Contents ii Exam board specification map iv Introduction vi Topic checker * Topic checker answers * Biology Unit B1a Human Biology The nervous system 2 Hormones 4 Controlling reproduction 6 Diet and exercise 8 Cholesterol and salt 10 Medical drugs 12 Recreational drugs 14 Pathogens and disease 16 Antibiotics 18 Vaccination 20 Unit B1b Evolution and Environment Adaptation 22 Reproduction 24 Cloning and genetic engineering 26 Extinction and evolution 28 Natural selection 30 Pollution 32 Global warming 34 Chemistry Unit C1a Products from Rocks Atoms and elements 36 Reactions and compounds 38 Limestone 40 Ores and iron 42 Alloys 44 Copper, titanium and aluminium 46 Hydrocarbons 48 Burning fuels 50
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Contents
ii
Exam board specification map iv
Introduction vi
Topic checker *
Topic checker answers *
Biology
Unit B1a Human BiologyThe nervous system 2Hormones 4Controlling reproduction 6Diet and exercise 8Cholesterol and salt 10Medical drugs 12Recreational drugs 14Pathogens and disease 16Antibiotics 18Vaccination 20
Unit B1b Evolution and EnvironmentAdaptation 22Reproduction 24Cloning and genetic engineering 26Extinction and evolution 28Natural selection 30Pollution 32Global warming 34
Chemistry
Unit C1a Products from RocksAtoms and elements 36Reactions and compounds 38Limestone 40Ores and iron 42Alloys 44Copper, titanium and aluminium 46Hydrocarbons 48Burning fuels 50
A01_BSCI_REV_GCSE_4479_FM.indd 2 2/10/09 13:54:18
Contents
iii
Unit C1b Oils, Earth and AtmosphereAlkenes 52Polymers 54Plant oils 56Food additives 58Structure of the Earth 60The atmosphere 62Noble gases 64
Physics
Unit P1a Energy and ElectricityHeat transfer 66Effi ciency 68Cost of electricity 70The National Grid 72Generating electricity 74Renewable energy sources 76Resources compared 78
Unit P1b Radiation and the UniverseThe electromagnetic spectrum 80Some uses of electromagnetic radiation 82Communication signals 84Hazards of electromagnetic radiation 86Atomic radiation 88Half-life 90Observing the universe 92
Exam questions 94
Answers to exam questions 112
Complete the facts *
Complete the facts answers *
Answers to practice questions 114
Glossary 118
Web links *
Last-minute learner 121
* Only available in the CD-ROM version of the book
A01_BSCI_REV_GCSE_4479_FM.indd 3 2/10/09 13:54:19
Receptors detect changes in the environment called stimuli.
Information from receptors travels along neurones to the brain.
The brain coordinates the response.
Reflex actions are fast and automatic.
The nervous system
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A Receptors and stimuli
A stimulus is a change in the surroundings. Stimuli include sound, light, chemicals, touch, pain, pressure, temperature and changes in position.
key factA receptor is a cell or
group of cells that can detect a stimulus. For example, receptors in the ear detect sound, receptors in the eye detect light, and receptors in the tongue detect chemicals in food and drink.
B Neurones and the brain
Nerve cells are called neurones. They carry information from one place to another in the body as electrical signals.
key factInformation travels as electrical impulses along
nerve cells from the receptors to the brain.
The brain coordinates the response to the stimulus. The response involves effectors and other nerve cells.
C Synapses
key factA synapse
is the gap between two nerve cells.
Electrical impulses cannot cross the synapse. Instead, chemicals called neurotransmitters diffuse across it. They are produced by one of the nerve cells, and make the other nerve cell send information.
Ears, eyes and the tongue are sense organs. You don’t need to know about their structure or function for the exams.
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The nervous system and hormones are involved in this control.
Hormones are chemicals secreted by glands.
The bloodstream transports hormones to their target organs.
Hormones
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A Some conditions to control
The body’s cells and the chemicals they contain are damaged if the conditions change too much.
key factThe internal conditions that must be controlled
within tight limits include:• water content (the different chemicals in the body must not be too dilute or too concentrated)• ion content (such as sodium ions from the salt in our food)• blood sugar level (to provide cells with a constant source of energy)• temperature (enzymes work best at a certain temperature).
B Controlling water and ion content
Water leaves the body from the lungs when we breathe out.
Water and ions leave the body from the skin when we sweat and from the kidneys in urine.
C Sports drinks
The manufacturers of sports drinks claim that their products are better than ordinary drinks when people take exercise. Sports drinks contain dissolved ions and sugars. The aim is to replace the water, ions and sugars lost from the body during exercise.
You may be given information in a table or graph about sports drinks to evaluate in the exam.