Mike Cole i7 HODDER EDUCATION

Mike Cole
i7
HODDER
EDUCATION

Biolo Laboratory Practical Book Mike Cole i7 HODDER EDUCATION AN HACHET TE UK COMPANY

Biolo
Laboratory
Practical Book
Mike Cole
i7
HODDER
EDUCATION
AN HACHET TE UK COMPANY

Safety checked but not trialled by CLEAPSS A health and safety check for this text has been carried out. However, the Publishers accept no legal responsibility on any issue arising from this check; whilst every effort has been made to carefully check the instructions for practical work described in this book, it is still the duty and legal ob ligation of schools to carry out their own risk assessment in accordance with local health and safety requirements. ® IGCSE is the registered trademark of Cambridge International Examinations. Answers to selected questions can be found at www .hoddereducation.com/cambridgeextras This text has not been through the Cambridge endorsement process. The Publishers would like to thank the following for permission to reproduce copyright material: Questio ns from the Cambridge I GCSE Biology papers are reproduced by kind permission of Cambridge International Examination Papers . Cambridge International Examinations bears no responsibility for the example answers to questions taken from its past question papers which are contained in this publication. Photo credits p.1 © sciencephotos I Alamy; p . 34 © D.G. Mackean; p . 130 © D.G. Mackean Every effort has been made to trace all copyright holders, but if any have been inadvertently overlooked the Publishers will be pleased to make the necessary arrangements at the first opportunity. Although every effort has been made to ensure that website addresses are correct at time of going to press, Hodder Education cannot be held responsible for the content of any website mentioned in this book. It is sometimes possible to find a relocated web page by typing in the address of the home page for a website in the URL window of your browser. Hachette UK's policy is to use papers that are natural, renewable and recyclable products and made from wood grown in sustainable forests. The logging and manufacturing processes are expected to conform to the environmental regulations of the country of origin. Orders: please contact Bookpoint Ltd, 130 Milton Park, Abingdon, Oxon OX14 458. Telephone: ( 44) 01235 827720. Fax: (44) 01235 400454. Lines are open 9.00- 5.00, Monday to Saturday, with a 24-hour message answering service. Visit our website at www.hoddereducation.com © Mike Cole 2015 First published in 2015 by Hodder Education An Hachette UK Company Carmelite House 50 Victoria Embankment London EC4Y ODZ Impression number 5 4 3 2 1 Year 2017 2016 2015 All rights reserved. Apart from any use permitted under UK copyright law, no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, or held within any information storage and retrieval system, without permission in writing from the publisher or under licence from the Copyright Licensing Agency Limited. Further details of such licences ( for reprographic reproduction) may be obtained from the Copyright Licensing Agency Limited, Saffron House, 6-10 Kirby Street, London EClN 8TS. Cover photo © mathisa - Fotolia Typeset in 9 on 14pt Frutiger LT Std 45 Light by lntegra Software Services Pvt. Ltd., Pondicherry, India Printed and bound by CPI Group (UK) Ltd, Croydon, CRO 4YY A catalogue record for this title is available from the British Library I SB N: 978 1 4441 9161 5

Safety checked but not trialled by CLEAPSS
A health and safety check for this text has been carried out. However, the Publishers accept no legal
responsibility on any issue arising from this check; whilst every effort has been made to carefully check the
instructions for practical work described in this book, it is still the duty and legal ob ligation of schools to
carry out their own risk assessment in accordance with local health and safety requirements.
® IGCSE is the registered trademark of Cambridge International Examinations.
Answers to selected questions can be found at www .hoddereducation.com/cambridgeextras
This text has not been through the Cambridge endorsement process.
The Publishers would like to thank the following for permission to reproduce copyright material:
Questio ns from the Cambridge I GCSE Biology papers are reproduced by kind permission of Cambridge
International Examination Papers . Cambridge International Examinations bears no responsibility for the
example answers to questions taken from its past question papers which are contained in this publication.
Photo credits p.1 © sciencephotos I Alamy; p . 34 © D.G. Mackean; p . 130 © D.G. Mackean
Every effort has been made to trace all copyright holders, but if any have been inadvertently overlooked
the Publishers will be pleased to make the necessary arrangements at the first opportunity.
Although every effort has been made to ensure that website addresses are correct at time of going to
press, Hodder Education cannot be held responsible for the content of any website mentioned in this
book. It is sometimes possible to find a relocated web page by typing in the address of the home page for
a website in the URL window of your browser.
Hachette UK's policy is to use papers that are natural, renewable and recyclable products and made from
wood grown in sustainable forests. The logging and manufacturing processes are expected to conform to
the environmental regulations of the country of origin.
Orders: please contact Bookpoint Ltd, 130 Milton Park, Abingdon, Oxon OX14 458. Telephone: ( 44) 01235
827720. Fax: (44) 01235 400454. Lines are open 9.00- 5.00, Monday to Saturday, with a 24-hour
message answering service. Visit our website at www.hoddereducation.com
© Mike Cole 2015
First published in 2015 by
Hodder Education
An Hachette UK Company
Carmelite House
50 Victoria Embankment
London EC4Y ODZ
Impression number 5 4 3 2 1
Year 2017 2016 2015
All rights reserved. Apart from any use permitted under UK copyright law, no part of this publication
may be reproduced or transmitted in any form or by any means, electronic or mechanical, including
photocopying and recording, or held within any information storage and retrieval system, without
permission in writing from the publisher or under licence from the Copyright Licensing Agency Limited.
Further details of such licences ( for reprographic reproduction) may be obtained from the Copyright
Licensing Agency Limited, Saffron House, 6-10 Kirby Street, London EClN 8TS.
Cover photo © mathisa - Fotolia
Typeset in 9 on 14pt Frutiger LT Std 45 Light by lntegra Software Services Pvt. Ltd., Pondicherry, India
Printed and bound by CPI Group (UK) Ltd, Croydon, CRO 4YY
A catalogue record for this title is available from the British Library
I SB N: 978 1 4441 9161 5

Contents ('\ 0 z -I m z -I I.I> Experimental skills and abilities Skills for scientific enquiry 1 Using and organising techniques, apparatus and materials 1 Observing, measuring and recording 5 Handling experimental observations and data 7 Planning, carrying out and evaluating investigations 9 Experiments 1 Characteristics and classification of living organisms 1.1 Dichotomous keys 13 2 Organisation and maintenance of the organism 2 .1 Plant cells 17 2.2 Animal cells 20 3 Movement in and out of cells 3 .1 Osmosis and water flow 23 3.2 Turgor in potato tissue 27 3.3 Osmosis and tu rg or 30 3.4 Plasmolysis 34 3.5 Partial permeability 37 4 Biological molecules 4.1 Food tests 40 4.2 Application of the food tests 45 5 Enzymes 5 .1 Extracting and testing an enzyme 48 5.2 The effect of temperature on enzyme activity 51 5.3 The effect of pH on enzyme activity 55 iii

Contents
('\
0
z
-I
m z
-I
I.I>
Experimental skills and abilities
Skills for scientific enquiry 1
Using and organising techniques, apparatus and materials 1
Observing, measuring and recording 5
Handling experimental observations and data 7
Planning, carrying out and evaluating investigations 9
Experiments
1 Characteristics and classification of living organisms
1.1 Dichotomous keys 13
2 Organisation and maintenance of the organism
2 .1 Plant cells 17
2.2 Animal cells 20
3 Movement in and out of cells
3 .1 Osmosis and water flow 23
3.2 Turgor in potato tissue 27
3.3 Osmosis and tu rg or 30
3.4 Plasmolysis 34
3.5 Partial permeability 37
4 Biological molecules
4.1 Food tests 40
4.2 Application of the food tests 45
5 Enzymes
5 .1 Extracting and testing an enzyme 48
5.2 The effect of temperature on enzyme activity 51
5.3 The effect of pH on enzyme activity 55
iii

6 Plant nutrition V'I I- z w I- z 6 .1 Is chlorophyll necessary for photosynthesis? 59 0 V 6.2 Is light necessary for photosynthesis? 63 6.3 Is carbon dioxide necessary for photosynthesis? 66 6 .4 Is oxygen produced during photosynthesis? 70 6.5 Th e effect of light intensity on the rate of photosynthesis 73 6.6 Gas exchange during photosynthesis 76 6.7 Th e importance of different mineral elements 79 7 Human nutrition 7 .1 Energy from food 83 8 Transport in plants 8 .1 Tr ansport in vascular bundles 87 8.2 Rates of water uptake in different conditions 90 8.3 To find which surface of a leaf loses more water vapour 94 9 Transport in animals 9 .1 Physical activity and pulse rate 97 10 Diseases and immunity 11 Gas exchange in humans 11.1 Oxygen in exhaled air 102 11. 2 Carbon dioxide in exhaled air 106 11 .3 Volume of air in the lungs 109 12 Respiration 12.1 Using up oxygen during respiration 112 12.2 Releasing energy in respiration 116 1 2.3 Anaerobic respiration in yeast 119 iv

V'I 6 Plant nutrition
I- z
w
I- z 6 .1 Is chlorophyll necessary for photosynthesis? 59
0
V
2 Is light necessary for photosynthesis? 63
3 Is carbon dioxide necessary for photosynthesis? 66
.4 Is oxygen produced during photosynthesis? 70
5 Th e effect of light intensity on the rate of photosynthesis 73
6 Gas exchange during photosynthesis 76
7 Th e importance of different mineral elements 79
Human nutrition
.1 Energy from food 83
Transport in plants
.1 Tr ansport in vascular bundles 87
2 Rates of water uptake in different conditions 90
3 To find which surface of a leaf loses more water vapour 94
Transport in animals
.1 Physical activity and pulse rate 97
Diseases and immunity
Gas exchange in humans
1 Oxygen in exhaled air 102
2 Carbon dioxide in exhaled air 106
.3 Volume of air in the lungs 109
Respiration
1 Using up oxygen during respiration 112
2 Releasing energy in respiration 116
2.3 Anaerobic respiration in yeast 119
iv

13 Excretion in humans ('\ 0 z -I m z 14 Co - ordination and response -I I.I> 14.1 Gravitropism in pea radicles 124 14.2 Phototropism in shoots 127 14.3 Region of response 1 30 15 Drugs 16 Reproduction 16 .1 Insect-pollinated flowers 1 34 16.2 Th e growth of pollen tubes 1 36 16.3 Germination: the need for water 140 16 .4 Temperature and germination 143 17 Inheritance 18 Variation and selection 19 Organisms and their environment 20 Biotechnology and genetic engineering 20 .1 Th e effect of pectinase on fruit pulp 1 50 21 Human influences on ecosystems Past exam questions Practical Test past exam questions 155 Alternative to Practical past exam questions 165 V

13
Excretion in humans ('\
0
z
-I
m z
14 Co - ordination and response -I
I.I>
14.1 Gravitropism in pea radicles 124
14.2 Phototropism in shoots 127
14.3 Region of response 1 30
15
Drugs
16
Reproduction
16 .1 Insect-pollinated flowers 1 34
16.2 Th e growth of pollen tubes 1 36
16.3 Germination: the need for water 140
16 .4 Temperature and germination 143
17 Inheritance
18
Variation and selection
19
Organisms and their environment
20 Biotechnology and genetic engineering
20 .1 Th e effect of pectinase on fruit pulp 1 50
21 Human influences on ecosystems
Past exam questions
Practical Test past exam questions 155
Alternative to Practical past exam questions 165
V

Author's acknowledgment With thanks to, and in memory of, D. G. Mackean (1926-2013) whose first book, Introduction to Biology, transformed the appearance of school textbooks in 1962 and who, though this and other books including GCSE Biology and /GCSE Biology, i nspired biology students around the world for over 50 years.

Author's acknowledgment
With thanks to, and in memory of, D. G. Mackean (1926-2013) whose first book,
Introduction to Biology, transformed the appearance of school textbooks in 1962 and who,
though this and other books including GCSE Biology and /GCSE Biology, i nspired biology
students around the world for over 50 years.

Skills for scientific enquiry Introduction The aim of this book is to help you develop the skills and abilities needed to pe r form practical laboratory work. We start by introducing the apparatus and measuring techniques that you will use most often. Then we show you how to make and record measurements accurately. Methods for handling the observations and data you have collected will then be described. Finally we discuss how to plan, carry out and evaluate an investigation. You should then be ready to work successfully through the experiments and laboratory activities that follow. Using and organising techniques, apparatus and materials In an experiment you will first have to decide on the measurements to be made and then collect together the apparatus and materials required. The quantities you will need to measure most often in laboratory work are mass , length and tim e. • What apparatus should you use to measure each of these? • Which measuring device is most suitable for the task in hand? • How do you use t he device correctly? Balances A balanc e is used to measure the mass of an object. There are several types available. • In a beam balance the unknown mass is placed in one pan and balanced against known masses in the other pan. • In a lever balance a system of levers acts against the mass when it is placed in the pan. • A digital top-pan balance, which gives a direct reading of Fi gure 1 A digi ta l top-pan the mass placed on the pan, is shown in the diagram. ba lance 1

Skills for scientific enquiry
Introduction
The aim of this book is to help you develop the skills and abilities needed to pe r form
practical laboratory work. We start by introducing the apparatus and measuring techniques
that you will use most often.
Then we show you how to make and record measurements accurately. Methods for
handling the observations and data you have collected will then be described.
Finally we discuss how to plan, carry out and evaluate an investigation. You should then be
ready to work successfully through the experiments and laboratory activities that follow.
Using and organising techniques, apparatus
and materials
In an experiment you will first have to decide on the measurements to be made and then
collect together the apparatus and materials required. The quantities you will need to
measure most often in laboratory work are mass , length and tim e.
• What apparatus should you use to measure each of these?
• Which measuring device is most suitable for the task in hand?
• How do you use t he device correctly?
Balances
A balanc e is used to measure the mass of an object. There
are several types available.
• In a beam balance the unknown mass is placed in
one pan and balanced against known masses in the
other pan.
• In a lever balance a system of levers acts against the
mass when it is placed in the pan.
• A digital top-pan balance, which gives a direct reading of Fi gure 1 A digi ta l top-pan
the mass placed on the pan, is shown in the diagram. ba lance
1

• The unit of mass is the kilogram (kg). V'I w j:: ::::; • The gram (g) is one-thousandth of a kilogram: 1 g = 111000kg = 10 - 3 kg = 0.001 kg. iii • The smallest mass that can be measured on the scale setting you are using is probably 1g <{ 0 z or 0.1 g. <{ ..... V'I ..... Ruler and vernier scales ),! ..... V'I j:! • The unit of length is the metre (m). z w • Sub multiples are: ~ 0::: w 1decimetre (dm) = 10-1 m c.. X w 1centimetre (cm)= 10 -2 m o -3 1 millimetre (mm) = 1 m o-6 1 micrometre (μm) = 1 m 1 kilometre (km)= 10::lm • A ruler is often used to measure lengths in the centimetre range. • The correct way to measure with a ruler is shown in Figure 2, with the ruler placed as close to the object as possible. co rrect ~ w,ong ' ' ,,.' ! . 11 / 70 80 ruler --- Figure 2 The reading is 76mm or 7.6cm. Y ou r eye mu st be direct ly above the mark on the sca le or the thi ckne ss of the ruler ca u ses parallax errors. • Some instruments such as barometers and microscopes have a vernier scale to enable small lengths to be measured, usually to 0.1 mm. • One end of the length to be measured is made to coincide with the zero of the millimetre scale and the other end with the zero of the vernier scale. 2

V'I • The unit of mass is the kilogram (kg).
w
j::
::::; • The gram (g) is one-thousandth of a kilogram: 1 g = 111000kg = 10 - 3 kg = 0.001 kg.
iii
<{ • The smallest mass that can be measured on the scale setting you are using is probably 1g
0 z or 0.1 g.
<{
..... ..... V'I
Ruler and vernier scales
),!
..... V'I
j:!
z • The unit of length is the metre (m).
w
~ • Sub multiples are:
0::: w 1decimetre (dm) = 10-1 m
c..
X
w
1centimetre (cm)= 10 -2 m
o -3
1 millimetre (mm) = 1 m
o-6
1 micrometre (μm) = 1 m
1 kilometre (km)= 10::lm
• A ruler is often used to measure lengths in the centimetre range.
• The correct way to measure with a ruler is shown in Figure 2, with the ruler placed as
close to the object as possible.
co rrect ~
w,ong
' '
,,.'
!
. 11 /
70 80
ruler ---
Figure 2 The reading is 76mm or 7.6cm. Y ou r eye mu st be direct ly above the mark on the sca le or
the thi ckne ss of the ruler ca u ses parallax errors.
• Some instruments such as barometers and microscopes have a vernier scale to enable
small lengths to be measured, usually to 0.1 mm.
• One end of the length to be measured is made to coincide with the zero of the millimetre
scale and the other end with the zero of the vernier scale.
2

vernier scale mm scale VI 2:5 ..... ..... ..,, VI 0 ::,:, VI 0 m z 5 10 -I :;; r'i m z 0 C ::6 -< 10 20 mm Figure 3a A vernier scale is a small sliding scale that is 9mm long but divided into 10 equal divisions: 1 vernier division= 9/ 10 mm = 0. 9mm = 0.09cm object 0 A B I I I I I I I I {, I I {, 5 + I 10 10 20 mm Figure 3b The length of the object is between 1. 3 and 1.4cm. The reading to the next decimal place is found by finding the vernier mark that exactly lines up with a mark on the millimetre scale. H ere it is the 6th mark and so the length of the object is 1. 36cm since: OA: 08-AB = 1. 90cm - (6 vernier divisions) = 1. 90 - (6 x 0.09)cm = 1. 90 - 0.54cm = 1. 36cm Clo c ks and timers • Clocks, watches and timers can be used to measure time inte rva ls . In an experiment it is important to choose the correct timing device for the required measurement. • The unit of time is the second(s) . • A stop wa tch will be sufficient if a time in minutes or seconds is to be measured, but if times of less than a second are to be determined then a dig it a l timer is necessary. 3

vernier scale mm scale VI
2:5
.....
.....
..,,
VI
0
::,:,
0 VI
m z
5 10 -I
:;;
r'i
m z
0
C
::6
-<
10 20
mm
Figure 3a A vernier scale is a small sliding scale that is 9mm long but divided into 10 equal divisions:
1 vernier division= 9/ 10 mm = 0. 9mm = 0.09cm
object
0 A B
I I
I I
I I
I I
I {,
I
{,
5 + I 10
10 20
mm
Figure 3b The length of the object is between 1. 3 and 1.4cm. The reading to the next decimal place
is found by finding the vernier mark that exactly lines up with a mark on the millimetre scale. H ere
it is the 6th mark and so the length of the object is 1. 36cm since:
OA: 08-AB
= 1. 90cm - (6 vernier divisions)
= 1. 90 - (6 x 0.09)cm
= 1. 90 - 0.54cm
= 1. 36cm
Clo c ks and timers
• Clocks, watches and timers can be used to measure time inte rva ls . In an experiment it is
important to choose the correct timing device for the required measurement.
• The unit of time is the second(s) .
• A stop wa tch will be sufficient if a time in minutes or seconds is to be measured, but if
times of less than a second are to be determined then a dig it a l timer is necessary. 3

V'I • When using a stopwatch, reaction times may influence the reading . w j:: ::::; • For time intervals of the order of seconds, a more accurate result may be obtained by iii measuring longer time intervals - for example, time pulse rate over 60 seconds rather <{ 0 z than over 15 seconds and then calculate an average value. <{ ..... • To measure very short time intervals, a digital timer that can be triggered to start and stop V'I ..... by an electronic signal from a microphone, photogate or mechanical switch is useful. ),! ..... V'I j:! z Changing measurements w ~ • Take readings more frequently if values are 0::: w c.. changing rapidly. X w • It will often be helpful to work with a partner who watches the timer and calls out when to take a read i ng. • Pressing the lap-timer facility on the stopwatch at the moment you take a reading freezes the time display for a few seconds and will meniscus -- -;- _.,... enable you to record a more accurate time measurement. • For rapidly changing measurements it may be necessary to use a tickertape timer or a datalogger and computer. Measuring cylinders Figure 4 When making a rea din g th e • The volume of a liquid can be obtained by m eas uring cylinder sho uld be ve rti ca l pouring it into a measuring cylinder. and yo ur eye sho uld be level with th e • Measuring cylinders are often marked in bo tt om of th e c urv ed liquid s ur face - th e millilitres (ml) where 1 millilitre= 1 cm 3 meni sc us. (F or mercury th e meni sc us . 3 3 fo rmed is c urv ed o pp os it ely to th at of • Note that 1 litre= 1000cm = 1 dm . o th er liquids a nd you shou Id read th e level of th e t op of th e meni sc us in a Safety m erc ur y therm o met er or baromet e r.) Here are a few simple precautions to help ensure your safety when carrying out experiments in the laboratory. • Always wear shoes - to protect your feet if a heavy weight should fall on them. • Hot liquids and solids - set in a safe position where they will not be accidentally knocked over; handle with caution to avoid burns . • Toxic materials - materials such as mercury are tox ic; ta ke care not to allow a mercury thermometer to roll onto the floor and break . • Tie back long hair - to prevent it being caught in a flame. • Personal belongings - leave in a sensible place so that no one will trip over them! • Protect eyes and skin from contact with corrosive and harmful chemicals - any reagent used for any of the ex periments in this book must be treated with caution. Ask for y our teacher's advice before handling them. Sodium hydrox ide, hydrochloric 4

V'I • When using a stopwatch, reaction times may influence the reading .
w
j::
::::; • For time intervals of the order of seconds, a more accurate result may be obtained by
iii
<{ measuring longer time intervals - for example, time pulse rate over 60 seconds rather
0 z than over 15 seconds and then calculate an average value.
<{
..... V'I • To measure very short time intervals, a digital timer that can be triggered to start and stop
.....
),! by an electronic signal from a microphone, photogate or mechanical switch is useful.
..... V'I
j:!
z Changing measurements
w
~
0::: • Take readings more frequently if values are
c.. w
X changing rapidly.
w
• It will often be helpful to work with a partner
who watches the timer and calls out when to
take a read i ng.
• Pressing the lap-timer facility on the stopwatch
at the moment you take a reading freezes
the time display for a few seconds and will meniscus -- -;- _.,...
enable you to record a more accurate time
measurement.
• For rapidly changing measurements it may
be necessary to use a tickertape timer or a
datalogger and computer.
Measuring cylinders
Figure 4 When making a rea din g th e
• The volume of a liquid can be obtained by
m eas uring cylinder sho uld be ve rti ca l
pouring it into a measuring cylinder. and yo ur eye sho uld be level with th e
• Measuring cylinders are often marked in bo tt om of th e c urv ed liquid s ur face - th e
millilitres (ml) where 1 millilitre= 1 cm 3 meni sc us. (F or mercury th e meni sc us
.
• Note that 1 litre= 1000cm 3 = 1 dm 3 fo rmed is c urv ed o pp os it ely to th at of
.
o th er liquids a nd you shou Id read th e
level of th e t op of th e meni sc us in a
Safety
m erc ur y therm o met er or baromet e r.)
Here are a few simple precautions to help ensure your safety when carrying out
experiments in the laboratory.
• Always wear shoes - to protect your feet if a heavy weight should fall on them.
• Hot liquids and solids - set in a safe position where they will not be accidentally
knocked over; handle with caution to avoid burns .
• Toxic materials - materials such as mercury are tox ic; ta ke care not to allow a mercury
thermometer to roll onto the floor and break .
• Tie back long hair - to prevent it being caught in a flame.
• Personal belongings - leave in a sensible place so that no one will trip over them!
• Protect eyes and skin from contact with corrosive and harmful chemicals - any
reagent used for any of the ex periments in this book must be treated with caution.
Ask for y our teacher's advice before handling them. Sodium hydrox ide, hydrochloric
4

acid, pyrogallic acid, enzyme solutions, iodine, Benedict's reagent and other chemicals VI 2:5 ..... suggested in this book must be handled with care. Alcohol (ethanol) is flammable. ..... ..,, VI • Bun se n flam es and flamma bl e liquids - use the safety flame, or turn the Bunsen ~ burner off when not in use. Make sure the Bunsen flame is out before handl i ng flammable VI 0 liquids, such as alcohol (ethanol). An alternative may be to heat water up using a kettle. m z -I • Biologic al organism s a nd mate ri a ls - ensure biological organisms and materials are :;; r'i sourced and stored appropriately and handled with care. Ensure suitable disposal, as m z 0 appropriate. Wear eye protection and gloves. Avoid hand to mouth contact and wash C ::6 hands thoroughly after practical activities. -< Observing, measuring and recording Having collected together and familiarised yourself with the equipment and materials needed for an experiment, you are now ready to start making some observations and measurements. • It will be helpful at this stage to draw a clearly labelled diagram of the experimental set-up. • You should also r ecord any difficulties encountered in carrying out the experiment and any precautions taken to achieve accuracy in your measurements. • Do not dismantle the equipment until you have completed the analysis of your results and are sure you will not have to repeat any measurements! • How many significant figures will your data have? • How will you record your results? Make a list of the apparatus you use in an experiment and record the smallest division of the scale of each measuring device. Significant figures Every measurement of a quantity is an attempt to find its true value and is subject to errors arising from the limitations of the apparatus and the experimental procedure. • The number of figures given for a measurement, called significa nt figures, indicates how accurate we think it is. More figures should not be given than are justified. • For example, a measurement of 6.7 has two significant figures. The measurement 0.235 has three significant figures, the 2 being most significant and the 5, which we are least sure about (since it could be 4 or 6), being the least significant. • When doing calculations your answer should have the same number of si gnificant figures as the measurements used in the calculation. For example, if your calculator gives an answer of 1.23578, this would be 1.2 if your measurements have two significant figures and 1.24 if your measurements have three significant figures. • Note that in deciding the least significant figure you look at the following figure. If that is less than 5, yo u round down (1.23 becomes 1.2) but if it is 5 or above, you round up (1.235 becomes 1.24). • If a number is expressed in standard notation, the number of significant figures is the number 2 of digits before the power of 10. For example, 6.24 x 10 has three significant figures. • If values with different numbers of significant figures are used to calculate a quantity, 5 quote your answer to the smallest number of significant figures.

acid, pyrogallic acid, enzyme solutions, iodine, Benedict's reagent and other chemicals VI
2:5
.....
suggested in this book must be handled with care. Alcohol (ethanol) is flammable. .....
..,,
VI
• Bun se n flam es and flamma bl e liquids - use the safety flame, or turn the Bunsen
~
burner off when not in use. Make sure the Bunsen flame is out before handl i ng flammable
0 VI
liquids, such as alcohol (ethanol). An alternative may be to heat water up using a kettle. m z
-I
• Biologic al organism s a nd mate ri a ls - ensure biological organisms and materials are :;;
r'i
sourced and stored appropriately and handled with care. Ensure suitable disposal, as m
z
appropriate. Wear eye protection and gloves. Avoid hand to mouth contact and wash 0
C
::6
hands thoroughly after practical activities. -<
Observing, measuring and recording
Having collected together and familiarised yourself with the equipment and materials needed
for an experiment, you are now ready to start making some observations and measurements.
• It will be helpful at this stage to draw a clearly labelled diagram of the experimental set-up.
• You should also r ecord any difficulties encountered in carrying out the experiment and
any precautions taken to achieve accuracy in your measurements.
• Do not dismantle the equipment until you have completed the analysis of your results
and are sure you will not have to repeat any measurements!
• How many significant figures will your data have?
• How will you record your results?
Make a list of the apparatus you use in an experiment and record the smallest division of the
scale of each measuring device.
Significant figures
Every measurement of a quantity is an attempt to find its true value and is subject to errors
arising from the limitations of the apparatus and the experimental procedure.
• The number of figures given for a measurement, called significa nt figures, indicates
how accurate we think it is. More figures should not be given than are justified.
• For example, a measurement of 6.7 has two significant figures. The measurement 0.235
has three significant figures, the 2 being most significant and the 5, which we are least
sure about (since it could be 4 or 6), being the least significant.
• When doing calculations your answer should have the same number of si gnificant
figures as the measurements used in the calculation. For example, if your calculator
gives an answer of 1.23578, this would be 1.2 if your measurements have two
significant figures and 1.24 if your measurements have three significant figures.
• Note that in deciding the least significant figure you look at the following figure. If that
is less than 5, yo u round down (1.23 becomes 1.2) but if it is 5 or above, you round up
(1.235 becomes 1.24).
• If a number is expressed in standard notation, the number of significant figures is the number
of digits before the power of 10. For example, 6.24 x 10 2 has three significant figures.
• If values with different numbers of significant figures are used to calculate a quantity,
quote your answer to the smallest number of significant figures. 5

Systematic errors V'I w j:: ::::; iii The figure shows part of a ruler used to measure <{ 0 the height of a point P above the bench. z <{ • The ruler has a space of length x before the ..... V'I ..... zero of the scale. ),! = ..... V'I • The height of the point P scale reading + x j:! z = 5.9 +x. w ~ • By itself the scale reading is not equal to the 0::: w x. height of P; it is too small by the amount c.. X w • An error of this type is called a systematic error because it is introduced by the system. N • A half-metre ruler does not have a systematic error because its zero is at the end of the rule . • When using a rule to measure a height, the -,- :x rule must be held so that it is vertical. If it is I at an angle to the vertical then a systematic ••••••••••• bench error will be introduced. Figur e 5 In trodu ci ng a sys tem at ic error in to a • Check for any zero error when using a measureme nt measuring device. If it cannot be eliminated, correct your readings by adding or subtracting the zero error to them. Tables If several measurements of a quantity are being made, draw up a table in which to record your results. • Use the column headings, or start of rows, to name the measurement and state its unit. For example, in Experiment 9.1 (see page 97) you will use a table similar to one below to record your results. • Repeat the measurement of each obse r vation if possible and record the values in your table. If repeat measurements for the same quantity are significantly different, take a third reading . Calculate an average value from your readings. • Numerical values should be given to the number of significant figures appropriate to the measuring device . Column heading Repeat1 Repeat 2 Avera ge 6

V'I Systematic errors
w
j::
::::;
iii The figure shows part of a ruler used to measure
<{
0 z the height of a point P above the bench.
<{
• The ruler has a space of length x before the
..... ..... V'I
zero of the scale.
),! =
..... V'I • The height of the point P scale reading + x
j:!
z = 5.9 +x.
w
~ • By itself the scale reading is not equal to the
c.. 0::: w height of P; it is too small by the amount x.
X
w • An error of this type is called a systematic
error because it is introduced by the system.
N
• A half-metre ruler does not have a systematic
error because its zero is at the end of the rule .
• When using a rule to measure a height, the -,-
:x
rule must be held so that it is vertical. If it is
I
at an angle to the vertical then a systematic ••••••••••• bench
error will be introduced. Figur e 5 In trodu ci ng a sys tem at ic error in to a
• Check for any zero error when using a measureme nt
measuring device. If it cannot be eliminated,
correct your readings by adding or subtracting
the zero error to them.
Tables
If several measurements of a quantity are being made, draw up a table in which to record
your results.
• Use the column headings, or start of rows, to name the measurement and state its unit.
For example, in Experiment 9.1 (see page 97) you will use a table similar to one below to
record your results.
• Repeat the measurement of each obse r vation if possible and record the values in your
table. If repeat measurements for the same quantity are significantly different, take a third
reading . Calculate an average value from your readings.
• Numerical values should be given to the number of significant figures appropriate to the
measuring device .
Column heading Repeat1 Repeat 2 Avera ge
6

Handling experimental observations VI 2:5 ..... ..... ..,, and data VI ~ VI Now that you have collected your measurements you will need to process them. Perhaps 0 m z there are calculations to be made or you will decide to draw a graph of your results. -I :;; r'i Then you can summarise what you have learnt from the experiment, discuss sources of m z experimental error and draw some conclusions from the investigation. 0 C ::6 • What is the best way to process your results? -< • Are there some inconsistent measurements to be dealt with? • What experimental errors are there? • What conclusions, generalisations or patterns can you draw? Calculations You may have to produce an average value to process your results. Averages Sum the values for a quantity you have measured and divide the sum by the number of values to obtain the average. • For example, if you measure the length of a branch as 81.5cm and 81.6cm, then: (81.5 + = ---- 81.6) the average value 2 163.1 cm = 2 = 81.55cm = 81.6cm • The value has been given to three significant figures because that was the accuracy of the individual measurements. Graphs Graphs can be useful in finding the relationship between two quantities. • You will need about six data points taken over as large a range as possible to plot a graph. • Choose scales that make it easy to plot the points and use as much of the gr aph paper as possible. • Make sure you label each axis of the graph with the name and unit of the quantity being plotted. • Mark the data points clearly with a circle or a cross, using a sharp pencil. • Join up your points with a smooth line or curve. 7

Handling experimental observations VI
2:5
.....
.....
and data ..,, VI
~
VI
Now that you have collected your measurements you will need to process them. Perhaps 0
m z
there are calculations to be made or you will decide to draw a graph of your results. -I
:;;
Then you can summarise what you have learnt from the experiment, discuss sources of r'i
m z
experimental error and draw some conclusions from the investigation. 0
C
• What is the best way to process your results? ::6
-<
• Are there some inconsistent measurements to be dealt with?
• What experimental errors are there?
• What conclusions, generalisations or patterns can you draw?
Calculations
You may have to produce an average value to process your results.
Averages
Sum the values for a quantity you have measured and divide the sum by the number of
values to obtain the average.
• For example, if you measure the length of a branch as 81.5cm and 81.6cm, then:
= ---- (81.5 + 81.6)
the average value
2
163.1 cm
=
2
=
81.55cm
=
81.6cm
• The value has been given to three significant figures because that was the accuracy of the
individual measurements.
Graphs
Graphs can be useful in finding the relationship between two quantities.
• You will need about six data points taken over as large a range as possible to plot a graph.
• Choose scales that make it easy to plot the points and use as much of the gr aph paper as
possible.
• Make sure you label each axis of the graph with the name and unit of the quantity being
plotted.
• Mark the data points clearly with a circle or a cross, using a sharp pencil.
• Join up your points with a smooth line or curve.
7

One student's experimental data is displayed below: ~ j:: ::::; iii Light Intensity <{ 0 {arbitrary units} R ate of Photosynth es is {arbitra ry units} z <{ 0 0 ..... V'I ..... 1.0 2.0 ),! ..... V'I 2.0 4.0 j:! z 3.0 6.0 w ~ 4.0 7.8 0::: w c.. 5.0 8.0 X w 9 B C 8 7 6 Rate of 5 Ph otosy nthe sis 4 (Arbitrary Unit s) 3 2 0 0 1 2 3 4 5 Light In tensity (Arbitrary Unit s) Figure 6 Graph sho wing effect of light inten s ity o n the rate of ph otosy nthe sis. • When the readings in the table are used to plot a graph, a distinctive shape is formed. • Between points A and B, an increase in light intensity results in an increase in the rate of photosynthesis. • Between points B and C the rate of photosynthesis levels off. Errors • In practice, points plotted on a graph from actual measurements may not lie exactly on a straight line or curve of a graph due to experimental errors. • The 'best fit line' is then drawn through them, if appropriate. • If possible, r epeat any anomalous measurements to check that they have been recorded properly or try to identify the reason for the anomaly. Conclusions Once you have analysed your experimental results, summarise your conclusions clearly and relate them to the aim of the experiment. • State whether a hypothesis has been verified. If your results do not, or only partially, support a h ypothesis, suggest reasons why. • If a numerical value has been obtained, state it to the correct number of significant figures. Compare your results with known values if available and suggest reasons for any 8 differences .

~ One student's experimental data is displayed below:
j::
::::;
iii Light Intensity
<{
0 {arbitrary units} R ate of Photosynth es is {arbitra ry units}
z
<{ 0 0
..... V'I
.....
1.0 2.0
),!
..... V'I 2.0 4.0
j:!
z 3.0 6.0
w
~ 4.0 7.8
0::: w
c.. 5.0 8.0
X
w
9
B C
8
7
6
Rate of 5
Ph otosy nthe sis
4
(Arbitrary Unit s)
3
2
0
0 1 2 3 4 5
Light In tensity (Arbitrary Unit s)
Figure 6 Graph sho wing effect of light inten s ity o n the rate of ph otosy nthe sis.
• When the readings in the table are used to plot a graph, a distinctive shape is formed.
• Between points A and B, an increase in light intensity results in an increase in the rate
of photosynthesis.
• Between points B and C the rate of photosynthesis levels off.
Errors
• In practice, points plotted on a graph from actual measurements may not lie exactly on a
straight line or curve of a graph due to experimental errors.
• The 'best fit line' is then drawn through them, if appropriate.
• If possible, r epeat any anomalous measurements to check that they have been recorded
properly or try to identify the reason for the anomaly.
Conclusions
Once you have analysed your experimental results, summarise your conclusions clearly and
relate them to the aim of the experiment.
• State whether a hypothesis has been verified. If your results do not, or only partially,
support a h ypothesis, suggest reasons why.
• If a numerical value has been obtained, state it to the correct number of significant
figures. Compare your results with known values if available and suggest reasons for any
8 differences .

• State any relationships discovered or confirmed between the variables you have VI .... 2:5 .... investigated. ..,, VI • Mention any patterns or trends in the data. ~ • Identify and comment on sources of error in the experiment. For example, it may be very VI 0 difficult to eliminate all heat losses to the environment in a heat experiment; if that is the m z -I case, say so. Mention any sources of systematic error in the experiment. :;; r'i m z Planning, carrying out and evaluating 0 C ::6 -< investigations • Before you start an experiment it is important to define an aim and produce a logical and safe plan for the investigation. • You should identify the variables in the investigation and decide which ones to manipulate and which ones you should try to keep constant. To discover the relationship between variables you should change only one variable at a time. • Once you know what you will need to measure, you can decide on the apparatus and materials to be used. You should ensure that your measuring devices have sufficient accuracy for the job required. • Before you start the experiment, familiarise yourself with how to use the apparatus and develop a plan of work. It will be helpful to decide how to record your results; draw up tables in which to record your measurements if appropriate. • Describe how you carried out the experiment under 'Method' in your laboratory notes. It is useful to include a sketch of the experimental set-up here for future reference. • When you have obtained your results, manipulate data, draw graphs and ca r ry out the calculations needed to fulfil the aims of the experiment. • Then analyse your results and clearly state your conclusions from the investigation. • Finally, evaluate the experiment and discuss how it could be improved. Could some things have been done better? If so, suggest changes or modifications that could be made to the procedure or the equipment used in the investigation. 9

• State any relationships discovered or confirmed between the variables you have VI
.... 2:5
....
investigated.
..,,
VI
• Mention any patterns or trends in the data.
~
• Identify and comment on sources of error in the experiment. For example, it may be very
0 VI
difficult to eliminate all heat losses to the environment in a heat experiment; if that is the m z
-I
case, say so. Mention any sources of systematic error in the experiment. :;;
r'i
m z
Planning, carrying out and evaluating 0
C
::6
-<
investigations
• Before you start an experiment it is important to define an aim and produce a logical and
safe plan for the investigation.
• You should identify the variables in the investigation and decide which ones to manipulate
and which ones you should try to keep constant. To discover the relationship between
variables you should change only one variable at a time.
• Once you know what you will need to measure, you can decide on the apparatus and
materials to be used. You should ensure that your measuring devices have sufficient
accuracy for the job required.
• Before you start the experiment, familiarise yourself with how to use the apparatus and
develop a plan of work. It will be helpful to decide how to record your results; draw up
tables in which to record your measurements if appropriate.
• Describe how you carried out the experiment under 'Method' in your laboratory
notes. It is useful to include a sketch of the experimental set-up here for future
reference.
• When you have obtained your results, manipulate data, draw graphs and ca r ry out the
calculations needed to fulfil the aims of the experiment.
• Then analyse your results and clearly state your conclusions from the investigation.
• Finally, evaluate the experiment and discuss how it could be improved. Could some
things have been done better? If so, suggest changes or modifications that could be
made to the procedure or the equipment used in the investigation.
9

V'I w Questions j:: ::::; iii <{ 0 1 What measuring device would you use to obtain values for: z <{ ..... (a) the volume of liquid in a coffee mug V'I ..... ),! ..... V'I j:! z (b) the mass of an apple w ~ 0::: w c.. X w (c) the length of the pendulum of a grandfather clock (d) the temperature of a cup of tea (e) the time taken to run up 20 stairs (f) the time taken by an apple to fall through one metre (g) the dimensions of a textbook. 2 How would you obtain a value for: (a) the average time for one oscillation of the pendulum of a clock (b) the average mass of a pin? -+ 10

V'I w Questions
j::
::::;
iii
<{
0 z 1 What measuring device would you use to obtain values for:
<{
..... V'I (a) the volume of liquid in a coffee mug
.....
),!
..... V'I
j:!
z
w (b) the mass of an apple
~
0::: w
c..
X
w
(c) the length of the pendulum of a grandfather clock
(d) the temperature of a cup of tea
(e) the time taken to run up 20 stairs
(f) the time taken by an apple to fall through one metre
(g) the dimensions of a textbook.
2 How would you obtain a value for:
(a) the average time for one oscillation of the pendulum of a clock
(b) the average mass of a pin?
-+
10

VI 2:5 3 Complete the table below by stat in g the typical sma ll est d ivision of scale of each ..... ..... ..,, of the measuring devices li sted . VI ~ Device Smallest division of scale VI 0 metre ruler m z -I vernier scale :;; r'i stopwatch m z 0 digital t im er C ::6 digi tal balance -< liquid-in-g lass thermometer 100ml measuring cyl in der 4 Wri te the number 9.753864 to : (a) 3 sign ifi cant figures .......................................... . (b) 2 sign ifi cant figures .......................................... . (c) 1 sign ifi cant figure .......................................... . 5 The measurements in the table below were obta ined, during a student's school science exper im ent . Rate of Photosynthesis Temperature { °C ) {arbitrary units) 0 0 10 2.0 20 4.0 30 4.0 40 2.0 50 0.0 (a) (i) State the vari ab l es being measured. (ii) Name a vari ab le that must be kept fixed. (iii) Compl ete the following tab le: Manipulated variable Fixed variable Responding variable 11

2:5 VI
3 Complete the table below by stat in g the typical sma ll est d ivision of scale of each .....
.....
of the measuring devices li sted . ..,, VI
~
Device Smallest division of scale
0 VI
metre ruler m z
vernier scale :;; -I
r'i
stopwatch m
z
0
digital t im er
C
::6
digi tal balance -<
liquid-in-g lass thermometer
100ml measuring cyl in der
4 Wri te the number 9.753864 to :
(a) 3 sign ifi cant figures .......................................... .
(b) 2 sign ifi cant figures .......................................... .
(c) 1 sign ifi cant figure .......................................... .
5 The measurements in the table below were obta ined, during a student's school
science exper im ent .
Rate of Photosynthesis
Temperature { °C ) {arbitrary units)
0 0
10 2.0
20 4.0
30 4.0
40 2.0
50 0.0
(a) (i) State the vari ab l es being measured.
(ii) Name a vari ab le that must be kept fixed.
(iii) Compl ete the following tab le:
Manipulated variable Fixed variable Responding variable
11

V'I w (b) Plot a graph of temperature on the horizontal axis and rate of photosynthesis j:: ::::; iii on the vertical axis. <{ 0 z <{ ..... V'I ..... ),! ..... V'I <{ I- z w ~ 0::: w c.. X w nn nn n t (c) What can you conclude about the relationship between temperature and rate of photosynthesis over the temperature range given 7 12

w V'I
j:: (b) Plot a graph of temperature on the horizontal axis and rate of photosynthesis
::::;
iii on the vertical axis.
<{
0 z
<{
..... ..... V'I
),!
..... V'I
<{
I- z
w
~
0::: w
c..
X
w
nn nn n
t
(c) What can you conclude about the relationship between temperature and
rate of photosynthesis over the temperature range given 7
12

1 Characteristics and classification of living organisms 1.1 Dichotomous keys Aim To produce a dichotomous key for the identification of tree leaves . Theory Dichotomous keys help us to identify species. quince oak gingko biloba holly ash acacia willow hor se che st nut magnolia li me Figure 1 A range of l eaves 13

1 Characteristics and
classification of living organisms
1.1 Dichotomous keys
Aim
To produce a dichotomous key for the identification of tree leaves .
Theory
Dichotomous keys help us to identify species.
quince oak gingko biloba
holly ash acacia willow
hor se che st nut magnolia li me
Figure 1 A range of l eaves
13

V'I Apparatus :E !!! z 4: D paper CJ ex: D 0 pencil CJ z D ruler 5 ::::; D the leaf drawings from page 13, or actual specimens of a range of leaves u.. 0 z 0 Procedure ~ !:,,! u.. ii'i 1 Research a range of dichotomous keys using library resources or the internet. ~ ...I V 2 Observe the range of leaves and consider the key characteristics of each. 0 z 4: 3 Think about the characteristics that are most useful for placing the leaves into different V'I V groups. j:: V'I iii: 4 Produce a dichotomous key. You might find it helpful to produce a draft on a piece of w I- rough paper first. ~ ex: 4: 5 Draw your final dichotomous key in the Results section on the next page. ::c: V Safety! Ensure that you wash your hands after handling the leaves. Method Complete the following sentences: 1 Each stage of a dichotomous key presents the reader with .................................... choices. [1] 2 In order to produce an effective dichotomous key it is important to identity the .................... - .............. and .................................... between organisms, so that they can be placed into groups. [1] 14

V'I Apparatus
:E
!!! z
4: D
CJ paper
ex:
0 D pencil
CJ z D
5 ruler
::::; D
the leaf drawings from page 13, or actual specimens of a range of leaves
u..
0
z
0 Procedure
~
!:,,!
u..
ii'i
1 Research a range of dichotomous keys using library resources or the internet.
~
...I
V 2 Observe the range of leaves and consider the key characteristics of each.
0 z
4: 3 Think about the characteristics that are most useful for placing the leaves into different
V'I
V groups.
j::
iii: V'I 4 Produce a dichotomous key. You might find it helpful to produce a draft on a piece of
w
I-
~ rough paper first.
ex:
4: 5 Draw your final dichotomous key in the Results section on the next page.
::c:
V
Safety!
Ensure that you wash your hands after handling the leaves.
Method
Complete the following sentences:
1 Each stage of a dichotomous key presents the reader with .................................... choices. [1]
2 In order to produce an effective dichotomous key it is important to identity the
.................... - .............. and .................................... between organisms, so that they can be
placed into groups. [1]
14

- - Results Present your completed dichotomous key below. [2) Conclusions Test your key using a range of different leaves provided by your teacher. Ensure that you wash your hands af t er handling the leaves. How effective is your key? [1) 15

-
-
Results
Present your completed dichotomous key below. [2)
Conclusions
Test your key using a range of different leaves provided by your teacher. Ensure that you
wash your hands af t er handling the leaves. How effective is your key? [1)
15

Evaluation V'I :E !!! z 4: Having tested your key, is there anything you would change? [1] CJ ex: 0 CJ z 5 ::::; u.. 0 z 0 ~ !:,,! u.. ii'i ~ ...I V 0 z 4: V'I V j:: V'I iii: Extension w I- ~ ex: 4: Create another dichotomous key to identify specimens of shells. [2] ::c: V 16

V'I Evaluation
:E
!!! z
4:
CJ Having tested your key, is there anything you would change? [1]
ex:
0
CJ z
5
::::;
u..
0
z
0
~
!:,,!
u..
ii'i
~
...I
V
0 z
4:
V'I
V
j::
iii: V'I
w Extension
I-
~
ex:
4: Create another dichotomous key to identify specimens of shells. [2]
::c:
V
16

2.1 Plant cells Aim To observe plant cells using a light microscope. Theory Plant cells contain: cell wall, cell membrane, cytoplasm, nucleus, sap vacuole and chloroplasts. Apparatus D goggles D forceps D onion D microscope slide and cover slip D 0.01 M iodine solution D light microscope Procedure 1 Wear eye protection. Cover any cuts with waterproof dressings or wear gloves. 2 Using forceps, remove a small piece of epidermis from the inside of an onion scale. 3 Place the tissue on a clean microscope slide. 4 Add a drop of weak iodine solution. 5 Gently place a cover slip on the tissue. 6 View under a light microscope. 7 Wash hands throughly after activity. Method Complete the following sentences: 1 Care had to be taken when using iodine because [1] ................................................................................................................................................. . .......................... 17

2.1 Plant cells
Aim
To observe plant cells using a light microscope.
Theory
Plant cells contain: cell wall, cell membrane, cytoplasm, nucleus, sap vacuole and chloroplasts.
Apparatus
D
goggles
D
forceps
D
onion
D
microscope slide and cover slip
D
0.01 M iodine solution
D
light microscope
Procedure
1 Wear eye protection. Cover any cuts with waterproof dressings or wear gloves.
2 Using forceps, remove a small piece of epidermis from the inside of an onion scale.
3 Place the tissue on a clean microscope slide.
4 Add a drop of weak iodine solution.
5 Gently place a cover slip on the tissue.
6 View under a light microscope.
7 Wash hands throughly after activity.
Method
Complete the following sentences:
1 Care had to be taken when using iodine because [1]
................................................................................................................................................. . .......................... 17

:E 2 Iodine was used because [1] !!:? z ~ C, ,:,:: 0 w 3 In order to view the plant cells clearly, the magnification needs to be [1] ::c: 1- .... 0 w V z ~ z Results w 1- z <( :E Draw and label a sample of two or three of the cells as seen under the mi croscope. [2] 0 z ~ z Q ~ !!:? z ~ ~ ,:,:: 0 N Conclusions The parts of the plant cells that are clearly visible under the light microscope are [2] 18 .................................................................................................................................................................................. .

:E 2 Iodine was used because [1]
!!:? z
~
C,
,:,::
0
w 3 In order to view the plant cells clearly, the magnification needs to be [1]
::c:
1- ....
0
w
z V
z ~ Results
w
1- z
<(
:E Draw and label a sample of two or three of the cells as seen under the mi croscope. [2]
0 z
~
z
Q
~
!!:? z
~
,:,:: ~
0
N
Conclusions
The parts of the plant cells that are clearly visible under the light microscope are [2]
18 .................................................................................................................................................................................. .

- Evaluation .,, N ~ z Outline how this experiment could be improved, or made more reliable. [2) -I ('\ ,.... m ,.... V\ Extension 1 Observe a range of specialised cells under a light microscope. In particula r, look at root hair cells and xylem vessels. Explain how you think these are adapted to their function. [2] 2 View a cross-section of a dicotyledonous leaf under the microscope. Draw and label the cellular and tissue structures that you observe. [2) 19

-
Evaluation .,, N
~
z
Outline how this experiment could be improved, or made more reliable. [2)
-I
('\ m ,....
,....
V\
Extension
1 Observe a range of specialised cells under a light microscope. In particula r,
look at root hair cells and xylem vessels. Explain how you think these are adapted
to their function. [2]
2 View a cross-section of a dicotyledonous leaf under the microscope. Draw and
label the cellular and tissue structures that you observe. [2)
19

Animal cells 2.2 :E !!:? z ~ C, ,:,:: 0 w ::c: Aim 1- .... 0 w V z To observe an i mal cells using a light microscope. ~ z w 1- z Theory <( :E 0 z The nucleus, cytoplasm and cell membrane of animal cells can be viewed under a light ~ z microscope. Q ~ !!:? Apparatus z ~ ~ ,:,:: D 0 sterile cotton bud N D microscope slide and cover slip D beaker containing 70 % ethanol (or 1 % VirKon solution) D methylene blue solution D light microscope D beaker of disinfectant D goggles Procedure 1 Wear eye protection. 2 Gently rub the cotton bud on the inside of your cheek. 3 Rub the bud onto a clean microscope slide . 4 Discard the cotton bud into a beaker of absolute alcohol (ethanol). 5 Cover the smear on the microscope slide with a few drops of methylene blue and place the cover slip over the top. 6 View the sl ide under a light microscope. 7 When finished, place the microscope slide in a beaker of appropriate disinfectant. 8 Wash hands throughly after activity. Method Complete the following sentences : 1 Alcohol (ethanol) and disinfectant are used to ensure that [1] 20

:E 2.2 Animal cells
!!:? z
~
C,
,:,::
0
w
::c:
1- .... Aim
0
w
z V To observe an i mal cells using a light microscope.
z ~
w
1- z Theory
<(
:E
0 z The nucleus, cytoplasm and cell membrane of animal cells can be viewed under a light
~
z microscope.
Q
~
!!:? z Apparatus
~
,:,:: ~ D
0 sterile cotton bud
N D
microscope slide and cover slip
D
beaker containing 70 % ethanol (or 1 % VirKon solution)
D
methylene blue solution
D
light microscope
D
beaker of disinfectant
D
goggles
Procedure
1 Wear eye protection.
2 Gently rub the cotton bud on the inside of your cheek.
3 Rub the bud onto a clean microscope slide .
4 Discard the cotton bud into a beaker of absolute alcohol (ethanol).
5 Cover the smear on the microscope slide with a few drops of methylene blue and place
the cover slip over the top.
6 View the sl ide under a light microscope.
7 When finished, place the microscope slide in a beaker of appropriate disinfectant.
8 Wash hands throughly after activity.
Method
Complete the following sentences :
1 Alcohol (ethanol) and disinfectant are used to ensure that [1]
20

2 In order to view the cells clearly, the magnification needs to be [1] N N )> z ~ )> r- ('\ Results m r- r- V> Draw and label a sample of two or three of the cells as seen under the microscope. [2] Conclusions The parts of animal cells that are clearly visible under the light microscope are [2] 21

2 In order to view the cells clearly, the magnification needs to be [1] N
N
)> z
~
)>
r-
('\
Results m
r-
r-
V>
Draw and label a sample of two or three of the cells as seen under the microscope. [2]
Conclusions
The parts of animal cells that are clearly visible under the light microscope are [2]
21

:E Evaluation !!:? z ~ C, Outline how this experiment could be improved, or made more reliable. [1] ,:,:: 0 w ::c: 1- .... 0 w V z ~ z w 1- z <( :E 0 z ~ z Q ~ !!:? z Extension ~ ~ ,:,:: 0 N Observe a range of specialised cells under a light microscope. In particular look at ciliated cells, muscle cells and red and white blood cells . Ex plain how you think these cells are adapted to their function. [2] 22

:E Evaluation
!!:? z
~
,:,:: C, Outline how this experiment could be improved, or made more reliable. [1]
0
w
::c:
1- ....
0
w
z V
z ~
w
1- z
<(
:E
0 z
~
z
Q
~
!!:? z
Extension
~
,:,:: ~
0
N Observe a range of specialised cells under a light microscope. In particular look at
ciliated cells, muscle cells and red and white blood cells .
Ex plain how you think these cells are adapted to their function. [2]
22

3.1 Osmosis and water flow Aim To demonstrate the effect of osmosis. Theory If two solutions are separated by a partially permeable membrane, water will diffuse across the membrane from the dilute to the concentrated solution. This process is known as osmosis. Apparatus D retort stand and clamp D capillary tube D Visking dialysis tubing D elastic band D 30 % sugar solution with red dye D beaker with water D stopwatch D ruler D scissors D goggles 23

3.1 Osmosis and water
flow
Aim
To demonstrate the effect of osmosis.
Theory
If two solutions are separated by a partially permeable membrane, water will diffuse
across the membrane from the dilute to the concentrated solution. This process is known
as osmosis.
Apparatus
D
retort stand and clamp
D
capillary tube
D
Visking dialysis tubing
D
elastic band
D
30 % sugar solution with red dye
D
beaker with water
D
stopwatch
D
ruler
D
scissors
D
goggles
23

Procedure ~ w V u.. 0 ..... => 0 0 z <x: capillary tube ~ 1- z w ~ w 6 ~ rt') dialysis tubing ---+-- -+ co ntainin g sugar so luti on (with red dye) Figure 1 1 Wear eye protection. 2 Cut a 15 cm length of Visking dialysis tubing and soak in water for a few minutes. 3 Tie a knot in one end of the dialysis tubing. 4 Fill the tubi ng with the sugar solution and red dye. 5 Fit the tubing over the end of a capillary tube, ensuring that the capillary tube is immersed in the sugar solution. Secure in place with an elastic band. 6 Clamp the capillary tube so that the dialysis tubing is immersed in the beaker of water. 7 Note the starting level of the liquid, using the ruler, and then start the clock. 8 Make a note of your observations of the level of liquid in the capillary tube over the next 10 to 15 minutes. 24

~ Procedure
w
V
u..
0
.....
=>
0
0 z
<x: capillary tube
~
1- z
w
~
6 w
~
rt')
dialysis tubing ---+-- -+
co ntainin g
sugar so luti on
(with red dye)
Figure 1
1 Wear eye protection.
2 Cut a 15 cm length of Visking dialysis tubing and soak in water for a few minutes.
3 Tie a knot in one end of the dialysis tubing.
4 Fill the tubi ng with the sugar solution and red dye.
5 Fit the tubing over the end of a capillary tube, ensuring that the capillary tube is
immersed in the sugar solution. Secure in place with an elastic band.
6 Clamp the capillary tube so that the dialysis tubing is immersed in the beaker of water.
7 Note the starting level of the liquid, using the ruler, and then start the clock.
8 Make a note of your observations of the level of liquid in the capillary tube over the next
10 to 15 minutes.
24

Method Explain why the red dye was added to the sugar solution. [2) Results and calculations Make a note of your observations below. [2) Conclusions 1 How did the levels of liquid in the capillary tube compare at the beginning and end of the experiment? [1) 2 How can you explain this? [2) 25

Method
Explain why the red dye was added to the sugar solution. [2)
Results and calculations
Make a note of your observations below. [2)
Conclusions
1 How did the levels of liquid in the capillary tube compare at the beginning and
end of the experiment? [1)
2 How can you explain this? [2)
25

..... Evaluation V'I ..... w V u.. 0 Outline how this experiment could be improved, or made more reliable. [1] ..... => 0 0 z <{ ~ 1- z w ~ w 6 ~ rt') Extension Explain how you think the levels of liquid at the beginning and at the end of the experiment would compare if the sugar solution was more dilute. [2] 26

..... V'I Evaluation
.....
w
V
u..
..... 0 Outline how this experiment could be improved, or made more reliable. [1]
=>
0
0 z
<{
~
1- z
w
~
6 w
~
rt')
Extension
Explain how you think the levels of liquid at the beginning and at the end of the
experiment would compare if the sugar solution was more dilute. [2]
26

3.2 Turgor in potato tissue lJJ N -t C :,:, G) 0 :,:, .,, z Aim 0 ~ d To investigate turgor in potato tissue. -t vi VI C Theory m If two solutions are separated by a partially permeable membrane, water will diffuse across the membrane from the dilute to the concentrated solution. Apparatus D cork borer D knife D large potato D board D ruler D 2 test tubes D 20 % sugar solu t ion D water Procedure (a) place the potato (b) push the potato cy linder on a board and push o ut with a pencil the co rk borer firmly down int o the potato Figure 1 1 Prepare two potato cylinders using a cork borer, as shown in the diagram. 2 Carefully cut the two cylinders to the same length, ensuring they are at least so mm long. Make a note of this length. 3 Add water to one test tube and the sugar solution to the other. 4 Add a potato cy linder to each tube and leave for 24 hours. 5 Measure the length of each potato cylinder and note your observations in terms of the firmness or flabbiness of each potato cylinder. 27

3.2 Turgor in potato tissue lJJ
N
-t
C
:,:,
G)
0
:,:,
.,, z
Aim
0
~
d
To investigate turgor in potato tissue.
-t
vi
VI
Theory m C
If two solutions are separated by a partially permeable membrane, water will diffuse across
the membrane from the dilute to the concentrated solution.
Apparatus
D
cork borer
D
knife
D
large potato
D
board
D
ruler
D
2 test tubes
D
20 % sugar solu t ion
D
water
Procedure
(a) place the potato (b) push the potato cy linder
on a board and push o ut with a pencil
the co rk borer firmly
down int o the potato
Figure 1
1 Prepare two potato cylinders using a cork borer, as shown in the diagram.
2 Carefully cut the two cylinders to the same length, ensuring they are at least
so mm long. Make a note of this length.
3 Add water to one test tube and the sugar solution to the other.
4 Add a potato cy linder to each tube and leave for 24 hours.
5 Measure the length of each potato cylinder and note your observations in terms of the
firmness or flabbiness of each potato cylinder. 27

Method ..... V'I ..... w V u.. 0 What could be an alternative method to measuring the length of potato cylinders? [1] ..... => 0 0 z <{ ~ 1- z w ~ w 6 Results and calculations ~ rt') Make a note of your observations below. [2] Conclusions 1 How did the water and the sugar solution affect the length of the potato cylinders? [1] 2 How can you explain this? [2] 28

..... V'I Method
.....
w
V
u..
..... 0 What could be an alternative method to measuring the length of potato cylinders? [1]
=>
0
0 z
<{
~
1- z
w
~
6 w Results and calculations
~
rt')
Make a note of your observations below. [2]
Conclusions
1 How did the water and the sugar solution affect the length of the potato cylinders? [1]
2 How can you explain this? [2]
28

Evaluation lJJ N -t C :,:, Outline how this experiment could be improved, or made more reliable. [1] G) 0 :,:, .,, z 0 ~ d -t vi VI C m Extension Calculate the class average for the change in length for each of the cylinder s. (2) 29

Evaluation lJJ
N
-t
C
:,:,
Outline how this experiment could be improved, or made more reliable. [1] G)
0
:,:,
.,, z
0
~
d
-t
vi
VI
C m
Extension
Calculate the class average for the change in length for each of the cylinder s. (2)
29

and 3.3 Osmosis turgor ..... V'I ..... w V u.. 0 ..... => 0 Aim 0 z <{ ~ To review knowledge of diffusion and to illustrate turgor in a plant cell. 1- z w ~ w 6 Theory ~ If two solutions are separated by a partially permeable membrane, water will diffuse across the membrane from the dilute to the concentrated solution. Apparatus D syringe D Visking dialysis tubing D syrup or concentrated sugar solution D test tube D water D stopwatch D ruler D scissors D goggles 30

and
3.3 Osmosis turgor
..... V'I
.....
w
V
u..
0
.....
=>
0
0 Aim
z
<{
~
To review knowledge of diffusion and to illustrate turgor in a plant cell.
1- z
w
~
6 w Theory
~
If two solutions are separated by a partially permeable membrane, water will diffuse across
the membrane from the dilute to the concentrated solution.
Apparatus
D
syringe
D
Visking dialysis tubing
D
syrup or concentrated sugar solution
D
test tube
D
water
D
stopwatch
D
ruler
D
scissors
D
goggles
30

Procedure (b) kn ot tightly, after (a) place 3 cm 3 sy rup in the dialysis tubing expelling the air bubbles water dialysis tubing ->----+- co ntaining (c) the partly filled tubing sho uld sy rup be flexible enough to bend Figure 1 1 Wear eye protection. 2 Cut a 20cm length of Visking dialysis tubing and soak it in water for a few minutes. 3 Tie a knot at one end. 4 Using a syringe, place 3 cm 3 of syrup or strong sugar solution in the tubing. 5 Tie a knot in the open end of the tubing. 6 Note your observations on the floppiness of the dialysis tubing . 7 Place the tubing in a test tube filled with water for 45 minutes. 8 Once again, note your observations on the floppiness of the dialysis tubing. 31

Procedure
(b) kn ot tightly, after
(a) place 3 cm 3 sy rup in the dialysis tubing
expelling the air bubbles
water
dialysis tubing ->----+-
(c) the partly filled tubing sho uld co ntaining
sy rup
be flexible enough to bend
Figure 1
1 Wear eye protection.
2 Cut a 20cm length of Visking dialysis tubing and soak it in water for a few minutes.
3 Tie a knot at one end.
4 Using a syringe, place 3 cm 3 of syrup or strong sugar solution in the tubing.
5 Tie a knot in the open end of the tubing.
6 Note your observations on the floppiness of the dialysis tubing .
7 Place the tubing in a test tube filled with water for 45 minutes.
8 Once again, note your observations on the floppiness of the dialysis tubing.
31

Method ..... V'I ..... w V u.. 0 ..... 1 Explain why the dialysis tubing containing the sy rup or strong sugar solution was left in => 0 the test tube for 45 minutes. [2] 0 z <{ ~ 1- z w ~ w 6 2 Explain why dialysis tubing is used. [2] ~ rt') Results and calculations Make a note of your observations below. [2] Conclusions 1 How did the floppiness/firmness of the dialysis tubing compare at the beginning and end of the experiment? [1] 2 How can you explain this? [2] 32

..... V'I Method
.....
w
V
u..
0
..... 1 Explain why the dialysis tubing containing the sy rup or strong sugar solution was left in
=>
0 the test tube for 45 minutes. [2]
0 z
<{
~
1- z
w
~
6 w
2 Explain why dialysis tubing is used. [2]
~
rt')
Results and calculations
Make a note of your observations below. [2]
Conclusions
1 How did the floppiness/firmness of the dialysis tubing compare at the beginning and end
of the experiment? [1]
2 How can you explain this? [2]
32

Evaluation Outline how this experiment could be improved, or made more reliable. [1] Extension Explain how you think the floppiness/firmness of the dialysis tubing at the beginning and at the end of the experiment would compare if the sugar solution was more dilute. How could you investigate this? [2] 33

Evaluation
Outline how this experiment could be improved, or made more reliable. [1]
Extension
Explain how you think the floppiness/firmness of the dialysis tubing at the beginning
and at the end of the experiment would compare if the sugar solution was more
dilute. How could you investigate this? [2]
33

3.4 Plasmolysis ..... V'I ..... w V u.. 0 ..... => 0 Aim 0 z <{ ~ To observe the process of plasmolysis in plant cells. 1- z w ~ w 6 Theory ~ If two solutions are separated by a partially permeable membrane, water will diffuse across the membrane from the dilute to the concentrated solution. Apparatus D small piece of red onion scale epidermis D glass slide and cover slip D dropping pipette D 30 % sugar solution D light microscope D blotting paper Procedure Figure 1 Changing the wat er for sugar so luti on 1 Place a small piece of red onion scale on a microscope slide. Add a drop of water and cover with a cover slip. 2 Focus on a small group of cells using a microscope. Draw and label a diagram of what you observe. Not all the cells in red onion epidermis will contain pigmented cytoplasm. 34

3.4 Plasmolysis
..... V'I
.....
w
V
u..
0
.....
=>
0
0 Aim
z
<{
~
To observe the process of plasmolysis in plant cells.
1- z
w
~
6 w Theory
~
If two solutions are separated by a partially permeable membrane, water will diffuse across
the membrane from the dilute to the concentrated solution.
Apparatus
D
small piece of red onion scale epidermis
D
glass slide and cover slip
D
dropping pipette
D
30 % sugar solution
D
light microscope
D
blotting paper
Procedure
Figure 1 Changing the wat er for sugar so luti on
1 Place a small piece of red onion scale on a microscope slide. Add a drop of water and
cover with a cover slip.
2 Focus on a small group of cells using a microscope. Draw and label a diagram of what
you observe. Not all the cells in red onion epidermis will contain pigmented cytoplasm.
34

3 Place a few drops of sugar solution on the slide, to one side of the cover slip. 4 Use the blotting paper on the other side of the cover slip to draw the solution across, as shown in the photo. 5 Observe the cells under the microscope. Draw and label a diagram of what you see. Method Explain how you could calculate the actual size of an onion cell. [2] Results and calculations Make a note of you r observations and diagrams below. [2] 35

3 Place a few drops of sugar solution on the slide, to one side of the cover slip.
4 Use the blotting paper on the other side of the cover slip to draw the solution across, as
shown in the photo.
5 Observe the cells under the microscope. Draw and label a diagram of what you see.
Method
Explain how you could calculate the actual size of an onion cell. [2]
Results and calculations
Make a note of you r observations and diagrams below. [2]
35

Conclusions ..... V'I ..... w V u.. 0 ..... 1 How did exposure to sugar solution affect the vacuole and cytoplasm of the cells? [1] => 0 0 z <{ ~ 1- z w ~ w 6 ~ rt') 2 How can you explain this? [2] Evaluation Outline how this experiment could be improved, or made more reliable. [1] Extension Explain how you think a more concentrated sugar solution would affect the cells. [2] 36

..... V'I Conclusions
.....
w
V
u..
0
..... 1 How did exposure to sugar solution affect the vacuole and cytoplasm of the cells? [1]
=>
0
0 z
<{
~
1- z
w
~
6 w
~
rt')
2 How can you explain this? [2]
Evaluation
Outline how this experiment could be improved, or made more reliable. [1]
Extension
Explain how you think a more concentrated sugar solution would affect the cells. [2]
36

3.5 Partial permeability Aim To demonstrate dialysis. Theory The pore size of a Vi sking tubing membrane makes it partially permeable with r espect to iodine and starch . Apparatus D test tube D Vis k ing dialysis tubing D dropping pipette D 1 % starch soluti on D 0.01 M iodine solution D water D elastic band D stopwatch D ruler D scissors D goggles Procedure -+-l, f---dial ysis tubing co ntaining starch so luti on Figure 1 37

3.5 Partial permeability
Aim
To demonstrate dialysis.
Theory
The pore size of a Vi sking tubing membrane makes it partially permeable with r espect to
iodine and starch .
Apparatus
D
test tube
D
Vis k ing dialysis tubing
D
dropping pipette
D
1 % starch soluti on
D
0.01 M iodine solution
D
water
D
elastic band
D
stopwatch
D
ruler
D
scissors
D
goggles
Procedure
-+-l, f---dial ysis tubing co ntaining
starch so luti on
Figure 1 37

..... V'I 1 Wear eye protection. ..... w V 2 Cut a 15 cm length of Visking dialysis tubing and soak in water for a few minutes. u.. 0 ..... 3 Tie a knot at one end . => 0 4 Fill the dialysis tubing with the 1 % starch solution. 0 z <{ 5 Put the tubing in the test tube and secure with an elastic band. ~ 1- 6 Rinse the dialysis tubing and test tube with cold water. z w ~ 7 Fill the test tube with water and add a few drops of 0.01 M iodine solution. w 6 8 Leave for 15 minutes. ~ rt') 9 Note your observations in the Results section. Method Ex plain why it is

Cambridge IGCSE Biology Laboratory Practical Book