Support for ‘Experiments’ and ‘Try this’...

SUPPORT FOR ‘EXPERIMENTS’ AND ‘TRY THIS’ ACTIVITIES 1

Maslow’s hierarchyAim

To find out more about Maslow’s hierarchy and how it may relate to the students’ essential needs and development.

Suggested matrix table. Ticks should be used to indicate importance of needs from 0–3.

Essential needs?Aim

For the students to consider their own essential needs and how they may be manipulated by mass media and advertising companies.

Handy hints

Teachers may wish to provide students or teams with some magazines or advertising brochures to whet their appetite and begin discussions.

Do you get the message?Aim

To increase awareness of the power of non-verbal communication.

Handy hints

A warm-up activity in which the students are asked to show signals or expressions (without words or verbal cues) for the following may be useful:1. Stop2. Okay3. I’m listening . . .4. No way5. I agree6. Come on . . .

Mapping outAim

To create a mind map about a favourite hobby.

Equipment list

Coloured pencils

Does practice make perfect?Aim

To investigate if the time taken to complete a task is affected by practice.

SCIENCE QUEST BOOK 3

Support for ‘Experiments’

and ‘Try this’ activities

Support for ‘Experiments’


CHAPTER 1 BRAIN QUEST

Needs 0 1 2 3

Self-actualisation Personal growth and fulfilment

Esteem Self respect

Respect for others

High self esteem

Status

Love and belongingness

Close relationships with other people

Group membership

Safety Security

Protection

No fear for one’s life

Physiological Food

Water

Air

Sleep

Your quest

TRY THIS

TRY THIS

Coded communication1.4

TRY THIS

Total recall?1.6

TRY THIS

Getting it right1.7

EXPERIMENT

2 SCIENCE QUEST BOOK 3 3E

Equipment list Handy hints

The sheet of folded cardboard acts as a screen. The student tracing the pattern should not be able to see the actual drawing, only the image in the mirror. To save time, you could draw the figure eights and stars and issue them to students. Remember that the minimum mirror size required will be half the length and half the width of the drawing on the paper.

Student results and responses will vary. They may notice that their ‘star accuracy’ improves with practice, and that they have learned, by trial and error behaviour, to make fewer mistakes.

Looking back

I’m a little neuronAim

To help students to remember some of the key terms and the functions of neurons. This activity also provides them with the opportunity to use and develop various multiple intelligences.

Handy hints

The song may also be performed as rap (or in another style) or merely acted out in a mime to increase participation of all learners.

Your quest

What’s in a shoe?Aim

To relate the uses of a range of materials used in footwear to their properties.

Handy hints

Materials that might be expected to be found in shoes like the one pictured include rubber, leather, cotton or nylon (stitching), and hard and soft plastics (polymers). The activity is designed to stimulate students to think about what they already know about materials and their properties and uses. As such, answers will vary.

Thinking about materialsAim

To compare the origin, properties, uses and limitations of a range of materials.

Handy hints

This is a group activity that should allow students to work together to summarise their current knowledge about commonly used materials. It could be followed by some time in the library (or other place that allows access to the internet) to fill in any gaps that are left.

Making casein plasticAim

To make a polymer from the protein casein, which is present in milk.

Equipment list

• safety glasses• 100 mL of milk• white vinegar• 250 mL beaker• glass rod• 250 mL conical flask

• thermometer• filter paper and funnel• Bunsen burner, heatproof mat and matches• tripod and gauze mat

Handy hints

Fine muslin cloth or a piece of clean nylon stocking or pantyhose may be used in place of the filter funnel and paper. The tripod and Bunsen burner can be replaced with a hot plate.

Approximately 10 mL vinegar is needed to separate the curds and whey.

• retort stand, bosshead and clamps• stopwatch• A4 paper• plane mirror• pencil• cardboard

CHAPTER 2 FOLLOWING ORDERS

TRY THIS

CHAPTER 3 IT’S A MATERIAL WORLD

TRY THIS

TRY THIS

Plastic facts3.1

EXPERIMENT


Testing polymersAim

To investigate the properties of a range of polymers.

Equipment list

• samples of polythene, PVC, perspex, nylon, bakelite, polypropylene and casein

• safety glasses• tongs• Bunsen burner, heatproof mat and matches• large iron nail• 7 test tubes

Handy hints

Depending on the range of polymers provided, some will soften in the heat of the flame (thermoplastic polymers) and others will char (thermosetting polymers).

This experiment is best done as a demonstration by a teacher considering most classrooms do not have the facilities of a fume cupboard for use by all students at the same time.

The strength of fibresAim

To compare the strengths of polyester thread and cotton thread.

Equipment list

• polyester thread• cotton thread• scissors• retort stands and clamps• slotted masses• Newton force measurers• marking pen • 30-cm ruler

Handy hints

This experiment is open ended and therefore this list of equipment may not be exhaustive. Ensure that students plan their experiments and provide a list of requirements prior to beginning the exercise.

Making rayon, a regenerated fibreAim

To regenerate the fibre rayon from paper tissue.

Equipment list

• white tissue paper• 30 mL of 50% ammonia solution• 2 g copper carbonate• 60 mL 2M sulfuric acid• 3 × 100 mL beakers• small syringe• glass stirring rod• paper towels• tweezers• safety glasses

Handy hints

This experiment is best done as a demonstration by a teacher due to Hazardous Substances Regulations.

Comparing ceramicsAim

To compare the hardness and density of a range of ceramics.

Equipment list

• minerals kit for hardness testing• balance• 100 mL measuring cylinder• dropping pipette• 250 mL beaker• 400 mL beaker• samples of pottery, porcelain, fired clay, partially stabilised

zirconia (PSZ), brick, tile

Handy hints

PSZ is suggested as a possible substance to use in the experiment but it is not essential. PSZ is a ceramic which is sometimes used to make scientific crucibles. Modern crucibles could be a possible substitute for testing. One possible source of PSZ is:Nilcra Ceramics 8 Redwood Drive Clayton, Vic., 3168Ph: (03) 9550 9100 Fax: (03) 9550 9125

Making a colloidAim

To make a colloid and observe its properties.

Equipment list

• safety glasses• sulfur powder• methylated spirits• test tube• 2 × 400 mL beakers• hot water• funnel• filter paper• 250 mL conical flask• torch or slide projector

Suggested answers to questions

1. The colloid appears to change colour (becomes reddish).2. The colloid prevents the beam of light exiting (as light is

scattered and deflected by the solid particles).3. Methylated spirits and water.

Making gelsAim

To observe the formation of gels and describe their properties.

Versatile polymers3.2

EXPERIMENT

A new breed of fibres3.3

TRY THIS

EXPERIMENT

Space age ceramics3.4

EXPERIMENT

Colloids and gels3.5

EXPERIMENT

EXPERIMENT


Equipment list

• safety glasses• 0.1M iron (III) nitrate (Fe(NO3)3) solution• 0.1M copper (II) nitrate (Cu(NO3)2) solution• 1.0M sodium hydroxide (NaOH) solution• test tubes and test tube rack• dropping pipette

Handy hints

Copper sulfate solution will also produce a gelatinous precipitate when reacted with sodium hydroxide.


1. Colloids consist of particles suspended in a liquid — they do not separate out whereas precipitates would eventually settle to the bottom.

2. Both consist of solids and liquids.3. sodium hydroxide + iron (III) chloride iron (III)

hydroxide + Sodium chloride3NaOH + Fe(Cl)3 Fe(OH)3 + 3NaCl

Making and testing toothpasteAim

To make toothpaste and compare it with a sample of commercial toothpaste.

Equipment list

Handy hints

Laundry soap powder such as Velvet or Lux flakes can be used in place of the Castile soap. The advantage of Castile soap is that it is soft and blends easily. It may be obtained from some chemists. Extend the activity by using bottlebrushes or old toothbrushes to apply the two toothpastes to dirty ceramic tiles and compare their cleaning efficiency.

Do not allow the students to taste this toothpaste under any circumstances as it is not made under sterile conditions.

Note: This experiment takes a long time to complete. In order to reduce the time it is helpful for all ingredients to be weighed and placed into small containers beforehand.

ElectroplatingAim

To observe the process of copper metal electroplating onto an iron nail.

Equipment list

Handy hints

Clean the iron nail with some steel wool to ensure good fixing of the copper coat. Other objects, such as a stainless steel teaspoon, can be used in place of the iron nail. Extend the activity by weighing the iron nail and the copper electrode before and after electroplating the object. A simpler experiment can be done to show that metals can be plated with a covering of copper. Simply place a nail in copper sulfate solution. The nail will appear coated with copper. The coating is not, however, plated on and is easily removed. In this case, the coating is the result of the spontaneous reaction between iron and copper due to their relative reactivities. It is important to note that this is a different process to electroplating. In the spontaneous reaction, iron is consumed, whereas it is conserved in the electroplating exercise.


1. The nail becomes a black-copper colour.2. The plating metal will wear off only if the nail is not

scrupulously cleaned prior to the experiment (to remove any oxide film).

3. The substance coating the nail came from the copper sulfate solution.

Design your own waste disposal systemAim

To investigate and report on methods of improving household waste management and disposal.

Handy hints

The internet, particularly local government websites, probably provides the best source of up-to-date information on this topic.

Exothermic and endothermic processesNote: Part 1 is for teacher demonstration only.

Aim

To investigate the temperature change in four different chemical processes.

Equipment list

Cosmetics: face the facts3.6

EXPERIMENT

• safety glasses• 4 g glucose (a sugar)• peppermint oil• 1.5 g Castile soap• 11 g calcium carbonate• glycerol or corn syrup• mortar and pestle• spatula• electronic balance

• commercial brand of toothpaste

• 1M hydrochloric acid• Benedict’s solution• 4 dropping pipettes• test tubes and test tube

rack• test tube holder• Bunsen burner, heatproof

mat and matches

Testing your metal3.7

EXPERIMENT

• 250 mL beaker• copper electrode• clean iron nail

• 3 connecting wires• 1M copper sulfate solution• 6 volt power supply or battery

Civics and citizenship: Use it again

3.8

TRY THIS

CHAPTER 4 CHEMICAL ENERGY

Hot and cold4.1

EXPERIMENT• safety glasses• bench mat• 4 large test tubes and

test tube rack• 10 mL measuring cylinder• balance• thermometer (−10˚C to

110˚C)

• stirring rod• magnesium ribbon• sandpaper• 1M hydrochloric acid• lithium chloride• ammonium nitrate• potassium chloride


Handy hints

Parts 1 and 3 can be demonstrated with the aid of a data logger. See ‘S.9 Using data loggers’ on page 242 of the text for details. If a data logger is used for parts 1 and 3, it is suggested that beakers are substituted for the test tubes and 100 mL of dilute hydrochloric acid and 100 mL of water are used in the respective parts. Part 1 could be demonstrated and discussed before students complete parts 2–4.’

A lab coat is recommended in addition to safety glasses. If a significant temperature change is not achieved in part 1, use 1M or 2M hydrochloric acid.

Note: For the experiment to work more effectively, replace 0.5M hydrochloric acid with 1.0M hydrochloric acid.

Handy hints

Students might want to know more about the mechanism for airbag deployment. The sodium azide is hermetically sealed in a heavy metal container. The reaction is activated when a severe impact causes a steel ball to compress a spring and electrically ignite a detonator cap. The sodium reacts with moisture in the air to produce a sodium hydroxide dust. The ‘smoke’ produced during deployment consists mostly of the cornstarch or talc used to lubricate the airbag. Tests indicate that the air inside the car after deployment does not pose a health hazard.

Testing for electrical conductivityAim

To investigate a range of liquids for their ability to conduct electricity.

Equipment list

Handy hints

Distilled water: zero readingTap water: 1–2 mA (requires 50 mA range)Salt water: 120 mA (requires 500 mA range)Sugar: 1 mA (requires 50 mA range)


1. Distilled water should not conduct electricity.2. The best conductors of electricity were salt, and then

sugar.3. The change that occurred in the water to increase its

conductivity was the addition of ions.Note: If no readings are obtained with a milliammeter, try using a voltmeter.

An electric cellAim

To construct an electrochemical cell.

Equipment list

• copper strip, 1 cm × 5 cm• zinc strip, 1 cm × 5 cm• 50 mL 1M copper sulfate• 50 mL 1M zinc nitrate• 2 × 100 mL beakers• strip of filter paper• 0.5M potassium chloride solution• 2 connecting leads with alligator clips• galvanometer

Handy hints

Ammonium nitrate can be used in place of the potassium chloride. A more concentrated solution may improve the efficiency of the salt bridge.


1. Evidence of chemical reaction includes a reading on the galvanometer, changes in the appearance of the electrodes, and changes in the appearance of the solutions in each of the beakers.

2. Yes. A current registering on the galvanometer indicates chemical energy transforming into electrical energy.

3. Further changes may occur; these include increased deposits on electrodes, possible depletion of electrolyte, resulting in a smaller reading on the galvanometer.

From chemical energy to electrical energyAim

To observe the reaction between zinc metal and copper sulfate solution.

Equipment list

Handy hints

It is impressive if the zinc foil strip is folded so that a hook is formed and it can be hung on the inside edge of the beaker. The next day all that will be left of the zinc foil will be the hook. This activity can be extended by filtering and drying the copper. Weighing of the zinc foil and the resultant copper may give some students food for thought.


1. The zinc dissolves.2. Copper3. The solution turns clear indicating that a new substance

has been formed.

Making a batteryAim

To construct a battery that models Volta’s pile.

Equipment list

Blowing up4.2

Charge on the move4.3

EXPERIMENT

• power supply or cell (2 volt)• torch globe or milliammeter• 3 wires with alligator clips • 2 carbon electrodes• 100 mL beaker• distilled water

• tap water• salt • sugar• spatula or teaspoon• paper towel

Takeaway electricity4.4

EXPERIMENT

EXPERIMENT

• piece of zinc foil• sandpaper

• 1M copper sulfate solution • 100 mL beaker

Batteries, batteries4.5

EXPERIMENT

• clean, copper coins• filter paper• salt solution• aluminium foil• 2 connecting leads with

alligator clips

• light-emitting diode (LED)• multimeter• scissors


Handy hints

If a light globe cannot be made to glow, use a multimeter to detect the voltage. The multimeter probes can be used to apply pressure to the pile to improve contact between the layers.


1. The globe should light. If not, try increasing the number of coins (i.e. increase the number of layers in the pile).

2. Increase the size of the pile.

3. Light and heat.4. Chemical energy is transformed into electrical energy.

Handy hints

This spread can be cross referenced to spread 7.7, ‘Energy underground’.

Making changesAim

To investigate the changes that occur with the rearrangement of components in simple electric circuits.

Equipment list

• power supply (set to 6 volts)• 3 × 6 volt light globes and holders• 6 connecting leads with alligator clips or banana plugs• piece of plastic• iron nail

Handy hints

Have plenty of spare light globes on hand.

Probing a simple circuitAim

To investigate the electric current and voltage at various locations in an electric circuit.

Equipment list

• power supply (set to 6 volts)• a 6 volt light globe and holder• 6 connecting leads with alligator clips or banana plugs• a very long connecting lead (at least 2 m long)• switch• ammeter• voltmeter

Handy hints

It is a good idea to insist that students ask you to check their circuit before closing the switch to ensure that the ammeter is connected properly. In particular, ensure that the correct positive terminal is used. The last part, with the very long lead, could be done as a demonstration after the rest of the experiment is completed by students.

Changing resistanceAim

To investigate the effect of changing voltage on the resistance of light globes in a simple electric circuit.

Equipment list

• power supply (variable)• a 9 volt light globe and holder• 6 connecting leads with alligator clips or banana plugs• switch• ammeter• voltmeter

Handy hints

It is a good idea to insist that students ask you to check their circuit before closing the switch to ensure that the ammeter is connected properly. If you are concerned about students blowing light globes, you could use two 6 volt globes in series and measure the characteristics of just one of them. Alternatively, a variable resistor could be connected in series with the globe.

Breaking the codeAim

To practise decoding the colour codes on resistors.

Equipment list

an assortment of colour-coded resistors

Making the changeAim

To investigate the changes that occur in voltage and electric current in a simple circuit when the resistance within the circuit is changed.

Equipment list

• power supply (set to 6 volts)• a 6 volt light globe and holder• variable resistor• 6 connecting leads with alligator clips or banana plugs• ammeter• voltmeter

Handy hints

It is a good idea to insist that students ask you to check their circuit before closing the switch to ensure that the ammeter is connected properly.

Fossil fuels4.6

CHAPTER 5 ELECTRIC CIRCUITS

Go with the flow5.1

EXPERIMENT

Made to measure5.2

EXPERIMENT

A question of resistance5.3

EXPERIMENT

Controlling the flow5.4

TRY THIS

EXPERIMENT


Line-upAim

To observe the effect of connecting light globes in series.

Equipment list

• power supply (set to 6 volts)• three identical 6 volt light globes and holders• 5 connecting leads with alligator clips or banana plugs• ammeter• voltmeter

Handy hints

The questions at the beginning of the spread are there to stimulate discussion about the disadvantages of series circuits. The question about which canteen runs out of drinks first raises the issue of how long a battery lasts, or how quickly energy is used in a parallel circuit. In a parallel circuit energy is used more quickly.

Alternative pathwaysAim

To observe the effect of connecting light globes in parallel.

Equipment list

• power supply (set to 6 volts)• three identical 6 volt light globes and holders• 8 connecting leads with alligator clips or banana plugs• ammeter• voltmeter

A model electric jugAim

To make a model of an electric jug and calculate how efficiently it converts energy.

Equipment list

• power supply (set to 6 volts)• 60 cm length of nichrome wire• 250 mL beaker• 100 mL measuring cylinder• thermometer• watch with second hand or stopwatch• 5 connecting leads with alligator clips or banana plugs• ammeter• voltmeter

Storing it up for laterAim

To investigate the functioning of an electrolytic capacitor.

Equipment list

• power supply (set to 2 volts DC)• 1000 µF electrolytic capacitor• 100 Ω resistor• ammeter• switch• 6 connecting leads with alligator clips or banana plugs• stopwatch

Handy hints

If students are having difficulty with connecting circuits, use 8 leads instead of 6 so that they can more easily see where to connect the lead between X and Y to discharge the capacitor.

Design, create and testAim

To design a circuit for a two-way light switch.

Equipment list

• 2 pieces of wood (approx. 7 cm × 5 cm)• 6 small nails or screws• hammer or screwdriver• power supply (set to 6 volts)• 6 volt light globe and holder• 7 connecting leads

Handy hints

The connecting leads should have bare ends and/or alligator clips except for two that will be connected to the power supply. The correct arrangement for the circuit is shown in the figure below.

In a row or side by side?5.5

EXPERIMENT

EXPERIMENT

What’s watt?5.7

EXPERIMENT

Electronics: a small world5.8

EXPERIMENT

Design, creativity and technology: Solving problems with electric circuits

5.9

EXPERIMENT


Seeing the lightAim

To observe the effect on a ray of light when it intersects a variety of surfaces.

Equipment list

• ray box kit• power supply• several sheets of white paper• ruler and fine pencil

Handy hints

A ray is actually a line used to show the path of an infinitely thin beam light. You cannot see a ray because its size is infinitesimal. You can see a beam. A beam can be considered to consist of many rays. The room should be darkened for this activity. Make sure that students know at which end of the light box the black slides are placed and the location of the knob that allows them to adjust the lens so that the emerging beams are parallel to each other. You could allow students to spend about 10–15 minutes just playing with the light box to get to know how it works and to discover some properties of light in an unstructured way.

Floating coinsAim

To investigate the effect of refraction on the image of a submerged coin.

Equipment list

• 2 × 250 mL beakers• coin • evaporating dish

Handy hints

Very large evaporating dishes work well, but other containers such as ice-cream containers are also suitable. The water must be added very carefully so as not to displace the coin. The image will appear to be above the location of the real coin.

How much does it bend?Aim

To investigate angles of refraction as a light ray travels between media of different densities.

Equipment list

• ray box kit• power supply• sheet of white paper

Handy hints

The room should be darkened for this activity.

Searching for an imageAim

To investigate the images formed by a biconvex lens.

Equipment list

Handy hints

The experiment should be conducted in a darkened room. Before carrying out this experiment pass around some biconvex and biconcave lenses for the students to look at each other through. Ask them to work out which of the two lenses produces a magnified image and which produces a diminished image. Can either type of lens produce both magnified and diminished images? Which lens can produce an image that is upside down? Under what conditions can an upside down image be produced?

Focusing on lightAim

To investigate the effect of biconvex lenses on parallel rays of light.

Equipment list

Handy hints

This experiment should be conducted in a darkened room.

Getting a clear imageAim

To calculate both the range and the average closest reading distance for a group of students.

Equipment list

• ruler

Handy hints

A booklet called Eyes right has been produced by the Optometrists Association Australia (National Office, 240 Drummond Street, Carlton, Vic., 3053, Ph: (03) 9663 6833). It includes detailed, well-presented and extremely useful information about the eye and visual disorders.

Is it clear?

Aim

To undertake a test for astigmatism.

CHAPTER 6 KEEPING AN EYE ON LIGHT

Riding on a light beam6.1

EXPERIMENT

What happened to my legs?6.2

EXPERIMENT

EXPERIMENT

Through the looking glass6.3

EXPERIMENT

• candle• matches• jar lid to hold candle

• biconvex lens• lens holder• white card for screen

EXPERIMENT

• ray box kit• sheet of white paper

• power supply• ruler and fine pencil

It’s the image that counts6.4

EXPERIMENT

Improving your image6.5

TRY THIS


Handy hints

A whole-class discussion could be used to ascertain if any students see some of the lines less clearly. If no variation in vision of the lines is described by any of the students, they should be able to predict the effect and suggest why the fan chart is a good way to check for astigmatism. The question ‘Why is a fan chart better than a set of parallel lines for testing astigmatism?’ could be raised.

Keeping the light insideAim

To investigate total internal reflection.

Equipment list

• ray box kit• power supply• sheet of white paper

Handy hints

Show the students a bundle of optical fibres. Telstra have produced an educational package that includes information on the application of optical fibres.

What’s in white light?Aim

To demonstrate that white light is made up of the visible spectrum of coloured light.

Equipment list

Handy hints

As a demonstration, a pneumatic trough of water can be placed in front of a slide projector and a large rainbow can be cast onto a wall.

Adding coloursAim

To investigate the addition of coloured light.

Equipment list

• ray box• power supply• red, green, blue, yellow, magenta and cyan filters• white surface to use as a screen

Handy hints

The room needs to be as dark as possible for this experiment.


1. Red, green, blue and yellow, magenta, white.2. (a) white (b) white.

Subtracting colours with filtersAim

To investigate the subtraction of colour from light with the use of filters.

Equipment list

• ray box• power supply• red, green, blue, yellow, magenta and cyan filters• white surface to use as a screen

Handy hints

The room needs to be as dark as possible for this experiment. Suggested answers to questions:1. (a) blue and red (b) blue and green (c) green and red2. (a) green (b) red (c) blue3. White.

Handy hints

The Royal Society of Victoria has produced an informative booklet titled Volcanoes in Victoria. Written by Dr Bill Birch and available through the Royal Society of Victoria, the booklet provides interesting local information and is useful as a teacher guide and as background for a geological excursion.

Modelling folds and faultsAim

To model the formation of folds and faults in the Earth’s crust.

Equipment list

• 5 different-coloured foam kitchen sponges• 3 or 4 pieces of different-coloured plasticine• a thin sheet of polystyrene• knife or blade

Handy hints

Playdough can be used in place of plasticine.Playdough recipe:250 g plain flour (380 mL)130 g salt (125 mL)250 mL water25 g cream of tartar (40 mL)20 mL vegetable oil (1 tablespoon)1 mL dye (food colouring)Mix all ingredients in a saucepan or 500 mL beaker. Heat gently for 5 minutes or until the mixture becomes doughy. Knead on a board into an even dough. Store in plastic containers in the refrigerator to extend shelf life.

A look inside6.6

EXPERIMENT

Colour your world6.7

EXPERIMENT

• slide projector• triangular glass prism• sheet of A4 white paper

• ray box• power supply

Seeing in colour6.8

TRY THIS

EXPERIMENT

CHAPTER 7 THE DYNAMIC EARTH

Inside out7.1

Making mountains7.3

EXPERIMENT


Which mineral is it?Aim

To develop an understanding of features used to identify minerals.

Equipment list

• mineral kit• Mohs’ scale minerals or common materials to substitute for

unavailable Mohs’ scale minerals• magnifying glass• white ceramic tile

Handy hints

This exercise could simply be one in identifying the differences between minerals or, alternatively, it could be an identification exercise. In this case the minerals in the kit would be numbered. Students would then match their observations with the descriptions provided in the kit to identify the unknown minerals. Students should make only one attempt at scratching with each combination of minerals or materials. The scratching test is destructive and specimens can be damaged or destroyed if they are scratched too often. Mineral kits are available through the Monash University Science Centre (Ph: (03) 9905 1370) at low cost. The Minerals Education Centre (Ph: (03) 9629 1851, Fax: (03) 9629 8603) also provides free materials and guest speakers to schools.

Searching without disturbingAim

To model mineral exploration.

Equipment list

• tray of sand • 10 paperclips• blindfold (optional)• compass• paper and clipboard• ruler

Handy hints

Graph paper is the best choice for drawing up the grid.

Purification of copper by electrolysisAim

To purify an impure sample of copper by electrolysis.

Equipment list

• 150 mL 1M copper sulfate solution• 250 mL beaker• 10 cm length of copper pipe (impure)• 10 cm × 1 cm piece of copper foil (pure)• electronic balance• 2 connecting leads with alligator clips• 2 volt DC power supply

Now it’s your turnHandy hints

This activity is an excellent opportunity for further investigation and for role playing. The class forum suggested encourages thoughtful debate about the issue. Students could play particular roles which they devise themselves, or the teacher could assign roles. Roles that could be modelled might include the managing director of the mining company, an Aboriginal tribal elder, the president of the local town Chamber of Commerce, a member of Greenpeace, etc. Students could research uranium mining in the library using books or the internet. There are several sites that provide information for and against uranium mining. Students should be encouraged to research both sides of the debate, regardless of the role they might be playing in the forum. Organisations like the Uranium Information Centre and the Australian Conservation Foundation may also provide useful material.

Eco snakes and ladders

Handy hints

Students will have learnt about various environmental issues in the past and this activity allows them to distinguish between useful and harmful activities. The cards they produce in activity (b) will build on their understanding of the greenhouse effect. Once students have played the game several times, allow groups to swap cards so that different ideas are disseminated among the class.

How much energy do you get from food?Aim

To compare the amounts of energy supplied by a range of foods.

Equipment list

• a range of food packages that have a chart which shows how many kilojoules of energy are in each 100 g of the food or drink, e.g. cereal boxes, peanut butter jars, bread wrappers, yoghurt containers, muesli bar boxes, margarine containers, soup tins and drink containers

• graph paper and ruler

What’s in a rock?7.4

EXPERIMENT

The riches below7.5

EXPERIMENT

Extracting the metal7.6

EXPERIMENT

Civics and citizenship: Mining and the environment

7.8

TRY THIS

CHAPTER 8 THE ENERGY OF LIFE

Your quest

TRY THIS

Energy pirates8.1

TRY THIS


Handy hintsEnsure that you include packages from both high and low energy yielding foods.

Energy for livingAimTo develop the understanding that daily activities in which a person is involved all require energy, but the amount of energy they require differs.

Think: Further activities1. The difference between mass and weight could be

explored here by asking why the word ‘weight’ is shown in inverted commas.

2. A closer look at the molecules absorbed by the body could be considered here. Students might be interested in steroids, for example.

Using data: Further activities

Table 1: Approximate chemical energy content of

some foods in kilojoules per 100 g serve

1. Use the data in table 1 to determine the total energy intake of a person who ate the following meals and snacks. Table 2 above right shows how the data can be organised neatly.• Breakfast — 200 g milk, 2 slices of white bread toast

(25 g each slice), 20 g butter on toast and 1 poached egg (50 g)

• Lunch — sandwiches consisting of 4 slices of wholemeal bread (25 g per slice), 20 g margarine and 100 g cheese. Also a 200 g cup of tea with 10 g sugar and a 100 g apple.

• Dinner — 100 g chicken (fried) with 100 g baked potato, 100 g steamed broccoli and 100 g cooked carrots. Also 250 g ice-cream for dessert.

• Snacks — 100 g banana and 200 g glass of orange juice.2. If a chocolate bar contains 1108 kilojoules of energy, for

approximately how long would you need to do moderate exercise to use up this energy?

3. Use table 1 to calculate your energy intake for the breakfast that you had this morning. If the foods are not all listed in table 1 then you will need to use food packages or the library to find a reference containing a larger table of information.

Table 2: Energy intake for breakfast

What’s in a breath?AimTo identify some of the chemicals present in the human breath.

Equipment list• safety glasses and laboratory coat• 2 test tubes• 2 straws• dropping bottle of bromothymol blue• limewater• 2 × 250 mL beakers filled with iced water• cobalt chloride indicator paper• paper towel

Handy hintsEnsure that the second beaker of iced water is dried thoroughly before testing with the cobalt chloride paper. Condensation of water vapour from the air could occur on the outside of the beaker and this would make comparison of the two beakers confusing. Students might want to know how the limewater test works. A calcium carbonate precipitate is produced when carbon dioxide reacts with the limewater (calcium hydroxide solution):

Ca(OH)2(aq) + CO2(g) CaCO3(s) + H2O(l).

The limewater and bromothymol blue tests can be repeated with soda water to confirm that it is CO2 that causes the colour to change.

Pins and pain?AimTo demonstrate the body’s response to anaerobic respiration.

Fermenting funAimTo investigate the anaerobic respiration process of fermentation.

Food

Energy in kJ per

100 g Food

Energy in kJ per

100 g

cow’s milktea (black, no

sugar)coffee (black, no

sugar)orange juicesoft drinkpoached eggbuttermargarinewhite breadwholemeal breadCorn Flakes®

Weet-Bix®

Just Right®

white sugar

275

8

6188160628

298830111172971

1593140015661742

honeyjamcheddar cheesehamburgerbacon (rindless)chicken (fried)potatoes (baked)peasbroccoli (steamed)carrots (cooked)apple (raw)bananapear (raw)ice-cream

1295115017131523240

1206418100121125225235230670

TRY THISFood

Size of serve (g)

Energy of food in kJ per 100 g

Energy intake in

kJ

glass of orange juiceCorn Flakes®

milk on cerealslice of white breadmargarinehoney

Total energy intake

200 g25 g

100 g25 g10 g10 g

1881840275

117230111295

376460275293301130

1835

Energise me!8.2

EXPERIMENT

Life without oxygen?8.3

EXPERIMENT

EXPERIMENT


Equipment list

• safety glasses and laboratory coat• large side arm test tube• rubber stopper to fit side arm test tube• rubber hosing (25 cm) fitted with a short end of glass

tubing• test tube rack

• spatula of yeast

• spatula of sugar

• 20 mL of warm water• test tube half filled with water, with a few drops of

bromothymol blue added• dropping bottle of bromothymol blue indicator

Handy hints

A side arm conical flask can be used in place of the side arm test tube.

Out of the lightAim

To investigate the effect of blocking light from photosynthetic plant tissue.

Equipment list

• pot plant that has been kept in the dark for a few days• several strips of aluminium foil• scissors and sticky tape• hotplate• 500 mL beaker of boiling water• test tube of ethanol• forceps• iodine solution and dropping pipette• Petri dish• watchglass with a small sample of potato starch

Handy hints

The plant is kept in the dark for a few days so that the plant uses up starch that may be stored in the leaves. When it is placed back in the light, starch should be manufactured only in those sections of leaf exposed to light.

Think: Further activities

Good opportunity for a field trip. A visit to a freshwater pond, a nearby beach, a local creek or a national park could present an opportunity to look and listen for the presence of a variety of organisms and stimulate thinking about food chains and food webs. Even a small excursion to part of the school grounds (a garden bed, under a large rock, or a tree) could stimulate discussion of local food webs.

Imagine: Further activities

In order to make a food concentrate, humans have recently begun netting large amounts of krill from the Antarctic Ocean. Imagine you are a newspaper journalist writing an article on this. Use the diagram of the Antarctic food web to explain to the public the effects that this could have on the Antarctic ecosystem. Phytoplankton is an example of a producer.

The Antarctic food web

Looking at decomposersAim

To investigate the presence of decomposer organisms on fresh and sterilised specimens of living, dead and decomposing grass.

Equipment list

• safety glasses• 6 nutrient agar plates• fresh grass• grass that has recently died• decomposing grass• 3 paper bags• forceps• Bunsen burner, heatproof mat and matches• stapler and marking pen• tape• stereo microscope or hand lens

Handy hints

Ensure that students understand their experimental set up will be 6 Petri dishes labelled ‘fresh U’, ‘dead U’, ‘decomposing U’, ‘fresh S’, ‘dead S’ and ‘decomposing S’ respectively. Forceps may be pre-sterilised in sealed bags in an oven or autoclaved. The oven temperature for sterilising the grass samples should be high (>220°C) as fungal spores are capable of surviving cooler oven temperatures.

Blast off!Aim

To weave together various ideas from the chapter to be able to effectively consider the requirements for life and how these may all be met in a possible future real-life situation.

12---

12---

Catching energy8.4

EXPERIMENT

Flowing on . . .8.5

birds (petrel)

blue whalekrill

Adeliepenguin

birds (skua)

Weddellseal

squid

fish

Emperorpenguin

Leopardseal

killer whale

phytoplankton

Recycle me!8.6

EXPERIMENT

Blast off!8.10

TRY THIS


Handy hints

The various tasks of this activity may be delegated to different groups, however each group will need to liaise with the group prior to them to take their information for consideration. It is important to allow students to use their imagination and creativity for activity (c).

Looking back

Mind ‘n’ flashAim

To increase the student’s awareness of the links between key terms used throughout this chapter/unit of study.

Equipment list

green, orange, red, yellow and blue coloured flash cards (refer to the blackline masters)

Handy hints

It helps to have these cards made up ahead of time. The different coloured cards could be kept in various resealable plastic bags. In addition to this activity, the cards could be used for revision, acting out terms and quizzes.

What can I investigate?Aim

To exchange ideas to stimulate thinking about questions that could be investigated in a science laboratory.

Handy hints

Encourage students to think beyond science textbook experiments and consider their own hobbies or interests that might provide ideas. If discussion within groups is slow, it will help if you provide a few ideas to your students. There is a list of some ideas on p. 310 in Science Quest 1 3rd edition. A whole-class discussion of the final list of questions of each group may stimulate additional ideas.

Science teachers’ associations in each state and territory in Australia can provide information on a range of activities and awards for students who conduct their own extended experimental investigations or other creative science activities. These associations are all members of the Australian Science Teachers’ Association (ASTA). Their contact information at the time of publication is listed below.

Australian Science Teachers Association (ASTA)Telephone: (02) 6282 9377Email: [email protected]: www.asta.edu.au

Science Teachers’ Association of Victoria (STAV)Telephone: (03) 9385 3999 Email: [email protected]: www.stav.vic.edu.au

Science Teachers’ Association of Tasmania Inc. (STAT)Ph: (03) 6271 1111Email: [email protected] Internet: www.key.org.au/stat/

Science Teachers’ Association of NSW Inc. (STANSW)Telephone: (02) 9763 2751 Email: [email protected]: www.stansw.asn.au

Science Educators Association of the Australian Capital Territory Inc. (SEA*ACT)Internet: www.seaact.asn.au

South Australian Science Teachers Association (SASTA)Telephone: (08) 8224 0871Email: [email protected]: www.sasta.asn.au

Science Teachers Association of Queensland (STAQ)Telephone: (07) 3861 5444Email: [email protected]: www.staq.qld.edu.au

Science Teachers Association of the Northern Territory (STANT)Internet: www.stant.asn.au

Science Teachers Association of Western Australia (STAWA)Telephone: (08) 9244 1987Email: [email protected]: www.stawa.asn.au

TRY THIS

SCIENCE AT WORK

Science at work: It always starts with a question

S.2

TRY THIS

S.2–S.7


Additional ‘Experiments’ and ‘Try this’ activities can be found on the Teacher Support Kit CD-ROM. These include experiments that were published in previous editions of Science Quest, as well as other experiments that are relevant to Science Quest chapters.

Science Quest 3 chapter Spread reference Additional ‘Experiments’ and ‘Try this’ activities

Chapter 1 Brain quest 1.6 Total Recall Experiment: A stab in the dark

Chapter 4 Chemical energy 4.8 Fuel from living things Experiment: Making biogas

Chapter 8 The energy of life 8.1 Energy pirates Experiment: Relaxed energy

Experiment: Nuts about energy

8.3 Life without oxygen? Experiment: Flaming sugarThis is best as a teacher demo only.

Additional ‘Experiments’


Additional ‘Experiments’


SUGGESTED ANSWERS TO ‘THINK ABOUT THESE’ QUESTIONS 15

Chapter 1 Brain quest

Chapter 2 Following orders

‘Think about these’ questions Page Suggested answers

Which part of your brain is responsible for your ‘life support systems’?

4 It is the medulla oblongata, which is part of the hindbrain. It regulates heart rate, blood pressure and breathing.

What are some ways to manage anger?

7 There are many ways described on page 7. They include taking several deep breaths, listening carefully to other opinions, being willing to admit you are wrong and communicating your view without raising your voice.

How can your mood be influenced by neurotransmitters?

7 Neurotransmitters are chemicals that pass messages between nerve cells (neurons). Imbalances of the different neurotransmitters can change the way you feel and react.

How can you use thinking hats to help you solve problems and make decisions?

10, 11 The thinking hats help you to think about solving problems by thinking about them in different ways.

Why do you often get drowsy when it’s dark and wake up when it’s light?

14 The chemicals in your brain are affected by the amount of light detected by the photoreceptors in the retina of your eye. For example, a decrease in light levels causes the production of a hormone called melatonin, which causes drowsiness.

How do ‘uppers’ and ‘downers’ cause their effects?

24 ‘Uppers’ and ‘downers’ can increase or decrease the transmission of messages between nerve cells.

Which tools can you use to help you to sequence your thoughts?

28 Flowcharts, timelines, cycle maps and storyboards.


What do you have in common with all of the matter in the universe?

35 Atoms

When can negative feedback be a good thing?

39 Negative feedback is a mechanism by which the nervous system can balance changes in the internal conditions of the body that could be harmful.

When can you do something but not have to think about it?

39 When it involves a reflex arc. That is, when a nervous impulse follows a direct route from a sensory receptor to an effector (muscle or gland) without an interconnecting link to the spinal chord.

What does a ‘red-back on the toilet seat’ have in common with chemical warfare?

40 Both red-back spiders and chemical warfare use chemicals that specifically target the nervous system.

Which hormone gives you ‘butterflies’ in your stomach?

46 Adrenaline

Which types of chemical make plants ‘dance’ with the moon and the sun?

48 Hormones

How does a plant know when it’s time to flower?

49 Plants have internal biological clocks. The timing of flowering of many plants is controlled by the length of uninterrupted darkness.• Long-day plants (e.g. gladioli and cabbage) flower only when the number of daylight hours

is more than a certain critical maximum.• Short-day plants (e.g. daffodils and chrysanthemums) flower only when exposed to daylight

that is less than a certain maximum number of hours.• Day-neutral plants (e.g. potatoes and tomatoes), however, do not depend on daylight to

flower.

Which two hormones are scientists basing a male contraceptive pill on?

51 Androgen and progesterone

Suggested answers to

‘Think about these’ questions

Suggested answers to

‘Think about these’ questions


Chapter 3 It’s a material world

Chapter 4 Chemical energy


What is a polymer? 58 A very large molecule that consists of many repeating units.

What do a plastic fruit juice container, a toilet seat and a $100 note have in common?

60 They are all made from polymers ($100 note not mentioned in text).

What do jellies, aerosols and fog have in common?

67 They are all colloids.

Why were Roman soldiers so successful?

70 They used weapons like swords made from iron.

What is toothpaste made from? 68–69

An abrasive, such as calcium carbonate, and various other ingredients.

Where can you find chemical-free cosmetics?

68 You can’t find chemical-free cosmetics. All of the substances in cosmetics are chemicals.

How is paper recycled? 73 By mixing it with water to separate the fibres, removing chemical additives, and rolling it to produce cardboard or paper.

Why are redheads different? 69 Their hair contains melanin and an additional pigment made from iron.

Why are some plastics harder than others?

60–61

Harder plastics consist of chains of molecules that are linked together. In softer plastics, the chains can slide across each other.


What makes an icepack that contains no ice go cold?

82 A chemical process takes place in the icepack; this takes in energy from the injured area, cooling it down to reduce swelling.

What do a jack-in-the-box and a litre of petrol have in common?

81 They contain stored energy.

What makes an air bag inflate during a car accident?

84 In the air bag an explosive chemical reaction occurs in which nitrogen gas is produced.

Why is swimming during an electrical storm so dangerous?

86 Water is a good conductor of electricity. However, swimming pool and salt water contain additional electric charge in the form of ions, which make the water even better at conducting electricity.

What is a button cell and what is inside it?

91 A ‘battery’ used inside small devices like watches, calculators and hearing aids. Zinc powder, silver oxide and an electrolyte are found inside its steel or nickel walls.

Biting on aluminium foil can be a shocking experience. Why?

90 The aluminium foil, a filling in your mouth and your saliva behave like a battery, producing an electric current. The foil (negative electrode) sends electrons to the filling (positive electrode) with your saliva acting as the electrolyte.

Bottled gas, candle wax and petrol all come from one substance. What is it?

92–93

Crude oil.

How could burping cows change the way that we live?

97 The gas that they release, methane, could be used as a fuel.

Cow manure to replace petrol — is it possible?

96 Yes, it is possible. Cow manure can be converted to biogas, which is mainly carbon dioxide and methane. The methane can be used for heating and to power homes and farms.


Chapter 5 Electric circuits

Chapter 6 Keeping an eye on light


What actually moves when an electric current flows?

104–105

Electrons.

Why do some plugs on electrical appliances have three pins while others have two?

116–117

The third pin goes into the earth socket and is needed if an electrical device has an uninsulated metal casing.

What do electrons have in common with queues at the school canteen?

112 They can move ‘in parallel’ or ‘in series’.

What is a short circuit? 113 An easier pathway with little resistance to electric current. A short circuit is dangerous because a very large electric current can flow through it.

How is AC different from DC? 116 AC is alternating current, in which the current changes direction about one hundred times every second. DC is direct current, which travels in one direction only.

Why do you need a safety switch as well as fuses or circuit breakers in your meter box?

114 Safety switches can turn off the power much more quickly than fuses or circuit breakers. They provide more protection from electric shocks caused by faulty appliances.

Why is the bathroom a dangerous place to use electrical appliances?

117 Water is a good conductor of electric current. If an appliance makes contact with water and you touch it, you could be electrocuted.

Which appliance transforms energy more quickly, a toaster or a hair dryer?

118 A hair dryer transforms energy almost twice as quickly.

What is a kilowatt hour? 118 A unit of energy. One kilowatt hour is the amount of energy transformed by a 1 kW appliance in a period of one hour.

What is an LED and how is it different from a torch globe?

120 An LED is a light emitting diode. Like all diodes, LEDs are designed to allow electric current to flow through in only one direction. Light globes with filaments allow electric current to flow in either direction.


Why do your legs look shorter when you are standing in water?

132 Because the light coming from your legs bends, or refracts, as it emerges from the water. The light seems to be coming from a different direction.

How does a lens bend light? 134 The surface of the glass is curved so that when the light is bent it either diverges or converges.

Why is the lens in your eye more like jelly than glass?

136 So that it can change shape easily, becoming thicker to bend light more or thinner to bend it less.

Why do many older people read newspapers held at arm’s length?

138 As they grow older the lens is less able to change shape, making it difficult to focus on nearby objects like the print on a newspaper.

How do glasses help some people see more clearly?

138 When the focusing power of the eye is either not strong enough or too strong, glasses help by bending light inwards or outwards, so that a sharp image is produced on the retina.

How is it possible to take a photograph inside a living human body?

140 With a long tube called an endoscope. The endoscope contains flexible glass optic fibres through which light can travel without emerging.

Why is the sky blue? 143 The air scatters more light at the blue end of the spectrum than at the red end. As sunlight travels through the atmosphere, more blue light is scattered to your eye than red light.

Why is the sun so red at sunset? 143 The light from the sun travels through more air at sunset, and so much blue light is scattered that the light coming directly from the sun towards your eyes is mostly at the red end of the spectrum.

Why is it so important to wear sunglasses and choose them wisely?

148 Sunglasses protect your eyes from the ultraviolet radiation coming from the sun. Some sunglasses block out much of the visible light without blocking the more dangerous ultraviolet radiation.


Chapter 7 The dynamic Earth

Chapter 8 The energy of life


Where is the biggest volcano in the solar system?

156 Olympus Mons, on the planet Mars.

Why do volcanoes make a ‘ring of fire’ around the Pacific Ocean?

158 The ‘ring’ is a giant weakness in the Earth’s crust.

How could Captain Cook have walked to Australia 250 million years ago?

159 Across the giant continent Pangaea.

Why are the Himalayas still growing in height?

160 They are being pushed upwards as two of the plates that make up the Earth’s crust push against each other.

How can something as large as a continent move?

159 The movement of continents can be explained by continental drift. The continents move on the plates that the Earth’s crust is divided into.

Can rock actually bend? 160 Yes, by the forces beneath the Earth’s surface.

What would a rock say if it could talk?

162 It would be able to talk about the history of the Earth; describe prehistoric creatures, volcanoes, earthquakes and floods; and describe parts of the inside of the Earth.

How do geologists know where to mine for minerals?

164 By using cameras, radar and other sensors on satellites, and by chemical analysis of the sediments and surface water of lakes and streams.

From a damp green swamp to a lump of coal — how does it happen?

168 The remains of the damp green swamp are compressed by sediments that cover the swamp. As the remains are compressed, the water is driven out and the remains become hard and dry.

How can land be rehabilitated? 173 By reshaping the mine site to fit in with the natural surroundings and growing native vegetation to return the mine site to its natural state.


How much ‘weight’ can you lose by going to the moon?

184 You lose 83% of your ‘weight’ — but that’s entirely due to the smaller pull of gravity on the moon. The amount of matter in your body — your mass in kilograms — remains the same.

What can bacteria do that you can’t?

203 Some bacteria (called nitrogen-fixing bacteria) can use nitrogen in the air to make protein.

Which living things use the energy released in massive nuclear explosions to make food?

192 All green plants, algae and some other microscopic organisms that use the energy from the sun to photosynthesise.

How can you use a SWOT analysis to help you plan a project?

216 A SWOT analysis allows you to prepare a plan of action and to consider possible ‘blockers’ to the project. It also helps you to consider the strengths and weaknesses of the project.

What can the size of your ecological footprint tell you?

199 Your ecological footprint tells you the impact that your lifestyle may have on our planet’s resources. It is a measurement of how much biologically productive land your activities require.

Saint Joan of Arc, Leonardo da Vinci, Elvis Presley, John Lennon, Kurt Cobain — where are they now?

201 The atoms that comprised them are most probably part of the non-living environment (water, air or soil) or even part of another living thing.


Science at work


How do all scientific investigations begin?

223 A question.

Why is planning so important to a scientific investigation?

224 Planning ahead increases your chances of success. It helps you know ‘where you are going’ and what equipment you need.

Where do you go to research the topic of a scientific investigation?

226, 227

The library (non-fiction books including science textbooks, reference books, journals and magazines, information files, audio-visual resources) is a good place to start. Your science teacher, government departments and agencies, the internet, industry and even relatives or friends are other sources of information.

What is a controlled variable? 228 Controlled variables are variables that are kept constant so that the effect of other variables may be investigated.

How can a spreadsheet save you time in a scientific investigation?

235 A spreadsheet saves you time on data analysis by doing mathematical calculations such as adding, multiplying and averaging.

How does a data logger improve the gathering of data?

242 Data loggers allow you to collect large amounts of data over short time intervals or intervals too long for you to gather data yourself.

What great medical discovery was helped along by a single teardrop?

253 The discovery of penicillin.


Remember

1. Example:

2. Example:

3. (a) Cerebellum (b) Pons(c) Medulla oblongata(d) Hypothalamus(e) Cerebral cortex(f) Corpus callosum

Suggested answers to activities questionsSuggested answers to activities questions

CHAPTER 1 BRAIN QUEST

Your brain’s ‘chat rooms’1.1

my brain ancestral brain

Simple neuraltube with bulgesat one end

More developedand number ofdivisions and connections more complex

Ancestral bulges seen in

embryonicbrain

Forebrain,midbrain,hindbrain

Your thinking brain

Coordinatesmovement

Regulates heart rate,blood pressure and

breathing

Involved in sneezing,coughing

and vomiting

Regulates sleep

cerebral cortex

surface of cerebrum

cerebrum

forebrain

hindbrain midbrain

cerebellum medulla oblongata pons reticular formation

thalamus

hypothalamus

Emotions, hunger andbody-temperature

regulation

brain

SUGGESTED ANSWERS TO ACTIVITIES QUESTIONS 21

Remember

1. Anger.2. Anger is not always a bad thing. Controlled anger can

help motivate you to make positive changes. It can also help prepare your body for a possibly dangerous situation.

3. Adrenaline, cortisol.4. The amygdala is located in the limbic system of your

brain.5. Passing messages between neurons.6. Some drugs have a chemical structure similar enough to

a neurotransmitter to trick a matching receptor. 7. (a) Tryptophan, tyrosine and phenylalanine. These

amino acids can be found in rice, cottage cheese, peanuts, almonds, bananas and avocadoes.

(b) Tryptophan is important for the synthesis of serotonin. It can be found in peanuts, rice and cottage cheese.

8. Answers will vary, but could include:• definition/role• examples of neurotransmitters• effects of neurotransmitters• amino acids required• examples of foods as a source of amino acids

9. Any five of those shown in the figure on page 7. 10. Due to difference in the way that their brains are ‘wired

up’. Also due to the effects of hormones such as testosterone and oestrogen. Males and females can respond to stress differently because of these different hormones.

Remember

1.

2. Something could be improved or better.3. State ‘who’, ‘does’ (action verb) and ‘what’ for your

problem.4. The white thinking hat and first-floor thinking.

5. Target maps can help you to try and make sense of your finding. Target maps can help you to determine what is relevant to possible solutions and what is not.

6. Yellow hats and visual thinking tools can help you to develop your creative thinking.

7. Timelines and flowcharts may help you to sequence your tasks.

Think and discuss

8–10. Answers will vary.

Remember

1. Interpersonal communication is the transmission of information between two or more people. The sender encodes the message and the receiver decodes the message.

2. Verbal communication involves speaking or writing the words whereas non-verbal communication relies on other methods.

3. Verbal communication involves not only what we say, but how we say it. (This is referring to the selected words or prose selected to say what we want to communicate, e.g. the same message may be conveyed using different words to different audiences.)

4. Example:

Feeling angry?1.2

Essential problem solving1.3

What is the perceived problem?What is wrong?

What are the facts?

After finding out the facts, whatdo you now see as the problem?

What are some possible solutions or ideas?

Which is the best idea?

What is your action plan?

Coded communication1.4

’invisible’ physicalarea surrounding your body that you regard asyour personal territory

’invisible’ physicalarea surrounding yourbody that you regard

as your personalterritory

non-verbal

communication

personalspace

paralinguistics

kinesics

how or the waythat something

is said


Remember

1. The regular pattern of mental and physical changes that happen to you throughout a 24-hour time period.

2. The SCN is located in your hypothalamus, near where your optic nerves cross. The SCN is a pair of pin-sized structures made up of about 20 000 neurons. It controls your circadian rhythm (your body’s biological clock).

3. Photoreceptors in your retina detect light and create signals that travel along your optic nerve to your SCN. If there are decreasing levels of light, then your SCN sends this information to your pineal gland, which then produces melatonin that tells your body to be sleepy.

4. Increased levels of melatonin tell your body that it’s time to sleep and you begin to feel drowsy.

5. Your judgement of time and location can become distorted because serotonin and norepinephrine are involved in logical and consequential thinking.

6. Sleepiness may be because of the powerful sleep inducing chemical of your immune system called cytokines. Sleep may help you to conserve energy and other resources that your immune system may need.

7. Non-REM sleep makes up about 75% of your night’s sleep. You are most likely to dream in REM sleep.

8. The pons in your brain shuts off neurons in your spinal cord to temporarily paralyse your limbs so that you don’t act out your dreams.

9. Delta waves (1–3 Hz).

Remember

1. Learning is about gaining new knowledge and memory is about retaining and then retrieving that learned information.

2. The flowchart should show three steps: record the experience, store it in an appropriate part of your brain and retrieve or pull out the information.

3. Short-term memory processes information that you have just received. It has a limited ‘lifespan’ and may last only seconds or at most hours. Long-term memory processes information that has been selected for ‘storage’ over time. It can last days or even years.

4. You can transfer things from your short-term to your long-term memory by rehearsing information (practice) and applying meaning to it (understanding).

5. Hippocampus.6. Spatial memory, procedural memory, episodic memory,

working memory, and semantic memory.7. A mnemonic is something that helps you to remember

something else. It may take the form of a word, poem, story or image. An example is a tell-a-tale, in which you use the words or information that you need to learn to make up a story.

8. Traumatic or emotionally charged events may increase your chances of survival as you remember to protect yourself from a potentially dangerous situation.

9. Beta blockers can bind to the receptors on the cell surface and block adrenaline and noradrenaline and their stressful effects. This can prevent deep memory formation that may be ‘negatively charged’.

Remember

1.

Think and discuss

2. (a) By applying past experiences to new problems you can solve them faster and more effectively.

(b) By repeating a task and learning from your mistakes, you not only learn the task, but other things about yourself and how you learn.

(c) By becoming accustomed to a repeated stimulus, you can ignore it so that it is not so annoying. For example, a tap dripping or outside traffic.

3. Answers will vary.

Remember

1. Synapse.2.

3. Dopamine, acetylcholine and noradrenaline.4. Neurotransmitters.5. Increase or decrease the transmission of messages across

the synapse.6. Excitatory psychoactive drugs increase the transmission

of message across the synapse whereas inhibitory drugs decrease it.

7. (a) Uppers(b) Downers

8. (a) Barbiturates, benzodiazepines, heroin(b) Nicotine, caffeine, cocaine, amphetamines

Health: Sleep on it1.5

Total recall?1.6

Getting it right1.7

trial and errorlearning

habituation

imprinting

conditioning

insightlearning

behaviours thatdo not have

to be learned

inborn or inherited

behaviours thatcan change as

a result ofexperiences

example

ability to learn is innate

courtship

migration

competition

example

learnedbehaviour

innatebehaviour

Drugs on your brain1.8

Pre-synaptic neuron

Neurotransmitter carries messageacross synapse between neurons

Post-synaptic neuron


9. Example:

10. Can cause neuron death.11. The Venn diagram should show:

• Barbiturates only:– a small difference between a dose that produces

sedation and one that may cause death• Both barbiturates and benzodiazepines:

– Inhibitory psychoactive drugs– ‘Downers’ or depressants– May lead to tolerance and dependence– Both can help you to sleep

• Benzodiazepines only:– A very large difference between a lethal dose and

one that reduces anxiety or induces sleep

Remember

1. (a) Storyboards, flowcharts, timelines and cycles.(b) Matrix and affinity tables.(c) Priority grids, target maps, continuums and pie charts.(d) Concept maps, Venn diagrams and fishbones.

Looking backAll answers will vary.

Remember

1. Metabolism describes the way that cells carry out the chemical processes occurring within them that keep living things alive.

2. Biologists may be interested in the cells that make up an organism and how those cells help the organism to grow and maintain itself; chemists may see the organism as an amazingly complicated combination of atoms and molecules that are involved in millions of chemical

reactions every second; physicists and engineers may see organisms as incredibly sophisticated, self-controlling and self-repairing machines.

3. Like other matter in the universe, organisms are made up of atoms.

4. All life on Earth is made up of organic (carbon-containing) molecules.

5. Collections of atoms make up molecules and thousands or millions of molecules make up organelles.

6. Cells may differ in their size, shape and the number and kinds of organelles that they contain. These differences depend on the main job of the particular type of cell.

depressants

example

examples

inhibitorypsychoactive

drugs

excitatorypsychoactive

drugs

GHB

decrease synaptictransmission

increase synaptictransmission

drowsinessdrowsiness

hypothermia

breathingdifficultiesloss of

consciousness

increasedheart rate

increasedurine

production violentaggressivebehaviour

tremors

insomnia

insomnia

dizziness alertness

headaches reducedappetite

hallucinations

reducedpain sensation

reducedpain sensation

nauseapossibledeath

possibledeath

respiratorydifficulties

amnesia

possible strokesorgan failure and

heart attacks

heroin

cocaine

ecstasy

stimulants

Effectsof drugs

caffeine

reduced finemotorcontrol

increasedheart rate

increasedheart rate

Thinking tools: ‘See quest’ tools

1.9

CHAPTER 2 FOLLOWING ORDERS

The recipe for life2.1


7. Groups of similar cells that carry out a specialised job are called tissues. Organs are made up of one or more different kinds of tissue and carry out one or more main functions. Several organs working together make up a system.

Using data

8. Oxygen makes up the largest percentage in all organisms.

9. Humans contain the highest percentage of phosphorus.

10. Nitrogen: Human (3.3%); Maize (0.45%); Yeast (2.4%).11. Hydrogen makes up 10% (by weight) in all organisms.12. (a)

(b)

To summarise: Humans were highest in carbon, nitrogen and phosphorus and were lowest in oxygen; maize was highest in oxygen and lowest in carbon, nitrogen and phosphorus; hydrogen was the same for all.

13. (a) human — 15%(b) human — 18%(c) yeast — 11%(d) maize — 86%.

14.

15. Any suitable patterns suggested by students, e.g. oxygen in the highest amounts and potassium, sulfur and sodium in the lowest amounts. Hydrogen all the same. Humans generally have the higher percentages of elements except for oxygen. Maize generally contains the lowest percentages of elements except for oxygen, calcium and sulfur. Maize has the highest water content but is lowest in all other substances. Humans have the highest content of all the substances except for carbohydrate and water.

Remember

1. (a) A receptor detects the stimulus whereas an effector responds to the stimulus.

(b) A sensory neuron carries the impulse generated by the stimulus to the central nervous system; an interneuron then carries the impulse through the central nervous system; and the motor neurons take the impulse to the effectors.

(c) Neurons grouped together form a nerve.2. Students may draw a diagram, such as that shown on the

top of page 38 of Science Quest 3, or translate the answer into text similar to the answer for Remember 1(b) above.

3. A stimulus–response model suggests that there is a pattern in the way that the body responds to a stimulus. For example, the stimulus of the heat of a burning match prompts the response to move away from the match quickly without having to think about it.

4. When an increase in blood pressure is detected, and the body responds by performing activities that reduce the blood pressure. The reduced stimulus, which removes the need to continue the response, is called a negative feedback mechanism.

Remember

1. Animals can cause paralysis by producing cocktails of poisons that block the production and action of neurotransmitters at the synapses. The poison from a red-back spider, for example, empties the neurotransmitters out of their pockets at the end of the axon, hence interfering with the transfer of the message. This may result in paralysis or spasms.

2. (a) Plants can defend themselves against humans by producing chemicals that sting by strongly stimulating the pain receptors in the skin.

(b) Chemicals produced by plants like chrysanthemums target the nervous system of insects, resulting in their death.

Element Observations

carbon highest (18%) in humans, lowest (13%) in maize

hydrogen the same (10%) in all organisms

oxygen highest in maize (75%), lowest in humans (65%)

nitrogen highest in humans (3.3%), lowest in maize (0.45%)

phosphorus highest in humans (1.0%) and lowest in maize (0.06%)

Perc

enta

ge

am

ount

(by

wei

ght

)

0

10

20

30

40

50

60

70

80 Human body

Maize

Yeast

Carb

on

Hydr

ogen

Oxy

gen

Nitr

ogen

Phos

phor

us

Element

Substance

Approx. % (by weight)

of the human body

Approx. % (by weight) of maize

Approx. % (by weight)

of yeast

(a) water content 60 86 70

(b) minerals content 4.5 1.5 2.5

(c) carbohydrate content 0.1 8 11

Fast control2.2

Civics and citizenship: Chemical warfare

2.3


Think and discuss

3. The transmission of the nervous impulse is hampered, hence paralysis may occur.

4. Toxins may accumulate along food chains by a process called biological magnification. A possible consequence of this may be that humans or other high-order consumers may eat food, such as fish, which contains high levels of toxins.

5. Students are to use their general knowledge and imagination to suggest ways that this may be achieved. For example, they should use information about how the nervous system works and how these chemicals travel to it.

6. Insecticides kill insects.7. Nerve gas is used in warfare to harm people and other

organisms. This question could lead to a class debate on chemical warfare. Students may like to find out more about the Biological Weapons Convention and the status of chemical and biological weapons throughout the world.

Student responses will vary.

Remember

1. Hormones are chemicals that control and regulate functions like metabolism, growth, development and sexual reproduction in humans. In humans, hormones are produced in their endocrine glands.

2. Hormones are released directly into the bloodstream and are carried to all parts of the body, but only target cells respond in a particular way.

3. Metabolism, growth, development, sexual reproduction.4. Adrenaline is referred to as the ‘flight or fight’ hormone

because it prepares the body to escape from, or fight its way out of, a dangerous situation by increasing the heart rate and muscular actions and energy ‘levels’.

5. Insulin responds to increases in blood glucose levels by targeting cells that convert glucose from your blood into glycogen, which is then stored, therefore lowering your blood glucose levels back to ‘normal’. Glucagon has the opposite effect and raises blood glucose levels.

6. Oestrogen, progesterone and testosterone are sex hormones that can be responsible for many of the changes taking place during puberty.

7. Differences between the endocrine and nervous system.8.

Think and discuss

9. Students’ mind maps will vary, but it is important that their connections are accurate.

10. Advantages of adrenaline in modern-day living may include being able to perform well in tests, competitions and sporting activities. Disadvantages may include stress-related illnesses, violence and frustration about not being able to react in a ‘fight or flight’ mode to a particular situation at a given time.

11. By giving hormones that are no longer produced by the body, hormone replacement therapy may reduce the effects of menopause by ‘balancing’ or regulating women’s hormone levels.

12. Both control and co-ordinate activities in the body, use negative feedback to counteract change and regulate body response to stress.

Remember

1. Hormones and the ‘internal biological clocks’ of plants coordinate their life cycle.

2. Auxins, cytokinins, abscisic acid, gibberellin, ethylene.3. Root tip, leaves and buds, roots.4. When light shines on the tips of a plant’s shoots, auxins

are produced and released. These auxins travel down the plant and cause the cells on the side opposite the light to grow longer than those on the other side. This causes the stem to bend towards the light.

5. A circadian rhythm is a 24-hour cycle pattern. For example, the opening and closing of flowers is a circadian rhythm.

6. The length of uninterrupted darkness and hormones.7. (a) Long-day plants: gladioli, cabbage and hibiscus

(b) Short-day plants: daffodils, rice and chrysanthemums(c) Day-neutral plants: potatoes and tomatoes

Think and discuss

8. Short-day plants are likely to flower in the winter and long-day plants in the summer.

9. So that they can have more control over which plants flower or fruits ripen and when.

Remember

1. Scientists noticed that trees downwind of gas street lamps were shedding their leaves.

2. (a) Examples include timing of flowering, control of the ripening of fruit, cloning of plants from tissues, root development in cuttings and lengthening the life of flowers.

(b) Examples include fertility control for farm animals and controlling the growth of stock.

(c) Examples include the control of growth, diabetes, fertility and diseases such as goitre.

3. RU486 is also known as Mifeprex and ‘the abortion pill’.4. RU486 can be used for contraception or the termination of

pregnancy. It works by blocking the action of the hormone progesterone.

5. Other forms include patches, gels, implants and insertable vaginal rings.

6. (a) Androgen and progesterone.(b) Androgen blocks sperm development and

progesterone blocks the production of the hormone testosterone.

Endocrine system Nervous system

Speed of message slow Speed of message fast

Long time to take effect Takes effect rapidly

Response time long lasting Response time short lived

Effect widespread throughout body

Effect localised in body

Message travels through blood Message travels along nerves

Message is hormonal (chemical) Message is electrical

Science at work: Getting back into control

2.4

Slow control2.5

Plant moves2.6

Science at work: Harnessing hormones

2.7


Student responses will vary.

Looking back1. The incorrect term is underlined, and the correct term

(which is also found in the word puzzle) is supplied in parentheses:(a) The neuron (bloodstream) carries hormones to target

cells. Neurons are known as nerve cells. They carry electrical impulses through the nervous system.

(b) The master gland of the endocrine system is the adrenal (pituitary) gland. The adrenal gland is located near the kidneys and produces adrenaline, which has the effect of raising blood pressure, heart rate, breathing rate and supply of blood to the muscles.

(c) The brain and spinal cord make up the peripheral (central) nervous system. The peripheral nervous system is made up of the nerves that connect the central nervous system to the rest of the body.

(d) Organelles (neurotransmitters) carry messages across synapses. Organelles are made up of thousands of millions of molecules. Each molecule has a job to do that contributes to the life processes of a cell (e.g. mitochondrion).

(e) Each molecule (organ) has tissues which carry out particular functions. A molecule is a collection of atoms in an organism. All life on Earth is made up of organic (carbon-containing) molecules, such as glucose.

(f) Reflex actions and negative feedback mechanisms are examples of learned (innate) behaviour. Learned behaviour is that which develops in response to an organism’s experiences.

(g) Hormones are constantly being broken down, largely by the brain (liver). The brain is an organ that acts as the control centre of the body’s functions.

2. Student responses should vary.3. The flowchart should indicate the following terms in the

following order from smallest to largest.atoms molecules organelles cells tissues organs systems

4. Student responses will vary.5.

6. Mind maps produced by students will vary.7. Dendrites — 1; sensory neurons — 4; adrenal glands — 8;

pancreas — 9; nerve cell body — 3; effector — 6; axon — 2; pituitary gland — 7; motor neurons — 5

8. Nervous responses should include an outline of the reflex arc such as described in spread 2.2, ‘Fast control’. The endocrine responses may include information from spread 2.5, ‘Slow control’, in particular, ‘fight and flight’ response, e.g. the hormone adrenaline may be released to deal with a possibly dangerous situation.

Remember

1. Able to be moulded into different shapes.2. A polymer is a very large molecule which consists of

many repeating units called monomers.3. Carbon.4.

Think

5. many × tetrafluoroethene polytetrafluoroetheneHint: Many students, will not know that they need to use the word ‘catalyst’.6. (a) polyethene (or polythene or polyethylene)

(b) polyvinyl chloride (or PVC) (c) polystyrene (d) polypropene (or polypropylene).

Remember

1. They both consist of chains of monomer molecules. Thermoplastic polymers soften when heated and are easily melted. Thermosetting polymers are hard, rigid and sometimes brittle. They do not soften when heated and usually char.

2. PVC and polyethene (polythene) are thermoplastic polymers. Bakelite and melamine are thermosetting polymers.

3. A chemical bond between chains of monomer molecules in polymers.

4. Thermosoftening.

Think

5. (a) thermoplastic (b) thermosetting (c) thermosetting (d) thermoplastic.

6. The crosslinks in thermosetting polymers prevent the chains of monomers from sliding past each other.

Investigate

7. Student research.8. Photodegradation is the breaking down of materials by

light.

Thinking tools: Relations diagrams and mind maps

2.8

Characteristic Nervous system Endocrine system

What is carried Electrical impulses Chemicals called hormones

How information is carried

Via neurons Bloodstream

Speed of response Fast Slow

Length of effect Short Long

CHAPTER 3 IT’S A MATERIAL WORLD

Synthetic Manufactured: not natural

co-polymer polymer formed from two different types of monomer

monomer small molecule which repeats to form a polymer

plastic easily moulded

polythene polymer of ethene

catalyst speeds up a chemical reaction

Plastic facts!3.1

catalyst

Versatile polymers3.2


Remember

1. A natural fibre is made from plant or animal products. Synthetic fibres are made in chemical factories. They are mostly derived from petroleum. Examples of natural fibres include wool, cotton, linen and silk. Examples of synthetic fibres include nylon, polyester and rayon.

2. By forcing the softened plastic materials through a nozzle called a spinneret.

3. A natural polymer found in most plants.4. Fibres made from cellulose.

Think

5. Synthetic fibres can be produced more quickly, in larger quantities and at lower cost. Most synthetic fibres are easy to clean and care for. Some synthetic fibres are very strong and hard-wearing.

6. They are usually made from thermoplastic polymers which soften and melt easily when heated.

7. They have the advantage of the best features of each of the fibres. For example, a polyester/cotton blend has the cool, absorbent qualities of cotton along with the greater resistance to wear of the polyester fibres.

Investigate

8. Wool to make parachutes.9. Student research.11, 12. Student investigations.

Remember

1. Answers include: PSZ, pottery, porcelain, fired clay, brick, tile, cement and glass.

2. From weathered rock.3. To produce a shiny surface so that the pottery is more

attractive and less porous to water.4. Finely ground glass, coloured by adding compounds of

metals such as cobalt and copper.

Think

5. Hardness and resistance to wear; resistance to chemicals; low density.

6. It is made from a fine white clay called kaolinite and is fired at a higher temperature.

Evaluate and think

7. (a) The volume of the pendant is equal to the increase in volume of water.(39.5 – 22.0) mL of water = 17.5 mLDensity (in g/mL) = mass/volume= 338 g/17.5 mL= 19.3 g/mL

(b) Probably.(c) To eliminate the possibility that the pendant is not

made of a mixture with a similar density to that of gold. The pendant could also be made of another metal or compound with a density similar to that of gold.

Remember

1. A colloid is a cloudy mixture which contains particles that are too small to filter. Examples include muddy water, smoke, mist, fog, mayonnaise, milk, butter and ice-cream.

2. Solutions are not cloudy. There is no Tyndall effect in a solution.

3. A chemical like alum is added to the water, causing the colloidal clay particles to clump together and settle to the bottom of treatment tanks.

4. A colloid consisting of two different liquids.5. Casein.

Think

6.

7. The colloid is the clouds. Clouds are aerosols consisting of a liquid (tiny droplets of water) in a gas (air).

8. The smoke scatters the laser light so that it can be seen. Without smoke, fog or mist the laser beam would not be visible.

Remember

1. The removal of plaque.2. Because of the cooling effect of the water that evaporates

from it.3. Extracted from flowers, essential oils are used in

perfumes.4. A fine black powder made from stibnite or galena.5. A film of saliva, bacteria and food particles.6. Tooth decay and gum disease.

Think

7. No. Many, such as toothpaste and some skin creams, provide protection from disease. Sunscreens and lip balms protect the skin from the effects of the sun.

8. Such creams leave an oily or waxy film on the surface, preventing direct contact between the skin and the air. This prevents or reduces evaporation.

9. No! All substances are chemicals whether they are natural or not.

Remember

1. Metals are malleable, ductile, good conductors of electricity and are lustrous (shiny).

2. A mixture of a metal and other metals or non-metals.3. It can improve appearance, reduce cost and protect from

corrosion.

Think

4. The addition of other substances can overcome someof the disadvantages of pure metals. Few metalelements are suitable for common use in their pureform.

5. Tungsten has a very high melting point. 6. A small amount of another element can change the

properties of a metal considerably to make it more suitable for particular applications.

A new breed of fibres3.3

Space age ceramics3.4

Colloids and gels3.5

Type of colloid Contains Common examples

gel solid in liquid jelly, water-based paints, hair gel, some toothpastes

emulsion liquid in liquid mayonnaise, milk, butter, ice-cream, cream

aerosol liquid in gas mist, fog, some insect repellents, some deodorants

Cosmetics: face the facts3.6

Testing your metal3.7


7. By putting a thin coating of an expensive metal on the surface of a cheaper metal, the object can be made to look as if it were made entirely of the more expensive metal.

Remember

1. Recycling reduces the amount of new rubbish added to the environment and reduces the demand for oil.

2. The cost of collecting and sorting waste was too high compared to the cost of making new plastic.

3. The code helps consumers identify and sort plastics that are suitable for recycling. This makes recycling easier and cheaper.

4. Cullet is the name given to used glass bottles.

Think

5. Poisonous chemicals can leak into the soil, rivers and streams and endanger living things; landfill sites are unsightly; landfill sites occupy land that could be used for other things; landfill sites can be breeding grounds for insect pests like flies.

6. Energy is used by vehicles in the collection of waste, in melting down the cullet and in making the new glass.

7. The energy saving is very large and the amount of waste taken to landfill sites is reduced.

8. The cost of recycling compared to that of extracting more of the original resource; consumer demand for the recycled product; the environmental impact of extracting the resource.

Remember

1. Unlike metals, semiconductors are not good conductors of electricity.

2.

3. Doping makes silicon a better conductor of electricity.

Think

4. Plastic is solid, tough and easily moulded, suits the shape of silicon chips, and, because it is an insulator, does not interfere with the electrical properties of chips.

5. Aluminium and copper are much less expensive than gold and silver.

Think and create

1. (a) Polymers(b) (i) Words in inner circle: porcelain, pottery, clay,

PSZ(ii) Words in inner circle: smoke, fog, milk, butter,

mist, ice-cream(iii) Words in inner circle: iron, copper, tin

Looking back1.

2. Many possible answers include: cling film (polythene), squeeze bottles (polythene), clothes (nylon, polyester), benchtops (melamine), electrical switches (bakelite), drain pipes (PVC).

3. Sample answer: Polymers are made in chemical reactions in which chemical bonds join monomers together. A chemical called a catalyst can be used to speed up the chemical reaction.

4. Sample answer:

5. (a) oil(b) The fibres are made by pushing the softened plastic

materials through small holes in a nozzle.(c) Sample answer:

Semiconductor Neither a conductor nor insulator

Component A part of an electronic circuit

Conductor A substance in which electricity can flow

Microprocessor A chip that can store and process information

Doping Adding small amounts of another element

Civics and citizenship: Use it again

3.8

Semiconductor magic3.9

Thinking tools: Target maps and Venn diagrams

3.10

Ceramics Plastics Metals

Tile and brick:• resistant to

heat• less dense

than metals• hard surface

Electrical switches and benchtops:• made from

thermosetting polymers which can be moulded into shape but are hard and rigid

• do not melt when heated

Saucepans:• malleable (can be

beaten into a variety of shapes)

• good conductor of heat

• lustrous (shiny)Electric wiring:• ductile (can be

drawn into a wire)• good conductor

of electricity

Consumer

Advantages Disadvantages

cheaper flammable

easy to care for clinging

1. E R 2. M I C S 3.

L 4. R5. M U L S I O N L E

M 6. L A Z E7. I 8. E Y S

A 9. A T U R 10. L 11.

12. E T I N E 13. I L

A U G R 13. 14. B15. O L Y M E R S O A R

Y T 16. I L V E 17.

S E O E U18. 19. T T O N 20. Y L O N S

R A T21. E C Y C L E

C A

E

N A

G

T

C

F

O

RS

G

N

T

P

OC

R

C

P


6. (a) Wool, cotton, silk, linen(b) Polyester, nylon(c) Rayon


8. (a) An emulsion.(b) The bottle indicates that the mixture is a liquid.

Because no particles are visible the mixture must be made up of only liquids. The label also indicates that the salad dressing is a mixture of two liquids. Therefore, although the mixture is a colloid it is more correctly described as an emulsion.

9. Small amounts of other elements (such as phosphorous, arsenic, boron and gallium) are added to silicon to make it a better conductor. This process of adding other elements is called doping.

10. Answers will vary.11. (a) Some of the most important properties are:

(i) rigidity, strength, lightweight(ii) rigidity, strength, rust-resistant(iii) slightly flexible, hard(iv) flexible, heat insulator(v) shiny, hard (to resist scratching), rust resistant(vi) rigid, hard, rust-resistant, lightweight.

12. (a) Plastics are lighter than many metals. Using plastics could make cars lighter and improve fuel economy. They can be easily moulded into shape. Plastics do not rust and would not need to be painted.

(b) Answers will vary.

Your questThink

1.

2. (a) Thermal energy(b) Thermal energy (although some is used for car

heating), sound energy, light energy(c) Thermal energy(d) Thermal energy, sound energy, light energy(e) Light energy, kinetic energy

3. (a) Chemical energy (from food) kinetic energy

thermal energy light energy(b) Chemical energy (from food) kinetic energy

potential energy (c) Potential energy kinetic energy sound and a tiny

amount of thermal energy(d) Chemical energy electrical energy thermal

energy light energy(Most torch globes are incandescent — they emit light when the filament gets hot.)

Remember

1. An exothermic process is one in which energy is released to the surroundings, increasing the temperature. An endothermic process is one in which energy is absorbed from the surroundings, lowering the temperature.

2. (a) melting (b) condensing.3. Melting.

Think

4. (a) Exothermic(b) Calcium chloride + water calcium

chloride in solution(c) No new substance has been formed.

5. Endothermic6. (a) Exothermic

(b) Exothermic(c) Endothermic

Remember

1. A substance in the airbag explodes, releasing nitrogen gas, which inflates the bag. The explosion is set off when a device inside the car detects that the car has slowed down very rapidly.

2. Sodium azide sodium + nitrogen gas3. Dynamite4. The chemical reaction that takes place releases large

amounts of energy and gas which can exert great pressure.

5. Hydrogen + oxygen water

Manufacturer


cheaper to make oil is expensive

can be made in large quantities

processes can be dangerous

Environment


avoids clearing of natural vegetation to plant crops like cotton

pollution caused by manufacturing

avoids shearing of sheep which could be regarded as cruel

waste is not biodegradable

CHAPTER 4 CHEMICAL ENERGY

Chemical reactionChemical energy is usefully transformed into:

(a) Sparklers lit on a birthday cake

Light energy

(b) Petrol burned in a car Kinetic energy, potential energy (when going uphill)

(c) Kerosene burnt in a lantern Light energy

(d) Dynamite exploded in a rock Kinetic energy

(e) Wood burning on a fire Thermal energy

Hot and cold4.1

Blowing up4.2


Think and discuss

6. Exothermic. Energy is released.7. Student opinion, which can be investigated further by use

of biographies. Nobel’s great wealth came largely as a result of the manufacture of dynamite. Its use as a weapon that killed many and harmed humanity may have prompted him to give something back that benefited humanity.

8. Energy is not a chemical.

Remember

1. By losing an electron or gaining an electron.2. A positive sodium ion.3. A negative chlorine ion.4. A process in which an electric current causes a chemical

reaction to occur.

Think

5.

6. Water on the ground and in swimming pools contains many dissolved ions, making it a very good conductor of electricity. Energy from lightning is transferred easily to a person on a wet golf course or in a swimming pool.

7.

Remember

1. When zinc metal is placed in a copper sulfate solution, the zinc metal dissolves and copper metal is formed. The zinc metal atoms pass electrons to the copper ions. The copper ions become copper metal.

2.

3. Atoms are closely packed and can give up some of their electrons to form positive metal ions and some free moving electrons.

4. Chemical energy is transformed into electrical energy.

Think

5. The flow of electric current.6. In the form of ions. The positive potassium ions move

into the copper half-cell to replace the copper ions that reach the electrode. The negative chlorine ions move into the zinc half-cell to balance up the new zinc ions that are produced at the zinc electrode.

Remember

1. A positive electrode, a negative electrode and an electrolyte.2. A battery is a group of cells connected together.3. The negative electrode.4. The chemicals originally inside the cell take part in the

chemical reactions until there are no longer enough of them to keep the chemical reactions occurring. That is, the reactants have all turned into products.

Atom Gains or loses electricityPositive or negative ion

fluorine gains 1 electron negative

zinc loses 2 electrons positive

oxygen gains 2 electrons negative

sodium loses 1 electron positive

silver loses 1 electron positive

chlorine gains 1 electron negative

Charge on the move4.3

positiveelectrode

negativeelectrode

The positive sodium ions

move towardsthe negative

electrode.

The negative chlorine ionsmove towardsthe positiveelectrode.

battery

+ –

salt water

Cl–

Cl–

Cl–

Cl– Cl–

Cl–

Cl–Cl–

Na+

Na+

Na+

Na+Na+

Na+

Na+

Na+

Takeaway electricity4.4

Zn

Zn

Cu2+

Cu2+

Cu2+

CuCu

CuZn

Zn2+

Zn2+Zn2+e–e– e–

e–e–

e–

battery

+

+

+

++

+

+

++

+–

–

–– –

–

–

–

–

+

–

–

copper sulfate

zinc nitrate

galvanometer

electronselectrons

copper metalzinc metal

strip offilter papersoaked inpotassiumchloride

+ –

Cl–K+

copper ions (positive)+ electrons copper

metal atoms

zinc metal atoms zinc ions (positive)+ electrons

SO42–

NO3–

Cl–Cu2+Zn2+

K+

Batteries, batteries4.5


Analyse and evaluate

1.

The crude oil can be heated in a tower so that it becomes a gas. As the gaseous hydrocarbons rise they cool. Those with more carbon atoms and higher boiling points condense first, at lower parts of the tower. As the number of carbon atoms in the hydrocarbons decreases, the boiling points decrease and they condense progressively further up the tower.

Remember

2. From decaying plants and animals over tens or hundreds of millions of years.

3. methane + oxygen carbon dioxide + water vapour4. A compound of hydrogen and carbon.5. Components of crude oil.

6. It is highly flammable but leakages cannot be detected because it cannot be seen or smelt.

Think and discuss

7. The plants and animals that decay to form fossil fuels originally obtained their chemical energy as a result of the transformation of energy from the sun by photosynthesis.

Remember

1. Gases that trap some of the energy leaving the Earth’s surface.

2. Carbon dioxide, methane, chlorofluorocarbons (CFCs) and nitrogen oxides (only three needed).

3. The warming of the Earth’s surface by the atmosphere. It is necessary to support life on Earth.

Think and discuss

4. The greenhouse effect is natural and keeps a balance between the amount of energy coming into the Earth’s atmosphere and surface and the amount of energy leaving the atmosphere and surface. The enhanced greenhouse effect is an increase in the temperature of the surface due to a warmer atmosphere. The warming of the atmosphere is caused by an increase in the amount of greenhouse gases in the atmosphere, mainly due to human activity.

5. Some of the energy transformed when fossil fuels are burnt heats the atmosphere. The transformation of nuclear energy also heats the atmosphere. Increased activity on the sun can also contribute to global warming.

6. The clearing of forests, paper production, and the burning of waste have all contributed to the increase in carbon dioxide.


7. (a) (i) 14.8°C, 298 ppm (ii) 15.1°C, 312 ppm (iii) 15.0°C, 333 ppm.

(b) There are gases other than carbon dioxide that affect global temperatures; natural events like volcanoes also change the temperature of the atmosphere and surface.

(c) They do not provide proof. They do, however, provide strong evidence.

(d) Student opinion.

Remember

1. (a) Fuels made from plant and animal tissue.(b) A gas made from plant and animal waste.(c) Plant and animal tissue.

2. In a biogas digester, from plant and animal wastes.3. Sugar or corn.4. Its use helps to improve air quality, and reduces the

production of greenhouse gases. Ethanol will become more attractive as fossil fuels become scarce.

Think

5. It can assist in the disposal of waste in big cities, and can reduce the amount of methane (a greenhouse gas) in the atmosphere.

6. A solution related to this spread is the separating of garbage into ‘bio-garbage’ and other garbage. This would allow some of it to be used as biofuel.

7. Disadvantages include: the area required to plant enough trees to supply energy needs; the production of smoke and ash, which would be dispersed over surrounding areas.

Component Uses (only one example needed)

petroleum gases heating fuel, gas bottles

gasoline motor vehicle fuel, making plastics and detergents

naptha making motor vehicle fuel, plastics, pesticides, fertilisers and rubber

kerosene aviation fuel, paint solvents, in paraffin for heating and lighting

diesel oils motor vehicle fuel, oil heaters and in making asphalt

residue lubricating oils, petroleum jelly, candle wax, bitumen

Fossil fuels4.6

1 2 3 4 5 6 7 8 9 100

50

100

150

–150

–100

–50

Boili

ng p

oint

(°C

)

Number of carbon atoms

Civics and citizenship: Greenhouse Earth

4.7

Fuel from living things4.8


Think and create

1.

2.

Looking back1.

The famous scientist is Alessandro Volta.

2. Sample answers:

3. (a) Kinetic energy(b) Thermal energy(c) Potential energy and/or kinetic energy

4. (a) Thermal energy, sound energy, light energy(b) Light energy(c) Thermal energy, sound energy, light energy

5. An endothermic chemical process takes place inside it. The chemical process takes energy from the surroundings, cooling the contents.

6. These reactions are exothermic. When you exercise you get hot and your body temperature increases. This is because of the energy released by the chemical reactions occurring in your muscles.

7. (a) The melting of ice is an endothermic process. The energy required to allow the molecules to break away from each other is absorbed from the surroundings.

(b) The condensation of steam is an exothermic process. The steam condenses as it releases energy to the surroundings.

8. (a) Sweating is a physical process because no new substances are formed.

(b) Sweating is an endothermic process that takes in energy from the skin to cause liquid water to evaporate.

9. A chemical reaction inside the airbag produces nitrogen gas, which inflates the airbag.

10. Chemical explosions take place much more quickly than other exothermic chemical reactions. They are violent and/or noisy.

11. copper ions + electrons copper metalzinc metal zinc ions + electrons

12. It is reasonable to describe fossil fuels as packaged solar energy because fossil fuels are formed from the remains of plant or animals. Plants rely on solar energy to make their own food and animals rely on plants or other animals that eat plants for food. The chemical energy in fossil fuels therefore originated with solar energy. Examples might include coal, natural gas and oil.

13. The ‘enhanced greenhouse effect’ is a higher-than-normal amount of energy trapped in the atmosphere. It is largely caused by the burning of fossil fuels, which produces carbon dioxide and other gases that absorb energy, preventing it from leaving the atmosphere.

StatementEndothermic reactions

Exothermic reactions

Electrolysis Burning of fossil fuels

Energy is released to the surroundings

Energy is absorbed from the surroundings

Oxygen is always a reactant

Always caused by an electric current

A new substance is produced

Object or device

Light energy

Sound energy

Kinetic energy

Thermal energy

Electrical energy

Any battery

Torch cell

Camp stove

Car

MP3 player

Bombardier beetle

Air bag

d y n A m i t e

c e L l

o x y g E n

g r e e n h o u S e

e l e c t r o l y S i s

m e t A l s

m e t h a N e

e n D o t h e r m i c

e l e c t R o d e

i O n

c o n d u c t i V i t y

e l e c t r O l y t e

b i o f u e L s

b u t T o n c e l l

h y d r o c A r b o n s

Thinking tools: Matrixes and Plus, minus, interesting

4.9A. burning petrol in a car B. chemical reactions in fireworks C. chemical reactions in a battery D. explosion of dynamiteE. burning of coal


Your questRemembering the basics

Think

Answers will vary. Pair or group responses should be discussed with the whole class. Definitions of terms can be found in the glossary (see pages 254–61 of the textbook).

A simple circuit

Think

1. (a) Electric current flows. You can tell because the globe glows.

(b) Two batteries provide twice as much energy (and power) to the globe.

2.

The order in which the components are placed in the circuit diagram is not important.

Remember

1. A power supply, a load and a conducting path.2. The filament in the globe.3. Chemical energy.4. To control whether or not the conducting path is complete.5. Copper has little resistance to the flow of electric current.6.

7. It measures a change in the potential energy of charge as it moves between one place and another.

8. The amount of electric charge passing a particular point in an electric circuit every second.

Think

9. Sample answers: (a) light globe (b) loudspeaker (c) electric radiator (d) fan.

10.

Remember

1. Electric current.2. Voltage gain or drop (or potential difference).

Think

3. The voltmeter is incorrectly connected in series with the light globe — it should be connected in parallel. The terminals of the ammeter are connected the wrong way around — the positive terminal of the ammeter should be connected to the positive terminal of the battery.

4. The ammeter is not represented from directly in frontof the scale. There would be a parallax error in reading it.

Using data

1. 15 V.2. 0.4 A or 400 mA.3. R = V/I

= 12 V/0.8 A= 15 Ω

4. The resistance does not change and the graph of V versus I yields a straight line.

Remember

5. Insulators have a very large electrical resistance.6. The electric current is proportional to the voltage drop

across it. Or, in symbols, I α V.

Think

7. V = RI= 100 Ω × 0.250 A= 25 V

8. (a) When I = 200 mA, V = 1.5 VR = V/I

= 1.5 V/0.200 A= 7.5 Ω

(b) No. The resistance is not constant. When the voltage is 3.0 V, the current is 360 mA and the resistance isR = V/I

= 3.0 V/0.360 A= 8.3 Ω

(c) Electric current would double.

Remember

1. The voltage and current.2. Electric current decreases.

Think

3. (a) The resistance could be up to 5% more or less than 27 000 Ω.

(b) 27 000 Ω + 5% of 27 000 Ω= 27 000 Ω + 1350 Ω= 28 350 Ω

Investigate

4. The length of the resistor that is part of the circuit increases as the slider is turned or the dial is turned.

CHAPTER 5 ELECTRIC CIRCUITS

+ +– –

Go with the flow5.1

+ – + –(a) (b)

+ –

Made to measure5.2

A question of resistance5.3

Controlling the flow5.4


Remember

1. (a) decrease. (b) remain the same.2.

3. An alternative pathway for electric current with very little resistance.

4. Fuses and circuit breakers can open the main circuit and stop the flow of current when the current becomes too large.

5. A circuit breaker has a special switch that opens automatically if the current is too large. A fuse melts when the current is too large.

Think

6. All of the other globes stop working because there is no electric current flowing through the series circuit.

7. The other globes continue to work. Only the current through the ‘blown’ globe stops flowing when the globes are connected in parallel.

8. A parallel arrangement is better in most situations because each globe can then have its own switch. If the globes are connected in series you would have to have either all the lights on or all the lights off. Also, if one globe in a parallel arrangement ‘blows’, the others are not affected.

9. (a) There should be a switch in each ‘arm’ of the circuit so that all of the lights can be switched on or off separately. Ethelred’s design only allows either all of the lights on or all of the lights off.

(b) It would be best connected in parallel so that either or both lights can be turned on. If it is connected in series the owner could only have both lights on or both lights off.

10. (a) C(b) C(c) A and B(d) A and C(e) none(f) none

11. Sample answer: The rate of movement of the students is greater in the parallel queues than in the series queue with the same number of canteen staff. In a parallel electric circuit, the rate of flow of electric charge is greater than in a series circuit with the same voltage. If one of the parallel queues is stopped for some reason, the others continue to move — just as if one part of a parallel circuit stops working, the other parts continue to work. In a series arrangement, if there is a hold up or break in either of the canteen queues, all movement stops.

Remember

1. AC stands for alternating current. DC stands for direct current.

2. The transformers reduce the voltage from 240 volts to the required 9 volts or 12 volts.

3. The appliance should be replaced or taken to a qualified repairer.

4. Water is a good conductor of electric current. If an appliance makes contact with water and a person touches it, he or she could be electrocuted.

Think

5. (a) chemical energy stored in coal(b) gravitational potential energy.

6. The third socket is connected to the ground and is there because metal appliances have plugs with three pins. The third pin needs to be connected to the ground in case of a fault in the appliance.

Remember

1. A watt is a unit of electrical power. 2. A 60 W light globe transforms 60 J of electrical energy into

heat and light every second.

Evaluate

3. (a) 100 W × 3600 s = 360 000 J = 360 kJ(b) 800 W × 120 s = 96 000 J = 96 kJ

4. (a) 5 kW × 0.5 h = 2.5 kWh;2.5 kWh @ 12 cents per kWh = 30 cents

(b) 0.070 kW × 8 h = 0.560 kWh;0.560 kWh @ 12 cents per kWh = 7 cents

5. (a) 1700 W × 120 s = 204 000 K = 204 kJ(b) 650 W × 180 s = 117 000 J = 117 kJ

6. (a) 2 kW × 4 h = 8 kWh; 8 kWh @ 14 cents per kWh = $1.12 (b) 0.200 kW × 2 h × 7 = 2.8 kWh:

2.8 kWh @ 14 cents per kWh = 39 cents

Remember

1. Thousands of miniature electronic components. 2.

Remember

1. An electronic engineer uses knowledge about electric circuits to design and improve devices that solve problems.

2. Electronics is growing quickly because people are becoming more dependent on computers and electronic communication. Also, commonly used devices are increasingly being controlled by computers. Other reasons may be given, including the decreasing cost of electronic devices.

In a row or side by side?5.5

+ –(b) 6 V6 V(a)

+ –

Electricity at home5.6

Component Circuit symbol Function

capacitor to store electric charge for a short time

diode to allow current to flow in only one direction

transistor to act like switches, changing the size or direction of electric current

What’s watt?5.7

Electronics: a small world 5.8

+(a)

(b)

(c)

Design, creativity and technology: Solving problems with electric circuits

5.9


Think

3. 4.

Think and create

1–3. Answers will vary.4. These flowcharts are only examples. The order in which

connections are made may vary. In the case of the parallel circuit (a) the second globe could be connected directly to one terminal of the cell and the end of the switch furthest from the cell.(a)

(b)

Looking back1. (a) A device that provides electrical energy.

(b) A measure of the amount of electrical energy gained or lost by electric charge.

(c) A measure of the amount of electric charge passing a particular point in an electric circuit every second.

SQ3 TSK Fig A4.07

+ – + –

back door switch

front door switch

doorbell

Thinking tools: Concept maps and flowcharts

5.10

Connect one end of lead 1 to the positive terminal of the cell

Connect other end of lead 1 to

one side of the switch

Connect one end of lead 2 to the

other side of the switch

Connect other end of lead 2 to one side of globe 1

Connect one end of lead 3 to the unconnected side of globe 1

Connect other end of lead 3 to the negative terminal of the cell

Connect lead 4 from one side of globe 2 to one side of globe 1

Connect lead 5 from the other side of globe 2 to the other side of globe 1

Close switch

Connect lead 8 from the negative terminalof the voltmeter to the other side of globe 2

Connect one end of lead 1 to thenegative terminal of cell 1

Connect other end of lead 1 to thenegative terminal of the ammeter

Connect one end of lead 2 to thepositive terminal of the ammeter

Connect other end of lead 2

to one side of the switch

Connect one end of lead 3to other side of the switch

Connect other end of lead 3to one side of globe 1

Connect one end of lead 4to unconnected side of globe 1

Connect other end of lead 4to one side of globe 2

Connect one end of lead 5to unconnected side of globe 2

Connect other end of lead 5to the positive terminal of cell 2

Connect one end of lead 6to the negative terminal of cell 2

Connect other end of lead 6to the positive terminal of cell 1

Connect lead 7 from the positive terminalof the voltmeter to the side of globe 2 that isconnected to the positive terminal of cell 2


(d) A map of an electric circuit.(e) The path along which electric current flows in an

electric circuit.(f) The part of an electric circuit in which electrical

energy is converted into other useful forms of energy.

(g) In a line.(h) Side by side.(i) An object with little resistance to the flow of electric

current. (j) An object with a lot of resistance to the flow of

electric current.2. (a) The purpose of the transformer is to reduce the

voltage across the mobile phone battery. (b) The purpose of the rectifier is to change the

alternating current flowing from the power point to a direct current.

3.

4.

5. P = VI⇒ I = P/V

= 1200 W/240 V= 5 A

6. 70 W × (8 × 60 × 60)s= 2 016 000 J= 2016 kJ

7. 20 kW × 10 h × 7 = 1400 kWh8. 0.650 kW × 1/30 h = 0.0217 kWh;

0.0217 kWh @ 14 cents per kWh = 0.3 cents9. (a) B and C (b) D and E.

10. (a) 4 volts (b) 12 volts (c) 6 volts.11. (a) 200 mA (b) 300 mA (c) 500 mA.12. Globes D and E.13. Globes D and E.14. By placing a wire between the terminals of the

battery.15. (a) 0.200 A

(b) R = V/I = 4 V/0.200 A = 20 Ω16. (a) Capacitor

(b) Transistor (c) LED (light-emitting diode)(d) Silicon diode

17. Answers will vary.18. (a) Resistor

(b) Diode(c) Light-emitting diode (LED)(d) Capacitor(e) Transistor

19. (a) To control the voltage and electric current.(b) To allow current to flow in only one direction.(c) To allow current to flow in only one direction and

transform electrical energy into light energy.(d) To store electric charge for a short time.(e) To act like a switch, changing the size or direction of

electric current.20. (a) Photonics is an area of science that uses light

together with electronics to perform tasks. (b) Examples of photonics devices (5 required) include:

LEDs, CD players, CD burners, optic fibres, solar cells and remote controls.

Your quest

Think

1. Answers will vary and depend on students’ existing knowledge of light.

Think and discuss


Think

3. Answers will vary. Examples include:(a) camera, telescope, binoculars, light meter(b) magnifying glass, spectacles (glasses), contact lenses,

telescope, microscope(c) television, movie projector, stage lights, optic fibres.

4. Cameras, telescopes, binoculars, magnifying glasses, spectacles (glasses), contact lenses, microscopes and projectors all have lenses.

5. A lens changes the direction of light. Lenses can make light rays bend towards or away from a point.

Remember

1. A ray of light is a line that is used to show the path of light.

2. You see a beam of light when particles in the substance through which it is travelling scatter the light.

3. (a) Most of the light travels through the substance.(b) Just enough light travels through the substance to

enable you to detect objects on the other side. However, you cannot see them clearly.

(c) All of the light is absorbed or reflected.

Think

4. A ray is a line used to show the path of light, while a beam is a stream of light rays.

5. A real light ray is so very thin that it cannot be seen. The lines that are drawn to represent the path of light are also called rays.

Quantity Unit Abbreviation

voltage volt V

electric current ampere A

resistance ohm Ω

electrical power watt W

electrical energy joule J

electrical energy kilowatt hour kWh

+ –

+ –

+ –

V

A

6V

CHAPTER 6 KEEPING AN EYE ON LIGHT

Riding on a light beam6.1


6. No. It does not emit its own light. It is visible from Earth because of the light reflected from the sun.

7. Scattering is the reflection of light in many directions by many particles. The surface of a mirror, on the other hand, is so smooth that light coming from one direction is all reflected so that it emerges in parallel rays. See the following diagram.

8. (a) window; glass full of water(b) shower screen; thin paper; wax paper(c) wall; pencil. Most objects are opaque.

Remember

1. The change in speed of light as it travels from one substance into another. Unless the light crosses the boundary between the substances at right angles, the light bends.

2. Towards the normal.

Think

3. (a)

4. (b) It looks larger.

The image of the head of the fish will lie somewhere on the dotted line of sight shown in the diagram. This image is behind the real fish, so the spear should be aimed in front of the image.

Imagine

5.

(a) Higher. The diagram above shows that the girl’s head is seen by the fish due to reflected light travelling from her head to the eyes of the fish. Because of refraction, the light appears to be coming from a point above the girl’s head.

(b) The sketch should show the part of the girl’s body above the water surface as elongated. The part of her body below the surface would appear normal.

Remember

1. Biconvex lens:

2. Biconcave lens:

3. The distance between the focus (the point to which parallel rays of light converge) and the lens.

Think

4. Examples include: movie projector, slide projector, overhead projector, magnifying glass, spectacles, contact lenses, binoculars.

5. When a beam of light emerges from a diverging lens it appears to be coming from a single point — a virtual

focus. See the diagram below.

6. The light doesn’t actually come from or go through the focus. It just appears to come from the focus.

Reflection from aplane mirror

Scattering

What happened to my legs?6.2

coin

imageof coin

normal

line of sight

normal

line of sightfor fish

approximate locationof image of head

Through the looking glass6.3

virtual

focus

focal length


Imagine

7. (a) Hold the lens above a surface so that the sun’s rays come to a point. Measure the distance between the lens and this point.

(b) Hold the lens near a wall so that a sharp image of the scenery outside a window on the opposite side of the room falls on the wall. Measure the distance between the lens and the wall. The rays coming from the sun and travelling through the lens are almost perfectly parallel. They therefore converge at a point very, very close to the focus. The rays coming from a distant window are also approximately parallel. Therefore an image of the scenery outside the window will be very close to the focus of the lens.


1.

(a) Approximately 8 cm.(b) It decreases more rapidly as a person gets older. For

the group represented in the table this is between 50 and 60 years.

Remember

2. The cornea.3. The action of the lens in obtaining a sharp image on the

retina.4.

5. The ciliary muscles control the shape of the lens by relaxing or contracting.

6. As the body ages, the lens of the eye becomes less flexible, preventing it from bulging as much when looking at distant objects.

7. Messages are sent from the eye to the brain through the optic nerve.

Think

8. It slows down. Light slows down when it bends towards the normal as it passes from one substance into another. Because the cornea converges light, we know that the light bends towards the normal at its surface.

9. Light coming into the eye from nearby objects is spreading out more than light coming from distant objects. It therefore needs to be bent more. A thicker lens bends light more than a thin lens made of the same material.

Investigate

10. (a) lens (b) aperture(c) film.

Remember

1. Myopia (short-sightedness).2. A concavo-convex lens that converges parallel rays of

light.3. Glasses with lenses that converge light at the bottom and

diverge it at the top. They are used by older people to assist them with distance vision (the diverging part of the lens) and close vision while reading (the converging part).

Think

4. (a) Hyperopia (long-sightedness).(b) Presbyopia.(c) Cataracts.(d) Astigmatism.(e) Myopia (short-sightedness).

5. The plastic lens that replaces the original lens cannot change shape and therefore cannot change its focal length.

Remember

1. A long flexible tube containing optical fibres.2. Examining the stomach; searching for problems in joints;

looking inside the lungs; performing laser surgery (three answers only are required).

3. The light travels in straight lines. If it strikes a boundary between the glass and air, it is totally internally reflected. It is unable to emerge from the glass.

Think

4. Two possibilities are opening up the stomach in surgery or using X-rays (barium sulfate absorbs X-rays and, if it is ingested, X-rays can be used to trace its path through the stomach). The endoscope is less invasive than internal surgery, which also carries the risk of infection or negative response to anaesthetics. X-rays are avoided where possible because of their cancer-causing properties.

5. No. Total internal reflection can occur only when light bends away from the normal.

It’s the image that counts6.4

0 10 20 30 40 50 60

20

40

60

80

100

120

Ave

rage

smalle

st d

ista

nce

(cm

)

Age (years)

(a) (b)

Improving your image6.5

A look inside6.6


Remember

1. Red, orange, yellow, green, blue, violet.2. The air scatters more light at the blue end of the spectrum

than at the red end. As sunlight travels through the atmosphere, more blue light is scattered to your eye than red light.

3. The light from the sun travels through more air at sunset and so much blue light is scattered that the light coming directly from the sun towards your eyes is mostly at the red end of the spectrum.

Think

4. The light from the sun can be ‘split’ into different colours by raindrops as seen in a rainbow. White light from the sun and artificial sources can be separated into different colours by a triangular prism.

5. When white light is separated into different colours by a triangular prism, the blue light is bent more thanthe red light. It would therefore be expected that blue light slows down more than red light as it enters theglass.

6. Dispersion is the separation of white light into its different colours as a result of bending as it passes from one substance into another. It results from the refraction of light. Scattering is the reflection of light by many particles.

Remember

1. All of the colours of the spectrum except red are absorbed by the surface. Red light is reflected.

2. These three secondary colours can be combined together to produce white light.

3. All of the colours of the spectrum are absorbed by the filter. Only red light passes through the filter.

4. Both red and blue light pass through the filter. 5. Cones or cone cells.6. Red, green and blue.

Think

7. Red and green.8. (a) Red — red light is reflected from the shirt.

(b) Black — the red shirt reflects only red light. There is no red light emitted by blue lights. Therefore no light is reflected by the shirt.

(c) Red — yellow light is composed of red and green light. There is therefore some red light reflected by the shirt. The green light is absorbed by the shirt.

9. All of the colours of the spectrum except blue are absorbed by the dye or material that the shirt is made of. Blue light is reflected. The only colour reflected from the shirt into your eyes is therefore blue.

10. Colour television images are produced when separate beams of red, green and blue are transmitted to the screen in different strengths. In colour printing, the colours that you see occur because of light reflected from yellow, magenta and cyan dots.

Remember

1. Burning of the eyelids and surrounding skin; inflammation and burning of the cornea; death of cornea cells; cataracts; damage to cells on the retina.

2. Ultraviolet radiation has more energy than visible light.3. Between 10 a.m. and 2 p.m. (11 a.m. and 3 p.m. when

daylight saving is in operation).4. Sunglasses with polarised lenses reduce the glare caused

by the reflection of light from smooth surfaces like sand or snow.

5. Some sunglasses absorb visible light, making the pupil open up more than it would without sunglasses. This allows more ultraviolet radiation to pass through to the lens and retina.

Think

6. Answers will vary. Absorption of ultraviolet radiation should be listed first.

All answers will vary.

Looking back1.

2. (a) A ray is a line that is used to show the path of light. A real light ray is so very thin that it cannot be seen. A beam is a stream of light rays.

(b) Reflection is the bouncing of light from a surface. Scattering is the reflection of light in many directions by many particles.

(c) Refraction is the change in speed of light as it moves from one substance into another. Dispersion is the separation of white light into its colours. It occurs because different colours are bent different amounts when they are refracted.

(d) Most light travels through a transparent substance. Just enough light travels through a translucent substance to enable you to detect objects on the other side; however, you cannot see them clearly.

(e) Converging means closing in towards a point. Diverging means spreading out.

(f) Concave means curved inwards. Convex means curved outwards.

(g) A focus is a point towards which light converges. A virtual focus is a point from which diverging light rays appear to be coming.

(h) A gastroscope is an endoscope which is used to examine the stomach. An arthroscope is an endoscope which is used to search for problems in joints.

(i) Cones and rods are receptor cells in the retina. Cone cells detect different colours whereas rod cells detect the brightness of light.

Colour your world6.7

Seeing in colour6.8

Health: Fun in the sun6.9

Thinking tools: Cluster maps and double bubble maps

6.10

(a)

(b)

(c)

(d)

biconvex lens triangular prism

biconcave lens rectangular prism


3.

4. (a) The light ray slows down when it enters the glass.(b) The light ray speeds up when it emerges back into

the air.5. The light coming from the flower bends as it moves from

the water into the air, as shown on the right side of the diagram. It appears to be coming from a different direction. There is a very small amount of bending due to the glass, but because the glass is thin, the change in direction is insignificant. As a result the part of the flower that is in water looks larger. The light coming from the part of the flower out of the water travels in a straight line. Again, the very small deviation due to the glass is not significant because the glass is thin.

6. As a result of refraction at the water–air boundary, the light reflected from the bottom of your legs appears to be coming from above where it is really coming from. Refer to the figure on page 132 of the text.

7. (a) Convex.(b) The focal length is greater than 10 cm. In order to

produce a ‘right-way-up’ image, the object (the page of the comic book in this case) must be between the lens and the focus.

(c) The magnifying glass would need to be moved further away from the page so that is at a distance greater than the focal length.

8. A thin convex lens has a greater focal length because it does not bend the light as much.

9. Clockwise, from top right: retina, optic nerve, cornea, lens, iris, suspensory ligaments.retina: acts as a screen to receive the image.optic nerve: carries signals from the retina to the brain.cornea: does most of the bending of light, so that the light goes through the lens.lens: bends light to produce a sharp image on the retina.iris: opens and closes the pupil to control the amount of light entering the lens and falling on the retina.suspensory ligaments: cause the lens to bulge in order to provide sharp images of nearby objects.

10. Creative writing. Answers will vary.11. (a) Myopia.

(b) Spread light out (diverge it) before it reaches the cornea so that it forms an image on the retina instead of in front of it.

(c)

12. Red, green and blue are described as primary colours because red, green and blue light can be combined to produce white light. Different combinations of these colours can be used to create all other colours.

13. (a) The light travelling along the fibre is bent so much when it meets the glass–air boundary that it is totally internally reflected.

(b) In endoscopes, optical fibres are used to direct light into the part of the body being observed and to direct light reflected from inside the body to the outside so that an image can be obtained.

(c) Optical fibres are smaller. lighter, more flexible and cheaper than electrical cables.

14. All colours are combinations of different proportions of red, green and blue light.

15. When white light passes through a blue filter all colours are absorbed except blue.

16. (a) When blue paint is illuminated by white light, blue light is reflected from it. The other primary colours are absorbed.

(b) A white shirt can look red if the lighting at a dance or concert is red.

(c) A green shirt reflects only green light. It absorbs the other primary colours. If the lighting at a dance or concert is red, blue or any other colour that does not contain any green light, a green shirt will appear black. This is because no light is reflected from it.

air

observer

Part of flower

out of water

Part of flower

in water

observer

airwater

air

thin lens

thick lens

light from adistant object

sharp imageon retina

convexo–concavelens

total internal reflection


17. Two important features of sunglasses for best eye protection are their ability to absorb ultraviolet radiation and polarising lenses. Absorption of ultraviolet radiation is the most important feature. Ultraviolet radiation can

cause sunburn around and in the eye. Polarising lenses are important because they reduce glare, allowing you to see more colour and detail.

Your questThink

2. Answers will vary.3. Substances listed by students will vary.4. Answers will vary but should include events like

volcanoes, earthquakes, weathering, erosion, extreme weather events and animal behaviour (especially human).

Remember

1.

2. The build-up of pressure in the mantle forces magma upwards through a weakness in the Earth’s crust.

3. Neither dormant nor extinct volcanoes are active. However, extinct volcanoes have not erupted for thousands of years and show no signs of erupting whereas dormant volcanoes have erupted more recently and may erupt again.

4. Hot springs are formed when hot rocks beneath the surface heat underground water and the hot water bubbles up to the surface through holes in the crust.

Think

5. Magma is molten rock below the Earth’s surface. Lava is the molten substance that remains after gases are released from the magma as it surges out of the volcano.

6. It should be considered to be a dormant volcano because it last erupted less than about 25 000 years ago.

Remember

1. A theory that suggests that the Earth’s crust is divided into a number of moving plates.

2. The plates move on a layer of partially molten rock in the upper mantle.

3. Oceanic crust is thinner than continental crust. It is also denser.

4. (a) Earthquakes occur.(b) Oceanic crust sinks below continental crust in a

process called sublimation. Powerful earthquakes occur and explosive volcanoes are created. Mountain ranges can form.

(c) Underwater volcanoes appear and ocean ridges form and spread as rising magma cools.

5. An area of the Earth’s crust above an extremely hot part of the mantle.

6. One of two large continents that are believed to have been formed over 200 million years ago. The continents of Africa, South America, Antarctica and Australia were all part of Gondwanaland.

Think

7. A region of weakness in the Earth’s crust around the Pacific Ocean. It exists because it forms boundaries between some of the plates that make up the Earth’s crust.

8. • The location of earthquakes and volcanic activity form lines that divide the Earth into a number of regions.

• The present day continents could fit together like a giant jigsaw puzzle, suggesting that they have moved.

• Fossils of the same land animals have been found in all of the southern continents. This suggests that they may have been joined together at some time.

• The rocks further away from ocean ridges are older than those closer to them. This suggests that new rock is being formed, pushing older rock aside and causing the crust to move.

9. The continental drift theory is a theory that suggests that the continents are moving. The theory of plate tectonics provides an explanation for the apparent movement of the continents.

Remember

1. Folding is the bending and crumpling of rock caused by forces beneath the Earth’s surface.

2. Two of the plates that make up the Earth’s surface are pushing together, folding rock upwards.

3. A syncline is a fold that bends downwards while an anticline is a fold that bends upwards.

4. The sideways movement along the fault where two blocks of crust slip horizontally past each other.

CHAPTER 7 THE DYNAMIC EARTH

Layer Description

atmosphere Layer of gases surrounding Earth, to a height of approximately 145 km. Made up of gases such as nitrogen and oxygen.

hydrosphere Water on or at the Earth’s surface, including oceans, lakes, rivers, rain and mist.

crust Solid rock. Varies in thickness from as little as 5 km under the ocean to about 70 km under mountain ranges like the Himalayas.

mantle Partially molten rock. Temperatures mostly between 500°C and 2000°C. About 2900 km thick.

outer core Molten iron and nickel. Temperatures mostly between 4000°C and 6000°C. About 2300 km thick.

inner core Mostly iron. Solid owing to extreme pressure. Temperatures up to 7000°C. About 1200 km thick.

Inside out7.1

What’s on your plate?7.2

Making mountains7.3


5. The difference is best illustrated with the diagram below.

Think

6. Mountains can be formed by normal faults or reverse faults as illustrated in the answer to Remember 5. They can also be formed by a block sinking between others or by a block being pushed up by others.

7. When rocks fold, it is quite possible that they will crack under pressure, forming a fault.

Remember

1. A naturally occurring solid substance with a definite chemical composition.

2. An element found naturally in its uncombined form. Examples (two required) include diamond and gold.

3. Quartz, mica and feldspar.4. Colour, lustre, streak, hardness, crystal shape, crystal

size, density (five required).5. 6.

Think

6. A rock is a mixture of minerals, and can contain many different minerals. A mineral is a compound or an element that occurs naturally.

7. Small crystals indicate that the rock formed by the quick cooling of molten material. Large crystals indicate that the rock formed by the slow cooling of molten material.

8. Try to scratch them with each other. The one without a scratch on it afterwards is harder.

9. Calcite.10. It is a mineral because it occurs naturally, it is solid and

has a definite composition (NaCl).

Remember

1. A mineral containing a metal of value.2. A region of rock in which a mineral is concentrated and

which is large enough to be mined.3. It is used to restore previously mined areas or stored until

the newly mined area is ready to be restored.4. When the mineral ore is deep below the surface or it is

too expensive to remove the overburden.5. A method in which a large hole is made in the ground,

exposing the ore body.

Think

6. Answer could include: Satellite and aerial exploration; the gathering of samples of sediments, water samples and small samples of soil and rock; magnetic techniques used by ground surveyors.

7. Oxygen is found in the Earth’s crust in the form of minerals. It is present in the chemical compounds of which most minerals are made, chemically combined with other elements such as silicon, aluminium and iron.

8. The very deep shafts that need to be made require expensive equipment. Making them safe is expensive. Underground mining requires many more miners than open-cut mining, where large machinery can be used to remove large amounts of mineral ores.

9. Open-cut mining disturbs the environment much more due to the massive clearing of vegetation. It also leads to more erosion as the vegetation that holds the soil together is removed.

Remember

1.

2. Gangue is the name given to the unwanted substances that are mixed with the mineral ore in the rock.

Think

3. (a) good electrical conductivity; ductility(b) resistance to corrosion; malleability(c) hardness, ductility, colour and lustre.

4. Smelting in the blast furnace and conversion in the converter (both part of the reduction process); electrolysis during the purification process.

Create

5. Aluminium extraction is discussed in Lofts et al., Living with Science and Technology Book 3, Jacaranda, 1992.

Zinc refining is discussed in McCullough, K., Science, People and Environments, Jacaranda, 1990.

Other resources can be obtained from the Minerals Education Centre, Victoria; Ph: (03) 9629 1851 Fax: (03) 9629 8603; Email: [email protected]

Remember

1. Coal, oil and natural gas.2. It is harder and contains less moisture.3. The rock, soil and vegetation removed from above the

coal.4. Its low efficiency as a fuel does not justify the cost of

underground mining. Underground mining is also dangerous.

5. Reasons include: the threat of cave-ins and flooding; the poisonous methane gas in coal; the carbon monoxide produced when explosives are used; the dust produced by the coal.

6. Renewable resources are natural ones that can be replaced. Non-renewable resources are those that cannot be replaced as they are used up.

Think

7. It is where the major reserves of brown coal are. It is cheaper to transmit electricity over long distances than it is to transport coal.

(a)

(b)

normal fault

reverse fault

What’s in a rock?7.4

The riches below7.5

Stage Purpose

concentration to remove the gangue (unwanted materials) from the mineral ore

reduction to remove the elements other than the required metal from the mineral ore

purification to remove impurities still remaining in the metal after the reduction process

Extracting the metal 7.6

Energy underground7.7


8. 165 m × 120 = 19 800 m = 19.8 km (based on estimate in text p. 130).

9. It burns more quickly because the surface area of the coal exposed to the oxygen with which it reacts is much greater.

10. Reasons include: Natural forests provide a habitat for many organisms. Removal of natural forests destroys habitats and interferes with food webs, endangering many (if not all) of the organisms in the forests. The trees in natural forests absorb carbon dioxide from the atmosphere and return oxygen to the atmosphere. They play a vital role in keeping the balance of gases in the atmosphere. When natural forests are detroyed they are sometimes replaced with non-native vegetation because natural forest takes too long to regenerate.

11. Fossil fuels are formed from the remains of living things, all of which relied on energy from the sun either directly (plants and other organisms that photosynthesise) or indirectly (animals and other organisms that depend on plants for food).

Remember

1. An Environmental Impact Statement.2. An EIS predicts how the proposed mine will affect the

area’s existing flora and fauna, towns and roads and the local community and environment. It also reports on proposed new towns and roads, outlines alternative plans that might have less impact on the environment, and describes measures to be taken to monitor and control pollution. It also explains rehabilitation proposals for the area.

3. Reconstruction of land so that it can be used again after the completion of mining.

4. Collecting seeds of natural vegetation and replanting them after mining. The land surface is shaped so that erosion is prevented.

5. Sulfur dioxide.6. When these coals are burned, sulfur dioxide is

released. This reacts with moisture in the air to formacid rain.

7. It has a much lower sulfur content than the coal used in North America and Europe.

8. The solid waste products of metal extraction.

Think

9. Factors include: economic benefits, effect on the environment, effect on the living organisms living in the area, effect on the people living in the area, the creation of employment.

10. Some suggested answers:

11. To assist the government, community organisations and the general population in forming an opinion about whether or not the mine should proceed.

12. Arguments include: reduces the need for mining; prolongs the life of natural resources; reduces littering, reduces the amount of rubbish dumped in tips.

Think and create

1. (b) Suggested answer. Headings could vary.

2. Examples for each category include (at least six required):Rocks: sandstone, shale, limestone, basalt, granite, coalMinerals: quartz, mica, feldspar, talc, gypsum, calcite, fluoriteMetals: aluminium, iron, calcium, potassium, sodium, magnesium, zinc, lead, gold

Looking back1.

Benefits Disadvantages

increased employment pollution

increased wealth disruption of and threat to living things

changes the local community; for example, from quiet rural area to industrial region

production of metal in demand

visual scar on surface

Civics and citizenship: Mining and the environment

7.8

Thinking tools: Affinity diagrams and SWOT analysis

7.9

matter

Volcanoes Earth layers

Crust movements

Mineral

extraction

Crust

movements

crater eruption

lava active extinct

dormant

crustatmosphere

mantleinner coreouter core

hydrosphere

earthquakes folding faulting

subduction plate tectonics continental drift

concentration reduction smelting

electrolysis purification

froth flotation

1. 2. 3. 4.

5. V E R B U 6. D E N O

R O E T R

M T 7. Y N C L I N E

A H E C

N 8. I S W L

T R 9. A I L I N G 10.

M 11. B 13. N M12. 13. N G A E A L E E

C L S E 14. I L

T 15. A 16. T

I R 17. U S T R E I

V E T A N18. E Y S E R 19. R O T H G

D

O

G

E

R

A

S

C

ST

O

P

F

L

B

G

O

P A


2. (a) Outer core(b) Mantle(c) Crust(d) Inner core(e) Atmosphere

3. An extinct volcano is one that has not erupted for thousands of years. An active volcano is one that is erupting or may erupt at any time.

4. The Ring of Fire encircles the Pacific Ocean. It exists because of a giant weakness in the Earth’s crust at the boundaries of plates.

5. (a) The plates move due to convection currents in the partially molten mantle.

(b) When two plates slide past each other earthquakes can occur.

(c) According to the plate tectonics theory, the Himalayas are growing because the Indo-Australian Plate is pushing against the Eurasian Plate.

6. Ocean ridges are caused by plates moving apart. Subduction zones are caused by ocean crust and continental crust push against each other.

7. Oceanic crust slides underneath continental crust because it is denser than continental crust.

8. The streak of a mineral is the powdery mark it leaves when it is scraped across a hard surface such as a ceramic tile.

9. Moh’s scale provides an approximate measure of the hardness of a mineral.

10. Try to scratch one mineral with the other. The harder mineral leaves a scratch on the softer mineral.

11. (a) Labels clockwise from top right: continental crust, magma, solid upper mantle, oceanic crust

(b) top diagram — normal fault; bottom diagram — reverse fault

(c) top label — anticline; bottom diagram — syncline.12. Mineral ores near the Earth’s surface can be mined using

the open-cut method. This involves creating a large hole in the surface to expose the rocks containing the mineral ores. The rocks are then broken up with explosives. Mineral ores deeper in the surface require underground mining, which involves digging shafts and tunnels deep into the ground to remove the rocks containing the mineral ore.

13. The flowchart should show the following with text and/or diagrams:• crushing of the ore with a heavy weight• ball mill — balls crashing down on ore in a barrel• froth flotation• furnace in which copper concentrate reacts with air

and carbon• converter in which further chemical reactions take

place to produce almost pure copper• electrolysis• plate of pure copperThe figure on page 167 of the text could be used as a guide.

14.

15. Black coal is harder and contains less water than brown coal.

16. (a) Coal is formed by the compression of rotting plant matter from forests and swamps. Oil and gas are formed by the compression of the remains of sea animals and plants and subsequent chemical reactions.

(b) Coal is solid and can be mined at or near the surface in open-cut or underground mining. Oil and gas are liquid and gas respectively and can be obtained by drilling through the layers of rock under which they are trapped.

17. There are limited reserves of fossil fuels; they will eventually run out. In addition, the use of fossil fuels produces greenhouse gases.

18. (a) The rock directly above the rock in which oil is trapped is not porous.

(b) Natural gas.19. Answers will vary. Issue suitable for group discussion.20. There are numerous examples of occupations that are

involved in the mining industry. They cover a very wide range including: underground miners, engineers, chemists, labourers, accountants, geologists, geophysicists, surveyors, journalists and builders.

Remember

1. The food molecules absorbed by the body are involved in chemical reactions inside the cells. The energy released in these reactions is used by the body, and

the atoms from the molecules are used for growth and repair.

2. We need food to gain the energy we require to survive. (Food is also needed for growth and repair.)

3. Metabolism is the name given to the collective chemical reactions that occur in living organisms.

Mineral ore Metal Uses of the metal

haematite iron making steel for buildings, other construction, appliances, cans, other containers and engine blocks

bauxite aluminium electrical equipment, cars, aircraft, ships, cans, aluminium foil and cooking utensils

chalcopyrite copper electrical wire, pipes for carrying water and natural gas, electrical and lighting fixtures, tubing in air conditioners, fridges and car radiators, plumbing fittings and making alloys

sphalerite zinc galvanised iron and steel, making alloys

galena lead storage batteries (e.g. car batteries), radiation shields, weights (for SCUBA divers), solder, ammunition

pentlandite nickel making alloys (including coins and stainless steel), electroplating, batteries

cassiterite tin tinplate (steel coated with tin), solder and other alloys

gold gold jewellery, coins, dentistry, electronic and computer circuits

CHAPTER 8 THE ENERGY OF LIFE

Energy pirates8.1


4. Basal energy requirement is the amount of energy that is required to keep an organism’s body working while it is in the resting state.

5. Mass is the amount of matter in an object. Weight is a measure of the downward pull of an object. Your mass would not change if you went into space, to the moon or to another planet. Your weight would change.

6. The amount of energy in food is measured in kilojoules (kJ).

Think

7. An energy transformation is when one type of energy is changed into another. An example is the transformation that occurs when the chemical energy in food is changed into heat energy of the body.

8. Metabolism occurs in all living organisms. Plants are living organisms, therefore metabolism must occur in plants.

9. Living energy converters can grow and repair themselves. Non-living energy converters cannot do this.

10. The human body requires fuel to keep it moving as does a motor vehicle.

11. Cellular respiration converts chemical energy in food into a form that the cells can use. This can be described as a type of burning because it produces the same products as burning wood or petrol, and it also releases energy.

12. Various answers expected, all types of vehicles or motors.

Investigate

13. Responses will vary.14. Student research.15. Student research.16. The unit is named in honour of the English physicist,

James Joule 1818–1889.

Remember

1. Aerobic respiration converts the chemical energy in food into a form of energy that your body can use.

2. Enzymes control the rate of reaction.

3. glucose + oxygen carbon dioxide + water + energy

4. C6H12O6 + 6O2 6CO2 + 6H2O + energy5. Aerobic respiration takes place in the mitochondria,

which are small organelles inside cells.6. ATP stands for adenosine triphosphate.7. ATP is found in cells of living things and is required to

provide the energy needed for many chemical reactions in the cells, for cell maintenance, sending messages, making complex molecules from simple ones and other important jobs performed by cells.

8. The energy released from aerobic respiration is used to make ATP.

9. For aerobic respiration to occur, the cells need a supply of nutrients (food eaten) and a supply of oxygen (air breathed).

Think, investigate and discuss

10. Water is also released in sweat through the sweat glands, in urine via the bladder and in saliva through the mouth.

11. Food and water are stored in the cells of the body, but gases are not. Therefore humans need to breathe continuously to keep up the supply of oxygen essential for aerobic respiration.

12. As the rate of exercise increases, the rate of aerobic respiration increases. Visual thinking tools will vary, but flowcharts and relations diagrams would be most suitable.

13. Answers will vary.14. They breathe more rapidly.15. For student research.

Remember

1. During times of prolonged or extreme exercise.2. It converts stored glucose into lactic acid which can

cause cramp and prevent muscles from working.3. Oxygen debt occurs after anaerobic respiration, when

large amounts of oxygen are needed to remove a build-up of lactic acid in muscles.

4. Panting and a rapid heartbeat after exercise help supply the body with the required amounts of oxygen to pay off oxygen debt.

5. Glucose lactic acid + energy6. Anaerobic respiration

7. Glucose ethanol + carbon dioxide + energy8. Aerobic respiration produces the most energy.9. Humans or any other animal name is acceptable for this

answer.10. End products are ethanol (alcohol) and carbon dioxide.

Think

11. (a) Anaerobic respiration does not require oxygen, so the sprinter could run the race without the need to breathe, and still have the energy to complete the race.

(b) Panting increases the intake of oxygen into the body to help pay off the oxygen debt.

(c) Extra oxygen enters the body via the lungs during panting.

12. Lactic acid stops muscles from working. If a tapeworm excretes it directly into its host it will not need to deal with the acid.

13. As an anaerobe, this bacteria would be able to survive and reproduce inside canned foods.

14. Anaerobic respiration will yield 1 kJ of energy from every gram of glucose because glucose is only partly broken down, therefore only a small part of its stored energy is released. Aerobic respiration produces about 16 kJ of energy from the same amount of glucose.

Remember

1. The energy in food originally comes from the sun.2. Photosynthesis takes place in chloroplasts, which are

small compartments inside the cells of plants, algae and some micro-organisms.

3. Water and carbon dioxide react together during photosynthesis.

4. Oxygen and glucose are the two chemicals produced during photosynthesis.

5. Sunlight and the chemical chlorophyll.6. Glucose can be converted into starch, cellulose or

protein and then be stored.7. Water molecules can be split into hydrogen and oxygen

atoms.8. Colours of visible light are red, orange, yellow, green,

blue, indigo and violet. The green wavelengths of visible light are reflected.

Think and discuss

9. By testing for the presence of starch.10. To eliminate variables.

Energise me!8.2

enzymes

enzymes

Life without oxygen?8.3

enzymes

enzymes

Catching energy8.4


11. It could be stored in stems and roots.12. Temperature may affect the rate of photosynthesis.13. Glucose stores chemical energy for the plant.14. Photosynthesis can be said to be the reverse of aerobic

respiration because the reactants of photosynthesis are the products of aerobic respiration and the products of photosynthesis are the reactants of aerobic respiration. Also, photosynthesis is an energy absorbing process, whereas respiration is an energy releasing process.

15. During a 24-hour period a plant will be photosynthesising during the daylight hours. It will respire throughout the whole 24-hour period.

16. Plant leaves tilt toward the sun in order to capture the maximum amount of sunlight; leaves and petals unfurl; seedlings grow towards the light; and fluids move around inside the plant to distribute water, food and nutrients (only two examples required).

17. Plants are important to life on Earth because they produce more oxygen than they need and it is released to the atmosphere. This creates an oxygen-rich atmosphere which can support animal life.

Remember

1. Less than 1% of the incoming solar radiation is used in photosynthesis.

2. Energy is lost to the environment (in the form of wastes, heat, kinetic energy and sound energy) at every link in the food chain, therefore food chains can only be a certain length before there is not enough energy to pass on.

3. They are similar in that they are both methods of energy conversion. They differ in that they take place in different cellular organelles, photosynthesis produces glucose for storage, respiration uses the stored glucose to produce energy, photosynthesis uses carbon dioxide, while respiration produces it, and photosynthesis cannot be performed by animals.

4. Plants are called producers because they are able to ‘produce’ the energy rich food molecules, glucose, from the non-food molecules water and carbon dioxide in the process called photosynthesis.

5. The chemical energy in food is used to keep the body warm, and allow its parts to move. Some of this energy is stored when new tissues are made inside the body.

6. Energy is transferred from the body in the following ways:• chemical energy in undigested food passes out of the

body in faeces• the body heats the surrounding air• movement• speech

7. A first-order consumer is one that eats producers. A second-order consumer is one that eats a first-order consumer. A third-order consumer is one that eats a second-order consumer and so on. Each level of consumer takes in chemical energy from the previous order consumer and at each stage energy is lost to the environment.

8. All of the energy that is released by living organisms is converted to thermal energy which heats the environment. It then radiates into space.

9. An ecological footprint is a measure of how much biologically productive land our activities require. If people understand the idea of their personal or community’s ecological footprint it can make them more aware of the need to take personal and collective action to support a sustainable lifestyle.

Think and discuss

10. (a) The source of energy is the sun. There is a finite amount of energy. Some light energy is captured by plants and converted into chemical energy. This chemical energy flows through ecosystems through food chains and food webs. Your ecological footprint can indicate how much of an impact your lifestyles has on the planet’s resources — how much energy you use. As there is a finite energy supply, some ecological footprints will suggest some individuals, communities or countries use more than their fair share. Not all ecological footprints are globally sustainable.

(b) Students should describe lifestyles that do not have a detrimental effect on our planet’s resources. They should not be too ‘greedy’ in their use of our planet’s resources.

(c) Eating more plants (vegetables, grains and fruit rather than lots of higher-order consumers); eating less (obesity issue); not wasting energy (e.g. turn out light, use less electricity, walk instead of drive etc.).

(d) Responses will vary, but should include some of the ideas above.

(e)–(h) Responses will vary.

Remember

1. The wastes that animals produce are carbon dioxide, methane, perspiration and urine.

2. When a dead organism is burnt the two main chemicals that are released to the atmosphere are carbon dioxide and water.

3. The body of an organism that is buried is broken down by decomposer organisms.

4. The decomposers break a body down into simpler chemicals, some of which they consume for food. Examples of decomposers are fungi, bacteria and protozoans.

5. Photosynthesis.6. Transpiration is necessary so that water can travel into

the plant, providing water for the photosynthesis reaction. The water also carries dissolved nutrients necessary for other plant cellular functions. Water also keeps the plant cells turgid and thus gives strength to the plant structure.

7. The only organisms that can absorb and use nitrogen from the air are the nitrogen-fixing bacteria.

8. Animals and plants need nitrogen so that they can make protein molecules which are essential for growth.

Think and discuss

9. Nitrogen-fixing bacteria absorb nitrogen molecules from the air and when they die the nitrogen is released in a form that can be absorbed by plants. Nitrifying bacteria absorb ammonia, which is produced from the breakdown of decaying animals and animal waste, and turn it first into nitrites and then into nitrates. Denitrifying bacteria are able to turn nitrates back into nitrites, ammonia and nitrogen gas.

10. Photosynthesis plays an important role in the carbon cycle. It removes carbon dioxide molecules from the air and rearranges the atoms in these molecules so that the carbon atoms become part of the glucose molecule. These glucose molecules are the basic building blocks of all food, so eventually carbon atoms that were in the air become carbon atoms in food. Once food has been consumed these carbon atoms become carbon atoms in the bodies of living organisms.

Flowing on . . .8.5

Recycle me8.6


Using data

1.

2. (a) The nutrients are present in the urine and milk from the cows.

(b) Site C is unfenced and animal waste can still get into the water.

(c) They could encourage the growth of algae and the ‘green slime’ that was found in the dam.

3. Site B. It has a pH closest to fresh water and significantly lower nutrient levels than the other sites. Water temperature, dissolved oxygen and turbidity are not significantly different from those recorded in site C. The logs added to site B provide breeding places. Apart from other apparently unsuitable conditions, Site A is probably far too warm.

4. The water leaving the farm contains fewer nutrients that could damage natural habitats, has a closer to neutral pH and a lower temperature.

Think and discuss

5. Water in freshwater streams that flow to the sea is replaced by rain and melting snow.

6. They were competing with the native fish that would normally inhabit the wetlands. The European carp is an introduced species that interferes with the natural food web.

7. Planting native trees and dumping old logs provide natural habitats for native animals and plants in the wetlands. They provide shelter, breeding sites and a source of food for organisms in the food web.

8. Student opinion.

Remember1. Decomposers break down dead plant and animal

material and return the nutrients to the soil.2. Agriculture is the controlled growth of other

organisms by humans in order to maximise food production.

3. In natural ecosystems organisms do not consciously control the growth, nor conditions of growth, of other organisms. In an artificial ecosystem humans control the growth of other living organisms.

4. Herbicides, fertilisers and insecticides are used to ensure that the soil can support the crops or animal stock that are grown on it. Herbicides kill other plants that compete with the crop plants, fertilisers are added to the soil to replace nutrients that are removed by harvesting, and insecticides are used to kill insects that consume the crops.

Think and discuss5. Agriculture interferes with a natural food web because

it restricts the number of producers and consumers. A natural food web is a complex set of feeding relationships between many organisms. Herbicides and insecticides kill organisms that would compete for the food supply in the artificial ecosystem.

6. If a monoculture is infected with a disease, is invaded by an insect pest, or experiences unfavourable weather conditions, the whole crop may be destroyed.

7. Other problems that need to be solved by agricultural scientists and farmers include salinity due to deforestation and soil erosion due to land clearing.

Science at work: Watching over water

8.7

Dissolved oxygen (%)

Nitrate level(mg/L)

Soluble phosphatelevel (mg/L)

pH Conductivity(EC)

Turbidity(NTU)

KEY: Site A (settling dam)Site B (fenced wetland)Site C (unfenced wetland)

site Anot

tested

55

70

0.189

1.144

0.484

0.106

0.429

0.191

7.8

9.7

8.1

860

15401610

55

180

41

Science at work: Artificial ecosystems

8.8


Investigate 10. Crop rotation is the process of growing different types of

crops in different sections of a farm. Since different plants have different nutrient requirements, annual rotation of crops around different parts of the farm reduces depletion of particular nutrients in the soil.

11. An agronomist studies the science of land cultivation, soil management and crop production.

12. Hydroponics is the growth of plants without the use of soil. The plants grow in gravel which is submerged in an aqueous solution containing all the essential nutrients for growth.

Remember1. Earth is considered to be Biosphere 1.2. Biosphere 2 contains; a desert, a saltmarsh, tropical

savanna, ocean and a rainforest.3. To develop a closed ecological system for research and

education, so scientists could gather information to assist in the development of strategies to solve some of Earth’s environmental problems and the hurdles of developing colonies in space.

4. Both are closed systems.5. People would breathe out carbon dioxide faster than the

plants could take it up, and breathe in oxygen faster than the plants could produce it.

6. The oxygen concentration had fallen, carbon dioxide concentrations were fluctuating and nitrous oxide levels had increased. Fresh air was needed to rescue the inhabitants.

7. The microbes consumed oxygen and added carbon dioxide to the atmosphere.

8. The air would have become unbreathable long before it did.

9. Greater cloud cover reduced the amount of light available for photosynthesis, consequently plant growth slowed and food production dropped.

10. Water was cycled through condensation, artificial rain, evapotranspiration, and soil sub-drainage.

11. Predicting Earth’s future in terms of atmospheric changes such as increases in carbon dioxide levels.

Think and discuss

12. (a) Extra moisture suited the survival of shrubs and grasses which would otherwise not survive in a dry desert area.

(b) The number of desert plants may be increased by altering the climate to make it more suitable for their survival. The amount of moisture available in the desert area would need to be controlled.

13. (a) The increased size of the grass may lead to increase in photosynthesis which would result in an increase in the uptake of carbon dioxide and an increase in the production of oxygen.

(b) The increased size of the grass may choke out more desirable plants such as food crops for the Biospherians. This plant may also provide habitat for undesirable insect pests.

All answers will vary.

Looking back1. Word puzzle solution

Highlighted word is respiration.2. (a) A = producer

B = first-order consumerC = second-order consumerD = decomposer

(b) 1 = photosynthesis 2 = consuming 3 = consuming4 = respiration 5 = decomposition 6 = respiration

3. (a) Matter recycling is the continuous movement of atoms through living organisms and the non-living environment. This recycling occurs through processes including photosynthesis, respiration, decomposition, and combustion. Because of this recycling most of the atoms that were on Earth when it formed are still here. Energy is not recycled in the same way. Energy flows through living organisms and through the environment. It is not created nor destroyed but is all ultimately converted to thermal energy which heats the environment. It then radiates out into space. The energy that radiates out into space is balanced by the radiation coming in from the sun.

(b) Transpiration is the flow of water from the soil, through the roots and the body of the plant, through to the leaves. Transpiration is driven by heat from the sun. It causes water to evaporate through the stomata of the leaves where it enters the atmosphere as water vapour. Photosynthesis is a chemical reaction between carbon dioxide and water which produces glucose and oxygen. The reaction occurs in the chloroplasts in the presence of light and chlorophyll. Transpiration provides the water necessary for the photosynthesis reaction to occur.

(c) After the food we eat is digested, glucose molecules are absorbed into the cells. The air that we breathe contains oxygen. This oxygen is also absorbed into our cells. In the cells’ mitochondria these two molecules, glucose and oxygen, react in the energy releasing reaction, aerobic respiration.

4. The activity reinforces the Law of Conservation of Energy. Students answers may vary as a direct conversion of figures is not given in the text.

5. Any shortage of the inputs of photosynthesis would limit this reaction, e.g. light, carbon dioxide, water and also presence of chlorophyll. This activity reinforces limitations providing an example. It may be useful to encourage students to draw on personal experience to suggest other situations where limiting factors are relevant.

Science at work: Biosphere 28.9

Thinking tools: SWOT analyses and fishbone diagrams

8.11

M I T O C H O N D R I A

B A C T E R I A

D E C O M P O S E R S

C H L O R O P H Y L L

C H E M I C A L

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C A R B O N

P H O T O S Y N T H E S I S

N I T R O G E N

F O O D

O X Y G E N


Remember

1. Curiosity, ability to observe accurately, ability to hypothesise, ability to explain.

2. Observing, experimenting, hypothesising.3. Galileo wrote about the need for controlled experiments.

Many of the scientists who followed him used the scientific methods that he wrote about, and scientists continue to use these methods.

Think

4. The way that scientists worked changed greatly during the seventeenth century, largely as a result of Galileo’s work and writing.

5. Technologies include the telephone, fax, computers, motor vehicles and other forms of rapid long-distance transport, electricity generation and distribution, and computers.

6. Examples include the telescope, the microscope and the printing press, which made the distribution of information easier.

1. (a) Cell D2 contains nothing.(b) Cell C5 contains a part of a label for the column

heading.(c) F9 = E9/C9

F10 = E10/C102. (b) Methylated spirits: 3.01 s, turpentine: 53.25 s, water:

55.74 s, oil from E. rossi: 193.58 s, oil from E. nortonii: 104.69 s.

3. (a) Average speeds are, respectively: 11.7 m/s, 8.3 m/s, 5.0 m/s, 5.0 m/s, 3.3 m/s. There are only five time intervals. Either the Time = 0 row or the Time = 15 row should be left blank.

(b) 6.7 m/s. Note that the average speed over the total time is the total distance divided by the total time, not the average of the average speeds. In this instance it is coincidental that the result is the same. To illustrate this to students, calculate the average speed of a journey in which a car travels 240 km at 80 km/h and a further 240 km at 60 km/h. The average of the average speeds if 70 km/h. However, when you calculate the average speed in the correct way, the result is different. The total distance is 480 km. The total time is 3 hours (at 80 km/h) plus 4 hours (at 60 km/h). The average speed is, therefore, total distance divided by total time, which is 480 km divided by 7 h, or 68.6 km/h. The average is closer to 60 km/h than 80 km/h because the car travelled at 60 km/h for a longer time interval than it travelled at 80 km/h.

Think

1. (a) magnesium + hydrochloric acid magnesium chloride + hydrogen

(b) The reaction is exothermic. Energy is released to the surroundings during the reaction.

2. (c) The reaction is endothermic. Energy is absorbed from the surroundings during the reaction.

(d) Answers will vary, but reasons include convection currents in the water, uneven hearing of the container and uneven dissolving of ammonium nitrate.

Expanding your database

2. (b) Effect of hot nail.3. It would be useful to know if the plastic melts easily.

Remember

1. Objectivity and honesty.2. Scientific arguments are usually based on evidence,

whereas economic and legal arguments sometimes ‘bend the truth’.

Think

4. The most objective situation is (d), because it is the real situation. Situations (a) and (c) are the least objective as both can be influenced by viewpoints.

Remember

1. The world’s first electric cell.2. X-rays.3. Penicillin.

Think

4–6. Answers will vary.

SCIENCE AT WORK

S.1 What is a scientist?

S.8 Information and communication technology: Using spreadsheets

S.9 Information and communication technology: Using data loggers

S.10 Information and communication technology: Using databases

Science at work: Objective science

S.11

Science at work: Accidents and observations

S.12

Support for ‘Experiments’ and ‘Try this’...

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