The diagram shows two sections of skin from a runner. One section was observed on a cold morning and the other after running in warm weather. Table 1 gives ...
Question 1 Report
The diagram shows two sections of skin from a runner. One section was observed on a cold morning and the other after running in warm weather. Table 1 gives measurements made by scientists at the same time.
| Condition | Mean skin blood flow / cm3 min-1 | Mean sweat production / cm3 min-1 |
|---|---|---|
| Cold morning | 0.8 | 0.0 |
| Warm-weather run | 3.6 | 1.4 |
(a) Use Table 1 to calculate the increase in mean skin blood flow during the warm-weather run. [2]
(b) Describe the changes in skin blood flow and sweat production shown in Table 1. [2]
(c) Explain how these changes help to keep the runner's body temperature near 37 degrees C. [3]
Answer Details
(a)
\[3.6-0.8=2.8\text{ cm}^3\text{ min}^{-1}\]
The increase in skin blood flow is \(2.8\text{ cm}^3\text{ min}^{-1}\). [2]
(b) Skin blood flow increases, from \(0.8\) to \(3.6\text{ cm}^3\text{ min}^{-1}\). Sweat production also increases, from zero to \(1.4\text{ cm}^3\text{ min}^{-1}\). [2]
(c) More blood flows through capillaries close to the skin surface, so more heat is transferred from blood to the surroundings. Sweat evaporates, and evaporation uses heat energy from the skin and body. Both processes help lower temperature towards \(37\,^{\circ}\text{C}\). [3]
Download The App On Google Playstore
Everything you need to excel in your exams
