the net flow of blood from the heart at moment Q.
114 exam-style questions on OCR GCSE Biology 2.2 The challenges of size, covering 2.2.1 Exchange surfaces and surface area : volume ratio, 2.2.2 Substances transported in organisms, 2.2.3 The human circulatory system, 2.2.4 The heart and blood vessels, 2.2.5 Red blood cells and plasma, 2.2.6 Uptake of water and mineral ions by plants, 2.2.7 Transpiration and translocation, 2.2.8 Xylem and phloem, 2.2.9 Environmental factors and water uptake, and 2.2.10 Using a potometer. Each one has a worked solution and a mark scheme showing where the marks go.