00 SL2 SI.indd

Contents
1.1
1.2
1.3
1.4
Thinking about reactions
Types of elements
Compounds
Chemical reactions
Reaction rate
Chapter review
Chapter 2
2.1
2.2
2.3
Making life easier
Thinking about machines
Machines
The lever
‘Having an inclination’
Turn, turn, turn
Chapter review
Chapter 6
6.1
6.2
6.3
6.4
Forced to move
Thinking about forces
What is a force?
It’s a drag!
Going down!
The need for speed
Chapter review
Chapter 5
5.1
5.2
5.3
5.4
Sensational waves
Thinking about waves
Electromagnetic waves
Light
Heat
Sound waves
Chapter review
Chapter 4
4.1
4.2
4.3
4.4
Acids and bases
Thinking about acids and bases
Introducing acids and bases
Detecting acids and bases
pH and the environment
Chapter review
Chapter 3
3.1
3.2
3.3
3.4
Chemical reactions
2
2
5
14
17
25
30
32
32
35
38
47
56
contents
Chapter 1
v
58
58
61
69
77
83
90
92
92
95
101
106
113
120
Science Link s 2
Introduction
122
122
125
133
137
141
150
Rock of ages
152
Thinking about rocks
A matter of scale
Igneous and sedimentary rocks
The ravages of time
A journey in time
Chapter review
152
155
158
171
178
182
iii
Chapter 7
7.1
7.2
7.3
7.4
Thinking about the universe
The night sky
Exploring the universe
Wonders of the universe
A dangerous universe
Chapter review
Chapter 8
8.1
8.2
8.3
Systems for survival
Thinking about survival
Nutrients needed by plants and animals
Digesting dinner
Transport systems in animals
Pathways in plants
Chapter review
Chapter 10
10.1
10.2
10.3
10.4
Ecosystems
Thinking about ecosystems
There’s no place like home!
Guess who’s coming for dinner?
Changes to ecosystems
Chapter review
Chapter 9
9.1
9.2
9.3
9.4
Universe exposed
Keeping healthy
Thinking about health
The diet that works!
Caring for your body
Disease—we are not alone!
Our environment, our health
Chapter review
Chapter 11
Index
Skills link
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184
187
195
205
214
220
222
222
225
233
238
250
252
252
255
265
272
276
280
282
282
285
294
301
310
316
318
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About the authors
Jacinta Devlin has taught general science, mathematics and VCE Physics over her ten
years at Kilbreda College, Mentone. She co-authored the first 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 authors
Esther Anderson, Rosetta Batsakis, David Coffey, Naomi Coghlan, Trish Kirley,
Katrina Markwick, Julie Radford, Yvonne Sanders, Mira Starek, Lyn Tounson.
Expert teacher Review Panel
John Roberts, Brett Barber, Shameem Hashmi, Paul Naughtin, Victoria Stats and Linda Wilson.
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Get Fit Health
Resort
You 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
fitter 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
Activity 10
.1
Dining for health
What to do
1
Draw a dinner plate (full size) showing how much of each of the five 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
first one? What changes could you make to improve your diet, or is it balanced already?
Energy and weighing in the kilojoules
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
Food 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.
work
EXPERIMENT
Peanut power
1 0 .2
Aim
!
To determine the amount of energy that can be obtained from burning a peanut.
TESTTUBE
Materials
•
•
•
•
•
•
raw peanut
small measuring cylinder
water
test-tube
balance
thermometer
•
•
•
•
•
•
cork
long needle
Bunsen burner
retort stand
bosshead and clamp
bench mat
Safety
Don’t leave the burning peanut unattended and
make sure the room is well ventilated.
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BOSSHEAD
ANDCLAMP
M,
WATER
NEEDLE
PEANUT
RETORT
STAND
CORK
Figure 10.7
How to set up your experiment.
Method
1
Measure out 10 mL of water in the measuring cylinder and pour the water into the testtube; 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 ‘flag’ on the needle ‘flagpole’.
4 Light the Bunsen burner and use it to set the peanut alight, making sure that the Bunsen
burner flame 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 finished burning, measure and record the water temperature again.
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.
10
Evaluation
1
Did you have any problems with the method? List any.
2 Suggest some ways to improve the method.
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.
WRITINGNEEDLEWORK
GOLFBOWLINGWALKINGGARDENINGHOUSEHOLDCHORES
TENNISDOUBLES
chapter
1
keeping healthy
Discussion
TENNISSINGLESDANCINGSWIMMING
PLAYINGFOOTBALLCYCLING
SPRINTINGAEROBICSSQUASHWALKINGUPHILLACTIVESPORTS
%NERGYNEEDEDK*PERMINUTE
Figure 10.8
Energy used per minute in various activities (for a 50 kg person).
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.
287
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!
26.0
25.0
Above
desirable
weight
Body mass index
24.0
Females
23.0
Males
22.0
21.0
20.0
19.0
18.0
17.5
17.0
16.5
16.0
15.5
15.0
14.5
14.0
13.5
13.0
12.5
12.0
11.5
11.0
10.5
10.0
18.0
Age
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:
weight
BMI =
(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 fit. 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 labels
Most foods contain a mixture of the
three types of nutrients—carbohydrates,
proteins and lipids—as well as various
vitamins, minerals and water.
investigat
i o n 1 0 .3
What you need
The packaging from a variety of different
food products, in particular the nutrition
information label for that product.
What to do
Working in groups of three or four,
examine the nutrition information
label for each food product.
keeping healthy
1
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
10
highest to lowest fat content.
chapter
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 difficult to compare them?
Extension
Obtain food labels for different brands
of the same type of food and
compare them.
Present your findings in a format of
your choice.
Figure 10.10
A ‘nutrition information’ label indicates the various
amounts of nutrients in a food product.
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.
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in action
e
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that cheerful chocolatey feeling
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.
Figure 10.16
Chocolate contains
about 300 chemicals,
some of which
interact with the
brain’s ‘feel good’
systems.
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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 five 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.
keeping healthy
chapter 10
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 flavonoids.
Moderate consumption of other flavonoid-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.
choquestions
colatey feeling
1
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
Acne
Tooth decay
Migraine
Cardiovascular disease
Feelings
3 Prepare a poster presentation or role-play explaining the health
benefits of chocolate.
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KEY TERMS
10
acne
air pollution
antibodies
bacteria
balanced diet
basal metabolic
rate
body mass index
dermis
dust
energy
epidermis
fitness
healthy
immunity
infectious
diseases
kilojoules (kJ)
noise pollution
non-infectious
diseases
pathogen
sebaceous
glands
skin
smog
toxic chemicals
virus
Chapter review
ke
k
key
ey
y id
ideas
Use 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.
involves eating a variety of foods, in specific quantities.
A
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.
are caused by bacteria and viruses.
Most
is the body’s defence mechanism against a specific disease-causing
organism.
Many of the
problems today such as
caused by motor vehicle emissions and industry.
The accumulation of
are
in the lungs causes lung disease.
can damage your hearing.
Industrial wastes produce
that pollute our water supplies.
review questions
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
take 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
316
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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2 Explain why the skin is considered a very
important organ of the body. Include a diagram
of the skin and its components.
8 Create an issues map answering the question
of whether the purpose of immunisation is to
cure or prevent a particular disease.
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.
9 Match the disease in column B with the cause
in column A.
A
B
Infection
Lung cancer
Genetic
Influenza
Ageing
Lead poisoning
Environmental
Alzheimer’s disease
Lifestyle
Cystic fibrosis
4 Design a poster or advertisement promoting the
10 Create role-plays to show the negative effects
benefits of regular exercise.
of alcohol, cigarettes or drugs. Combine with
5 Work in a group to draw an outline of the
other groups to make a presentation covering
human body on a large piece of paper.
the three.
Mark on this outline the factors that indicate a
11 Conduct a class debate about compulsory
healthy body. Compare your healthy bodies with
vaccination of children before entering school.
other groups.
12 Visit Asthma Victoria’s website to find out
6 Australia has strict quarantine laws to prevent
more information on asthma. Prepare a
infectious diseases being brought into the
multimedia presentation that covers the
country. Animals from overseas must be isolated
following points.
to make sure that they are not carrying diseases
• Explain what asthma is.
such as rabies.
• List the triggers of asthma.
(a) Find out how long animals from other
• Discuss why people get asthma.
countries must be kept in quarantine.
• Describe the signs and symptoms
(b) Describe the symptoms of rabies and what
of asthma.
causes it.
• Find out how to help a person who is
7 Research and investigate ways to reduce
having an asthma attack.
air pollution at home. Present your report
• Find out the treatments available for
in a format of your choice.
asthma sufferers.
reflection health
complete
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.
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