IGCSE & GCSE Biology by D. G. Mackean

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 20. Personal health

Page 176

1. The answer will depend on personal data.
2. Dental decay. Avoid frequent or prolonged exposure to sugary substances.
    Gum disease. Clean the teeth regularly to remove plaque.

Page 179

1. Tolerance of a drug means that the user needs larger and larger doses to achieve the desired
    effect. Dependence means that the user has a craving for the drug and cannot give it up
    without experiencing distressing withdrawal symptoms.
    Being ‘hooked’ on a drug means that the user is dependent on it.
2. a Athletics. Amphetamines raise the blood pressure to dangerously high levels.
    b Examinations. Amphetamines increase confidence but not accuracy. You could be writing
    rubbish with confidence.
3. Alcohol causes vasodilation in the skin. The heat-gain sensors in the skin send impulses to
    the brain and induce a feeling of warmth. But the vasodilation also increases loss of heat from
    a warmer skin.
4. Alcohol increases reaction time so that it takes longer for the driver to react to a hazard though
    it also induces a false feeling of confidence.
5. There is a risk that morphine and heroin will lead to tolerance in users, so that the addicts have to
    constantly increase doses to get the desired effect.

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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