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Introduction v

Chapter 1 Chemical reactions 2 Thinking about reactions 21.1 Types of elements 51.2 Compounds 141.3 Chemical reactions 171.4 Reaction rate 25 Chapter review 30

Chapter 2 Acids and bases 32

Thinking about acids and bases 322.1 Introducing acids and bases 352.2 Detecting acids and bases 382.3 pH and the environment 47 Chapter review 56

Chapter 3 Sensational waves 58 Thinking about waves 583.1 Electromagnetic waves 613.2 Light 693.3 Heat 773.4 Sound waves 83 Chapter review 90

Chapter 4 Forced to move 92 Thinking about forces 924.1 What is a force? 954.2 It’s a drag! 1014.3 Going down! 1064.4 The need for speed 113 Chapter review 120

Chapter 5 Making life easier 122 Thinking about machines 1225.1 Machines 1255.2 The lever 1335.3 ‘Having an inclination’ 1375.4 Turn, turn, turn 141 Chapter review 150

Chapter 6 Rock of ages 152 Thinking about rocks 1526.1 A matter of scale 1556.2 Igneous and sedimentary rocks 1586.3 The ravages of time 1716.4 A journey in time 178 Chapter review 182

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About the authorsJacinta Devlin has taught general science, mathematics and VCE Physics over her ten years at Kilbreda College, Mentone. She co-authored the fi rst edition of Heinemann Science Links 1 and 2, and was a contributing author to Heinemann Physics 12 2nd edition.

Helen Cochrane is a general science, maths, biology and information technology teacher with over 20 years of experience. She now works as a science writer and consultant, with a special interest in research into human learning.

Rhonda Coffey has taught science for 25 years in the Geelong region. She has always been keen to introduce ICT and investigative practices into the science curriculum, working in the three areas of science, ICT and library in schools. She has been a Science in Schools Professional Development Leader and currently works as a science writer.

Contributing authorsEsther Anderson, Rosetta Batsakis, David Coffey, Naomi Coghlan, Trish Kirley, Katrina Markwick, Julie Radford, Yvonne Sanders, Mira Starek, Lyn Tounson.

Expert teacher Review PanelJohn Roberts, Brett Barber, Shameem Hashmi, Paul Naughtin, Victoria Stats and Linda Wilson.

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Chapter 7 Universe exposed 184

Thinking about the universe 1847.1 The night sky 1877.2 Exploring the universe 1957.3 Wonders of the universe 2057.4 A dangerous universe 214 Chapter review 220

Chapter 8 Ecosystems 222 Thinking about ecosystems 2228.1 There’s no place like home! 2258.2 Guess who’s coming for dinner? 2338.3 Changes to ecosystems 238 Chapter review 250

Chapter 9 Systems for survival 252

Thinking about survival 2529.1 Nutrients needed by plants and animals 2559.2 Digesting dinner 2659.3 Transport systems in animals 2729.4 Pathways in plants 276 Chapter review 280

Chapter 10 Keeping healthy 282

Thinking about health 28210.1 The diet that works! 28510.2 Caring for your body 29410.3 Disease—we are not alone! 30110.4 Our environment, our health 310 Chapter review 316

Chapter 11 Skills link 318

Index 334

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Heinemann Science Links 2

Get Fit Health ResortYou are part of a team employed to run a camp for family groups to teach them how to live a healthy lifestyle. Families stay for 3–5 days. You will provide food and activities that will help them make a start at becoming fi tter and healthier, and enable them to continue this when they return home. You will also run seminars on hygiene and avoiding disease.

Work in groups of three or four.

• Brainstorm a range of different areas such as nutrition, balanced diet, types of physical activity, amount of physical activity, hygiene and ways of preventing disease.

• Consider the backgrounds and age of the participants.

• Consider how you are going to provide food for people of different cultural backgrounds.

• Discuss what handouts you are going to provide in your information sessions.

• Decide what sorts of equipment you will need.

Develop an advertising brochure that includes a daily program detailing meals, activities and seminars. You will present it at the completion of the chapter.

Extension

Develop a brochure or electronic presentation for one of the seminars. Select from:

• Personal hygiene

• Fit for life

• Avoiding disease

• Why vaccinate?

Figure 10.2

Work it!

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S C I E N C E work

Dining for health

What to do

1 Draw a dinner plate (full size) showing how much of each of the fi ve food groups you should eat. To do this, divide your plate into parts that represent each food group. Draw or cut out pictures from old magazines of foods and put these on your dinner plate.

2 Now repeat the activity for the food you ate yesterday. Does this dinner plate look like your fi rst one? What changes could you make to improve your diet, or is it balanced already?

Activity 10 . 1 What to do

Energy and weighing in the kilojoulesFood provides us with the energy we need to play sport, do work and even think. It is needed for all of the activities that we do, even sleeping. Energy comes from the carbohydrates, fats and proteins in food. The amount of energy a food provides is measured in kilojoules (kJ). A term that was previously used to measure energy was calories. One calorie is approximately equal to 4 kilojoules. Even when you are thinking, you are using up energy or burning up kilojoules. Different activities burn up different amounts of kilojoules. Sitting in the classroom for an hour uses up 300–600 kilojoules!

The energy available from food can be measured by burning (oxidising) it. In the body, energy is released when food is oxidised during cellular respiration. Refer to Chapter 9 Systems for survival for more information about cellular respiration.

Figure 10.6

What do these foods have in common? Yes, they could be for breakfast, but each of these foods provides 100 kilojoules. A banana will give you enough energy to run for about 10 minutes!

S C I E N C E work

Peanut power

Aim

To determine the amount of energy that can be obtained from burning a peanut.

Materials

• raw peanut • cork

• small measuring cylinder • long needle

• water • Bunsen burner

• test-tube • retort stand

• balance • bosshead and clamp

• thermometer • bench mat

Safety

Don’t leave the burning peanut unattended and make sure the room is well ventilated.

EXPERIMENT 10 .2!

Figure 10.7

How to set up your experiment.

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The number of kilojoules needed each day is different for each person. It depends on factors such as age, sex, weight and how active you are.

During puberty and adolescence, your body grows and develops rapidly and requires more energy. An average 13-year-old female may require approximately 9000 kJ of energy per day, whereas a 13-year-old male needs about 10 500 kJ of energy per day.

Figure 10.8

Energy used per minute in various activities (for a 50 kg person).

Method

1 Measure out 10 mL of water in the measuring cylinder and pour the water into the test-tube; measure and record its temperature.

2 Weigh the peanut and record its mass.

3 Insert the needle through the peanut and then into a cork so that the peanut sits above the cork like a ‘fl ag’ on the needle ‘fl agpole’.

4 Light the Bunsen burner and use it to set the peanut alight, making sure that the Bunsen burner fl ame does not heat the water.

5 Rotate the bosshead and clamp so that the test-tube is over and as close as possible to the burning peanut. Allow the burning peanut to heat the water in the test-tube.

6 When the peanut has fi nished burning, measure and record the water temperature again.

Discussion

1 Heat and other forms of energy are measured in joules. To heat 10 mL of water by 1ºC takes 42 joules of energy. Calculate how much heat was released by your burning peanut.

2 How much heat would be released by burning 1 gram of your peanut?

3 Not all the energy released by your peanut could be recorded in this experiment. Explain why.

Extension

Compare the energy available, per gram, of various types of nuts. You could use a spreadsheet for your calculations and presentation of results.

Evaluation

1 Did you have any problems with the method? List any.

2 Suggest some ways to improve the method.

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The speed at which you convert food and oxygen into energy is called your basal metabolic rate or BMR. Some people can eat a lot without gaining weight because they have a higher basal metabolic rate. Others have a lower basal metabolic rate, which means that they convert food into energy more slowly and gain fat more easily.

If people eat more food than they need (for the activities that they do), it is stored as fat and they put on weight. Hormonal imbalance is another reason why people become overweight. Obesity (extreme overweight) can place an enormous strain on the heart, as well as on joints, and can increase the chances of getting diabetes and other diseases.

The only way to lose weight is to eat less food than your body uses. Exercise may also help burn up kilojoules—it usually makes you feel good too!

Figure 10.9

Graph showing body mass index (BMI) linked to age for maximum desirable weight.

Data regarding weight as it is linked to height, age and sex has been used to create a guide to the desirable weight for a person. This is called the body mass index or BMI, which is calculated as:

BMI = weight

(height)²

where weight is in kilograms and height is in metres.For adults, a person is considered to be not overweight if their

BMI is 25 or less. For people under 18 years old, the graph in Figure 10.9 can be used to establish the maximum desirable weight for younger people. Many young people worry about their body shape, even those who are active and fi t. It is important to realise that we are all meant to be different shapes and sizes.

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S C I E N C E work

Using nutrition information labelsinvestigation 10 .3Most foods contain a mixture of the

three types of nutrients—carbohydrates, proteins and lipids—as well as various vitamins, minerals and water.

What you need

The packaging from a variety of different food products, in particular the nutrition information label for that product.

What to do

1 Working in groups of three or four, examine the nutrition information label for each food product.

2 In a data table, note the amounts of energy, carbohydrates, proteins and lipids (fats and oils) contained in each food product.

Discussion

1 List the food products in order of highest to lowest energy contents.

2 List the food products in order of highest to lowest fat content.

3 Which food product do you think is the healthiest? Least healthy? Why?

4 ‘Serving size’ is often different for different food products. Did this make it diffi cult to compare them?

Extension

Obtain food labels for different brands of the same type of food and compare them.

Present your fi ndings in a format of your choice.

If you don’t eat enough food, your body will use up any stored fat reserves and you will lose weight. Sometimes people who want to be thin go to extreme lengths to lose weight and develop eating disorders. Anorexia nervosa is a psychological disorder in which someone believes that they are overweight and so diets or avoids food altogether to lose weight. They continue to lose weight even when their weight is dangerously below normal levels. Approximately 5% of people with anorexia die from starvation or by suicide.

Figure 10.10

A ‘nutrition information’ label indicates the various amounts of nutrients in a food product.

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Eating a balanced diet seems to be one of the keys to staying healthy. Most of the time we try to eat sensibly. But sometimes we want a treat. For many people, having a treat means having chocolate. This may not be as bad for us as we might think.

The Swiss are the biggest chocolate consumers in the world, enjoying 10.1 kg per person a year (in 2000).

A recent Dutch survey found that Switzerland was the happiest country in the world. You have to

wonder…

In 2000 the top fi ve chocolate-consuming countries in the world were Switzerland, Austria (9.1 kg per person), Ireland (8.8 kg per person), Germany (8.2 kg per person) and Norway (8.1 kg per person).The average Australian eats about 7.5 kg per year.

Over the years, chocolate has developed a bad reputation. It has been associated with

a number of evils such as acne, tooth decay and migraine. Chocolate neither causes nor

aggravates acne. Studies of students with mild to moderate acne showed that eating chocolate had no

effect on their acne condition. The sugar in chocolate does contribute to the development of cavities, but no more

than sugar from other foods. Poor dental hygiene is the primary cause of tooth decay. Chocolate may actually help to prevent cavities. Cocoa butter, the main fat in chocolate, is solid at room temperature, but has a very low melting point. Chocolate is one of the few foods that melts in your mouth. The cocoa butter coats the teeth and may protect them from plaque formation.

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Figure 10.16

Chocolate contains about 300 chemicals, some of which interact with the brain’s ‘feel good’ systems.

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For most migraine sufferers, chocolate can’t start the migraine chain reaction by itself. Numerous international trials have found that other factors, such as stress (as a result of tiredness, excitement or anger) and hormones, need to be present at the same time. Fasting and eating some other foods may also play a role. More research is needed before chocolate can be completely cleared, but the evidence so far seems promising for chocolate lovers.

Chocolate may also help us to stay healthy. Cocoa beans are rich in antioxidants called fl avonoids. Moderate consumption of other fl avonoid-containing foods such as red wine and tea is correlated with a reduction in cardiovascular disease.

Recent research has turned up a chemical made in the brain and found in chocolate that may hold the key to why we crave the sweet. It is called anandamide. The name comes from an ancient Indian word ananda, meaning ‘bliss’. Anandamide relieves pain, helps us relax and generally improves our mood. Although the brain makes anandamide, we don’t feel happy all the time because the chemical is broken down and inactivated very quickly. But chocolate not only contains anandamide, it also contains substances that slow the chemical’s breakdown, so we can enjoy its mood-improving effect longer.

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chocolatey feelingquestions1 How could eating chocolate help make Switzerland one of the

happiest countries in the world?

2 Complete the following table.

Issue Cause or reason Effect of chocolate

AcneTooth decayMigraineCardiovascular diseaseFeelings

3 Prepare a poster presentation or role-play explaining the health benefi ts of chocolate.

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10 Chapter review

key ideasey ideasy idkekkey ideaskkey ideaskeyUse the key terms to copy and complete the following sentences.

Being means eating the right foods, getting plenty of exercise, avoiding harmful substances and having good mental health.

A involves eating a variety of foods, in specifi c quantities.

Food provides us with for the activities that we do.

not only provides protection, it helps regulate heat and water loss.

produce sebum, which is responsible for pimples or .

Regular exercise improves our , which is essential for a healthy body.

Most are caused by bacteria and viruses.

is the body’s defence mechanism against a specifi c disease-causing organism.

Many of the problems today such as are caused by motor vehicle emissions and industry.

The accumulation of in the lungs causes lung disease.

can damage your hearing.

Industrial wastes produce that pollute our water supplies.

acneair pollutionantibodiesbacteriabalanced dietbasal metabolic

ratebody mass indexdermisdust energyepidermisfi tnesshealthyimmunityinfectious

diseaseskilojoules (kJ)noise pollutionnon-infectious

diseasespathogensebaceous

glandsskinsmogtoxic chemicalsvirus

1 Make a list of all the food you would eat in an average day. Use a ‘calorie counter’ to determine the number of kilojoules that you

review questionstake in per day. Use Table 10.7 to determine whether you eat too little, too much or the right amount for a person your age and sex.

Table 10.7 Recommended energy intakes (kJ) for adolescents

Age (years) Males Females

10–11 8 100–9 100 7 300–8 200

11–12 8 700–9 800 7 700–8 700

12–13 9 200–10 300 8 100–9 100

13–14 9 800–11 000 8 400–9 500

14–15 10 500–11 800 8 600–9 800

15–16 11 100–12 500 8 700–9 900

16–17 11 700–13 200 8 800–10 000

17–18 12 000–13 500 8 800–10 000

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reflection health

2 Explain why the skin is considered a very important organ of the body. Include a diagram of the skin and its components.

3 Are the following true or false? Rewrite the false statements to make them true.(a) Viruses are smaller than bacteria.

(b) Viruses reproduce only inside other cells.

(c) Viruses are killed by antibiotics.

(d) Viruses do not need nutrients.

(e) The common cold is a disease caused by viruses.

(f) Viruses need oxygen to survive.

4 Design a poster or advertisement promoting the benefi ts of regular exercise.

5 Work in a group to draw an outline of the human body on a large piece of paper. Mark on this outline the factors that indicate a healthy body. Compare your healthy bodies with other groups.

6 Australia has strict quarantine laws to prevent infectious diseases being brought into the country. Animals from overseas must be isolated to make sure that they are not carrying diseases such as rabies. (a) Find out how long animals from other

countries must be kept in quarantine.

(b) Describe the symptoms of rabies and what causes it.

7 Research and investigate ways to reduce air pollution at home. Present your report in a format of your choice.

8 Create an issues map answering the question of whether the purpose of immunisation is to cure or prevent a particular disease.

9 Match the disease in column B with the cause in column A.

10 Create role-plays to show the negative effects of alcohol, cigarettes or drugs. Combine with other groups to make a presentation covering the three.

11 Conduct a class debate about compulsory vaccination of children before entering school.

12 Visit Asthma Victoria’s website to fi nd out more information on asthma. Prepare a multimedia presentation that covers the following points.• Explain what asthma is.

• List the triggers of asthma.

• Discuss why people get asthma.

• Describe the signs and symptoms of asthma.

• Find out how to help a person who is having an asthma attack.

• Find out the treatments available for asthma sufferers.

By now, you should have developed some strategies for maintaining good health, as well as the idea that being healthy is something that we can strive for whatever age we are. Look at the list that you made at the start of the chapter. As a class, discuss what changes you need to make to this list. Make a new list based on these changes.

Find out, if possible, what sorts of foods your parents, grandparents or older relatives ate when they were growing up. What sorts of exercise routines did they follow? As a class, compare their lifestyles as teenagers with yours today.

Present your program for your Get Fit Health Resort.

complete

A B

Infection Lung cancer

Genetic Infl uenza

Ageing Lead poisoning

Environmental Alzheimer’s disease

Lifestyle Cystic fi brosis