preliminary senior science · 4.7 technologies to purify and treat water 31 4.8 a technology to...

Marilyn SchellMargaret Hogan

PRELIMINARY SENIOR SCIENCE

© Science Press 2007First published 2007 Reprinted 2011

Science PressPrivate Bag 7023 Marrickville NSW 1475 AustraliaTel: (02) 9516 1122 Fax: (02) 9550 [email protected]

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of Science Press. ABN 98 000 073

Contents

Introduction vVerbs to Watch vi

Dot Points

Water for Living viiPlants ixHumans at Work xiLocal Environment xiii

Questions

Water for Living 1Plants 43Humans at Work 81Local Environment 123

Answers

Water for Living 175Plants 189Humans at Work 201Local Environment 217

Dot Point Preliminary Senior Science iii Contents

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Notes

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Contents iv Dot Point Preliminary Senior Science

Science Press

Introduction

What the book includes

syllabus for the following topics in the Year 11 Senior Science course:

Also included are typical experimental results for students to analyse if the third column of the syllabus indicates

Format of the book

The book has been formatted in the following way:

1. Main topic statement (column 1 of syllabus)

1.1etc Syllabus requirement from columns 2 and 3.

1.1.1

1.1.2

worth in an examination. As a rough rule, every two lines of answer might be worth one mark. Note that in

science involved is worth only one mark.

How to use the book

You may have done work in addition to this with your teacher as extension work. Obviously this is not covered, but you may need to know this additional work for your school exams.

spend more time revising later, and allow you to spend your study time more productively.

Dot Point Preliminary Senior Science v Introduction

Science Press

account, account for State reasons for, report on, give an account of, narrate a series of events or transactions.

analyseIdentify components and the relationships among them, draw out and relate implications.

applyUse, utilise, employ in a particular situation.

appreciate Make a judgement about the value of something.

assess

results or size.

calculate

clarifyMake clear or plain.

classifyArrange into classes, groups or categories.

compare Show how things are similar or different.

constructMake, build, put together items or arguments.

contrastShow how things are different or opposite.

critically (analyse/evaluate) Add a degree or level of accuracy, depth, knowledge

deduceDraw conclusions.

demonstrateShow by example.

describeProvide characteristics and features.

discussIdentify issues and provide points for and against.

distinguishRecognise or note/indicate as being distinct or different from, note difference between things.

evaluateMake a judgement based on criteria.

examine

explainRelate cause and effect, make the relationship between things evident, provide why and/or how.

extractChoose relevant and/or appropriate details.

extrapolateInfer from what is known.

identifyRecognise and name.

interpret Draw meaning from.

investigate

justifySupport an argument or conclusion.

outlineSketch in general terms; indicate the main features.

predict Suggest what may happen based on available information.

propose Put forward (a point of view, idea, argument, suggestion etc) for consideration or action.

recall Present remembered ideas, facts or experiences.

recommend Provide reasons in favour.

recount Retell a series of events.

summariseExpress concisely the relevant details.

synthesisePut together various elements to make a whole.

Verbs to Watch

Verbs to Watch vi Dot Point Preliminary Senior Science

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Dot Point Page

1. Water for living 21.1 Water as a solvent 21.2 Water in food 41.3 Water in living things 51.4 Water in blood and cells 61.5 Water uptake by plants 71.6 Investigating water loss in plants 81.7 Plant adaptations to reduce water loss 81.8 Investigating water loss in animals 101.9 Animal adaptations to reduce water

loss 112. Water for health and life 122.1 The hydrological cycle 122.2 Water in the local area 152.3 Australian ecosystems and rainfall 172.4 Water pollution and salinity in Australia 182.5 Human impacts on water 192.6 Groundwater solutions 20

issues 203. Water maintaining Australian

environments 213.1 Fertilisers, herbicides and pesticides 213.2 Carrying fertilisers and pesticides into

water 213.3 Investigating effects of fertiliser on

plant growth 223.4 Impact of pollution on water systems 24

3.5 Impact of metals, phosphates and nitrates on water 25

Dot Point Page

3.6 Bioassays for water purity 263.7 Impact of sediment, leaching and

bioaccumulation 274. Chemicals impact on water 284.1 Causes and impacts of algal blooms 284.2 Conditions for algal blooms 284.3 Impacts of algal blooms in rivers 284.4 Reducing chemicals in agriculture 294.5 Reducing water pollution by

households 294.6 Investigating household use of water 294.7 Technologies to purify and treat water 314.8 A technology to reduce water pollution 325. Reducing water pollution 335.1 Indicator organisms in water 33

5.3 The local catchment area 345.4 Investigating the local catchment area 345.5 Investigating the purity of water in the

catchment area 355.6 Sources of water contamination in

catchments 37

5.9 Use and treatment of local water 385.10 Disasters involving water pollution 40

Answers to Water for Living 175

Water for Living

Dot Point Preliminary Senior Science vii Water for Living

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Water for Living viii Dot Point Preliminary Senior Science

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Plants

Dot Point Preliminary Senior Science ix Plants

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Dot Point Page

1. Functioning of plants 441.1 How plants function 441.2 Plants as autotrophic organisms 45

2. Germination of seeds 472.1 Investigating germination of seeds 472.2 Effects of temperature, moisture and

oxygen concentrations 50

seeds 542.4 Effects of cold storage, vacuum

packing and dehydration 562.5 Effects of heat beds, lime pelleting

and misting on seeds 56

3. Growth of seedlings 58

3.2 Researching variables affecting plant growth 59

3.3 A factor affecting seedling growth 643.4 Effect of variables on seedling growth 653.5 Effects of light intensity and wavelength

on growth 654. Water requirements of plants 694.1 Adaptations of xerophytes, mangroves

and epiphytes 69

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watering systems 714.3 Technological developments in

supplying water 725. Asexual reproduction 735.1 Vegetative propagation and

regeneration 735.2 Cloning plants 755.3 Genetic advantages and disadvantages

of cloning 755.4 Processes and uses of tissue culture 755.5 The Wollemi pine 776. Maintaining diversity 79

6.2 Endangering Australian plants 796.3 Protecting a rare Australian species 796.4 Conservation of a rare Australian 79

species6.5 Reasons for conserving Australian 80

plants6.6 Methods used to maintain 80

biodiversity6.7 Seed and gamete banks 80

Answers to Plants 189

Plants x Dot Point Preliminary Senior Science

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Humans at Work

Dot Point Preliminary Senior Science xi Humans at Work

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1. Risks to the human body 821.1 The Occupational Health and Safety

Act 821.2 Hazards in the workplace 831.3 Injury from hazards in the workplace 831.4 Sources of risk 841.5 Health and safety audit 851.6 Impact of understanding on safety 871.7 Understanding the body and safety

awareness 872. Safety and the respiratory system 882.1 The respiratory system 882.2 Mucus in the respiratory system 902.3 The respiratory system and the

environment 902.4 Inhaled solids and the respiratory

system 912.5 Safety in the school and workplace 923. Safety and the eye 943.1 Structure and function of the eye 943.2 Function of tears 953.3 Effect of injuries on vision 953.4 Development of protective eyewear 973.5 Composition of protective eyewear 983.6 Eye protection at work 1003.7 First aid and the eye 1013.8 Light and eye safety 1014. Safety and the ear 1034.1 Structure and function of the ear 103

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4.2 Investigating learning in a noisy environment 105

4.3 Causes of industrial deafness 1104.4 Sensory fatigue and hearing loss 1104.5 Uses of earmuffs and earplugs 1115. Safety and the brain 1125.1 Thickness and strength of skull bones 1125.2 The skull protects the brain 1135.3 Concussion 1135.4 Bruising brain tissue 1135.5 Uses of hard hats and safety helmets 1135.6 Design and uses of hard hats and

safety helmets 1135.7 Energy transfers and transformations 1145.8 Laws/regulations on the use of hard

hats and safety helmets 1156. Safety and muscles, joints and bones 1176.1 Investigating the relationship between

bones, tendons, ligaments and cartilage 1176.2 The axial skeleton, synovial joints

and muscles 1176.3 Ligaments, tendons and cartilage in

joint movement 1206.4 Repetitive sprain injury 1206.5 Repetitive actions and injury 1216.6 Safe lifting practices 1226.7 Strengthening exercises for sport

and work 122

Answers to Humans at Work 201

Humans at Work xii Dot Point Preliminary Senior Science

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Local Environment

Dot Point Preliminary Senior Science xiii Local Environment

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Dot Point Page

1. Biotic and abiotic factors 1241.1 Difference between biotic and abiotic

factors 124

terrestrial environments 1261.3 Distribution and abundance of species 127

populations 130

resources 1382. Energy and matter in ecosystems 1402.1 Investigating food chains and webs 1402.2 Cycling of materials in ecosystems 1442.3 Water, carbon, oxygen and nitrogen

cycles 1452.4 Uses of energy in organisms 1472.5 Flow of energy through a natural

ecosystem 1473. Aquatic and terrestrial ecosystems 1493.1 Population sizes in ecosystems 1493.2 Factors affecting predator and prey

populations 1513.3 Decomposers in the local ecosystem 1543.4 Trophic interactions between

organisms in the local ecosystem 154

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3.5 Risks in investigating a local environment 156

ecosystem 157

in a local ecosystem 1603.9 Adaptations of organisms in the local

ecosystem 1644. Impact of humans on the

environment 1664.1 Uses of the local environment in

the past 166

about the local environment 1674.3 Human impacts on the local

environment 1684.4 Importance of features of the local

environment for groups 1694.5 Views of different groups on the

human impact on the local environment 1704.6 Criteria for local government

regulations 171

Answers to Local Environment 217

Local Environment xiv Dot Point Preliminary Senior Science

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Dot Point Preliminary Senior Science 1 Water for Living

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Water for Living

Water for Living 2 Dot Point Preliminary Senior Science

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1. Water is essential for the health of humans and other living things.

the solute and solvent in each case.

1.1.1 Distinguish between the terms solute, solvent and solution.

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1.1.2 Some students decided to test the solubility of a number of substances. For each of the following mixtures, identify which substance is the solute and which is the solvent.

Mixture Solute Solvent

Salt and water

Paint and turps

Grease and alcohol

Copper sulfate and water

1.1.3

(a) Identify three substances you tested that dissolved in water.

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(b) Identify three substances you tested that were insoluble.

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(c) Outline one safety precaution you took for this experiment and explain why this is necessary.

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(d) Comment on the reliability of your experimental results.

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(e) Suggest a possible improvement in the method you used for your investigation.

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1.1.4 Some students decided to compare the solubilities of sodium chloride and sodium carbonate. They wrote up their method as:

Pour some water into two beakers.

Add sodium chloride to one beaker.

Add sodium carbonate to the other beaker.

See if they are soluble.

how the students could improve their method.

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1.1.5 The following diagrams show a solution before heating and after heating. Deduce which substance is the solvent and justify your deduction.

After heatingBefore heating

Particles of substance B

Particles of substance A

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amount of water present in a variety of fruits, vegetables and meat.

1.2.1variety of fruits, vegetables and meat.

(a) Describe the method you used for this investigation.

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(b) Describe how you could calculate the percentage of moisture present in each food.

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1.2.2in a variety of fruits, vegetables and meat. The method they used was:

Collect a variety of samples of meat, fruit and vegetables.

Weigh about 10 grams of each sample.

Place each sample on a Petri dish.

Place the dishes of food into an incubator.

Observe the samples each day for one week.

Weigh the samples.

Discuss one problem with this method and describe how you could improve it.

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1.2.3 A group of students decides to compare the water content of green beans and potatoes.

State an hypothesis for this experiment.

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1.2.4and chicken. The hypothesis tested is that chicken contains more water than the same mass of beef. After testing, the following results are found:

Food Moisture content (%)

Chicken – sample 1 76

– sample 2 73

– sample 3 75

Beef – sample 1 73

– sample 2 74

– sample 3 77

(a) Draw a conclusion based on these results.

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(b) Suggest reasons to account for the variability of measured water content of the samples of chicken.

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1.3 Identify the relative amount of water in a variety of living things.

1.3.1 Fresh samples of a number of plant products were tested for moisture content. The results obtained were:

Type of plant Moisture content Percentage moisture content (%)

Peas 35 g water in 50 g peas

Tomatoes 9.5 g water in 10 g tomatoes

Potatoes 77 g water in 100 g potatoes

Apples 63 g in 75 g apples

(a) Complete the table by converting the water content of each plant tested to a percentage.

(b) Compare the relative amounts of water in these substances.

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1.3.2 Water is often referred to as a universal solvent. Discuss this statement.

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1.4 Describe the importance of water as a solvent in the:

1.4.1 Water makes up more than two thirds of the human body and is essential for the proper functioning of the body. Identify some functions of water in the body.

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1.4.2 Describe the importance of water as a solvent in the bloodstream.

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(a) Water is present in cells of living things. Use diagrams to show the structure of a typical plant and animal cell.

(b) Explain what is meant by a turgid cell and why the turgidity of cells is important in plants.

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(c) Describe the effect of hot, dry weather on plants.

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1.4.4 Identify functions of water in the cytoplasm of cells.

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1.4.5 The average person needs to drink about 2 litres of water daily to replace water lost from the body. Identify how we get this water.

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1.5 Discuss ways in which plants optimise water uptake.

1.5.1(a) Describe how plants obtain water.

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1.5.2 Plant cells depend on water to maintain their shape and allow for transport of substances. Discuss ways in which plants optimise water uptake.

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1.5.3of water through plants.

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water loss.

1.6.1 Describe how you investigated adaptations of plants that assist in reducing water loss.

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1.6.2 A group of students decided to see if removing the leaves from a branch of a plant would reduce the loss of water from the plant. They decided to use celery for their experiment.

They chose two identical sticks of celery and removed the leaves from one. Both sticks of celery were placed in identical containers of water. A plastic bag was placed over each stick.

The next day the students observed the celery and noticed that water had collected inside the plastic bags.

(a) Which bag would you predict to have more water inside.

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(b) Justify your prediction.

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1.6.3 Identify adaptations you observed that could help plants reduce water loss.

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1.7 Discuss ways, using examples, that plants reduce water loss such as:

1.7.1

(a) Identify the part of the plant that controls the loss of water from a plant.

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(b) The following diagram shows the structure of a stomate on the underside of a leaf. Describe how it controls the loss of water from plants.

Stomate

Pore (opening)

Guard cells

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(c) Explain why the guard cells of stomates cannot be closed all the time.

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1.7.2 Plants which live in dry conditions have adaptations in their structure, their physiology (how they work) and their behaviour that allow them to conserve water. Explain how each of the following adaptations helps the plant reduce its water loss:

(a) a thick outer coating (cuticle) on leaves

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(c) dropping leaves in times of drought

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1.7.3 Identify the method used to reduce water loss by the plants in each of the following photographs.

(a) (b)

(c) (d)

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1.8 Gather, process and analyse information to identify the different ways in which a range of terrestrial animals reduce water loss.

1.8.1 Identify three ways in which terrestrial animals reduce water loss.

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1.9 Discuss ways, using examples, that animals reduce water loss such as:

1.9.1(a) Distinguish between urea, uric acid and urine.

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(b) The excretion of urine involves loss of water from the body. For animals living in hot, dry climates this water loss may lead to dehydration. Identify two ways in which animals living in such environments reduce water loss in the excretion of wastes and give an example of each.

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1.9.2 Nocturnal behaviour is one way for animals to help conserve water in a dry environment.

(a) Identify the meaning of the term nocturnal.

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(b) Explain how nocturnal behaviour helps animals conserve water in a dry environment.

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1.9.3 Describe how reduced activity and lying in the shade during the hot part of the day can help animals survive in hot, dry climates.

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1.9.4 Describe how living in burrows during the hot part of the day can help animals survive in hot, dry climates.

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2. Water is an important factor in the maintenance of Australian environments.

2.1 Outline types of surface and ground waters in the hydrological cycle such as:

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2.1.1 The following diagram provides a model for the hydrological cycle.

Transpiration

Sea

CondensationPrecipitation

Streams Evaporation

InfiltrationUnderground water flow

PrPrececipipititatatioiooonn

Evaporation

(a) Explain what is meant by the hydrological cycle.

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(b) Identify and describe two processes that occur during the hydrological cycle.

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chemical processes.

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2.1.2 A teacher carried out a survey of the ideas about the water cycle held by 100 Year 11 Science students and found that some of them expressed the incorrect ideas listed below. Replace each

(a) The water cycle involves mainly freezing and melting of water.

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(b) Water only gets evaporated from the oceans and the lakes in the water cycle.

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(c) Rain falls out of the sky when the clouds evaporate.

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(d) Clouds are made of water vapour.

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(e) Humid air is oppressive and heavy. It is more dense than dry air.

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2.1.3

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(b) Identify the state in which most water occurs on Earth.

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2.1.4

(a) Describe the relationship between ground water and the water table.

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(b) Describe the use of ground water in Australia.

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2.1.5

Distribution of the world’s water

Oceans 97%

All water

Easily accessible

surface fresh water

Fresh water

Fresh water 3%

Icecaps and glaciers 79%

Easilyaccessiblesurfacefresh water 1%

Lakes 52%

Soil moisture 38%

Water within livingorganisms 1%

Atmospheric water vapour 8%Rivers 1%

Ground water20%

(a) Identify the following percentages:

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(b) State whether each of the following statements is true or false:

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(iv) There is more water underground than in all the rivers and lakes of the world combined.

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2.2 Process information from secondary sources to map the location and type of surface and ground water in the local area.

2.2.1 The following diagram shows the Great Artesian Basin which is the largest and deepest known basin in the world. It occupies an area of 1 800 000 km2 and has been estimated to contain between 9 and 65 cubic kilometres of ground water. Most of the water enters along

of a few metres per year.

Australia

N

GreatArtesian

Basin

1000 km0

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(b) Account for the importance of the Great Artesian Basin in Australia.

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2.2.2 Identify your local area and describe the surface and ground water in your local area. Include a map in your answer.

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2.2.3your local area.

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2.3 Analyse information from secondary sources to outline the relationships between rainfall and types of Australian ecosystems

2.3.1 The maps below show the rainfall and some types of ecosystems that occur in Australia.

Analyse the information in these maps and use this to outline the relationship between rainfall and types of ecosystems in Australia.

1500 12501000

750

500

250

250

200

250

500750

10001500

Western Australia

Northern Territory

South Australia

Queensland

Victoria

Tasmania

1000

1500

3500

100

200

1250

750500

250

1000

200

500750

1000

25003500

2500

1500

Rainfall (mm)

New South Wales

Rainforest

Forest

Woodland and shrubland

Grassland

Desert

Ecosystems

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2.4 Discuss the effects of water pollution and ground salinity on the continued supply of fresh water to living things and provide examples of these occurring in Australian environments.

2.4.1

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2.4.2 Complete the following table to show sources of fresh water pollution and their effects on the environment.

Pollutant Source Effects

Sediment

Nutrients – ammonia, nitrates and phosphates

Faecal bacteria

Heavy metals, e.g. lead, mercury, cadmium and other chemicals

Pesticides, herbicides, fungicides

2.4.3

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(b) Salt occurs naturally in the Australian landscape. Salinity of rivers and soil can develop naturally, however when ecosystems become disturbed by humans the movement of salt into rivers and soil may accelerate. Identify some actions of humans which have led to an increase in salinity of rivers and soil in Australia.

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(c) Identify some effects of salinity on buildings.

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(d) Identify one area in Australia where salinity is a problem.

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2.5 Process, analyse and present information from secondary sources to assess human impact on one aquatic ecosystem or water source in Australia and identify some consequences of this impact and one possible rehabilitation technique.

2.5.1

by salinity.

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(b) Account for the increase in salt content, explain the impact of this on society, and suggest

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2.6 Identify possible solutions to environmental problems associated with the use of ground water.

2.6.1 Salinity problems along Australian rivers have been largely caused by rises in the water table. A number of solutions have been suggested to deal with such ground water problems in Australia. Discuss three of these.

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increasing problems with water supplies across NSW.

2.7.1relation to increasing problems with water supplies across NSW. Outline a problem addressed by one of these bodies and a policy introduced to deal with this problem.

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3. A wide range of chemicals used in human activity may impact on water systems.

in the Australian context.

3.1.1

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3.1.2 Name a fertiliser and explain why fertilisers are used in Australia.

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3.1.3 Identify examples of chemicals used as a herbicide and as a pesticide and discuss problems associated with their use in Australia.

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3.2 Identify the conditions under which fertiliser and pesticides may be carried into water systems.

3.2.1 Identify the conditions under which fertiliser and pesticides may be carried into water systems.

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the effect of various concentrations of fertiliser on plant growth.

3.3.1(a) State the hypothesis you tested.

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(b) Describe the method you used to investigate the effect of various concentrations of fertiliser on plant growth.

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(c) Identify the dependent and independent variables in this experiment.

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(d) Identify variables that needed to be controlled to make this a valid experiment.

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(e) Tabulate the results you obtained from your investigation.

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(f) Comment on the reliability of your experimental results.

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3.3.2concentrations of fertiliser on the growth of 5 groups of identical seedlings.

Group A B C D E

Concentration of fertiliser (%) 0 0.1 0.5 1.0 1.5

Average growth of seedlings (mm/week) 5 mm 7 mm 8 mm 8 mm 8 mm

(a) Graph these results on the grid below.

(b) Draw a conclusion based on these results.

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(c) Explain the purpose of group A plants.

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(d) The instructions for this particular fertiliser were to mix 10 mL fertiliser with 2 litres of water and apply to the plants. Comment on these results in light of these instructions.

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(e) Some farmers add fertiliser at greater concentrations than recommended by the manufacturer.

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3.4 Assess the impact on water systems of the release of substances produced or used by households, such as:

3.4.1 Identify substances produced or released by households that pollute our water systems.

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3.4.2its release on water systems.

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3.5 Identify the use of and impact on water systems of substances such as:

3.5.1(a) Identify what is meant by heavy metals.

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(b) Explain why heavy metals are considered a problem in the environment.

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(c) Complete the following table to show the sources of the heavy metals lead and mercury in water systems and their possible effects on the body.

Heavy metal Source Effects

Lead

Mercury

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3.5.2 The release of phosphates and nitrates into waterways can result in eutrophication.

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(b) Identify the conditions under which eutrophication is likely to occur.

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3.6 Process information from secondary sources on methods of bioassay for water purity.

3.6.1

(a) Describe what is meant by a bioassay.

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(b) Identify uses of bioassays.

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(c) Describe the use of bioassays to test water samples.

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3.6.2During 1998, water contamination hit the headlines when it was found that two protozoans, cryptosporidian and giardia were present in some samples present.

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(b) Oultine how such organisms are usually removed from the water supply.

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3.7 Identify the impact on aquatic ecosystems of factors such as:

3.7.1

Factor Impact

Accumulated sediment

Leaching from tips

Bioaccumulation


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4. Strategies to reduce water pollution can be a result of personal initiative or government legislation.

4.1 Gather information from secondary sources to identify causes and impacts of algal blooms in waterways in NSW.

4.1.1 Describe how you gathered information about algal blooms in NSW waterways.

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4.1.2 Comment on the reliability of the information you gathered about algal blooms.

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4.2 Identify conditions under which algal blooms may occur in the rivers of New South Wales.

4.2.1 Describe conditions under which algal blooms may occur in the rivers of New South Wales.

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4.3 Describe impacts of algal blooms in rivers.

4.3.1 Describe impacts of algal blooms in rivers.

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4.4 Discuss alternative strategies to the use of chemicals in agriculture to reduce water pollution.

4.4.1 Discuss possible alternative farming practices that do not involve the use of chemicals in agriculture, and the need for these alternative strategies.

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4.5 Describe some of the strategies that households can use to reduce water pollution.

4.5.1 Describe some of the strategies that households can use to reduce water pollution.

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4.5.2 Explain the need to use recycled water or treated sewage or desalinate sea water in Australia.

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activity such as:

and identify ways in which it can be reduced.

4.6.1household for one activity.

(a) Identify the activity you investigated.

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(b) Describe the method you used.

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4.6.2 Identify ways to reduce water use in the home.

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4.6.3 The following information shows the volumes of water used by a household for various activities. Use a bar graph to represent this information.

Activity Water used for each use (litres)

Toilet flush 6

Bath 80

Shower (15 minutes) 150

Dishwasher 70

Washing up (by hand) 8

Washing machine 150

Washing car 300

Watering garden (20 minutes) 500


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4.6.4 The following illustration shows activities around a home.

EXTRASTRONG

FERTILISER

(a) Put a cross on any activities which are wasting water and state how these could be changed.

(c) Identify any examples of pollution.

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4.7 Gather, process and present information from secondary sources on the latest technologies being used to purify and treat water.

4.7.1(a) Identify secondary sources you used to research technologies used to purify and treat water.

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(b) Comment on the validity of the information in the sources you accessed.

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4.8 Identify an example of technology being used and developed to reduce water pollution and

4.8.1

(a) Outline an example of technology being developed and used to reduce water pollution.

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5. Water pollution at the local level impacts on global water quality.

5.1 Discuss types of indicator organisms that are found in safe water supplies and those found in polluted water.

5.1.1 Discuss types of indicator organisms that are found in safe water supplies.

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5.1.2 Discuss types of indicator organisms that are found in polluted water.

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5.1.3 The following table lists the numbers of colonies of faecal coliform bacteria considered safe in water used for different purposes. Use a suitable graph to represent this information.

Water use Safe faecal coliform colony count per 100 mL

Drinking water 0

Swimming 200

Fishing 1000

Sewerage effluent 2000


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5.2.1

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5.2.2 Use the following key to solve the puzzle below.

Key:

a b c d e f g h i j k l m

Κ

n o p q r s t u v w x y z

# $ & ! € & Y †

Puzzle:

€ € € # Κ $ Κ

Solution:

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5.3 Identify a local catchment area and the sources of water feeding into this catchment.

5.3.1 Identify a local catchment area and the sources of water feeding into this catchment.

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5.3.2 Identify some activities that are permitted in a catchment area and some that are not permitted.

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5.4 Gather information on the source of water feeding into the local catchment area using maps or

5.4.1 Describe how you gathered information on the source of water feeding into the local catchment area.

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5.4.2 Sketch the catchment that you studied.

the indicator organisms present in a local catchment area and from these deduce the chemical purity of water.

5.5.1

present in your local catchment area.

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(b) Describe the results of your investigation of your local catchment area.

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5.5.2 Explain safety precautions necessary when investigating water in a local area.

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5.5.3 A class of Year 11 Senior Science students investigated two local creeks which were part of the local catchment area. One group collected organisms, another carried out chemical tests and a third group tested turbidity. Their results are shown below.

Use these test results to compare the chemical purity of the creeks and justify your deductions.

Organisms foundNumbers found

Creek A Creek B

Frogs 2 10

Mayfly nymph 1 6

Yabbies 2 8

Mosquito larvae 20 0

Chemical and other testsResults

Creek A Creek B

pH 4 6.5

Turbidity Visibility to 50 cm Visibility to 1.0 metre

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5.5.4 Describe two chemical tests you carried out on water from a local catchment area.

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5.6 Describe possible sources of contamination that may enter catchments.

5.6.1 Contamination of water catchments may be caused by land clearing, industry, agriculture and urbanisation. Describe examples of contamination from each of these sources.

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5.7 Describe the types of tests that are used to monitor and assess local water quality.

5.7.1 Complete the following table to show the available tests for monitoring water contaminants and the contaminants each test will detect.

Test for contaminants Contaminants detected by this test

Flame tests

Turbidity

Acidity – indicators, pH meters, pH probes and data loggers

Dissolved oxygen/ BOD

Tests for nitrogen and phosphorus content


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5.8 Explain how water quality in one area can impact on the water quality in other areas.

5.8.1

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5.9 Gather information from secondary sources concerning the use and treatment of local water.

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5.9.2 Match the water treatment processes listed below to the correct process outline.

Water treatment processes Process outline

(a) Screening ...................................(i) Sand filters are used to remove solids. A 2 m deep bed of sand is

used. The solids are collected when the sand filters are cleaned and are used as compost.

(b) Flocculation ................................ (ii) Fluoride is added to harden teeth.

(c) Sedimentation ...........................(iii) Chemicals, e.g. aluminium hydroxide are added to coagulate fine

particles and thus help to remove them.

(d) Filtration ......................................(iv) Chemicals are then added as needed, e.g. sulfuric acid may be

needed to break down organic matter, then limewater (calcium hydroxide) is added to neutralise any excess acid.

(e) Water testing ............................. (v) Sludge collected from settling tanks is dried and disposed of.

(f) Chemical treatment ................. (vi) Chlorine is added to kill micro-organisms.

(g) Disinfection ................................(vii) Water testing is carried out for ions, colour, pH, hardness, turbidity,

conductivity, micro-organisms.

(h) Fluoridation ................................ (viii) Solid objects (e.g. organisms, twigs) are screened out.

(i) Sludge processing ................... (ix) Slow water flow allows particles to settle to the bottom.

5.9.3 Complete the following table to explain the addition of the listed chemicals during the water

Chemical additive Reason for adding chemical

Aluminium hydroxide or iron(III) chloride

Sulfuric acid

Limewater or other alkali

Fluoride

Chlorine


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5.10 Gather, process and present information from secondary sources to identify some major disasters involving water pollution.

5.10.1 Identify two major disasters involving water pollution.

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5.10.2

Water is our most precious resource. Without water, life would not exist on our planet and

to become one of the most pressing resource issues of the 21st century. In some areas, such as India and Africa, surface water supplies are shrinking and groundwater supplies are being depleted faster than they can be replenished.

and polluted water sickens more than 1 billion people each year. Population growth will cause a rapid increase in agricultural demand for water. Water pollution adds enormously to existing problems of water scarcity by contaminating large volumes of available water, thus making it unsuitable for use. If we continue at the present increasing rate of use it is estimated that by the year 2030 the global water demand for fresh water will exceed the supply.

Approximately one out of every three people in the world experiences moderate to high water stress. Moderate water stress levels are said to occur when water consumption exceeds renewable freshwater supply by 10 per cent. The UN expects the global water situation to get considerably worse over the next 20 years. It estimates that by 2025 the proportion of the

three people.

Globally, water supplies are unevenly distributed. Some countries experience an abundant water supply. Other countries experience severe water shortages. In rich countries, people use between 850 and 1000 litres of water each day. In wealthy urban communities, an abundance of irrigated gardens and household appliances is responsible for an increase in household water consumption. In poor areas where people rely on public taps for their water, consumption drops to between 20 and 70 litres each per day. Where there are no taps at all and people (usually women) have to travel to collect water, daily consumption often drops to between 2 and 5 litres. This is close to the absolute biological minimum people need to stay alive.

(a) Explain why obtaining supplies of fresh water is likely to become one of the most pressing resource issues of the 21st century.

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(b) Identify household appliances that account for some of the increase in consumption of water in wealthy urban communities.

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(d) Identify the increase in water stress predicted by this article.

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(e) Tabulate the maximum and minimum daily water usage mentioned in this article for people living in different areas.

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Dot Point Preliminary Senior Science 173 Answers

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Answers

Answers 174 Dot Point Preliminary Senior Science

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Water for Living

1.1.1 Solute – substance which gets dissolved, e.g. sugar. Solvent – substance which does the dissolving, e.g. water. Solution – the mixture obtained when one substance dissolves in another, e.g. sugar solution.

1.1.2Mixture Solute Solvent

Salt and water salt water

Paint and turps paint turps

Grease and alcohol grease alcohol

Copper sulfate and water copper sulfate water

1.1.3 (a) Various, e.g. sucrose, sodium chloride, copper sulfate, sodium hydrogen carbonate (carb. soda), fertiliser.

(b) Various, e.g. copper carbonate, chalk, sand.

(c) Wash hands thoroughly after the experiment as some of the chemicals tested may be toxic, e.g. copper sulfate.

(d) Reliability is determined by repeating an experiment to see if you always get the same results. You may have repeated the experiment or you may have compared your results with those of other students in your class. If the results were consistent then they are reliable.

(e) Various, e.g. Test solubility in hot water as well as cold water, test a wider range of substances.

1.1.4 The teacher was correct as this method would not provide a fair test of the relative solubility of each substance. For a validexperiment, the only variable that should change is the independent variable – in this case the identity of the chemical to be tested. All other variables must stay the same. The students must:

or estimate the amount of chemical left after a stated time interval.

1.1.5 Substance A is the solvent – there are fewer particles of A in the second beaker, so it has evaporated on heating. Substance B is the solute, the same number of particles is present before and after heating.

1.2.1 (a) Various, e.g.

Collect a variety of samples of meat, fruit and vegetables.

Weigh about 10 grams of each sample.

Record the exact weight.

Place each sample on a Petri dish.

Place the dishes of food into an incubator.

Observe the samples each day for one week.

Weigh the samples each day until the weight is constant.

(b) Percentage of moisture in food = decrease in weight/initial weight × 100

1.2.2 Weighing once is not enough as all of the water may not have evaporated yet. They should weigh every day until they are getting the same weight all the time. Then they will know that all the water has evaporated from the samples.

1.2.3


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1.2.4 (a) These results do not support the hypothesis that chicken contains more water than beef. The average water content is

(b) Food samples can vary in water content based on how they have been treated, e.g. if they have been washed in water, some water may have been absorbed; some may have been exposed to the air or different air temperatures prior to testing; some chicken samples may have been frozen.

1.3.1

(b) Tomatoes contained the most water, followed by apples and potatoes with peas containing the least water.

1.3.2 This statement is based on the fact that water dissolves so many things. It does not dissolve everything, e.g. fats and oils arenot soluble in water.

1.4.1 Various, e.g.

For transport of substances dissolved in blood; most chemical reactions occur in solution in cells; a reactant in photosynthesisin plants; to help excrete wastes; to lubricate joints.

1.4.2 Water dissolves many substances that can be present in blood, e.g. food, hormones and waste products such as urea and carbon dioxide. It acts as a solvent for these substances.

This is very important as these substances must be able to be transported around the body and they do so dissolved in blood. For example, food is absorbed into blood vessels in the villi of the small intestine and from there must travel to all cells forrespiration; waste products must be carried away from all the body cells, urea travels to the kidneys and carbon dioxide to thelungs, for excretion. Hormones are produced by glands, such as the ovaries and testes. They go directly into the bloodstream and travel dissolved in blood to wherever they are needed in the body.

1.4.3 (a)Animal cellPlant cell

Largevacuole

Nucleus

Cytoplasm

Cell membraneCell wall

Chloroplast

(b) If a plant cell contains lots of water the contents will press against the cell wall and the cell is described as turgid.Turgid cells help to maintain the structure of the plant – they give it rigidity so it can stand up and expose its leaves to the Sun.

1.4.4 Thousands of chemical reactions occur in the cytoplasm of cells. Most of these reactions occur in solution. Water is the solvent in cells.

1.4.5

1.5.1 (a) Water is absorbed from the soil by the root hairs of plants. It travels from the roots to all parts of the plant through special tissue called xylem.

(b) Photosynthesis:

1.5.2

area under the ground, or grow deep into the ground, to maximise the water absorbed. A process called the transpiration stream draws the water up the stem and helps pull more water from the soil into the plant.

1.5.3 Transpiration is the movement of water from the roots, up through the stem, into the leaves and out through the stomates. As the water evaporates from stomates, more water is drawn up to replace the water lost. This is called the transpiration stream.


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1.6.1 Various, e.g.

Your teacher may have provided plants or you may have visited a national park, botanic gardens, the school grounds or a nursery to examine a range of plants and identify adaptations that would help them reduce water loss.

1.6.2 (a) The one over the celery stem with leaves.

(b) Reducing the leaves of a plant would reduce the loss of water from the plant as you would reduce the number of stomates.

1.6.3 Various, e.g. thick cuticles, sunken stomates, reduced leaf size, a hairy surface.

1.7.1 (a) The stomates, which are mainly found on the lower surface of the leaves.

(b) When plenty of water is available the guard cells may allow the pore of the stomate to open so water can evaporate. When water is scarce, the guard cells close the pore so water cannot be lost.

(c) Stomates also allow for the diffusion of gases, e.g. carbon dioxide and oxygen into and out of the plant for photosynthesis and respiration.

1.7.2 (a) The cuticle is the waxy layer that covers the outside of leaves. It is made of cutin which is impermeable: it will not allow water to pass through. Some plants, e.g. eucalypt trees have a thick cuticle to help reduce evaporation.

(b) The bigger the leaf, the greater the area exposed to the drying effects of sunlight and also the greater the number of stomates likely to be present and so the greater the loss of water. Some plants have small leaves so they have a smaller area over which they lose water by evaporation, e.g. wattle, cactus.

(c) Dropping leaves reduces the area over which water can be lost by evaporation from stomates and also reduces the area of plant exposed to the sunlight so during drought some plants drop their leaves to reduce water loss, e.g. eucalypts.

1.7.3

(b) Leaves reduced to scales/needles (hakea).

(c) Thick outer cuticle and leaves hang down (eucalypt).

(d) Reduced leaf area (wattle).

1.8.1 Impervious skin coverings, excretion of concentrated or solid wastes, nocturnal behaviour.

1.9.1 (a) Urea is the soluble waste product formed by the metabolism of proteins. It is toxic if it accumulates in the body so must be excreted.

Uric acid is a solid form of nitrogenous waste produced by some animals living in dry environments to conserve water.

(b) Various, e.g.

Camels and kangaroos conserve water by excreting very concentrated urine. Reptiles and birds in desert regions excrete wastes as solid uric acid.

1.9.2 (a) Active at night and sleep during the day.

(b) In hot, dry climates water is lost as sweat especially during the heat of the day. To reduce this water loss, many desertanimals sleep during the hot daylight hours and are active at night when it is cool. This reduces the production of sweat and thus reduces water loss.

1.9.3 In hot, dry climates water is lost as sweat especially during the heat of the day. To reduce this water loss, many animals reducetheir activity and shelter in shady places during the hot daylight hours. For example, kangaroos and wallabies are active at dawn and dusk and rest during the heat of the day.

1.9.4 In underground burrows, the air is relatively cool and has high humidity so animals living in burrows lose less water via sweatthan those living at the surface in hot, dry areas.

2.1.1

Precipitation – water falling as rain, snow or hail.

(c) Physical because there is no new substance formed, water is simply changing from one state to another. In chemical processes a new substance is formed.


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2.1.2which falls to Earth.

(b) Water can evaporate from plants (transpiration), animals (perspiration), puddles and the ground as well as from large bodies of water.

(c) Rain begins to fall when drops of water in the cloud are too heavy to remain airborne.

(e) Humid air is less dense than dry air. It has more water vapour in it and water molecules are lighter than the other molecules in air.

2.1.3 (a) The oceans, dams, lakes, rivers and wetlands.

2.1.4 (a) Ground water is water found under the ground. This includes water in artesian basins and in caves. The water table is

water.

(b) More than half of Australia relies on ground water for all except drinking water. The high mineral content makes it unsuitable for drinking. It is used extensively for irrigation and in some areas is being used faster than the water can be replaced.

(c) Wells are drilled down to the water table and water pumped out. This is called bore water.

2.1.5

(b) (i) True

(iv) True

2.2.1 (a) An underground reservoir of fresh water surrounded by impermeable rock that will not let the water escape.

(b) It provides the only reliable source of water through a large part of the arid inland areas of Australia. The water is used for irrigation, stock and domestic use (when treated). Thousands of bores take water from the basin and there is concern that it is being used too fast and some areas may go dry.

2.2.2 Various. Your map could be based on a road map, a tourist map or an aerial photograph, e.g. from the Internet. It should include any rivers, lakes, dams and known ground water. There may also be wetlands or caves in your area.

2.2.3 Various. You may have found information at your local library or council or on the Internet. Australian Government State of Environment reports are useful for information about different areas.

2.3.1 Various, e.g.

Rainforests occur in areas with high rainfall.

Forest occurs along the southern coast in areas of high rainfall.

Grassland occurs in areas with rainfall less than 500 mm.

Desert areas have a rainfall below 250 mm.

2.4.1 Various, e.g.

sediment from erosion of soils.


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2.4.2 Various, e.g.

Pollutant Source Effects

Sediment Wind and water erosion of land Fertile topsoil removed.Light cannot penetrate water.Water temperature rises.Aquatic organisms die.

Nutrients – ammonia, nitrates and phosphates

Sewage spills Water becomes cloudy.Stimulate plant growth so excess growth of algae can occur (algal blooms).Toxic blue-green algal blooms may occur.Algal blooms die off and oxygen is used for their decay. Water becomes stagnant and aquatic organisms die.

Faecal bacteria Faeces in run-off or seepage from urban areas, grazing paddocks, septic tanks, stormwater

Cause disease, e.g. diarrhoea, dysentery, salmonella and typhoid fever.

Heavy metals, e.g. lead, mercury, cadmium and other chemicals

Chemical use in home and industry and disposal of excess and waste

Toxic to aquatic organisms and people. Accumulate in sediments and in tissues of organisms.Accumulate in food chain.

Pesticides, herbicides, fungicides

Run-off from agricultural use Toxic, can kill not only targeted organisms but also others.Toxic to humans.

2.4.3 (a) The presence of salt in surface soils or rocks or dissolved in rivers or ground water.

(b) Various, e.g.

Clearing land, irrigation of extensive areas.

(c) Increased rate of corrosion of metals, bricks become spotted with precipitated salt and then crumble.

2.5.1

(b) Increased salinity has been caused by clearing surrounding land of the natural vegetation and irrigation of large areas which have led to rising water tables.

This area supplies domestic, industrial and agricultural water to a large area of eastern Australia, so this river system is vital to the economy and food production. Its increasing saltiness is leading to the establishment of salt deserts in some areas. If this increase in salinity is not halted and reversed the whole area could eventually become a wasteland and there would not be enough food to support the population.

(c) Various, e.g.

cause minimal damage.

2.6.1 Various, e.g.

out through their leaves (transpiration). Even in areas of crops we can maintain native vegetation in strips along waterways and between crop areas.

tolerant native pastures. In urban areas, councils need to consider zoning, reduce land clearing for developments, and

further along the river system. People in urban areas can do a lot to reduce wastage of water, in homes, on gardens and in industry. Also, water use for irrigation can be reduced to a minimum. For some crops, standing water can be used


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2.7.1 Various, e.g.

Problem – Increasing population and the need to supply larger volumes of unpolluted water.

NSW Government – Catchment Management Authorities Act 2003. This established 13 catchment management authorities in NSW. Each authority is responsible for managing natural resources

3.1.1 Fertiliser – substance added to soil or water to increase the growth rate of plants by providing essential nutrients.

Herbicide – substance used to kill unwanted plants, e.g. those competing with crops.

Pesticide – substance used to kill unwanted animals, e.g. rats and insects such as locusts.

3.1.2 Plants need nutrients to grow, especially minerals, e.g. calcium, iron and magnesium, and nitrogen and phosphorus in the form

of nitrates and phosphates. The amount of these chemicals present in soil can vary with the type of rock that formed the soil. Australian soils are generally not very fertile soils. Sandstone, which is the main rock in the Sydney Basin, produces a soil

3.1.3 Various, e.g.

Herbicide – Dalapon – used to control plants that compete with orchards, lawn and crops such as beans.

Pesticide – Methoxychlor – used to kill insects on fruit, vegetables and alfalfa.

The use of such chemicals needs to be carefully controlled and monitored as they can potentially cause harm to people and other animals, e.g. Dalapon can cause liver and kidney damage and Methoxychlor affects the nervous system, causes liver and kidney damage and affects growth.

3.2.1 In agricultural areas fertiliser, pesticides and also herbicides are often administered to crops by aerial spraying. This causesconsiderable concern as, despite precautions, such as spraying only on relatively calm days, the spray may drift across water supplies, e.g. dams and rivers causing contamination.

eventually makes its way into rivers and dams, causing contamination.

3.3.1 (a) Various, e.g. The greater the concentration of fertiliser, the taller the bean seedlings will grow.

(b) Various. You should:

to the same height)

Note that you are not testing germination (seed growth) so if you are growing your plants from seeds your experiment will not start until all the seeds have sprouted.

you administered it to the plants

light and use the same soil

(c) The independent variable will be the various concentrations of fertiliser that you used.

The dependent variable will be how you measured the growth, e.g. did you measure each plant and calculate average increase in height over each week or some other method.

(d) The type and age of plants should be the same throughout, they should all receive the same amount of sunlight and water (at the same time of day), they should be in the same pots and soil/potting mix, temperature and wind (if outside) conditions should be the same.

(e) Various – you should rule up a table, remember to put headings and include units (e.g. mm) in the heading.


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(f) State whether you repeated the experiment or compared your results with those of other groups doing the same experiment. If the results were always the same then your results are reliable.

3.3.2 (a)

E

21.5

D

1.0

C

10

5

Growth ofseedlings(mm/week)

0.50.10

A

B

Concentration of fertiliser (%)

Seedling growth with fertiliser

there was no further increase in the growth of the seedlings.

(c) These plants act as the control. They allow the tester to ensure that the results really were due to the addition of fertiliser. Having a control improves the validity of the experimental method.

(e) It is easy to understand why the farmer thinks that way. However, the manufacturer makes recommendations about

most suitable concentration to use. If the farmer uses more than the recommended concentration, it will not be able

3.4.1 Various, e.g. Oils, detergents, bleaches and toilet cleaners, insoluble materials, sewage.

3.4.2 Various. For each substance you should describe how it is used in the home, how it gets into waterways and the damage it can potentially do there.

Follow this with an assessment statement.

For example, Oil – Oil from cooking food, from cars and from dirty clothes is washed down drains and enters waterways or

it clings to animals such as birds causing damage to their feathers and it can cause turbidity which can lead to the death of

3.5.1 (a) Metals with high atomic masses, e.g. mercury, lead, copper, barium, silver, arsenic and cadmium.

(b) They inferfere with enzyme systems and body metabolism, cannot be easily eliminated from the body, bioaccumulate (build up to high levels in tissues) and biomagnify (increase along the food chain), persist in the environment for long periods of time and over recent years their concentrations in the environment have increased.

(c) Heavy metal

Source Effects

Lead Lead water pipes, lead-based solder and other alloys containing lead, mining and extracting lead from ores, old paint, lead glazing on pottery, stained glass lead linings, batteries

Damage to kidneys and nervous system, causes anaemia, learning disabilities

Mercury Batteries (no longer manufactured), mercury waste released by industrial production, electric switches

Damage to kidneys and nervous system, loss of hair, insomnia, birth defects

(b) Bioaccumulation – the accumulation of substances in the tissues of the body. This happens with heavy metal

3.5.2 (a) An increase in the nutrient content of water leading to excessive algal growth (an algal bloom) which is followed by decay of the organisms and depletion of oxygen in the water. This results in the water becoming stagnant.


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(c)

The decomposition of the algae (by

bacteria and other micro-organisms)

uses up the oxygen in the water

Algae die as all nutrients used up.

Algae grow rapidly, some producing

toxins

Water becomes stagnant

Shortage of dissolved oxygen

leads to the death of aquatic organisms

Excess nutrients, particularly nitrogen

and phosphorus wash into the water

as pollution

water. They produce toxic products and can cause diarrhoea and skin rashes.

In 1991 toxic blooms formed on many Australian rivers due to drought, warm weather and pollution. It occurred

3.6.1 (a) A bioassay involves using an organism to test for chemical toxicity (e.g. using a canary to detect methane in a coal mine).

(b) Drugs and skin products are tested on laboratory animals before they are released for use of humans. Organisms are

seeds) are all used for bioassays of water samples. Each type of organism reacts in predictable ways to various environmental contaminants.

3.6.2 (a) Cryptosporidium and giardia cause abdominal cramps, diarrhoea, nausea and vomiting. They indicate that the water

contaminated water.

(b) By disinfecting with chlorine and sometimes also ammonia.

3.7.1Factor Impact

Accumulated sediment Increases turbidity (cloudiness) of water; fills in wetlands; reduces water flow; covers vegetation; blocks drains and watercourses; damages aquatic organisms, e.g. fish gills.

Leaching from tips Substances leached from tips can include nutrients and toxic chemicals. The nutrients can contribute to algal blooms when they reach waterways or ground waters. Toxic chemicals get into the food chain.

Bioaccumulation Substances such as heavy metals accumulate in the tissues of the body of organisms (bioaccumulation). These then pass on through the food chain, so organisms high in the food chain can have very high levels of toxic substances in their bodies.


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4.1.1the Internet.

You should be able to describe references that you used. For Internet sites, give complete URL; for books give title, author,publisher and date of publication; for personal contacts, give name of person, title and occupation.

4.1.2 Various. Comment on the agreement you found between information provided in different sources (this is one reason for using a range of resources). Also comment on the likely reliability of the sites you chose to access. Reliable websites would be those

4.2.1cause an increase in the concentration of phosphorus and nitrogen compounds in the waterways, especially nitrates and phosphates.

accumulate and promote the growth of large numbers of algae in the waterway, algal blooms form.

4.3.1 Algal blooms cause increased cloudiness (turbidity) of the water. The algal bloom consists of such large numbers of algae that they use up all of the nutrients in the water. They then die and the decomposition of their bodies uses up the oxygen in

(cyanobacteria) are present, then they may also cause illness in people and other animals due to toxins.

4.4.1 Various, e.g.

Alternatives include: Using physical barriers, e.g. mulching around plants to prevent slugs and snails reaching the plants.

Biological control – releasing an organism that will kill the pest and not damage the crop.

Chemicals such as fertilisers, herbicides and pesticides are used on agricultural crops to maximise yield. Some of these are toxic

off into water courses and contribute to water pollution. Some accumulate within living things and along the food chain.

4.5.1 Various, e.g.

Do not put food scraps, oil and grease, unused paint or other chemicals down the sink, compost all possible food scraps, use minimal detergent, pick up pet faeces, disconnect any downpipes and stormwater from the sewer.

4.5.2 Australia is a very dry continent, suffering regular droughts and hence an unreliable water supply. Also, increasing salinityof natural waterways and increased pollution are reducing our available water supplies. At the same time, an increasing population has led to greater demand for water, for drinking, growing more food and increased industry. In the future, as population increases, it will be necessary to recycle water, desalinate sea water or even to treat sewage to meet water demands.

4.6.1

(b) Various, e.g.

Alternatively, you might have used your water meter, reading it before and after an activity such as a washing machine cycle. Of course, you would have to ensure that no other water was being used in the house at the time.

4.6.2 Restrict the time you spend in the shower, turn off the tap when brushing teeth and use a cup of water, check that there are no

ones, follow water restrictions in the garden, use a broom rather than a hose to clean paths, wash your car with a bucket of water and the car parked on a lawn.


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4.6.3

GardenCarWashingmachine

Washingup

Dish-washer

500

450

400

350

300

250

200

150

100

50

Volumeof waterused (L)

ShowerBathToilet

Water use

Activities


Car should be washed, on grass, with bucket of water only, no hose.

Child should not be playing with the hose.

Girl is hosing path – this should be swept.

(b) Various, e.g.

(c) Dog droppings on footpath; fertiliser left open in yard; rubbish falling out of bin; leaves being washed down drain; car suds going down drain; weed killer should be out of the reach of children.

4.7.1videos and/or the Internet.

You should be able to describe references that you used. For Internet sites, give complete URL; for books give title, author, publisher and date of publication; for personal contacts, give name of person, title and occupation.

(b) Validity will be high if you have used information from reliable sources, e.g. universities, government departments. Be aware that sites of companies that sell products may give a biased view in favour of products they sell.


giardia and cryptosporidium could be kept out of our water supply. They could also be used to purify catchment water and allow water from households and industry to be recycled. This would ensure the water supply in droughts.

of water as well as increasing the volume of water available for use. Increases in population and an uncertain rainfall

As technology improves, and products are mass produced, new technologies often become more affordable and thus their use spreads to more areas and applications. It is often the case that a need in society has resulted in new and improved technology .

5.1.1 Safe water supplies contain a diversity of organisms. Organisms which are sensitive to pollution, and thus only found in safe

5.1.2and faecal coliform, e.g. E. coli.


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5.1.3

SewageFishing

2000

1000

Faecalcoliform count(colonies/100 mL)

Swimmingwater

Drinkingwater

Source of water

Bacteria in water

5.2.1

5.2.2 Water is essential for life.

5.3.1 Various – you should be able to describe and sketch your local catchment area. Include dams, rivers, towns.

Burragorang. This is the lake formed by Warragamba Dam and is fed by the Cox, Wollondilly and Kowmung rivers.

5.3.2 Permitted activities include picnicking, bushwalking and recreational activities.

Not permitted include: swimming or boating on the dams, farming. logging or urban development, industry or the use of chemicals such as insecticides.

5.4.1

5.4.2 Various, e.g. Sydney catchment area.

Warragamba Dam

KATOOMBA

WINDSOR

PARRAMATTA

SYDNEY

WOLLONGONG

KIAMA

Tallowa Dam

Cox's River

Grose River

Nepe

an R

iver

Nepean River

Geor

ge R

iver

Nattai River

Kowm

ung R

iver

Wollondilly Rive

r

Wingecarribee RiverWingecarribee Reservoir

Cordeaux Dam

Cataract Dam

Lake Burragorang

CAMPBELLTOWN

Woronora Dam

MITTAGONG

Nepean Dam

Avon Dam

5.5.1 (a) Various. You should identify the catchment area you investigated, stating exactly where you carried out your

– describe what you did. You may also have examined water specimens under the microscope and cultured a sample on nutrient agar plates to estimate bacteria present.

(b) Describe the plant and animal life you detected in the area you studied and comment on the diversity of organisms in the area. Describe the results of tests you carried out such as water turbidity, pH and salt concentration.

5.5.2 Remember that streams may be polluted so wear gloves when collecting and testing water to protect against possible acidic or other corrosive materials coming in contact with the skin and wear protective glasses to prevent such substances entering the eye. Corrosive/acidic substances could burn the skin.


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these could make you ill.

5.5.3 Creek A was polluted, creek B was not polluted.

can tolerate polluted water with low oxygen concentration.

The turbidity readings indicate that the water in creek A was relatively turbid (50 cm visibility) compared to water in creek B (1.0 m). This could be caused by erosion particles or large numbers of algae.

The pH of creek A (4) showed that it was acidic which could indicate pollution by acidic substances. The pH of creek B was only very slightly acidic (6.5).

5.5.4 Various, e.g.

We tested for the presence of chloride ions by adding a few drops of silver nitrate solution. We rated the cloudiness on a scaleof 1 to 5. The more cloudiness produced the greater the concentration of chloride ions present in the water.

We tested for the presence of carbonate ions by adding dilute hydrochloric acid to a sample. If bubbles are produced then thewater has carbonates such as sodium carbonate present.

5.6.1 Various, e.g.

Land clearing – Removal of plants means soil is not held together by roots and can be eroded. Erosion results in soil particlesand salt grains being washed into waterways.

Industry – Careless or illegal use of chemicals by industries, or dumping of chemicals illegally can contaminate waterways and catchments, e.g. corrosive acids, and alkalis, radioactive wastes, toxic heavy metals. Also leaching of chemicals from an industrial site, including mines, or corrosion from structures in the area can cause the release of corrosion products into theenvironment.

Agriculture – Animal urine and faeces, e.g. from cattle grazing near waterways, can be washed into waterways that enter catchments. Dead and decaying organisms can be present and bacteria can enter the water from such sources. Insecticide, herbicide and fertilisers applied to crops can be carried by rain or irrigation water into waterways and when these chemicals are sprayed the spray may drift across the catchment.

Urbanisation – Nutrients from grass clippings and animal droppings, sewerage seepage from septic tanks and sewerage

5.7.1Test for contaminants Contaminants detected by this test

Flame tests Metal ions especially heavy metals.

Turbidity Insoluble solids such as silt, clays, sludge suspended in the water. An indication of erosion and microbe contamination such as algae and faeces.

Acidity – indicators, pH meters, pH probes and data loggers

Acids or alkalis, acid rain.

Dissolved oxygen/BOD Low DO indicates increased activity of aerobic microbes which use up the oxygen. High BOD can be due to sewerage or industries such as food processing, paper production.

Tests for nitrogen and phosphorus content

Indicates sewage, fertiliser or detergents in water.

5.8.1

into estuaries, lakes and eventually the ocean. Pollutants may also seep into ground water and spread to other areas.


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5.9.1

Filtration

Sedimentation

Flocculation

Screening

Sludgeprocessing

Fluoridation

Disinfection

Addingchemicals

Watertesting

5.9.2 (a) (viii) (b) (iii) (c) (ix) (d) (i) (e) (vii) (f) (iv) (g) (vi) (h) (ii) (i) (v) 5.9.3

Chemical additive Reason for adding chemical

Aluminium hydroxide or iron(III) chloride

Coagulates fine suspended particles so that they will sediment or can be more easily filtered.

Sulfuric acid Breaks down organic wastes and aids coagulation.

Limewater or other alkali Neutralises acid and restores neutral pH.

Fluoride Hardens tooth enamel and helps prevent tooth decay.

Chlorine Bleaches coloured matter in the water and disinfects the water by killing micro-organisms.

5.10.1

The Exxon Valdez disaster in Alaska in 1989.

5.10.2 (a) Many areas are already short of water, the population is increasing at a very rapid rate and much of our drinking water has been polluted.

(b) Dishwasher, washing machine. (c) When water consumption exceeds renewable freshwater supply by 10 per cent. (d) From 1/3 to 2/3 of the population by 2025. (e)

AreaDaily water use per person (L)

Maximum Minimum

Rich countries 1000 850

Poor areas 70 20

Very poor areas (no taps) 5 2


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preliminary senior science · 4.7 technologies to purify and treat water 31 4.8 a technology to...

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