An engineer builds two hollow model torsos, P and Q. Each torso contains water and has an identical heater that supplies energy continuously. Both torsos start at the same temperature and are kept in the same room.
A pump can deliver water to the porous outer surface of each torso, where the water can evaporate.
In model P, the pump delivers water continuously at a rate of 6 cm3 min−16\ \mathrm{cm^3\ min^{-1}}6 cm3 min−1.
In model Q, a temperature sensor sends information to a controller. The controller can switch an identical pump on or off.
| time in minutes | internal temperature of P in ∘C^\circ\mathrm{C}∘C | internal temperature of Q in ∘C^\circ\mathrm{C}∘C | pump rate in Q in cm3 min−1\mathrm{cm^3\ min^{-1}}cm3 min−1 |
|---|---|---|---|
| 0 | 39.0 | 39.0 | 6 |
| 5 | 37.8 | 37.8 | 6 |
| 10 | 36.7 | 37.0 | 0 |
| 15 | 35.6 | 37.3 | 0 |
| 20 | 34.8 | 37.7 | 6 |
| 25 | 34.1 | 37.1 | 0 |
Evaluate which model is more suitable for representing the coordinated homeostatic control of body temperature. Use the information in the table and your biological knowledge.
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.