IGCSE Biology 2nd edition

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 control


Page 139
1. Principally; put on more or warmer clothing; take shelter in a warm environment. Minor
    actions; hot drinks, use external sources of heat, vigorous exercise.
2. Heat is one of the forms of energy produced by respiration both in active muscles and all other
    tissues. The heat is distributed round the body by the blood circulatory system.
3.

Gains Losses (to the environment)
Respiration
External sources e.g. sunlight
central heating, hot food and drink
Conduction
Convection
Radiation
Evaporation
4. a The hairs b Vasoconstriction, cessation of sweating.
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.

Downloads
Download the answers in PDF format below
Section 1, Chapters 1-5
Section 2, Chapters 6-9
Section 3, Chapters 10-12
Section 3, Chapters 13-17
Section 3, Chapters 18-20
Section 4, Chapters 21-24
Section 5, Chapters 25-27
Section 5, Chapters 28-29
Section 6, Chapters 30-34
Section 6, Chapters 35-37
Section 7, Chapters 38-39
Section 8, Chapters 40-41


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