An ultrasound scanner measures the total volume of blood moving in each direction in two veins during 20 contractions of the surrounding skeletal muscles.
| Vein | Total volume moved towards the heart in cm3\mathrm{cm^3}cm3 | Total volume moved away from the heart in cm3\mathrm{cm^3}cm3 |
|---|---|---|
| P | 88 | 0 |
| Q | 86 | 58 |
Calculate the net volume of blood moved towards the heart in vein P and in vein Q during the 20 contractions.
Explain which vein is likely to contain valves that do not close properly.
67 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.