hsc senior science - sciencepress · dot point hsc senior science iii contents ... 1.6...

HSC SENIOR SCIENCE

Marilyn SchellMargaret Hogan

© Science Press 2007First published 2007 Reprinted 2008, 2011

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

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 98 000 073 861

Contents

Introduction vVerbs to Watch vi

Dot Points

Lifestyle Chemistry viiMedical Technology – Bionics ixInformation Systems xiDisasters xiii

Questions

Lifestyle Chemistry 1Medical Technology – Bionics 47Information Systems 95Disasters 135

Answers

Lifestyle Chemistry 177Medical Technology – Bionics 195Information Systems 215Disasters 229

Dot Point HSC Senior Science iii Contents

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Contents iv Dot Point HSC Senior Science

Science Press

Introduction

What the book includes

syllabus for the following topics in the Year 12 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 HSC 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.

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

apply Use, utilise, employ in a particular situation.

appreciate Make a judgement about the value of something.

assess

results or size.

calculate

clarify Make clear or plain.

classify Arrange into classes, groups or categories.

compare Show how things are similar or different.

construct Make, build, put together items or arguments.

contrast Show how things are different or opposite.

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

deduce Draw conclusions.

demonstrate Show by example.

describe Provide characteristics and features.

discuss Identify issues and provide points for and against.

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

evaluate Make a judgement based on criteria.

examine

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

extract Choose relevant and/or appropriate details.

extrapolate Infer from what is known.

identify Recognise and name.

interpret Draw meaning from.

investigate

justify Support an argument or conclusion.

outline Sketch 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.

summarise Express concisely the relevant details.

synthesise Put together various elements to make a whole.

Verbs to Watch

Verbs to Watch vi Dot Point HSC Senior Science

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Dot Point Page

1. Physical and chemical properties 21.1 Physical and chemical properties 21.2 Everyday chemicals 31.3 Types of mixtures 41.4 Solutions, colloids and suspensions 71.5 Examples and uses of solutions, colloids and suspensions 71.6 Investigating colloids and suspensions 81.7 Investigating surface tension 101.8 Explaining surface tension 111.9 Surfactants 111.10 Effects of soap, skin cleansers and shampoos on oil 122. Emulsions, colloids and surfactants 142.1 Investigating an emulsion 142.2 Composition and properties of an emulsion 142.3 Investigating properties of an emulsion 152.4 Emulsifying agents in cleaning products 18

and surfactants 192.6 Cleaning agents as surfactants and emulsions 20

2.8 Biodegradability of soaps and detergents 213. Cleaning products and skin 233.1 Investigating human skin 233.2 Functions of skin 24

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3.4 Acidity and pH 253.5 Investigating pH of skin and skin products 253.6 Maintaining skin pH 27

3.8 Components of soaps, cleansers and shampoos 294. Solvents 304.1 Investigating solubility of medications 304.2 Water and alcohol as solvents 314.3 Cosmetics and medications using water as solvent 314.4 Cosmetics and medicines using alcohol as solvent 324.5 Properties and uses of solvents in cosmetics and medicines 324.6 Subdermal implants 325. Absorption of drugs 345.1 Parts of the digestive system 345.2 pH of the stomach and small intestine 365.3 The stomach and small intestine digest food 365.4 Solubility of medicines and body action 385.5 Solubility of drugs determines how it is given 395.6 Solubility of drugs and their absorption 405.7 Designing drugs 405.8 Vitamins and solubility 41 Answers to Lifestyle Chemistry 177

Lifestyle Chemistry

Dot Point HSC Senior Science vii Lifestyle Chemistry

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Lifestyle Chemistry viii Dot Point HSC Senior Science

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1. Biomaterials and biomedical devices 441.1 Variety of biomedical devices and materials 441.2 History of cochlear implants or heart valves 462. The heart and circulation 482.1 Structure and function of the heart 482.2 Investigating exercise and heartbeat 512.3 Aspects of heartbeat 532.4 Production of electrical signals in heartbeat 542.5 Heartbeat problems 552.6 Role of a pacemaker 562.7 History of pacemakers 562.8 Materials used in pacemakers 582.9 Problems due to faulty heart valves 58

2.11 Materials used for body parts 602.12 Model of heart valves 60

2.16 Research into heart transplants 633. The skeletal system 643.1 Functions of the skeletal system 64

3.3 Investigating the parts of a joint 653.4 Investigating types of joints 663.5 Describing joint types 67

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3.7 Parts of a bone 693.8 Investigating silicone 693.9 Properties and uses of silicone 703.10 Uses of silicone joints 703.11 Properties and uses of UHMWPE 703.12 Strength of UHMWPE 713.13 Properties and uses of superalloys 73

3.15 Cemented and uncemented implants 743.16 Bonding implants with bone 744. Life support systems 764.1 Structure and functions of the respiratory system 764.2 Function of the diaphragm in breathing 774.3 Investigating carbon dioxide in inhaled and exhaled air 784.4 Cardiopulmonary resuscitation 79

4.7 Life support systems in hospitals 804.8 Monitoring devices that maintain life 805. Understanding the body 81

5.2 Researching advantages and

5.3 Advantages of minimally invasive surgery 82

5.5 Impacts of technology on understanding the body 83

Answers to Medical Technology – Bionics 195

Medical Technology – Bionics

Dot Point HSC Senior Science ix Medical Technology – Bionics

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Medical Technology – Bionics x Dot Point HSC Senior Science

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1. Energy transfer in information systems 881.1 Types of communication systems 881.2 Classifying information systems 881.3 The information transfer process 891.4 Forms of energy 901.5 Researching information transfer processes 901.6 Energy transformation in communication systems 921.7 Timeline of communication 931.8 Advantages of using a range of systems 952. Electromagnetic radiation carries information 962.1 Composition of the electromagnetic spectrum 962.2 Communication using the electromagnetic spectrum 972.3 Investigating wave modulation 982.4 Using microwaves and radio waves for communication 1013. Properties of electromagnetic radiation 1033.1 Transmission of information by waves 1033.2 Useful properties of electromagnetic radiation 103

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3.3 Properties and uses of electromagnetic waves 1033.4 Investigating AM and FM reception 105 4. Geostationary satellites 1074.1 Satellites in communication 1074.2 Height of satellites 1084.3 Direction of satellite dishes 1085. Energy transmission by electrical impulses 1105.1 Energy transfers by digital technologies 1105.2 Energy transfers in communcation technologies 1115.3 Image scanning and transmission by digital technology 1115.4 Coding a digital image 1126. 1146.1 Investigating transmission through

communication 117

Answers to Information Systems 215

Information Systems

Dot Point HSC Senior Science xi Information Systems

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Information Systems xii Dot Point HSC Senior Science

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1. Natural and human induced disasters 1241.1 Identifying disasters 1241.2 Insurance contracts and disasters 1241.3 Natural disasters in Australia 1261.4 Australian disasters involving human activity 1261.5 Australian disasters involving nature and human activity 1271.6 A database of Australian disasters since 1970 1272. Monitoring and predicting weather 1292.1 Atmospheric pressure and air currents 1292.2 Atmospheric pressure and isobars 1312.3 Investigating effects of differences in air pressure 1312.4 Air pressure and weather 1322.5 Tropical cyclones and tornadoes 1332.6 Movement of a tropical cyclone 1342.7 Technology and understanding meteorology 1362.8 Monitoring weather patterns 1372.9 Satellite photographs and weather predictions 137

138

3.2 Energy transformations in L waves 1403.3 Using P and S waves to locate an

3.4 Locating an epicentre 142

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3.10 Effects of slope of land and wind

4. Warning devices 1534.1 Energy transformations in warning devices 153

device 1574.5 Evacuation procedures in emergencies 1585. Emergency services 1595.1 Researching emergency services 1595.2 Coordinating emergency services during disasters 1595.3 Technological developments in disaster warnings 160

Answers to Disasters 229

Disasters

Dot Point HSC Senior Science xiii Disasters

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Disasters xiv Dot Point HSC Senior Science

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Dot Point HSC Senior Science 1 Lifestyle Chemistry

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Lifestyle Chemistry

Lifestyle Chemistry 2 Dot Point HSC Senior Science

Science Press

1. The use of a substance depends on its chemical and physical properties.

1.1 Identify that a wide range of substances is used daily as part of our food, our hygiene, our entertainment and maintenance of our health.

1.1.1 In our daily lives we use and come in contact with a wide range of substances. Complete the following table, by listing chemicals that we use in each of the listed areas of our lives.

Area Chemicals

Food

Hygiene

Entertainment

Maintenance of health

1.1.2 Rule lines to match the following examples of chemicals with the listed types of substance.

Type of substance Examples of chemicals

Solvent for fats Grease and oil

Solvent for sugar Ammonium compounds

Bleach Soap and detergent

Antibacterial agent Sulfur dioxide

Acid in citric fruit Crushed limestone or quartz

Abrasive Citric acid

Preservative Sodium hydroxide in oven cleaner

Cleaning agent Sodium hypochlorite

Lubricant Water

1.1.3 The uses of chemicals depend on their chemical and physical properties.

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(b) Distinguish between physical and chemical properties.

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(c) Identify the following properties as either physical or chemical.

(i) melting point ................................................................................................................................................................

(ii) hardness ..........................................................................................................................................................................

(iii) malleability ...................................................................................................................................................................

(iv) decomposition .............................................................................................................................................................

(v) reaction with acid ......................................................................................................................................................

(vi) density ..............................................................................................................................................................................

1.2 Process and analyse information to identify the range of chemicals used in everyday living including:

and outline any precautions that may be needed in the use and handling of these chemicals.

1.2.1 Complete the following table to identify the range of chemicals used in everyday life and any precautions needed when handling these chemicals.

Chemical Use Precautions

Detergents

Lubricants

Pesticides

Solvents

Metal cleaners

Body hygiene chemicals

Cosmetics

Preservatives


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1.2.2

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1.2.3 State the names of chemicals that could be used for each of the following purposes:

(a) lubricant ........................................................................................................................................................................................

(b) preservatives for food ...........................................................................................................................................................

(c) solvent ............................................................................................................................................................................................

(d) metal cleaner ..............................................................................................................................................................................

(e) to adjust the pH/acidity (e.g. for pools, food and gardens) .............................................................................

(f) abrasives .......................................................................................................................................................................................

(g) to kill microbes .........................................................................................................................................................................

1.2.4 Use a diagram to model the arrangement of molecules of oil, water and alcohol in a mixture.

1.3 Explain that mixtures can be:


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1.3.1 List the main components present in each of the following common mixtures.

Mixture Components of mixture (what is in it)

Air

Sea water

Soft drink

Tea

Milk

Toothpaste

1.3.2

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solution, another is a suspension and the third one is a colloid. Outline simple observations that would allow you to identify which is the solution, suspension and colloid.

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1.3.3 Identify each of the following substances as a solution, suspension or colloid.

(a) black tea (strained to remove tea leaves) ...................................................................................................................

(b) hand cream ..................................................................................................................................................................................

(c) soft drink ......................................................................................................................................................................................

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(e) mayonnaise or tartare sauce ..............................................................................................................................................


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1.3.4(a) A group of scientists carried out experiments and came up with the following list of

characteristics of solutions, colloids and suspensions. Put the correct heading on each column.

(i) ........................................................ (ii) ...................................................... (iii) .....................................................

Size of particles between 10-3 and 10-6 mm smaller than 10-6 mm larger than 10-3 mm

Do particles settle on standing?

No No Yes

Is there a residue after filtering?

No No Yes

Can you see a light beam shining through it?

Yes No Yes

Does an electric field have any effect on it?

Yes – some particles will move to an electrode

No No

(emulsion or foam).


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1.3.5 (a) Emulsions and foams are two types of colloids. Distinguish between these two types.

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(b) Label the following diagrams of three different types of colloids.

(iii) Foam(ii) Water-in-oil emulsion(i) Oil-in-water emulsion

1.3.6 The following colloids are called foams because they are made from tiny gas bubbles

case.

Colloid Liquid Gas suspended

beer foam

whipped cream

soapsuds

meringue (pavlova)

1.4 Identify that solutions, colloids and suspensions occur in a wide range of consumer products.

1.4.1 Solutions, colloids and suspensions occur in a wide range of consumer products. Explain what is meant by the term consumer product.

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1.4.2 List the following consumer products under the correct heading to classify each as a solution, suspension or colloid.

Consumer products: milk, shaving cream, mayonnaise, white coffee, pot of tea (with tea leaves), wine, beer foam,

whipped cream, nail polish remover, whisky, muddy water, toothpaste, clear apple juice, orange juice with pulp, butter, hair spray.

Solution Suspension Colloid

identify examples of suspensions and colloids and outline one advantage of a mixture being in each form.

1.5.1

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(b) Outline the sources you used to gather information about suspensions and colloids.

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1.5.2 (a) Identify one example of a suspension and one example of a colloid that you have studied.

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(b) For each of the substances named in part (a), outline an advantage for it being in that form.

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1.5.3It is used on itchy rashes. Identify this as a suspension or colloid and outline an advantage for it being in that form.

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1.5.4administering penicillin in this form.

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(b) Explain why these emulsions are also called colloids.

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moisturisers.

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produce a range of suspensions and colloids that are used by consumers including:

1.6.1 (a) Identify a suspension and a colloid that you produced during this course.

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1.6.2 A student whisked together some oil and vinegar to make salad dressing. He allowed the mixture to stand. After 5 minutes he noticed that the water had settled to the bottom and there was a layer of oil coating the top of the water. Classify this mixture as a solution, suspension or colloid and justify your answer.

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1.6.3 (a) A group of Year 12 students make mayonnaise from a recipe using raw eggs, salt, pepper,

mustard, oil and vinegar. The ingredients are to be beaten together until blended. Identify any

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mentioned in the above ingredients. Explain.

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also as an emulsion.

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1.6.4 Raw egg whites are placed in a bowl and beaten until they form a stiff white mixture. Twenty minutes later its appearance is unchanged. Identify the type of mixture formed.

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1.6.5 (a) Milk sold in shops has been homogenised. Outline the meaning of homogenised.

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(b) Identify an advantage of homogenised milk over milk coming straight from a cow.

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1.7.1

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(b) The following diagrams show the shape of the meniscus for water and mercury in clean

(i) ....................................................... (ii) .....................................................

(c) Account for the different shapes of these menisci.

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1.7.4

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(b) Identify some conclusions you drew, as a result of your investigation, about the ability of insects to walk on water.

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1.8 Explain surface tension in terms of the forces experienced by particles at the surface of a liquid.

1.8.1

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1.9 Describe surfactants as substances that affect the surface tension of a liquid.

1.9.1

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(b) Identify an advantage of adding a surfactant to water.

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1.9.2She then adds three drops of detergent to the water. Predict and explain the effect of the addition of detergent.

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1.9.3 The following diagrams show two identical leaves. One has been sprayed with water containing an agricultural solution containing a surfactant and other chemicals. The other has been sprayed with plain water.

A B

(a) Identify the leaf that has been sprayed with the agricultural product. ......................................................

(b) Suggest a reason for spraying the leaves of a plant with chemicals. ...........................................................

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(c) Suggest a reason for adding a surfactant to the spray. .........................................................................................

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1.10 Process and present diagrammatic information to describe the effects of soaps, skin cleansers and shampoos on the solubility of oil.

1.10.1 Soaps, skin cleansers and shampoos can dissolve oil because of the chemical structure of surfactants.

(a) Use a diagram to show the structure of soap.

(b) Describe this structure in words.

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(d) Use a diagram to help describe how the soap structure allows oils to dissolve in water.

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1.10.2 What do soaps, skin cleansers and shampoos have in common?

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1.10.3 Use a diagram to help describe the removal of oil from skin using water and soap.

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2. A wide range of cleaning products is made from colloids and surfactants.

a solution and suspension.

2.1.1 Identify some substances that could be used as emulsifying agents.

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2.1.2 (a) Name the emulsion that you prepared in the laboratory.

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(b) Describe the method you used to prepare this emulsion.

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(c) List the tests you carried out on this emulsion to compare its properties to that of a solution and a suspension.

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(d) Compare the properties of your emulsion to the properties of solutions and suspensions.

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(e) Discuss the reliability of your results.

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2.2 State the relationship between the properties of an emulsion and the types of molecules present.

2.2.1

(a) Describe a molecule of water. Use a diagram in your answer.

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(b) Compare a molecule of oil to that of water.

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2.2.2 There are two main types of emulsions. In some emulsions, oil is suspended in water; in other emulsions, water is suspended in oil.

Property Oil-in-water emulsion Water-in-oil emulsion

Solubility in water Soluble (can be diluted)

Feel warm or cool on skin Warm

Usually thin or thick Thicker

Ability to conduct electricity Relatively good conductors

Adding dyes Oil-soluble dyes will spread

Examples

2.2.3

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information about the properties of different emulsions and use available evidence to compare those properties.

2.3.1 (a) Identify two emulsions that you tested.

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(b) Identify the properties you tested and outline how you tested for these properties.

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(c) Explain why you tested those properties.

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(d) Discuss the results of your tests and draw conclusions from these results.

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(e) Discuss the validity of the method you used.

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(f) Discuss the validity of your conclusions.

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2.3.2 A group of students makes two skin creams using different ingredients. They carry out the

Their tests and results are described below.

Test Skin cream A results Skin cream B results

Rub hand cream on your skin and see if it feels cold

Does not feel cold Feels cold

Heat a small quantity of the hand cream in a hot water bath

No change Breaks down

Add a few drops of a water-soluble food dye to the hand cream

Streaks of colour form on the surface of the cream

Colour mixes with cream

(a) State any conclusions you can draw about the skin creams.

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(b) Explain why cream A would be the better cream to use on hands.

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your choice.

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(d) Comment on the reliability of these results.

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(e) Comment on the validity of the conclusions drawn.

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2.3.3 Another group of students decides to compare cream with butter they make from the cream. Their tests and results are shown below.

Test Cream results Butter results

Rub cream and butter (both at room temperature) on your skin and see if it feels cold.

Does feel cold Does not feel cold

Heat a small quantity of the cream and butter in a hot water bath.

Emulsion breaks down Butter melts

Add a few drops of dilute hydrochloric acid to butter and cream.

The cream breaks down Butter breaks down

Add a few drops of a water-soluble food dye to the butter and cream. Mix a little.

Colour spreads evenly through cream

Streaks of colour form on the surface of the butter

Try to mix in 3 mL of water. Water mixes in easily Difficult to add water

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(b) Suggest a way that the students could have made butter from cream.

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emulsion. Use the experimental results to justify this statement.

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2.4 Outline the purpose of the emulsifying agent in a range of consumer cleaning products.

2.4.1

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2.4.2 Distinguish between a surfactant and an emulsifying agent.

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2.4.3

not remove and explain why this is so.

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(b) Identify why soap and detergents improve the cleaning ability of water.

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2.4.4 The diagram below shows the general structure of soap surfactants as consisting of a polar

Complete the following table to describe the properties, structure and uses of the three types of surfactants found in soaps and detergents.

Anionic surfactants Cationic surfactants Non-ionic surfactants

Property

Structure

Use


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2.5 Identify that soaps and detergents are emulsifying agents and surfactants.

2.5.1 (a) Complete the following table to distinguish between soaps and synthetic detergents.

Soaps Detergents

Made from

Structure

Properties

Effect in hard water

(b) Identify two properties of soaps and detergents that make them useful as cleaning agents.

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2.5.2

(a) a surfactant

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(b) an emulsifying agent

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2.5.3 The following diagram models the arrangement of water and surfactant molecules when the surfactant is anionic.

Grease

WaterSurfactant

Draw a diagram to model the arrangement of water and surfactant molecules when the surfactant is cationic.

2.6.1

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2.6.2 Arrange the following three diagrams in the correct order to show the cleaning action of soap or detergent molecules in water. Then label the diagrams.

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grease/oildirty clothes

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2.7.1

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2.8 Discuss the biodegradability of soaps and soapless detergents.

2.8.1 (a) Discuss the biodegradability of soaps.

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2.8.2 Suggest reasons for the development of detergents by chemists.

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2.8.3 Explain why in terms of the structure of detergents. Include diagrams in your answer.

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2.8.4 Modern detergents have lower phosphorus and nitrogen content than early detergents.

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detergents.


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3. Cleaning products used on the human body must be compatible with the physical and chemical properties of the skin.

3.1.1 (a) Identify the instrument you used to examine slides of human skin.

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3.1.2 (a) Label the following diagram to show the main components of human skin.

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–

–

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(b) Identify two things that have been left out of the above diagram. Use your textbook to help you add these to your diagram.

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3.1.3 Complete the following table to compare the functions of some parts of the skin.

Part of skin Function

Excretion of water, minerals and urea. Control of body temperature.

Collect information about temperature and pressure from the environment.

Hair follicle

Oil (sebaceous) glands

Contract to make hairs stand up when it is cold.

Supply food and oxygen to all skin cells and remove their wastes. Bring wastes to sweat glands to be excreted.

3.2 Identify the role of the skin as:

3.2.1 The skin is not very thick (it varies in thickness from 1 mm to 3 mm) and yet it has been

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3.2.2 Describe the way in which the skin helps to control body temperature.

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3.2.3

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3.2.4 Identify reasons why the skin must function as a means of separating the body from the surrounding environment.

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body.

3.3.1on the skin.

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3.3.2

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3.3.3

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3.4 Discuss the term pH in terms of its ability to describe the acidity of a substance.

3.4.1 Outline the meaning of the pH scale.

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3.4.2 Identify the natural pH of the skin and describe how you could measure the skin pH of students in your class.

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3.4.3 Compare the terms base and alkali.

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3.5.1 (a) Identify the skin and hair products which you tested for pH.

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(b) Describe the way in which you tested the pH of these products.

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3.5.2 A group of Year 12 students measured the pH of a range of products. Their results are shown in the table below.

Product pH

Product A 4.6

Product B 6.5

Product C 5.7

Product D 8.0

Product E 7.0

(a) Use a bar graph to represent these results.

(

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(c) Of the products tested, identify the one that is:

(i) of lowest pH .................................................................................................................................................................

(ii) most acidic ....................................................................................................................................................................

(iii) most basic ......................................................................................................................................................................

(iv) least suitable for using on skin ..........................................................................................................................

(v) neutral ..............................................................................................................................................................................

3.6 Explain the relationship between the natural pH of the skin and the action of:

3.6.1 Explain the relationship between the natural pH of the skin and the action of:

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(b) natural oil produced by skin glands

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(c) perspiration

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investigations to test the manufacturer’s claim(s) on a commercial product such as soap, shampoo or shower gel and use the available evidence to analyse the results and discuss the validity of the claim(s).

3.7.1

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(b) Describe how you carried out the test.

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(c) Outline the results you obtained.

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commercial product. Outline the meaning of the term validity in this context.

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(e) Discuss the validity of the claim you tested.

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3.7.2

claim cannot be validated.

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(b) A popular brand of foaming shower gel claims to:

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claim.

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3.7.3 A manufacturer claims that their brand of shampoo (S & S Shampoo) ‘leaves hair feeling soft

was based on responses to a survey given to 1000 women. These are shown below.

Question Answers

Strongly agree

Agree DisagreeStrongly disagree

1. After using S&S Shampoo my hair felt soft. 307 505 155 33

2. After using S&S Shampoo my hair felt like silk. 222 247 335 123

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3.8 Identify and explain the use of common components of body soaps, cleansers and shampoos and the reason for their use.

3.8.1 Complete the following table to explain the reason for the use of some common components of body soaps, cleansers and shampoos.

Common components of soaps, cleansers

and shampoosReasons for their use

Surfactants/emulsifiers

Oils

Fragrances

Dyes

pH balancers

Antimicrobe agents


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4. The nature of a solvent plays an important role in the application of a mixture.

4.1.1

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

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

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(d) Discuss the relevance of pH of the solvent used in this investigation.

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

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4.1.2 A group of Year 12 students decided to test the solubility of three medications in solutions with acidic, basic and neutral pH values. Their results are shown below.

Tablet/capsuleTime to dissolve (minutes)

Acidic Neutral Basic

A (tablet) > 60 > 60 3.5

B (tablet) 1.25 1.30 > 60

C (capsule) Did not dissolve Did not dissolvePartly dissolved after

24 hours

solubility to their digestion and absorption by the body.

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4.1.3

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4.2 Identify water and alcohol as commonly used solvents.

4.2.1 Distinguish between the terms solution, solvent and solute.

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4.2.2 Identify three common substances that dissolve in water.

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4.2.3 Identify three common household substances that dissolve in alcohol.

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4.3 Identify cosmetics and external medications where water is the solvent.

4.3.1 Identify cosmetics and external medications where water is the solvent.

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4.4 Identify cosmetics and external medications where alcohol is the solvent.

4.4.1 Identify cosmetics and external medications where alcohol is the solvent.

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4.4.2 Use the key provided to solve the puzzle below.

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

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

Puzzle:

Solution:

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4.5 Explain the relationship between the properties of solvents and their use in cosmetics and external medications.

4.5.1 Explain the relationship between properties of water and its use in cosmetics and medications.

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4.5.2 Explain the relationship between properties of alcohol and its use in cosmetics and medications.

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4.6 Identify data sources, gather, process, analyse and present information from secondary sources to identify how subdermal implants release their medication into the body.

4.6.1 Explain what is meant by a subdermal implant.

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4.6.2 Identify advantages of using a subdermal implant to administer a drug.

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4.6.3 Identify examples of substances that can be administered by subdermal implants.

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4.6.4 Compare subdermal implants with dermal patches.

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5. The solubility of materials used in drugs has an effect on the way in which the body responds to them.

5.1 Identify the parts of the digestive system.

5.1.1 (a) Describe the function of the digestive system.

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(b) Identify the main types of food.

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(c) Identify the end products formed by the digestion of carbohydrates, proteins and fats.

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5.1.2 (a) The following diagram shows the human digestive system as it would appear if removed

from the body and spread out. It is basically a long tube, which varies in thickness, with associated glands. Label the diagram.

(a)

(b)

(j)

(i)

(h)

(g)

(f)

(e)

(d)

(k)

(c)

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(b) To the above diagram, add the following labels to show the main area where the following processes occur:

5.1.3 Complete the following table to summarise the functions of parts of the digestive system.

Part of digestive system

Function

Teeth

Physically break up .................................................... into small .................................................... .

Salivary glands

Produce an .................................................... which starts the ...........................................................

digestion/breakdown of .................................................... into glucose.

Oesophagus/food pipe

Carries food from the ...................................................... to the ......................................................... .

Stomach

Produces hydrochloric ........................................................................................ and an

.................................................................................... called pepsin which digests/breaks down

.............................................................. into amino acids.

Small intestine

Secretes ..................................................................................... to digest food. Completes the

.................................................. of food. .................................................... digested food through its

walls into .................................................... vessels and.................................................... vessels.

Large intestine

................................................................... food passes .................................. of the body as

.................................. Absorbs .............................................. and some ............................................... .

Anus

Ring of .................................................... at the end of the ................................................ intestine.

Controls the release of .....................................................

Liver

Produces .................................................... which emulsifies (breaks up) .......................................

into small droplets so they can be digested.

Pancreas

Produces .................................................... to digest food in the .....................................................

Gall bladder

Stores .................................................... until it is needed.

5.1.4 The diagrams below show the tiny structures that line the inside of the small intestine.

Lymphvessel

Bloodvessel

Food

Networkof bloodvessels

Wall of small intestine

Tiny structures

Lymphvessel

} }


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(a) Name these tiny structures. ................................................................................................................................................

(b) Describe the role of these structures in obtaining nutrients.

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5.1.5 The following photograph shows a model of the human body. Label the parts indicated.

(f)

(d)

(b)

(g)

(e)

(c)(a) .........................................

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5.2 Discuss the difference in pH of the stomach and small intestine.

5.2.1 (a) Identify the difference in pH of the stomach and small intestine.

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(b) Account for the difference in pH of the stomach and small intestine.

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(

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5.3 Outline the role of the stomach and the small intestine in breaking down food.

5.3.1 Outline the role of the stomach in breaking down food.

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5.3.2 Outline the role of the small intestine in breaking down food.

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5.3.3 (a) Match the following:

Part of digestive system Function

Mouth Completes digestion of all foods

Stomach Starts digestion of carbohydrates

Small Intestine Digestion of proteins

(b) Identify the organs of the digestive system where enzymes are made.

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(c) Complete the following statements:

Digestion occurs in the ......................................, ...................................... and ................................................................ Digested food is absorbed in the .................................................... ..................................................... Undigested food is passed out of the .......................................... .......................................... through the ......................................

digested.

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5.3.4 The following diagrams show three chemical reactions that occur in the human digestive system. For each reaction, identify the raw material or product and state in which organ it occurs.

Chemical reaction Occurs in

(a)

.......................................................... glucose


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(b)

..................................Proteins

(c)

+

................................................ .................................. glycerol

5.4.1 Complete the following table to identify six ways in which medications can enter the body and the area of the body where the chemical will be absorbed.

Medication enters Absorbed by:

Stomach or small intestine

Rectum or vagina – suppositories

Inhaling through nose or mouth – aerosols or ‘puff’ powders

Skin – creams, ointments, dermal patches

Into blood or muscle tissue

Drops – into ear or eye

5.4.2 (a) Identify factors which determine the rate of absorption of medication.

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(b) Explain why the solubility of medication is an important consideration.

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(b) Outline the advantages of using an enteric coating on some medications.

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5.4.4how these work and explain their advantage over conventional tablets.

Slow-release capsuleSlow-release tablet

Outside coating

Thick coating(takes longerto dissolveand release

the medicine)Thin coating(dissolves quickly)

Layers of medicinegradually dissolve

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5.5 Identify that the manner of administration of a drug may be related to its solubility.

5.5.1 (a) Cough mixtures may contain medication that is dissolved in water or alcohol. What

determines the solvent in each case?

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(b) When people take tablets such as aspirin, they are usually advised to dissolve them in water

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5.5.2 Some medications are administered in a form designed to allow them to dissolve slowly so that the person does not receive too big a dose at a time. Identify whether a tablet can be

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5.5.3 (a) Distinguish between a tablet and a capsule.

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(b) Identify an advantage of a capsule.

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5.5.4 (a) Some drugs are administered directly into the blood. Suggest reasons for this.

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(b) Suggest ways that medications can be administered to bypass the intestine and liver and identify examples of drugs administered in these ways.

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(c) Injected drugs can be designed with varying solubility. Elaborate on this statement.

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5.5.5 Some medicines need to be shaken before use. Suggest a reason for this in terms of solubility.

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5.6 Account for the absorption of a drug and its action on/in the body in terms of its solubility.

5.6.1 Account for the absorption of a drug and its action on/in the body in terms of its solubility.

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tasks.

5.7.1 Explain why a knowledge of the solubility of materials can be used to design drugs for

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5.7.2 Identify four factors important in deciding how to design and administer a drug.

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5.8.1 (a) Identify what is meant by a vitamin.

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(b) Name some vitamins and identify their functions in the body.

Vitamin Function

A

B1

B12

C

D

K


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5.8.2

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5.8.3Explain why:

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Notes

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Dot Point HSC Senior Science 175 Answers

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Answers

Answers 176 Dot Point HSC Senior Science

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Lifestyle Chemistry

1.1.1 Various, e.g.Area Chemicals

Food Carbohydrates, proteins, fats, water, minerals, vitamins.

HygieneSoaps, detergents, deodorants, toothpaste, cosmetics, perfume, oven cleaner, ammonia cleaner, window cleaner, carpet cleaner, shampoo, conditioner, skin cleansers.

Entertainment Food, soft drinks, coffee, popcorn, photographic film coatings.

Maintenance of health Aspirin, panadol, antacid, dettol, antibiotics, antifungal preparations, acne preparations, vitamins and minerals.

1.1.2 Type of substance Examples of chemicals

Solvent for fats Sodium hydroxide in oven cleaner

Solvent for sugar Water

Bleach Sodium hypochlorite

Antibacterial agent Ammonium compounds

Acid in citric fruit Citric acid

Abrasive Crushed limestone or quartz

Preservative Sulfur dioxide

Cleaning agent Soap and detergent

Lubricant Grease and oil

1.1.3 (a) A characteristic of a substance.

(b) Physical properties are those that can be found by studying the substance itself rather than its reactions, e.g. hardness, conductivity, malleability, density. Chemical properties describe how a substance reacts, e.g. whether it reacts with water, oxygen or acids and if it decomposes when heated.

(c) (i) physical

(ii) physical

(iii) physical

(iv) chemical

(v) chemical

(vi) physical

1.2.1 Various, e.g.Chemical Use Precautions

Detergents Cleans dishes and clothes. May contain ammonia to kill bacteria.

Often alkaline so are corrosive; keep away from eyes. May be toxic so do not ingest. May cause rashes in some people so wear gloves.

Lubricants Reduces friction between moving parts, e.g. in cars, bikes, machinery.

Some are flammable – keep away from flames.

Pesticides Kills insects such as mosquitoes, flies and cockroaches, spiders, rats.

Toxic – do not swallow, inhale or spill on skin. Store securely away from children.

Solvents Dry-cleaning dissolves dirt on clothes; turps to clean paintbrushes; water to dissolve medicine, e.g. aspirin; drain and oven cleaners to dissolve fat in drains and ovens.

Some are flammable and toxic, e.g. turps and dry-cleaning fluid. Drain and oven cleaners are corrosive and will burn skin badly. Do not swallow, inhale or spill on skin. Store safely in well-ventilated area away from children.

Metal cleaners

Removes tarnish from jewellery, silver cutlery, brass ornaments.

May be toxic or corrosive. Do not swallow, inhale or spill on skin.

Body hygiene chemicals

Soap, deodorant and antiperspirant to reduce body odour; lotions and creams to treat acne; conditioner to reduce hair tangles. Antiseptics (e.g. Dettol, Solyptol and ammonia cleaners) kill bacteria.

Many contain chemicals which are toxic or may cause allergic reactions if eaten or absorbed. Do not swallow.

Cosmetics Perfumes to change the way we smell; make-up with artificial colours to change our appearance; hair spray or gel to keep hair in place.

Many cause allergic reactions in susceptible people. Sprays may be dangerous to inhale.

Preservatives Prevent bacteria growing in food as this will spoil the food and may cause illness if eaten.

Some, e.g. sulfur dioxide may cause asthma; some may cause learning difficulties. Eat minimal amounts.


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1.2.2 Two or more chemicals together in any proportion. The components are not chemically joined together, they keep their own

1.2.3

(b) Sulfur dioxide, vinegar, ethyl diamine.

(c) Water, alcohol, e.g. ethanol, methylated spirits.

(d) Phosphoric acid.

(e) Acids, e.g. hydrochloric, acetic and citric acid to lower pH; bases, e.g. sodium carbonate, sodium hydroxide to raise pH.

(g) Ammonium compounds, sodium hypochlorite, eucalyptus oil, tea tree oil.

1.2.4

OH

H +

OH

H

O

H

H OHH

OH

H

O

H

HOH H

OH

H

OHH

O H

H

OH

H

OH H

OH

H

OH

H

OH

H

OH

H

O H

H

OH

H

OH

H++

+

+

+

+ +

+

++

++

+

+ ++

++

OilAlcoholWater

1.3.1 Mixture Components of mixture (what is in it)

Air Nitrogen, oxygen, argon, carbon dioxide, water vapour and perhaps pollution and dust

Sea water Water, salts such as sodium chloride, plants and animals and perhaps pollution

Soft drink Water, dissolved carbon dioxide, sugar, colouring, flavours

Tea Caffeine, water, sugar and possibly milk

Milk Water, fats, proteins, sugars

Toothpaste Soaps, abrasives (e.g. ground-up limestone), thickeners, water, colour, flavour, glycerol

1.3.2 (a) Solution – mixture of a solute (gets dissolved) and a solvent (does the dissolving) which is the same throughout.

Colloid – mixture that contains particles that remain suspended for a long time (can be an emulsion or a foam).

(b) Solution has dissolved substances so these would not be visible. The solution would look uniform throughout. Suspension and colloid would both contain suspended particles. If both are left standing, the particles will settle out of the suspension, but in the colloid they will remain suspended for a long time.

1.3.3 (a) solution

(b) colloid

(c) solution

(d) suspension

(e) colloid


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1.3.4 (a) Headings should be: (i) Colloid

(ii) Solution

(iii) Suspension

(b) Various, e.g.

Light passes throughwithout scattering?

No

Residue left after filtering?or

Particles settle on standing?

Mixture

Yes

Solution or colloidSuspension

NoYes

ColloidSolution

Made of a liquidsuspended in another

liquid?

NoYes

Foam(gas in liquid)

Emulsion

1.3.5

(b)

Water Oil Oil Water Liquid Gas

(i) (ii) (iii)

1.3.6 (a)Colloid Liquid Gas suspended

beer foam beer air/carbon dioxide

whipped cream milk fats air

soapsuds soapy water air

meringue (pavlova) egg white air

1.4.1 A substance that is made commercially and sold for people to use.


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1.4.2Solution Suspension Colloid

Wine, whisky, nail polish remover, clear apple juice

Pot of tea (with tea leaves), muddy water, orange juice with pulp

Milk, shaving cream, mayonnaise, white coffee, beer foam, whipped cream, toothpaste, hair spray, butter

1.5.1

Secondary sources of information refers to printed materials in the form of books, videos, information on websites,

(b) Various, e.g. you may have used a text book (state author, title, publisher and date); the Internet (identify source

written by your teacher.

You may also have studied substances in the laboratory, in which case you should be able to identify the substances studied and describe the tests you carried out.

1.5.2 (a) Various, e.g. suspension – e.g. a pot of tea with tea leaves, orange juice with pulp included, calamine lotion. Various, e.g. colloid – e.g. milk, mayonnaise, whipped cream, meringue, margarine.

(b) Various, e.g. pot of tea – one advantage of a suspension is that the parts can be separated easily. If the tea is allowed to

Margarine – an advantage is the smooth texture of the colloid. This provides an attractive appearance and allows the margarine to be spread evenly.

1.5.3 Suspension – It must be shaken before use. It allows the powder to be spread evenly over the itchy area of skin caused by

itching.

1.5.4 Helps the fast delivery and absorption of the penicillin.

the particles do not settle out on standing.

(c) Moisturisers are used to replace lost oils and/or prevent skin drying out.

the skin so are useful if it is important not to block the pores, e.g. in teenagers with acne.

e.g. in moisturising sunscreens.

1.6.1 (a) Various, e.g. suspension – oil and vinegar; colloid – mayonnaise.

Other precautions – if you are making a product for people to eat or apply to their skin, ensure that you wash your

1.6.2 Suspension – the oil and water mix and then settle out.

1.6.3 (a) Containers for the ingredients, measuring spoons and cups of the size indicated in the recipe, a mixing bowl, beater or whisk (or a bottle with a lid for shaking the mixture).

prevents the layers settling out.

(c) Vinegar is a solution of acetic acid in water, so water is present even though it was not mentioned.

1.6.4


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1.6.5 (a) The composition throughout the mixture is the same; particles are evenly spread throughout the mixture.

milk is a colloid, the particles of cream are broken up into tiny particles which can stay suspended evenly throughout the milk.

1.7.1

1.7.2Drop of mercuryDrop of water

Unbalanced forces on particles at the surface pull the liquid intoa round/spherical shape. Attractive forces are stronger in mercurythan water.

1.7.3

(b) (i) water

(ii) mercury

(c) Water particles are attracted to each other, but they also have some attraction to glass so they tend to cling to the glass. Mercury particles are attracted to each other more strongly so they pull inwards and have little attraction to glass.

1.7.4

tension so they can walk on still water.

When insects walk on water, their feet make slight indentations in the surface.

Some insects cannot walk on water because the hairs on their legs pierce the surface.

1.8.1

but there is no balancing attraction upwards. Thus the result is for particles to pull together as if there is a skin on the surface.

Particle withunbalancedforces is pulledinto the liquid

Particlewith

balancedforces

1.9.1

(b) Reduces surface tension so the water is better able to wet a surface – it improves the ability of water to clean, allowing water to remove oil or dirt more easily because the water is in closer contact with the dirt.

1.9.2 The razor blade sinks. Detergent is a surfactant, it reduces the surface tension of the water so it can no longer support the razor blade.

1.9.3 (a) Leaf A.

(b) To deliver fertiliser or insecticide to the plant.

(c) The surfactant reduces surface tension so the water stays in closer contact with the leaves.


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1.10.1 (a)

Hydrocarbonnon-polar tail

Polar head

(head) end which may be positively charged, negatively charged or neutral. The hydrocarbon tail is hydrophobic

molecule has one end dissolved in water and the other end dissolved in oil, so the oil can dissolve in the water.

Oil

Polar head in the surrounding water

Hydrocarbonchainin the oil

1.10.2 They all contain molecules such as that shown in Question 1.10.1(a). This acts as a surfactant – it lowers the surface tension

together when they do not normally do so (e.g. oil and water).

1.10.3 The soap acts as a surfactant, reducing surface tension so water can wet the skin.

molecules. This attraction pulls the soap and dirt/oil out of the skin and keeps it suspended in the water so that the oil can be washed away.

Oil

Soap

Soapremovingoil

2.1.1detergents.

2.1.2 (a) Various, e.g. paint emulsion using pigment and water; a skin cream; mayonnaise.

pestle, mix with water and add an emulsifying agent, e.g. egg yolk. You should list the steps you took and include

(c) Various – Identify the solution and suspension you will use for a comparison and describe the tests you carried out.

(d) Tabulate your results and compare them with the table in Question 1.3.4.


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(e) To determine reliability, the experiment needs to be repeated a number of times, either by the same student or different students, using the same method. Comment on whether this occurred for your experiment.

2.2.1 (a) A water molecule is small; it consists of two atoms of hydrogen joined to one atom of oxygen. The water molecule is polar; it is slightly charged.

Hydrogen atom

Oxygen atom

Covalent bond

Water molecule

(b) A molecule of oil is much larger than a molecule of water. It is a hydrocarbon, consisting of many carbon and hydrogen atoms combined together. Oil is an even poorer conductor of electricity than water

2.2.2Property Oil-in-water emulsion Water-in-oil emulsion

Solubility in water Soluble (can be diluted) Insoluble (can not be diluted)

Feel warm or cool on skin Cool Warm

Usually thin or thick Thinner Thicker

Ability to conduct electricity Relatively good conductors Poor conductors

Adding dyesWater-soluble dyes, e.g. food colouring will spread

Oil-soluble dyes will spread

Examples milk, mayonnaise, cream cosmetics, butter, margarine, ointments

2.2.3

emulsion.

2.3.1 (a) Various – you may have tested margarine, milk, skin creams, suntan lotions, paints.

(b) Various – the tests you performed will depend on the emulsion you used.

For example: For skin creams and suntan lotions you might test oiliness, conductivity, ability to cover a surface area, smoothness, whether it washes off, if it feels cool on the skin, whether it makes skin feel smoother, if it can be stained by different types of dyes.

For margarines and butter you might test oiliness, taste, appearance, colour, creaminess, ability to spread evenly and any of the tests suitable for creams and lotions.

(c) For the properties you tested, explain their importance, e.g. people will not buy a paint unless it produces a smooth,

(d) Present your results in the form of a table and describe their implications. For example, if a skin cream leaves an oily layer would people buy and use it?

(e) To decide if your method was valid you should consider whether you controlled all variables except the one you were testing. Did your method really test what you set out to test? For example, if testing for coldness or warmth of a hand cream, did you put each cream on the same part of the body (e.g. back of hand) for each person.

results.

2.3.2 stable to heat.

results are reliable. The experiment needs to be repeated.


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How much cream was placed on the hand, which part of the hand and was it rubbed into the skin?

What was the temperature of the water bath used?

How much food dye was added, was it the same dye in each case and was it stirred?

Also, we cannot draw valid conclusions unless the results are reliable.

2.3.3

this emulsion.

2.4.1

into smaller sizes so they stay suspended. It acts as a surfactant as it allows substances to mix together when they would not normally do so.

2.4.2

An emulsifying agent is a substance that breaks the particles into smaller sizes so they stay suspended. It acts as a surfactant as it allows substances to mix together when they would not normally do so.

2.4.3 (a) Oil, grease, paint. Water is polar, it can dissolve other polar substances and ionic substances, e.g. salt, sugar, alkalis.

(b) Soap and detergents contain chemicals that are surfactants – they allow water to mix with substances such as grease

2.4.4Anionic surfactants Cationic surfactants Non-ionic surfactants

Property Highly sudsing. Excellent cleaning properties.

Breaks cell walls of bacteria (due to am-monium in the head).

Low sudsing.

Structure Negatively charged head and hydrocarbon tail.

Positively charged head and hydrocarbon tail.

Slightly charged head and hydrocarbon tail.

Use Laundry detergents; dishwashing liquids; hair shampoos; adding dyes to textiles; in engine lubricants; keep chemicals suspended in chemicals used in agriculture.

Disinfectants; antiseptic soaps; mouthwashes; nappy washes; antistatic agents; flocculants in sewage treatment.

Laundry detergents; automatic dish-washers; washing cars; cosmetics; paints; adhesives; insecticides and herbicides; extracting minerals (froth flotation).

2.5.1 (a)Soaps Detergents

Made from Fats and oils reacting with sodium or potassium hydroxide. Hydrocarbon chain from petroleum.

Structure Ionic or polar end and long, non-polar hydrocarbon tail. Anionic.

Similar structure – polar head and non-polar hydrocarbon tail. May be anionic, cationic or non-ionic.

Properties Cheaper to make, not very soluble, deteriorate with age,biodegradable.

More expensive, soluble in water, do not deteriorate with age, very stable. Early detergents were not biodegradable, modern ones are.

Effect in hard water

Do not lather well in hard water. Form a scum when washing with hard water.

Lather in hard water. No scum.

2.5.2 (a) A surfactant lowers surface tension. Soap lowers surface tension allowing water to come into closer contact with grease/oil/dirt.


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(b) Emulsifying agents keep particles suspended so they do not settle out. Soap attaches to dirt/oil/grease, pulling it from the clothes or skin and keeping it suspended so the water can carry it away. This occurs because the polar head of the

2.5.3

2.6.1

grease/oil from the surface and keep it suspended in the water so it can be washed away.

2.6.2

Grease being pulled from clothes as heads ofsoap/detergent are attracted to the water

Soap or detergent

Water

Grease/oil

Soap or detergent

Water

Clean clothes

Soap or detergent

Grease broken intosmaller drops andsuspendedin water

Dirty clothes

2.7.1 Able to be broken down by the action of living things, e.g. bacteria and fungi in the environment.

2.8.1 (a) Soaps are biodegradable. They break down when acted on by organisms such as bacteria and fungi. Soaps are

(b)

H

H

HC

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C


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During wars some countries had problems getting the raw materials to make soap, so soap became scarce and expensive.

with a similar structure to soap and thus replace soap.

was needed that could be used more successfully with hard water.

2.8.3tails.

H A branched chain

H

H

C

H

H

HH

H

C

HH

C

C

H

HH

C

H

H

C

C

H

H

C

H

H

C

H

H

C

H

H

H A straight chainC

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

2.8.4fertilisers, allowing rapid growth in the number of algae and other plants in the water. This is called algal bloom.

Eventually the algae die and lots of oxygen (dissolved in the water) is used up as they decay. This leaves the water

and are less likely to cause algal bloom.

Rapid growth ofalgae (calledalgal bloom)

Death of aquaticorganisms

Water becomesstagnant

Decay of algaeuses lots of

dissolved oxygen

As the algaeuse up the

nutrients they die

Increase in solublenitrogen and phosphorus

ions (nitrates andphosphates)

occurs in waterways

Water pollution,e.g. sewage,

fertiliser, detergentinto waterways

3.1.1 (a) Light microscope.

(b) Probably low power (×100) or possibly high power (×400).

3.1.2 (a)

Subcutaneoustissue

Dermis

Epidermis

Sweat glandOil glandMuscle

Hair follicleFatty tissue Hair follicle

Blood vessels

Nerves

(b) Nerves and blood vessels.


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3.1.3 Part of skin Function

Sweat glands Excretion of water, minerals and urea. Control of body temperature.

Nerve endings Collect information about temperature and pressure from the environment.

Hair follicles Growth of hair.

Oil (sebaceous) glands Make slightly acidic oil to protect the skin.

Hair muscles Contract to make hairs stand up when it is cold.

Blood vessels Supply food and oxygen to all skin cells and remove their wastes. Bring wastes to sweat glands to be excreted.

3.2.1 An organ is a structure composed of a number of types of tissue that work together to carry out a function in the body. Skin consists of nerve, muscle, gland and connecting tissues. These work together to perform a number of functions including separating the body from the external environment, assisting in body temperature control and protecting against entry by

3.2.2 In hot weather, more sweat is excreted from the skin. This evaporates. The heat needed to make the sweat evaporate comes

near the surface, bringing heat from the body and helping it cool down.

In cold weather, blood vessels in the skin constrict (close down) keeping blood deeper in the body so it stays warm and less sweat is produced. When cold the body shivers, the muscles contract to produce heat and hairs rise to trap air close to the body and maintain warmth (goose bumps).

3.2.3 The skin cells are physically packed close together to prevent microbes entering the body.

Oil glands produce an oily layer which helps prevent entry and also has a slightly acid pH of between 4 to 6, in which range most bacteria cannot survive.

Salty sweat produced by sweat glands can help to dehydrate some bacteria.

3.2.4

To keep microbes out of the body. To protect against excess light.

3.3.1Cornybacterium acnes (bacteria found in hair follicles), and Candida albicans (a fungus that thrives between toes, in mouth and vagina).

3.3.2the surface of our skin and by competing with pathogens.

3.3.3although some such as staphylococcus become dangerous if the skin is broken and they enter the blood. Dry areas of the skin have a relatively small population but moist areas, e.g. armpits have a larger population of microbes.

Washing the skin removes many organisms, but it is soon repopulated by those living in hair follicles and sweat glands.

The presence of the harmless microbes on skin helps to stop more harmful microbes becoming established. During illness, or when taking drugs such as antibiotics and the pill, our natural colonies of microbes are killed off and it becomes easier for other harmful organisms to invade.

3.4.1 pH is measured on a scale from 0 to 14. The position on the pH scale describes how acidic or basic a substance is. A pH of 7 is neutral. A pH below 7 is acidic and a pH above 7 is basic.

3.4.2indicator. Compare the colour with the colour chart. Wash off.

3.4.3 An alkali is a base that is soluble in water. They both refer to substances with a pH > 7.

3.5.1 (a) Various, e.g. soaps, shampoos, conditioners, moisturisers, skin cleansers, shower gels, and detergents for dishwashers and washing machines.

(b) Various – You may have dissolved a measured amount of each substance in water and added a few drops of an indicator, e.g. universal indicator, or used pH paper. You could also have used a pH meter or a pH probe and data logger.


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3.5.2 (a) pH of tested products.

2

4

6

8

A B C D E

pH

Products tested

(c) (i) A (ii) A (iii) D (iv) D (v) E

3.6.1

skin so they are able to live there. In fact, they contribute to the maintenance of the acidic pH of the skin by their secretions.

(b) Natural pH of the skin is within the range of 4.5 to 6, which is slightly acidic. This is largely due to the production

producing acids as part of their metabolism.

(c) Natural pH of the skin is within the range of 4.5 to 6, which is slightly acidic. Sweat contributes to this acidity. The pH of sweat can vary, e.g. sweat produced when you are hot tends to be more acidic than sweat produced during exercise and sweat produced by fear tends to be even more acidic (even lower pH).

3.7.1

(b) Various, e.g. For pH – Dissolve a small amount of the product in water. Use an indicator, pH meter, or probe to determine the pH. Repeat with another sample.

(c) Various, e.g. you may have found the pH of the product was 5.5.

(d) Is the claim fair? For example, does the shampoo really have the claimed pH of 5.5?

or close to that on the product label, then the claim was valid.

3.7.2claim is that the hair will be shinier than it was before using the shampoo, or shinier than after using another brand of

Ability to cleanse the skin can be tested either by measuring the amount of grease/dirt removed by the product or by

(c) Use a large sample of volunteers to test the shampoo. The sample should include males and females as well as people of all ages and from all groups of the population. Each volunteer would be asked to use the product to wash his or

it on the hair for the same length of time, wash it off the same way and dry it the same way. After using the product, each subject would try to comb the hair and rate it on a scale of 2 to 5, where 1 means no tangles and 5 means lots of tangles.


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3.7.3

There is no information as to how the people to be tested were selected or how they used the product.

The claim that hair feels soft after using S&S Shampoo is supported by these results as 81.2 per cent of those surveyed stated that their hair felt soft.

However, it is not known whether their hair was already soft before using the shampoo or if other shampoos left the hair feeling just as soft. The claim of hair feeling like silk is not supported by these results. 479 women said their hair felt like silk,

Also, it is not known whether their hair was already silky before using the shampoo or if other shampoos left the hair feeling just as silky.

3.8.1 Common components of soaps,

cleansers and shampoosReasons for their use

Surfactants/emulsifiers To help water attach to and remove oil particles and dirt, and allow the water to carry these away.

Oils To replace natural skin oils and protect the skin or hair from becoming dry.

Fragrances To make the product more attractive to consumers.

Dyes To make the product more attractive to consumers.

pH balancers To maintain the skin pH between 4 and 6.

Antimicrobe agents To destroy or slow the growth of microbes, e.g. those that cause dandruff, disease and/or body odour.

4.1.1

with a measured volume of water, timing how long it took for each capsule or tablet to dissolve. This experiment could have been carried out at different temperatures and different pH values.

(b) Independent – type of capsule/tablet; Dependent – time taken for capsule or tablet to dissolve.

(c) Various, e.g. size of capsules/tablets (same surface area); volume of solvent, e.g. water; pH; temperature.

(d) If the tablet/capsule is designed to dissolve in the mouth or small intestine it should be soluble in alkaline solution; if it is to dissolve in the stomach then it should be soluble in acidic solution.

(e) Various – when you tabulate information be sure to rule lines between columns, under headings and to rule off. You

4.1.2solutions. This tablet is designed to resist the acidic conditions of the stomach and start to dissolve in the alkaline conditions of the small intestine.

Tablet B was more soluble in acidic and neutral conditions (1.25 and 1.30 minutes) than in basic solution (more than an hour).

The capsule C was insoluble in acidic and neutral solutions and very slow to dissolve in basic solution. This is designed for

4.1.3 Slow release is an advantage when the medicine is needed all the time, e.g. for relief from constant pain and when the medication would be harmful if absorbed in a large amount at one time. It ensures a constant, low level dosage of the drug.

4.2.1 Solution is the mixture produced when a solvent dissolves a solute. The solute is the substance that gets dissolved, e.g. sugar; the solvent does the dissolving, e.g. water; the solution is the product.

4.2.2 Sugar, salt, bicarbonate of soda.

4.2.3

4.3.1 Shampoos, moisturisers, shower gels.

4.4.1 Perfumes, cough syrups, after shave lotions and skin toners.

4.4.2 Water is a universal solvent.


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4.5.1 Water is a polar substance and it is able to dissolve such a wide range of polar and ionic substances that it has been called the universal solvent. This makes water very useful for:

4.5.2

commercially as a solvent in medicines, e.g. antiseptic iodine is a solution of iodine dissolved in alcohol; in perfumes; hair sprays and insect repellants. It is especially useful for these purposes as it has a lower boiling point than water and thus evaporates more readily. Also it dissolves some medications that are not soluble in water.

4.6.1 A device placed under the skin to release drugs into the body at a controlled rate.

4.6.2 The person receives the drug regularly at a controlled rate.

No need to remember to take the drug.

The drug goes directly into the bloodstream – this bypasses the digestive system.

No injection is needed.

4.6.3 Hormones for contraceptive purposes; insulin for diabetics.

4.6.4 Dermal patches are attached to the skin so the drug goes directly into the bloodstream at a controlled rate. Dermal patches are easier to supply and remove than subdermal implants if the person or doctor decides they are no longer needed. However, they are only useful for drugs with molecules small enough to pass through the skin, e.g. nicotine.

5.1.1 (a) To break up food molecules until they are small enough to enable them to pass through the walls of the blood vessels and into the blood and from there into cells.

(b) Carbohydrates, proteins, fats, water, vitamins, minerals.

(c) Carbohydrates – glucose; proteins – amino acids; fats – fatty acids and glycerol.

5.1.2 (a) and (b)(a) Mouth

(b) Food pipe

(j) Bile duct

(i) Gall bladder

(h) Liver

(g) Salivary glands

(l) Appendix

(f) Anus

(e) Large intestine

(d) Small intestine

(k) Pancreas

(c) StomachDigestion of proteins

Digestion of carbohydrates

Digestion of carbohydratesDigestion of fatsAbsorption of most digested foods by villi


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5.1.3Part of digestive system Function

Teeth Physically break up food into small pieces.

Salivary glands Produce an enzyme which starts the chemical digestion/breakdown of starch into glucose.

Oesophagus/food pipe Carries food from the mouth to the stomach.

StomachProduces hydrochloric acid and an enzyme called pepsin which digests/breaks down proteins into amino acids.

Small intestineSecretes enzymes to digest food. Completes the digestion of food. Absorbs digested food through its walls into blood vessels and lymph vessels.

Large intestine Undigested food passes out of the body as faeces. Absorbs water and some vitamins.

Anus Ring of muscle at the end of the large intestine. Controls the release of faeces.

Liver Produces bile which emulsifies (breaks up) fats into small droplets so they can be digested.

Pancreas Produces enzymes to digest food in the small intestine.

Gall bladder Stores bile until it is needed.

5.1.4 (a) Villus (plural villi). (b) The villus absorbs digested food from the small intestine. It projects into the cavity of the small intestine, increasing

the surface area. The increased surface area makes absorption faster. The blood vessels in the villus absorb glucose and amino acids. The lymph vessels in the villus absorb fatty acids and glycerol.

5.1.5

(f) Large intestine

(d) Liver

(b) Heart

(g) Small intestine

(e) Stomach

(c) Ribs(a) Lungs

5.2.1 (a) The pH of the stomach is lower as it is acidic (approximately 2). The pH of the small intestine is above 7, it is alkaline (approximately 8).

(b) Hydrochloric acid, produced by the walls of the stomach produces this low pH.

The pH of the small intestine is above 7, it is alkaline due to the secretion of alkaline bile by the liver.

(c) The enzyme pepsin in the stomach can only digest/break down proteins into amino acids if it is in an acidic solution.

The alkaline environment in the small intestine is essential for the enzymes there to complete the digestion of food as they can only work in an alkaline (basic) solution.

5.3.1 The stomach walls produce an enzyme called pepsin which digests proteins, breaking them down into smaller molecules called amino acids. The enzyme pepsin will only work in an acidic solution. The stomach walls produce hydrochloric acid to aid digestion.

5.3.2 The small intestine produces enzymes to digest carbohydrates and fats. Enzymes also enter the small intestine from the pancreas. These enzymes only work in an alkaline solution. The liver makes bile which is alkaline. This comes down the bile duct into the small intestine so that digestion can take place there.

5.3.3 (a)

Part of digestive system Function

Mouth Starts digestion of carbohydrates

Stomach Digestion of proteins

Small Intestine Completes digestion of all foods


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(b) Salivary glands, stomach, small intestine, pancreas.

(c) mouth, stomach and small intestine; small intestine; large intestine, anus

(d) Carbohydrates glucose Proteins amino acids Fats fatty acids and glycerol

5.3.4 Chemical reaction Occurs in

(a)

glucoseCarbohydrates

mouth and small intestine

(b)

Proteins amino acids

stomach

(c)

+

glycerolFats fatty acids

mouth and small intestine

5.4.1 Medication enters Absorbed by

Mouth – liquid, tablet or capsule Stomach or small intestine

Rectum or vagina – suppositories Lining skin cells

Inhaling through nose or mouth – aerosols or ‘puff’ powders Cells lining the nasal passages and lungs

Skin – creams, ointments, dermal patches Skin cells and into blood

Injection Into blood or muscle tissue

Drops – into ear or eye Tissues of ear or eye – direct to affected site

5.4.2 (a) Way in which it is administered, e.g. spray, injection, cream, dermal patch, suppository, tablet (with or without coating); solubility; size of its molecules; rate at which it can diffuse across cell membranes; whether the environment is acidic, basic or neutral.

(b) Solubility determines the rate of absorption of the medication, how it is absorbed and the place and mode of

5.4.3 (a) Tablet coated with a polymer that will not dissolve in water or acidic solution, such as stomach acid, but will dissolve in alkaline solution.

(b) Some medicines such as aspirin can cause damage to the wall of the stomach and others are unstable in acidic conditions. These are covered with an enteric coating that will not dissolve in the stomach acid. When it reaches the alkaline intestine, it dissolves and releases the medicine for absorption.

5.4.4 The tablet has a number of layers each containing the active ingredient, so that it is released a bit at a time; the capsule contains a number of pellets, each with a different thickness outside layer so that the active ingredient of each pellet is

more even rate. This is better than having a large amount of medication and then nothing until the next tablet is taken. This is an advantage in chronic conditions where relief can be gained for a longer period.

5.5.1 (a) The solubility of the medication in water and alcohol.

case of aspirin it is also less likely to damage the walls of the stomach if it is already dissolved.

5.5.2 Yes, if too slow, it may pass out of the intestine before it has all dissolved.


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5.5.3powdery medication together.

noticeable if they are in a capsule; some medications are not soluble in water, they can be dissolved in some other solvent and enclosed in a capsule.

5.5.4of no use.

down medications into a form that will not do what was intended.

(b) Injection, e.g. insulin and some antibiotics; placing under the tongue/in the mouth, e.g. nitroglycerine for chest pain; inhaling, e.g. asthma medication.

(c) Some drugs are injected in a form that is very soluble if an immediate response is needed.

dissolving crystalline form.

5.5.5 The medication is insoluble so is present as a suspension and will settle on standing. Shaking provides for mixing so that there

5.6.1 Drugs/medication can only be absorbed and travel to where they are needed via the blood if they are soluble. This is necessary so they can pass across cell membranes to enter cells and/or the blood or lymph.

injected straight into the blood and travels in the blood to the liver.

Medications which are insoluble can be applied externally, e.g. to a rash or burn.

5.7.1 The solubility of a drug determines how, where and how fast a drug can be absorbed. This affects how and where we will

stomach for fast pain relief. However, this can damage the stomach walls. Aspirin in alkaline solution is soluble in water. An enteric tablet may be used for administering aspirin – the coating of the tablet prevents it from dissolving in stomach acid but allows it to dissolve in the small intestine. There it is absorbed slowly through the intestine walls.

5.7.2 Speed of relief needed; ease of access to the area to be treated; solubility of the drug; ease of administering the drug.

5.8.1 provided in the diet as it cannot be made by the body.

(b)

Vitamin Function

A Vision especially in dim light; necessary for immune system

B1 Release of energy from carbohydrates

B12 Formation of DNA and red blood cells

C Absorption of iron; release of stress hormones

D Absorption of calcium to make strong bones

K Needed for blood to clot

5.8.2

5.8.3

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