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Here you will find the answers to the 'in-text' questions which occur in IGCSE Biology (2nd edition) and GCSE Biology (3rd edition) by D. G. Mackean, published by Hodder Education, London, UK. Chapters: | Index | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | |
Chapter 15. The skin, and temperature controlPage 139
5. Your ‘core’ temperature changes very little. You feel cold when sensory organs in the skin detect and respond to heat loss. Similarly you feel hot when other receptors in the skin detect and respond to heat gain. These receptors send impulses to the brain which interprets them as ‘feeling cold’ or ‘feeling hot’. 6. a Sweat will not evaporate if the air round the body is very (a) humid, (b) still. b Sweat will evaporate more rapidly if (a) the humidity is very low and (b) if there is air movement to carry the water vapour away. 7. Negative feedback triggers reactions which counteract the changes and restore the system to its steady state. Positive feed back would assist the changes and lead to an ever-increasing change in the system. |
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