Scientists investigate the effect of a treatment on vasodilation. The table shows skin blood flow before and after the same increase in core body temperature.
Table
| Group | Blood flow before in arbitrary units | Blood flow after in arbitrary units |
|---|---|---|
| Without treatment | 30 | 90 |
| With treatment | 30 | 45 |
Which statement best describes the effect of the treatment?
It completely prevents vasodilation because final blood flow is lower.
It completely prevents vasoconstriction because final blood flow is higher.
It reduces the blood-flow response by 50%50\%50% compared with the untreated group.
It reduces the blood-flow response by 75%75\%75% compared with the untreated group.
44 exam-style questions on Edexcel GCSE Biology 7.3 Homeostasis and thermoregulation, covering 7.3.1 Importance of a constant internal environment, 7.3.2 Importance of homeostasis, 7.3.3a Thermoregulation via the skin and hypothalamus, and 7.3.3b Vasoconstriction and vasodilation in thermoregulation. Each one has a worked solution and a mark scheme showing where the marks go.