Researchers investigate whether exercise increases blood flow through capillaries near the skin surface. One group of volunteers rests while a different group cycles. Both groups are in a room at the same temperature. Mean surface blood flow is greater in the cycling group.
Which follow-up investigation would isolate exercise as the independent variable most effectively?
have every volunteer complete a resting trial and a cycling trial at the same room temperature
recruit more volunteers for the cycling group than for the resting group
ask the cycling group to cycle at several speeds without taking resting measurements
measure the resting group in a cool room and the cycling group in a warm room
78 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.