Senior
uthor
Lionel Sandner
Catherine Little
Science Education Consultant and Writer
formerly Lead Coordinator, Pan-Canadian Science Project
Program Coordinator
Science, Environmental and Ecologica l Studies
Toronto District School Board
ut or
Nora Alexander
Rosebank Road Public School
Durham District School Board
Mike Carlin
Jim Walsh
Instructor, Science and Technology
Facu lty of Education, University of Ottawa
Sandy M. Wohl
Instructor, Curriculum Studies
Faculty of Education, University of British Columbia
Vice-Principa I
Walter Scott Public School
York Region District School Board
Contrib ti g Authors
Glen Fatkin
Jay Ingram
North Surrey Secondary School
Surrey School District, BC
Doily Planet
Science Journalist
Discovery Channel Canada
Doug Herridge
Greensborough Public School
York Region District School Board
Sandra Mirabelli
Academic Consultant, Literacy, Grades 4- 8
Dufferin-Peel Catholic District School Board
Michael Lattner
Special Assign ment Teacher
Algonquin and Lakeshore Catholic District School Board
enior 'J chnology Con ult nt
Josef Martha
Science Education Consultant and Writer
PEARSON
formerly Northern Gateway Public Schools, AB
.
.
~
.
,
,.,
-
.~
'
PEARSON
Copyright if) 2008 Pearson Education Canada
a division of Pearson Canada Inc.
All rights reserved, This publicalion is protected by coPYright, and permission should be
obtained from the publisher prior to any prohibited reproduction, stor(lge in a retrie al
system, or t.ransmlssion in any form or by any means, electronic, mechanical, photocopying,
recording, or likewis For information regarding permiSSion, write to the PermiSSions
Department at Pearson Education Canada,
The information and activihes pr sen ted in this book have been carefully edited and
reviel./ved, However, the publisher shall not be liable for any damages reSUlting, in whole or
in part, fro m the reader's use of Ihls materiaL
Brand na mes that appea r in photographs of products in this textbook are intended to
provide students ilh a ens€ of the real-world applications of science and technology and
are in no way intended to endorse specific products
ISB , i3 978-0- 13-20804 9- 1
ISBN- IO 0- 13-208049-4
Th is work in alternate fo rm t is re produced
with the permission of the Canad ian
Reprograp hy colle ction ,
The books are fin anced by th e Ministry of
Edu cation , Ontario and are lent without
charge to vi sually handicapped studen ts,
Printed and bou d in Canada
1 234 5 TC
121 1 1098
PROJEG MA AG ER Yvonne Van Ruskenveld CEdvantage Press)
DEVELOPMENTAL EDITORS Nancy ndraos, Tricia Armstrong, Janis Barr, Susan Girvan,
Georgina Montgomery, Rosemary Tanner
CONTRIBUTI NG WRITERS Erin Khelouiati, Ken Peck
COpy EDITORS Moira Calder, Louise Oborne
PROOFR EADERS Jennifer Hedg s, Christine McPhee, Kari Magnuson
IN DEXER: Jennifer Hedges
PRODUGION COORDI NATO RS Sharlene Ross, Shonelle Ra mserran
SENIOR MAN UFAQURING COORDINATOR Jane Schell
DESIGN Alex Li
COMPOSITION: Carolyn E, Sebestyen
ILLUSTRATORS Kevin Cheng, David Cheung, Crowle Art Group, Jeff Dixon, Jane Whitney
PHOTO R SEARCH ER Terri Rothman
PUB LI SHER Reid McAlpin e
MANAGING EDITOR: Cecilia Cha n
R SCARCH AND CO lMUNICATION MANAG ER:
eborah Nelson
This book was prin ted using paper containing recycled fibre content.
iv
el11ents
Consultants and Reviewers
Mirella Sa nwalka
Curriculum Consultant
Science K- 12, Environment
York Region District School Board
Mariett a (Mars) Bloch
Director, Education SeNices
Let's Tal SCience
Raymond Wiersma
Lord Elgin Public School
Thames Val ley District School Board
t
Derek Totten
Curriculum Consultant
York Region District School Board
fade
Maureen Sims
51 Timothy Catholic School
Toronto Catholic District School Board
Sandra Mirabelli
Academic Consultan , Literacy, Grades 4 - 8
Dufferin-Peel Catholic District School Board
Catheri ne Costello
Education Consult ilt
formerly Curriculum C ordlnator, Literacy
York Region District School Bo rd
n al Educatio
J
Jane E. Sims
ducati on Consu ltan t
formerly Sir Sandford Fleming Academy
10ronto District School Board
Maureen Sims
st. Timothy Catholic School
Toran
0
Catholic District Sch 01BOdrd
Jane Forbes
Instructor, SCience and l echnology
Ontario Institute for Studies in Education, University of Toronto
I Education
Peter Bloch
orthern Secondary Sc 001
Toronto District School Board
Darin Corbiere
Consultant, Aboriginal Education
Tarant District School Board
Ingrid Bajewsky
ipissing University
truction
Randy Dumont
Kare n Hume
McMaster University
tudent Succes Leader
Durham District School Board
Ma rina Milner-Bolotin
Ryerson niversity
Dr. Nagina Parmar
Hospital or Sick Children (Toronto)
Sue Conti nell i
Grapeview Public School
District School Board of Niagara
s
Marietta Alibranti
uca Ion
Dennis Caron
t. Maurice Catholic School
Toronto Catholic District School Board
Leda Ostafichuk
Josyf Cardinal Slipyj Catholic Elementary School
Toronto Catholic District School Boa d
Bayview Midd le School
Toronto District School Board
Chris Atkinson
Math/Science!Technology Consultant
Catholic District School Board of Eastern Ontario
Angela Cule
Highview Public School
Hamilton-Wentvvorth District School Board
v
Jodie Hancox-Meyer
Anne Bradley
Doon Public Schoo l
Waterloo Region Distri d Sch oo l Board
51. James the Greater Catholic Schoo l
Catholic District School Board of Eastern Onta rio
Terry Jay
Helen Brown
Assikinack Public School
Imcoe County Distrid School Board
Gordon B. Attersley Public School
Durham District School Board
Kristi na Kerno han
Patricia Cava
Applecroft Public School
Durham District School Board
Sacred Hearl High School
Ottawa catholic District School Board
Jessica Kotsopoulos
Brenda Collins
Yorkhill Elementary School
York Region Distrid School Board
St. Jude Catholic School
London Catholic District School Board
Heather A. Mace
Joan D'Elia
Feath rston Drive Public School
Ottawa-Carl eton District School Board
Ruth Thompson Middle School
Peel District School Board
Au dra Mo rgan
Chris di Tomasso
Donviev Middle School
Toronto Dis rict School Board
Sacred Heart Catholic School
Catholic Dlstnd School Board of astern Ontario
Brian Murra nt
Jessica Egelnick
Regent Park Public School
Simcoe County District Scl100l Board
Royal Orchard Middle School
Peel District School Board
Jette Powrie
Jody Ferdinand
AJ. Charbonneau Public School
Orchard Park Public School
Halton District School Board
Renfrew County Distrid School Board
Rebecca Rid ler
Heidi Ferguson
Prince of Wal .s Public School
Simcoe County Distrid School Board
Ou r ady of Sorrows Catholic School
Renfrew Coun
athok Distri d School Board
Allan Savage
Aliso n Fernandes
Joseph Howe Senior Public School
Toronto District Sch ool Board
SI. Sebastian Catholic Elementary School
Dufferin-Peel Catholic District School Board
Jeffrey Schaeffer
Andy Forgrave
Bl ue Willow Public School
York Region Distrid School Board
Harmony Public School
Hastings and Prince Edward District School Boa rd
Robert Stronach
Donna Forward
Annette Street Public School
Toronto District. School Board
Sacred Heart Intermediate School
Ottawa Catholic District School Board
Casey Wilson
David Gillespie
WG . Davis Senior Public School
Peel District School Board
Roland Michener Public School
Durham District School Board
Susan Wilso n
Jocelyn Harrison
SI. Rita Catholic Elementary School
Dufferin-Peel Catholic District School Board
Dixon Grove JUnior Middle School
Toronto District School Board
ch r
Chris Atkinson
51. Francis Xavier Catholic School
Catholic District School Board of Eastern Onta rio
Jody Bonner-Vickers
l IN Walker School
Rainy River District School Board
vi
Pat Hoga n
st.
Francis de Sales Catholic School
Catholic District School Board of Eastern Ontario
Bill Hrynkiw
Nottingh m Public School
Durham District School Boa rd
•
.
•
Niza m Hussain
Brian Murrant
Military Trail Public School
Toronto District School Board
Victoria Harbour Elementary School
Simco County District School Board
Colleen Hutch eson
Tom Rhind
Glashan Public School
Otlawa-Carleton District School Board
Lakewood School
Ke watin-Patrici District chool Board
Terry Jay
Reb ecca Ridler
Assikinack Public School
imcoe County District School Board
Prince of Wales Public School
Simcoe County District School Board
Matt Johnston
Phil Sanders
Birch Cliff Public School
Toronto District School Board
Northdale Central Public School
Thames Valley Distnct School Board
Kristi Johnston Bates
Rey Sandre
51. Michael Catholic High School
Catholic District School Board of Eastern Ontario
51. Ma rk Catholic School
Toronto Catholic District School Board
Tom Karrow
Ryan Seale
Wellesley Public School
Waterloo Region District School Board
acred Heart Catholic chool
Catholic District School Board of Eastern Ontario
Kristin a Kern ohan
John Starratt
Applecroh Public School
Durham District School Board
Monsignor Michael O'Leary School
Simcoe Muskoka Catholic District School Board
Irene Kicak
Corinna Tave rna-Rossi
Glenview Se io Public chool
Toronto District School Board
Ka teri Tekakwitha Catholic Elementary School
York Catholic District School Board
Heather Lanning
Stacy van Boxtel
General Crerar Public School
Toronto District School Board
51. Andrew's School
Renfrew County Catholic District School Board
Jeff Laucke
Cathy Viscount
Roseda le Public School
Lambton Kent Dlstric School Board
Stanley Park Public School
Waterl oo R gion Dlstnct School Board
Nicholas Lemi re
Jan ice Whiton
HumbelWood Downs Junior Middle Academy
Toronto District School Board
Kateri Tekakwitha Catholic Elementary School
York Catholic District School Board
Tait l uste
Raymond Wiersma
Glenh ven Sen ior Public School
Peel District Sch 01 Board
Chippewa Public School
Thames Valley District School Board
Hugh Maclean
Craig Winslow
Centennial Public School
Water! a Region Dlstnct School Board
51. Martin School
iagara Catholic District School Board
Ma rjory Masson
Earl Beatty Juor and 5 nior Public School
Toronto District School Board
Irene McCuaig
Lakewood School
Keewatin-Patricia District chool Board
-Ine authors and Pearson Education Canada would like to than k all
the students who participated in focus groups and field tests during
the development of this boo .
Mary Sue Mcintyre
Monsignor Michael Ol eary School
Simcoe Muskoka Catholic District School Board
vii
.
~
J!:.
Ion
vi
Lisa Ackman
Highview Public chool
Renfrew Cou nty District School Board
Ann -M ari e Babineau
DA Moodie Public School
Ottawa-Carleton District School Bo rd
Savita Balagopal
Sir John A Macdonald Middle School
Peel District chool Boa rd
.
I
...
-
Michele Chomnia k
Abbey Lane Public School
Halton District School Bo rd
Brenda Collins
St Jude School
London District Catholic School Board
Cra ig Corbett
Rolling Meadows Public School
Halton District School Board
Rosalie Cross
Vijaya Balchandan i
Blossom Park Public School
Ottawa-Carleton District School Board
North Kipling Junior Middle School
Toronto District School Board
Mary Cuylle
Swarn aly Banerj ee-Modi
Tomken Road Middle School
Peel District School Boa d
Janet Bartolini
Hu b r Valley ViII ge Junior School
Toronto District School Board
Martin Beswick
Princess Margaret Public School
District School Board of Niagara
Shivani Bhagria
Huttonville Public School
Peel District School Board
Marlene Bilkey
Roberta Bondar Public School
Peel District School Board
Tracy Bridgen
Westdale Park Public School
Limestone District School Board
Hillcrest Public School
Peel District School Board
Kara Dalgleish
Bellmore Elementary School
Hamilton-We tworth District School Board
Brett Davis
Queen Eliza beth Publ iC School
Hastmg and Prince Edw rd District Schoo l Board
Ian Dawson
Roberta Bonda r Public School
Peel District School Board
Veronica Deignan
St. Elizabeth Catholic School
Waterloo Catholic District School Board
Sonia DiCola Kop ichan ski
Our Lady of Lourdes School
London District Catholic School Board
Nadine Dodds Cormack
Melissa Brownlow
W.H. Day Elementary School
Simcoe County District School Board
Earnscliffe enior Public School
Peel District School Board
Seana Donohue
Mahlon Bryanton
Beachburg Public School
Renfr w County District School Board
Sukw inder Buall
Elia Middle School
Toronto District School Boa rd
otre Dame High School
Ottawa Catholic School Board
Kristy Duncan
Lockview Public School
District chool Board of Niagara
Sam Falzone
Shayne Campbell
RJ Lang Elementary' & Middle School
Toronto District School Board
Kin g George Public School
Upp r Grand District School Board
Julia Farewell
Patricia Cava
Camilla Road S nior Public School
Peel District Scho ol Board
Sacr d Heart High School
Ottawa Catholic chool Board
Jodi Ferdinand
Lenn y Chiro
Amesbury Middle School
Toronto District School Board
viii
AJ. Charbonneau Public School
Renfrew County District School Board
J ••
.
Heidi Ferguson
Deb Hearn
OUf Lady of Sorrows
R nfrew County Catholic District School Board
McCrimm on Middle School
Peel District School Board
Ian Fischer
Tara Hewitt
51. Joseph High School
Ottawa Catholic School
Agnes Hodge Public School
Gra nd Erie District School Board
Erika Flem ing Gillespi e
Marc Hodgkinson
51. Andrews Public School
Waterloo Regional District School Board
Lorn Aven ue Public School
Thames Valley Distri ct School Boa rd
Kim Foley
Bryan Honsinger
Perth Road Public School
Limestone District School Boa rd
Carleton Public School
District School Board of Niagara
Donna Forward
Colleen Hutcheson
Sacred Heart High School
Ottawa Catholic School Board
Glashan Public School
Ottawa-Carl eton District School Board
Michae l Fran kfort
Wayne Isaac
Teston Village Public School
York Region District School Board
St. An drews Publ ic School
Waterloo Regional District School Board
Jeff Fra ser
Krista Jarvie
R berta Bondar Public School
Peel DistTict School Board
Huttonville Public School
Peel District School Board
Jennifer Freelandt
Brent Johnston
Immaculata High School
Ottawa Catholic School Board
w.T. Townsend
Publ ic School
Waterloo Region District School Board
Lorra ine Ganesh
Kristi Johnston-Bates
Fairwind Senior Publ ic School
Peel Dstrict School Board
St. Michael High School
Catholic District School Board of Eastern Ontario
Sarah Garrett
Darayus Kanga
King Georg Public School
Upper Grand District School Board
Hilltop Middle School
Toro nto District School Board
Krista Gauthier
Tom Karrow
Rockwood School
Renfrew County District School Board
Wellesley Pu bl ic School
Waterl oo Regional District School Boa rd
Frase r Gill
Adam Kelly
McCrimmon Middle School
Peel District School Board
Greenbank Public School
Ottawa-Carleton Districi School Board
Mike Glazier
Gita Khanna
London District Catholic School Board
Fisherville Junior High School
Toronto District School Board
Kevin Goode
Minesing Central Public School
Simcoe County District School Board
Shaunna Goode
Mount Ro al Public School
Peel District chool Board
Rob Green
Treeline Public School
Peel District School Board
Akaran Guyadin
Deb Kiekens
Earling Public School
Thames Valley District School Board
Amy Kilty Schwandt
Oxbow Public School
Thames Valley District School Board
Dr. Jean Kisoon-Singh
Mount Royal Public School
Peel District School Board
The Elms Junior Middle School
Toronto District School Board
ix
,
,.
....
Brenda Kus men ko
Elizabeth Mayock
FailWind Senior Public School
Peel District School Board
Harry J. Clarke Public School
Hastings and Prince Edward District School Board
Helen Laferriere
Monica McArthur-Joseph
Monsignor JE. Ronan School
imcoe Muskoka Cathohc District School Board
Erin Centre Middle School
Peel District School Board
Ma ri lyn Lajeun esse
Rob McBeth
Monsignor William Gleason Catholic School
Waterloo District School Board
Baden Public School
Wa erlno Region District Sc
001
BOdid
Jean-B en oit Lanca
Cara McCrae
Immaculata High School
Ottawa Catholic School Board
Centennidl Central Public School
Tham s Valley District School Board
Chris Lanis
Diana McFarland-Mundy
J hn nghsh Junior Middle School
Toronto Distnct School Boa rd
Queen Elizabeth Public Scho I
Ottawa Carleton Dlstlct School Board
Bill Legate
Dave McGaghran
Beavercrest Community School
Bluewoter Dis rict School Board
Ryerson Public School
Grand Elle District School Board
Natalie Leitch
Mark MCKinley
J.D. Hogarth Public School
Upper Gr nd District School Board
James Strath Public School
Kawartha Pine Ridge District Scho I Board
And rew Lesli e
Chris McKinnon
Hillcrest Public School
Simcoe County District School Board
St. Timothy Catholic School
Waterloo Catholic District School Board
Steve Logue
Hugh Mclea n
Cheyne Middle School
Peel District School Board
Centennial Public School
Waterloo Regional District 5 hool Board
Lara Loseto
Ma nish Mehta
Walter Scott Public School
York Region District School Board
Lisgar Middle School
Peel District School Board
And rew Lovatt
Paul Menicanin
51 Thomas Aquinas High School
Catholic District School Board of Eastern Ontario
Winona Public School
Hamilton Wentworth Dislnct School Board
Heather Mace
Cindi Mitchell
Featherstone Drive Public School
Ott wa-Carleton District School Board
Armadale Public School
ork Region District School Board
Jenn MacKin non
Yvan Moise
51 Agnes Catholic School
Waterloo Catholic District School Board
51. Paul High School
Ottawa CatholiCSchool Boar
Tracey MacMillian
Ginny Monagha n
Herman Street Public School
Renfrew County District School Board
Bristol Road Middle Schoo l
Peel District School Board
Art MacNeil
Lu is Morgadinho
McCrimmon Middle School
Peel District School Board
51 John A Macdonald Middle School
Peel District School Board
Sean Matheson
Fran k Muller
Highland Junior High School
Toronto District School Board
Bristol Road Middle School
Peel District School Boa rd
x
?
#'
•
I .••
.
'
Katie Muller
Clare Shannon
Gateway Public School
Upper Grand District School Board
Egremont Comm unity School
Bluewater District School Board
Trevor Orm erod
David Shulman
Elementary Instructional R ource Teacher
Peel District School Board
Germaine Mills Public School
York Region District School Boa rd
Joha nna Pastma
Denise Stansfield
Caistor Central Public School
District School Board of Niagara
Sir John A. Macdonald Middle School
Peel District School Board
Steacy Petersen
Trevor Starkes
Ko right Public School
Upper Grand District School Board
Ruth Thompson Middle School
Peel District School Board
Jennifer Phi llips
Corrina Strong
Humberwood Downs Junior Middle Academy
Toran 0 District School Board
Lisgar Middle School
P el District School Board
El izabeth Piw owa r
Enzo Tignanelli
Sir John A. Macdonald Middle School
Peel District School Board
51. Luke Catholic School
Waterloo Catholic District School Board
Julie Podesta
John Tovey
Hillcrest Public School
Thames Valley District School Boa rd
Nobleton Sr. Public School
York Region District School Board
Georg ina Purchase
Brandon Tse
Jack Donah ue Public School
Ottawa-Carleton District School Board
Lisgar Middle School
Peel District School Board
Rena Ro
Cathy Viscount
Sunny View Middle School
Peel Distnct School Board
Stanley Park Public School
Waterloo Regional District School Board
Lisa Ro me
Dana Wallace
Hawthorn Public chool
Peel District School Board
Si r Winston Churchill Public School
Ottawa-Carl eton District School Board
Michaeline Row berry
Greg Watson
Bristol Road Middle School
Peel District School Board
Port Weller Public School
District School Board of Niaga ra
Ernie Salac
Corey Wells
James Strath Public School
Kawartha Pine Ridge District School Board
Baxter Central Public School
Simcoe County District School Boa rd
Shirl ey Saund ers
Deborah Weston
Hawthorn Public School
Peel District School Boa rd
Lisga r Middle School
Peel District School Board
Tam ara Sayers-Pri ngle
Lisa Weston Tourigny
Harry J Clarke Public School
Hastings and Prince Edward District School Board
Sir Arthur Ca rty School
London District Catholic School Board
Ericka Schroeder
Annie White
Sl. Clemens Catholic School
Wat rloo Catholic Diskct School Board
Bennetto Elementary School
Hamilton-Wentworth District School Board
Ma nny Sci berras
Michelle Willson
John McCrae Public School
York Region District School Board
Cou rtland Public School
Grand Erie District School Board
Sandy Wilson
Hillcrest Public School
Thames Vall y District School Boa rd
xi
.
..•
-
'!'
.
•
,
Science and Technology Safety Procedures
Exploring Your Textbook - Investigating
Science and Technology 8
xx
XXIII
1 .0 Ch apter Review
2
32
A 19 Thinking about Science, Technology,
and Society Reverse Osmosis
33
Cellular processes sustain
living things
A Qu c lao One Big Cell
6
34
A20 Quick L b Meeting Basic Needs for Survival
37
A2 Thinking about Science, Technology,
Society, and the Environment Using an Insecticide 6
I 5 .Jr In
Composter7
Cells are the basic units of all
living things
8
A3 Quick L
11
Defining Livi n Things
1 .1 Living Thing s and Cell Th eo ry
A
12
t o ' n Make Your Ow Magnifier
AS During R
A6 Quir:
Reading Like a Writer
12
13
Lab Care and Use of a Microscope
Check and Reflect
16
1.2 Comparing Plant and Animal Cell s
What's the
01
A9 During Re'l
I
agnification7
Using Headings
0
nt What 15 Going on in the
38
A2 Duri g R dl
Combination otes
AU Inqu
Organisms
Visualizing with
39
ActiVit,. Observing Unicellular
41
42
C eck and Reflect
A24 Thinking about Science, Technology,
42
and Society Cooking and Freezing
15
A7 Thinking about Science, Technology, and
Society The Importance of Technology in Science
38
2.1 Uni ce llular Organisms
16
17
17
19
2 . 2 Mu lticellul ar Organisms and Cell
Specia lization
43
5
r I
oi Specialized Structures to
Do Specialized Jobs
43
A26 Learning Checkpoint Explaining the Size
46
A27 InqUiry
Organisms
c i i Y Observi ng Multicellular
47
21
A28 D~sign a lab Cells and Solutions
48
A II Quicl< Lab Preparing Dry Mount Slides
21
Check and Reflect
49
A 12 Quick Lab Preparing Wet Mount hdes
22
Check and Reflect
23
A29 Thinking about Science, Technology,
and Society Water for Celis
49
A 13 Thinking about Science, Technology,
and Society "Perfecting" Plants
2
Al0 Quick lab Building a Cell
2.3 Plant and Animal Cellular Processes
nt Yeast in Action
1 .3 The Flow of Materials Into and
24
Out of Cells
.. Du
Factory or a City
50
50
Visualizing the Celi as a
51
24
An Quick Lab Modelling Diffusion
53
A15 Learning Checkpoint Budd a Mind Map
25
Check and Reflect
54
A
28
A33 Thinking about Science, Technology,
and Society Helping Celis, Harming Cells
55
I
t Finding BUried Treasure
nq Iry A t! ty Diffusion Detective
A - II ':J
II
Y Activity Food fo Thought
29
Check and Reflect
30
rl
Microbiologists at Work
55
Al8 Thinking about Science, Technology,
and Society The Artificial Kidney
30
or
Solving the Mystery of Viruses
xii
31
2.0 Chapter Review
A34 Thinking about Science, Technology,
and Society Protecting Cells in the Environment
56
57
Healthy organisms depend on
the interaction of healthy cells,
tissues, and oraans .
Amoeba Race
A3S Quick L
61
3 .1 From Cells to Tissues to Organs
t r in
You r Body Ca n Heal Itself
oi
A37 Learning Checkpoint
~rob em
0"
ng
c
ote Taking
IVlty
58
62
62
64
Special-Effects
Technician
65
Check an d Reflect
66
A39 Thinking about Science, Technology,
and Society X-Rays and Magnetic Resonance
Imaging
66
3.2 Inter dependent Organ Syst ems
n P
40
An Open and Shut Case
I
1 ) J .,
qu
67
The tructure of a
I
Ne spa per Article
2 I
67
69
i Ynower Po er
I
70
Check and Refled
71
A43 Thinking about Science, Technology,
and Society How Loud Is "Too Loud"!
71
3 .3 The Im pact of Research in
Cell Biology
tar
J
o n Simple Solutions
A4S During Wri
I
What's Your Opinion!
is 0 1\
I
And y
Spread of Infectious Disease
Stopping the
AD ' .
a
n
Corn and Other Modified Plants
Growing Bt
72
72
75
76
Check and R fled
77
78
A48 Thinking about Science, Technology,
and Society What Kind of Testing Should
Be Done!
78
Making Connections Wow' Bacteria
79
3 .0 Cha pter Review
80
A49 Thinking about Science, Technology,
and Society Public Choic s Affect the Health
of C lis
81
Unit A Summary
82
Unit A Task
83
Unit A Review
84
ASO Thinking about Science. Technology,
Society. and the Environment What's the Limit!
87
...
.
,
~
hnol gy n Your Wo
123
Ar t ificial Limbs
c L b Clothes Peg Surgery
82 Thinking about Science. Technology.
Society. and the Environment Componen
a System
92
of
Mechanical systems use forces
to transfer energy.
83 QUick ab Lift Th is
92
94
Identifying Forces
g Poi
Making Connections
ur
B6 Learning Checkpoint Weight and Mass
98
Measuring Force with a
Spri ng Scale
The Force of Gra vity
LI
Check and Reflect
4. 2 Work an d Energ y
I
ui
L
Making Connections
107
Check and Reflect
B14 Thinking about Science. Technology.
and Society Giving Soci ety a Lift
4 .3 M echan ical Advantage
B
Everyday Machines
II I
130
132
B26 Learning Checkpoint Three Classes of
135
c
l-S
14 1
• Best Machine
for the Job
142
Check and ReRect
143
829 Thinking about Science. Technology.
and Society Th ink Before You Buy
143
5 .2 Efficiency
144
8 0 t r mg om Work Can Be a Drag
11 2
831 Learning Checkpoint Ca lculating Efficiency 147
In
112
113
Increasing Efficiency
144
149
Check and Reflect
150
833 Thinking about Technology, Society.
and the Environment Ontario's Bright Idea
150
1 13
Mechanical Engineer
151
116
817 Learning Checkpoint Mech anical Advantage 119
818 Learning Checkpoint Hum an Mechanical
Advantage
1 19
Calculating Mecha nical Ad antage 120
My Bi cycl e's Mechanical
xiv
" Choose a Simple Machine
III
B16 Learning Checkpoint Describ ing
Machine Forces
n
DL'n Readin To Predict or to Infer7
o
106
How Mu ch Work Does It Take7
130
nq i kr: tv Measuri ng the Mechanical
Advan ag of Simple Mach ines
hat Is Work 7
812 Learning Checkpoint Cal culating Work
5.1 Simple Machines and Mechanisms
104
106
1 26
129
Levers
105
125
u -I
Locating Simple Machines on
ountain Bike
a
103
105
89 Thinking about Technology. Society,
and the Environment The Right Shoe
Mechanical systems Involve
machines that are designed to
do work efficiently.
100
102
124
822 Thinking about Science. Technology,
and Society Garden Rake versus Leaf Blower
97
98
4.1 Force
4. 0 Chapter Review
Advantage
12 1
Check and ReRect
122
B21 Thinking about Science, Technology.
and Society Ca n Opener
12 2
5. 0 Chapter Review
834 Thinking about Science. Technology.
and Society Building a Modern Pyramid
152
153
,
.....
.
Systems have an impact on
our society.
1 54
835 Qu c La Your School's Waste
Man gement
157
6 . 1 Non-mechanical Systems in Society 158
6
Non-mechan ical Systems in
Sode~
158
7 During Wri i
Some Solutions
A Problem, its Causes, and
159
838 Quid L b Assembly Not incl uded
39 Quic
b Pro iding a Service to SOCiety
Check and Reflect
161
162
163
840 Thinking about Science, Technology,
and Society You: The Consumer
163
6.2 Assessing the Impact of Automation
and Alternative Systems
164
lIt
"1
I
To Mall or Not to Mall
That is the Question
b4
0 rlOg
ri inb Organizing Wri~ng ideas
164
1 5
843 Deci ion- Making Anal sis My Opinion of
Automation
171
Check and Reflect
172
844 Thinking about Science, Technology.
and Society Automating Your School's
Recycling Program
Making Connections The Trebuchet
6 .0 Chapter Review
172
173
174
845 Thinking about Science. Technology.
and Society Assessing the Change
175
Unit 8 Summary
176
Unit B Task
177
Unit B Review
178
846 Thinking about Science. Technology.
Society. and the Environment Rethinking
the Engine
181
.
-.
. .
,
.
•
....
.
"-
a
182
8.1 V iscosity and the Effects of
Temperature
ic
Pump Up the Volume
a
186
C2 Thinking about Science. Technology.
Society. and the Environment Fluids on the
Move
186
CI
210
Thick or Thin 7
ng
210
1 Du r Pe I
Monitoring
Comprehension With "Fix-up" Strategies
1 Desi
n
212
ab Flow Rate of Flu ids
214
215
Check and Reflect
Fluids are used in technological
devices anrf pver ria materials. 188
C3 Quick La Cartesian Diver
19 1
C18 Thinking about Science and Technology
Measuring the Flollv Rate of Gas
192
Fi nding F owing Fluids
ic Lab Function s of Fluids
t r ir
Dense and Denser
216
C20 Learning Checkpoint Ca lculate and
192
Com pa re
194
Co. 1 qUI
c IVI Ca lcul ting
ass-to-Volume Ratio
222
02 roblem- olvi
Hydrometer
224
195
Check and Reflect
216
8.2 Density and Buoyancy
~ 19
7.1 The M any Uses of Fluids
215
196
219
ctivity Homemade
Check and Reflect
C7 Thinking about Science and Technology
Useful Prope rties of Ruids
196
226
C23 Thinking about Science and Technology
Worldwide Shipping
7 .2 Fluids and the Partic le Th eory of
M atter
197
Colourful Crystal
197
C9 Learning Checkpoint Understanding the Text 199
Balloon Tricks
ck La
c
n
200
Mixtures of Matt r
01
Check and Reflect
202
226
Pressure Ca n - Teacher
r
Demonstration
25 I
Q
Ac'
227
Ity
Com pressing Fluid s
232
C26 Thinking about Science and Technology
Pipes and plumbing
232
n Yo r
a
Glowing Glass
204
cn Thinking about Science and Technology
Technology Tools
Viscosity. density, and
compressibility are all
propertl E: Of fl .. ·rfr
I .
La
Demonstration
YI
Your Wo
Meteorologist
233
8.0 Chapter Review
234
203
7 . 0 Chapter Review
CI
010
202
log
C27 Thinking about Science and Technology
Propane Tanks
235
20 5
Many technologies are based
on the proper ie!=: of fluids .
C28 Quick Lab Soap Foam
2'36
239
206
240
9 . 1 Fluid Systems
Full of Hot Air - Teacher
209
1
Pressure Push
o Du
' Itm~ Using a Venn Diagram to
Compare and Contrast
xvi
230
Check and Reflect
C12 Thinking about Science and Technology
When Water Freezes
227
8.3 Pressure in Fluids
240
243
I Du mg Writinr Tal k Time - A Rehearsa l for
Wri ting
246
o cion-Making Analy i The "Cost" of
Extracting Oi l
ble -S
ng Activ
248
Golf Ball Loader 249
Check and Reflect
250
04 Thinking about Science and Technology
Transporting Fluid
250
9 .2 The Impa ct of Fluid Spills
251
rttng P n Not Every Oil Spill Is
the Same
251
06 Learning Checkpoint Classifying Clean-up
Methods
c smnHousehold Fluids
I
nq
I
255
mg Analy i Disposing of
ct
257
Oil Spi ll Clean-up
Check and Reflect
25 8
260
09 Thinking about Science and Technology
Searching for the Source of Spills
260
Making Connections Quicksand
9 .0 Chapter Review
C40 Thinking about Science and the
Environment Ta king Care of Fluids
261
262
263
Unit C Summary
264
Unit C Task
265
Un·t""
266
eVlew
C41 Thinking about Science, Technology,
Society, and the Environment
Pipelille Problems
269
,.
, I
•
I
· ....
-
270
Taking a Closer Look at Earth's
Population
Check and Reflect
302
018 Thinking about Science and the
Environment The Unfreezing of the
Northwest Passage
302
274
02 Thinking about Science. Technology.
Society. and the Environment Caring for Our
Globa l Wat r Supply
Point Pelee : A Gr eat Lakes Microclimate
30 3
274
10.0 Ch apter R evi ew
019 Thinking about Science and the
Environment Predic ing Major Storms
Water on Earth exists in
different states and is always
moving and r.h~ ~ir
Ol Quick Lab Would You Drink It)
10.1 Earth 's Supply of Water
Water Systems Alphabet
279
280
80
05 Learning Checkpoint Liquid Wate
283
06 Learning Checkpoint The Watershed
Connection
287
o
ui<. Lab How Much Fresh Water Is
Available for Use!
o
I
ur
Make a
odel Aquifer
87
28
89
Check and Reflect
09 Thinking about Science and the
Environment Canad 's Groundwater Mapping
Program
28
10.2 Water's Influe nc e on W e ather
2 90
a nd Clim ate
01
Weather
ng Poi
Th Wat r Cycle and
Monitoring water systems is
critical for maintaining water
supply and
lit I
305
306
o
0
ic
Dissecting a Wat r Fil ration
Device - Teacher Demonstration
309
11.1 N atural a nd Human Factors
Affe cti ng Our W ater Supply
1 t
a ure and the Water Tab le
022 Learning Checkpoint You r Water Table
K- -L Chart
310
3 10
3 13
o ,) Problem-Solving ActiVity Clearing Muddy
Waters
315
Check and Reflect
3 16
024 Thinking about Science, Society. and
the Environment Competing for Water Use
3 16
11.2 Obtaining Wa ter Quality
31 7
290
How Much Do You Know
About Your Drinking Water!
317
321
012 Learning Checkpoint Water's Heat
291
29-
026 Learning Checkpoint The Water You Drin k
Oll QUICk ab Investigating Climate Data
295
o
0 ri
ead ng Main Idea or
Supporting Deta il?
014 Inqui
Actlvl~
Can It Take the Heat!
296
Check and Reflect
297
015 Thinking about Science and the
Environment Weather in the Media
297
29 8
Syste ms
I
Predicting the Effects of
Water System Change
o
1 nq iry Act'
Glacier
A
iJ27 nqui
Inspector
v
298
ty Researching a hanging
301
Be a Water Qua lity
322
Check and Reflect
323
028 Thinking about Science, Society. and
the Environment Down the Drain
323
11.3 M ana ging Our Wate r System s
I
10.3 The Effe cts of Ice on Water
xviii
304
324
How Much Do You Know
About Wastewater!
324
030 Learning Checkpoint Treatmg Waste Water 326
OJ 1 D
g e l The Question-Answer
Relationship
330
."
,.
.
..
l:IC
i
ab How Phosphates Affect Our
Wate r Supply
330
:3
sio
1m n I
Small Sound's Wa er Suppl y
I
••
"
Managing
331
D46 In ulfY Activit Changing Salt Water into
Fresh Water
355
Check and Reflect
356
356
Check and Refl ct
332
D47 Thinking about Technology, Society,
and the Environment Fog Water
D34 Thinking about Science, Society, and
the Environment Educating the Commu nity
33 2
Making Connections A Tea Cup of
Storm Clouds
333
Career Public Health Inspector
11 .0 Chapter Review
334
D35 Thinking about Science, Society, and
the Environment Lessons Leamed
Stewardship of our water
systems is needed to ensure
their sustain "lit I
Star in
0 n Daily Water Use in an
Average Canadian Home
u
~36
"1
340
340
n Gathering Information in
a Web
34 1
U
(" I •
Be a Water
atchdog
359
Unit 0 Summary
360
Unit 0 Task
361
Uf"'i 0
362
e e\l\
D49 Thinking about Science, Technology,
Society, and the Environment Water for All
365
Toolkits
366
Glossary
Index
405
411
Photo Credits and
Acknowledgements
417
34 4
Check and Refl ect
345
D40 Thinking about Technology, Society,
and the Environment You and Your Water Bill
345
12.2 Issues Relating to W ater's
Sust ainability
D48 Thinking about Society and the
Environment Group Actions
358
335
(;
What Does Stewardship of Water
Systems Look Li ke7
339
1 2 .1 Steward ship Thr ough Water
Con servati on
12.0 Chapter Review
357
346
Finding Messages
I
Behind Words
347
Writers Make Decisions
349
Deqslon M
Great Lakes Iss ue
ng Analysi Exploring a
350
Check and Reflect
35 1
D44 Thinking about Science, Society, and
the Environment Mini Media Analysis
35 1
1 2 .3 W at er Su stai na bility t hrough
Science and Technology
r
Solutions
r
352
Looking More Closely at
352
xix
--
Safety-
J~.
f'
"
Science and Technology
Safety Procedures
You will be doing many activities in this
book
When doing an activity, it is very
important that you follow the safety rules
below. Your teacher may have safety
instructions to add to this list. As yo n read
the rules, discuss with a partner or note
why each one is an example of commonsense safety.
7. If you have long or loose hair, tie it back.
Roll up long shirt sleeves.
8. Inform yonr teacher if you have any
allergies or medical cond itions, or
anything else that might affect your
work in the science classroom.
During the Activity
9. Report any safety concerns you have or
Before You Begin
1. Read and mal e sure you understand the
insh-uctions in the text or in any
handouts your teacher may provide.
Follow your teacher's direction always.
Never change or start an activity
without approval.
2. Watch for "Caution ' notes. These notes
will te ll you h ow to take extra care as
you work through the activity. Make
sure you understand what the cautions
mean.
hazards you see (such as spills) to your
teacher.
10. Don ' t eat, drink, or chew gum in your
science classroom.
11. Never taste anything in science class.
12. Never smell any substance directly.
Instead , gently wave your hand over it
to bring its vapours toward your nose, as
shown in the photo below.
3. Learn to recognize the warning sy mbols
t r hazardous materials shown in
Toolkit 1, pages 367-368 .
4. Keep your work area uncluttered and
organized.
5. Kn ow the 10cation of fire extinguishers
and other safety equipment.
6. Always wear safety goggles and any
other safety clothing as requested by
your teach er or this book.
Smell an odour by wafting it towa rd you.
xx
13. Handle all glassware carefully. If you see
cracked or broken glass, ask your teacher
how to dispose of it properly.
14. Handle knives and other sharp objects
with care. Always cut away from
yourself, and never point a sharp object
at ano ther person.
15. Heat solids and liquids only in open
heat-resistant glass containers and test
tubes. Use tongs or protective gloves to
pick up hot objects.
16. ,\Vhen you heat test tubes, make sure that
the open end is pointing away from you
and anyone else in the room. The photo
below shows the correct way to do this.
17. When heating a substance, make sure the
container does not boil dry.
18. If any part of your body comes in contact
with a chemical, wash the area
im mediately and thoroughly with water.
If you get anything in your eyes, do not
touch them. Wash them immediately
and continuously with water for
15 minutes. Inform your teacher.
19. Keep water or wet hands away from
electrical outlets or sockets.
20. Use tools safely when cutting, joining, or
drilling. Make SUTe you know how to use
any tools properly.
21. Use special care when you are near
objects in motion, gears and pulleys, and
elevated objects.
22. Make sure equipment is placed safely so
that people will not knock it over or trip
over it. Report any damaged equipment
to your teacher immediately.
23. Treat all living things with respect.
Follow your teacher's instructions when
working with living things in the
classroom or on a field trip.
When You Finish the Activity
24. Make sure you close the containers of
chemicals immediately after you
use them.
ake sure the open end of the test tube is pointing away
from you when YOLi heat it.
25 . Follow your teacher's instructions to
safely dispose of all waste materials.
xxi
.
~
•
,
...
26. Always wash your hands well wi th soap,
preferably liquid soap, after handling
chemicals or other materials. Always
wash your hands after touching plants,
soil, or any animals and their cages or
containers.
27. When you have finished an experiment,
clean all the equipment before putting it
away. Be careful with hot plates and
equipment that have been heated as they
may take a long time to cool down.
Wear the proper safety equipment when doing
Safety Skills
The picture shows a
science class performing
a science activity.
Unfortunately, some of
the students are not
following proper safety
procedu res. Work with a
partner to identify and
list the problem actions.
Then suggest a better,
safer way to perform
each action. After you
have finished, share
your observations with
the class.
xxii
SCi
nee activities.
Investigating Science and Technology 8
Discover how to use your Investigating Science and Technology 8 book.
Explore the different parts of your textbook by finding the answers to the
fonowing questions.
Discov.er
.
ou will study in
what are the four units y
J
8
1.
..
nd Techno ogy 7.
Investigating SCience a
. A7
rs are th ere in Unit .
2. How many chapte . d· to parts What are
E h chapter is dlVl de In
.
.
ac
7
many are there In
these parts called . How
ch apter 37
0 different types of
3 Find examples 0 f tw
.
f· d
.
. . Where WI\\ you In
reading activities.
each one
7
1. Find the Unit OveNiew for Unit B. Wha t Big
Ideas wi ll you learn as you explore this unit7
2. At the beginning of each chapter you can
find a list of key terms. How many key
terms are there in Chapter 57 Wh
.
ere can
you go to find the mea nings of these terms 7
3. Find a Take it Further margin feature in
Chapter 7 that describes plasma Wh
.
ere can
you go to explore thi s topic In more detail 7
4 . For some of the Inquiry Acti vities, there are
symbols at the top of th e Materials &
Equipment list Find and sketch three of
these symbols and deSCribe what they
mean. Ca n you find a place in you r textbook
where all of the symbols are explained 7
----~ L
11
1. Where ca n you fin d a summ ary of what
·111
.
you
WI earn In each section 7
2. Find a Words Matter margin feature from
Chapter 9 that describes what SCUBA
means. What can you learn about in a
Words Matter margin feature 7
3. When wou ld you use a Learning
Checkpoint7
d
R ad feature at
Look at the Getting Rea y to de
·t
1.
..
of Unit A. What oes I
the beginning
d the unit?
u do to help you rea
suggest yo
I f another Getting Ready
Find an examp e 0
k
to Read feature In your textboo .
the Toolkits located at
h
would you use
2. W en
k7 Find an activity that
the back of the boo .
refers you to Toolkit 2
..
Before Reading ActiVity
3 . Find an example
: chapter How could
at the beginning 0
nderstand the
this activity help you to u
o~
7
chapter better
.
.
f a Ch apter ReView
k t the headings or
.
4. Loo a .
.
Wh h headings occur In
d Unit ReView.
IC
.
I
an a .
h. h headings occur In on Y
both reviewS7 W Ie
.
7
one review.
xxiii
Fundamental Concepts
•
•
Big Ideas
I ~-----
-------------------------------~
Overall Expectations
ivl osq uitoes feed on th e blood of
an imals. They bite birds, cats, dogs,
peop le, and other an imals in their
hunt for food to ensure their
surviva l.
4
UNIT A
Cells
hen you get a mosquito bite, you may get an itchy red
bump v,rhere you were bitten. If you live in a country
n ear the equator, you may develop malaria after the bite. If you
live in North America , you may develop "Vest Nile virus. If you
get sick, you may have a fever or you may ache all over. We now
know what is happeni ng to our bodies during all these events.
Hovvever, until doctors and scientists were able to examine
human cells, they had no idea what was causing illnesses.
This unit is about celis, the tiny units that make up human
tissu s a11d organs. You will use a microscope to observe the
basic structures of plant and animal cells. You will find out
hO\'\1 cells function and interact and learn about processes
W
inside cells. You will also assess the impact of technologies that
change cellular structures and processes.
Mysterious Deaths
In 1999, there were reports in the northeastern United States
of unusually high numbers of dead birds. Similar reports were
released in southern Ontario in 200l.
Microbiologists, who study cells, examined the bird
carcasses to find out what was happening. They studied blood
and tissue samples under their microscopes, and they were able
to see a virus in the birds' blood cells. They compared the virus
they saw to other known viruses in North America and around
the world. Modern technologies such as advanced microscopes,
technologies for viewing cells, and electronic communication
helped them identify the West Nile virus.
By 2002, people were diagnosed with the virus, and
scientists were working to find out how they had become
infected. While birds carried the virus, they were unlikely to
pass it to humans unless people handled an infected bird
carcass. Mosquitoes, which dine on both birds and humans and
transfer saliva in the process, were identified as the organisms
that transmitted the virus.
Before the development of the microscope and the study of
cells, this i11ness would have been a mystery. People could
avoid the carcasses of birds to protect themselves, but it
would have taken much longer to realize that mosquitoes
were th e link.
Twenty percent of people infected with the virus will have a
mild fever, a rash, and a headache. Two percent will have much
more severe symptoms and, on rare occasions, they will die. The
rest of those infected will experience no symptoms at all.
Canadian communities now protect themselves by
monitoring mosquito populations, thanks to the knowledge
gained from studies of cells under a microscope.
West Nile viru s has killed crows, bl ue
jays, chickad ees, and robins. By
20 07, over 150 bird species were
identified as carriers of the virus.
Poo ls of standing water are idea l
places for mosquitoes to lay their
eggs.
,.
Explori ng
5
One Big Cell
Not al l cells are microscopic. You have probably
seen this cell in your kitchen at home. It is too big
to view with a microscope.
To examine a basIc structure of a cell.
membrane that also has tiny holes. The shell
and the membranes allow air into th e egg.
2. Answer the questions as a class.
1. 00 you think the co ntents of the egg cou ld
survive without the protective coating?
Procedure
2. Most cells are tiny. 00 you think they have a
1. Read the following description of an egg.
protective coating7 Explain your reasoning.
The photograph here shows the con tents of a
single cell. It is a specia lized cell for the
reproduction of a chicken. The yellow pa rt,
called the yolk, is a food source for the
developing ch icken. Th e clear, milky part,
called albumin, IS mostly protein.
These structures were in a protective
covering made up of a hard, outer she ll filled
with tiny holes and two layers of thin, flexible
A2
Th is chicken egg is a single cell.
Thinking about Science, Technology, Society,
and the Environment
m
~ E~
Using an Insecticide
One of the ways to contro l the spread of the
Consider This
West Nile viru s is to use in secticides to kill the
As a class, answer the following questions.
mosquitoes. This can be done
In
a variety of
ways. Spraying from the air will kill mature adults,
or chem icals can be used earlier In the season to
kill the eggs and larvae before they mature.
1. What would be the impa ct on society if
in secticides eliminated We st Nil e virus 7
2. What would happen In th e environment if
mosquitoes were eliminated through th e
use of In secticides 7
6
UNIT A
Cells
ontents
Cells are the basic units of all living things.
2.0
3.0
1. 1
Living Things and Cell Theory
1.2
Comparing Plant and Animal Cells
1.3
The Flow of Materia ls into and out of Cells
1m
Cellular processes sustain living things.
2. 1
Unicellular Organisms
2.2
Multicellular Organisms and
Cell Specialization I
2.3
Plant and Animal Cel lular Processes
Healthy organisms depend on the
interaction of healthy cells, tissues,
and organs.
3.1
From Cells to Tissues to Organs
3.2
Interdependent Organ Systems
3.3
The Impact of Research in Cell Biology
Anticipation Guide
The health of any organism - including you
The statements in an anticipation guide can
- depends on healthy cells. You are going
help you make sense of information by
to learn about cells, including their structure
activating your prior knowledge. Before
and how they function. Cells are the basic
unit of life that few people understand. Your
task wi ll be to find an entertaining way to tell
people about ce lls and their importance.
s
IQ
I
n
What should people know about their cells?
reading this unit, read each statement in the
anticipation guide provided. Circle "Agree" or
"Disagree" to indicate your position on each
statement. You will revisit the statements in
this anticipation guide when you have
finished reading the unit to see whether your
opinion has changed based on what you
have learned.
In this chapter, you will:
• explain why cells are considered to be the
basic units of life
• identify key organelles in plant and animal cells
and explain their fu nctions
• distingui sh between the processes of diffusion
and osmosis
Skills You Will Use
In this ch apter, you will:
• demonstrate th e proper care and use of a
microscope
Organisms are composed of cell s. Healthy
organisms have hea lthy cells. In order to ensure
good health, it IS essenti al to know more about
cells, wh at they are made of, and how they
fun ction .
~
LL.tt!rA-CNI
Skimming and Scanning Text Features
Different readin g tasks require different
reading styles. "S kimming," or quickly looking
across each lin e of text, gives an idea of the
subject matter and if it will be useful. Skim
the headings in cha pter 1. Will it help you
prepare mi croscope sl.ides7
To find a specific word or piece of
information, "scanning" by looking down or
diagonally across th e page will be more useful.
Scan chapter 1 for new vocabulary word s.
Key Terms
• cell theory
• diffusion
• eyepiece
• membran e
• organelle
• osmosIs
• selective perm eability· stage
Figure 1.1 This painting, which shows an early
anatomy lesson, was painted in 1632. In the
Netherlands, in those days, one dissection
each year was a public one, and spectators
could pay a fee to watch the proceed ings.
iving things need a suitable habitat that supplies their basic
needs for oxygen, food, and water. They convert energy
vvith these resources and cany out a variety of activities. Early
doctors and scientists could only guess at how living things
carried out these activities. Tbey studied whole plants and
animals, including huma ns, in an effort to find out. They were
very curious about how living things worked. They also needed
to know how organisms like the human body worked in order
to treat diseases and injuries (Figure 1.2.).
As early scientists continu ed their inquiries, they began to
cut dead organisms into smaller parts in an effort to see what
was inside. They looked at organ systems and individual
organs such as hearts and lungs. They looked at muscles and
brain tissue (Figure 1.1) . Scientists began to develop new ideas
about how living things worked, but unti1 the first microscopes
wer built, they had no way of seeing the smallest unit of living
L
Figure 1.2 Smallpox was once a
deadly disease that killed millions of
people. After the microscope was
developed, doctors were able to find
out what was causing the disease
and find a way to control it.
10
UNIT A
Cell s
things: the cell. The cell is the basic structural unit of an
organism and the building block of life.
Microscopes gave scientists their first glimpses of cens. As
microscopes improved, scientists saw that cells are made up of
tiny structures. They novv know tha t these structures cannot
work independently. Cell structures must work as part of the
cell unit to carry out activities.
Th chicken egg cell you examined in Activity A 1 was big,
and ostrich eggs are even bigger but most cens are incredibly
small. Most are much smaller than O.S mm, which is about the
size of the period at the end of this sentence. This is why
microscope technology is essential for the study of cells.
Figure 1.3 There are a number of
living and non-living things in this
scene.
Defining Living Things
In grade 7 you learned that biotic elements - living
things - need oxygen, food, water, energy, and a
suitable habitat. You can expand thiS explanation by
listing common charaderistics of all forms of life.
To develop definitions of living an d non-living
things
5. Each partner wi ll form a group with two other
classmates who have the same half of the
chart.
6. As a group, write a definition of a liVing or
non-l iVing thing.
7. As a class, combine group definitions of liVing
and non-living things, and create a genera lly
accepted definition of ea ch.
1. With a partner, create a T-chart with the
headings ''Livlng" and "Non-living:'
2. Together, think about things that are living, and
list the ch araderisti cs or features that these
things have. For example, you might say that
living things grow
3. Li st characteristics or features of non-living
things on th e other Side of your T-chart.
4. With scissors, cut your chart in half. One
partner will take the living list, and the other
wi ll take the non-living list.
8. The method used by you and your classmates
to define a liVing thing is similar to the method
used by scientists. They also created and
collected ideas, and then discussed and edited
them until they had an acceptable definition.
Despite this, a simple definition of life does not
exist in the scientific community. Not every
scientist is happy with the accepted definition.
Is there a portion of your class definition that
you think could be explained better7 How?
9. What do you think a scientist would need to
do If he or sh e disagreed With a generally
accepted definitIOn 7
Cell s are the basic units of al l living t hings.
11
Here is a summary of what you will learn in this section:
• Living things are made of cells.
• Scientists knew very little about cells before the Illicroscope was developed.
• Cell theory is a way to describe the nature of cells.
Figure 1.4 You can make a simple
magnifier with a wa ter-filled bottle.
Living things are all shapes and sizes. They can be plants or
animals. They can live in a variety of habitats - fro m the tops
of mountains to deep in the ocean. They have common basic
needs, and they are all made up of cells.
In order to study th ese living things, scienti ~; ts needed to be
able to see them more clearly. There are written references to
the use of some type of magnifier almost 2000 years ago.
However, technologica l advances in both glass making and the
grinding of lenses were required before magnification could be
improved. Len es for eyeglasses became available around the
end of the 13th century. Lens makers became more skilled at
grinding lenses as the demand for eyeglasses increased.
T he earliest microscope was a tube with a single lens at one
end and a plate for the object at the other. T he magnification
was 10 times the actual size of the object.
Make Your Own Magnifier
When light passes through a curved surface, it
bends slightly. As a result, the image we see of
the object beyond the curved surface seems
larger than the actual object. This knowledge
enabled people to magnify small objects. You
can experiment to make your own magnifier.
1. Place a large drop of water on a
microscope slide. Move the slide
carefully to view the writing on a
piece of newspaper.
12
UNIT A
Cells
2. Place a large drop of water on a clear
overhead sheet Move the sheet carefully
over a piece of newspaper to view the
writing on It.
3. Fill a test tube with water, and fit a stopper
in it. Turn it Sideways, and read through the
test tube.
4. Fill a clear plastic bottle with water, and
secure the cap. Turn it sideways, and read
through the water-filled bottle (Figure 1.4).
Microscopes and Cell Theory
Since most ce11s are too small to see with the unaided eye, the
existence and structure of cell remained unknown until the
late 1600s. It was An tony van Leeuwenhoek (1632-1723) who
built what is thought to be the first successful light microscope
(Figure 1.5). Van Leeuwenhoek had taught himself how to
grind and polish lenses in order to make his own magnifiers.
Eventually, he made tiny lenses that could magnify an object
up to 2 70 times. With this tool and a lot of curiosity, he
uncovered the mysteries of the microscopic world. H e was the
first person to see bacteria cells, yeast cells, and blood cells. H e
also observed the variety of life in a drop of pond water.
T
si Id a of
or
T he scien tists who came after van Leeuwenhoek used
increasingly effective microscopes. Over time, their discoveries
led to the following key ideas of the cell theory.
1. The cell is the basic unit of life. In other words, the ce11
is the smallest living organism that shows the characteristics of living thinos.
2. An organism can be as simple as one cell (unicellular),
like a paramecium, or it can be made up of trillions of
cells (multicellular), like an elephant.
Figure 1.5 Antony van Leeuwenhoek
built one of the first successful light
microscopes.
WORDS MATTER
The prefix" micro-" comes from the
ancient Greek word mikros, which
means" small." The Greek word skopos
means "watcher. " The prefix "tele-"
comes from the ancient Greek word for
"far. "
3. All cells are created from existing cells through a process
called cell division by which a cell divides into two
new cells.
~
------------------------------------------------------------~
L.&.~v~
Reading like a Writer
Textbook writers include a variety of text features
to help the reader navigate the text more easily.
chosen different ways to highlight these
specialized words 7 How does the "Words Matter-"
As you read pages 13 and 14, record any
feature help you with the scientific vocabulary
scientific vocabulary you encounter. Compare the
presented on these pages? What other text
different ways scientific vocabulary is presented
on these pages. Why might the writer have
features do textbooks contain that help readers
make sense of specialized vocabulary?
Ce ll s are the basic units of all living things.
13
The Com oun
Before they developed cell theory,
scienti sts believed in spontaneous
generation. Find out more about
this theory, and report back to your
classmates. Begin your resea rch at
ScienceSource .
o
o
o
o
o
o
o
o
o
e
L· h Micro
0
A compound light microscope uses li6h t focussed through
several different lenses to form a magnifi ed image of a
specimen. A modern compound microscope, like the one
shown in Figure 1.6 below, is a delicate an d expensive
insh'ument and n eeds to be handled with care.
Eyepiece or ocular lens This is the lens that
magnifies the specimen, usually by 10 times (lOx) .
This is the lens you look into.
Coarse adjustment knob Thi s knob moves the
stage up or down to focus on the specimen . This is
the first knob you use to focus on a specimen.
e
_
Tube The tube separates the ocular lens from the
objective lenses at a distance calculated for proper
mag nification.
Condense r lens This lens is under the stage . It helps
focus light onto the specimen on top of the stage.
Fine adjustment knob Use this lens to sharpen an
image under low and medium power. It is the only
adjustment knob needed with the high-power lens.
Revolving nosepiece This is where the objective
lenses are mounted. Rotate the lens to select low-,
medium-, or high-power lenses.
Objective lenses There are three lenses that
magnify the specimen: low-power (4x), mediumpower (lOx) and high-power (40 x). Keep the lenses
free of dirt and fingerprints.
Stage This is where you place a sl ide for
observation. Always keep the stage dry.
Stage clips These are used to hold a slide in
position on the stage.
Diaphragm This has different-sized holes that let
different amounts of light pass through the
specimen on the stage.
Lamp The lamp supplies the light that passes
through the specimen on the stage. Microscopes
that do not have a lamp may have a mirror to
collect and direct light.
Arm The arm holds the tube in place and is used to
carry the microscope .
. , Base This provides a stable platform for the
microscope. Always set it on a flat, dry, uncluttered
surface.
Figure 1.6 This com pound light microscope is typical of the on es found in many science classrooms.
14
UNIT A
Cel ls
Care and Use of a Microscope
When used correctly, microscopes are powerful
scientific tools. They are also expensive and
delicate. Refer to Toolkit 9 before you follow the
steps below to use them safely and effectively.
lens is about 1 cm from the stage. It will stop
at the correct position. Do not force it.
6. look through the ocular lens. Adjust th e
diaphragm until it is as bright as possible.
7. Place a prepared slide on the stage, and
To use a microscope correctly and follow safe
laboratory procedures
secure it With the stage clips. Check to make
sure the object 011 the slide is centred ovel'
the hole in the stage.
8. Look through the ocular lens.
compound light microscope
len s paper
prepared microscope slides
9. Slowly turn the coarse adjustment knob to
bring the object into focus. The image should
be very clear. If it is not, lise the fine
adjustment knob to make the image sharper.
10. Without adjusting the focus, rotate the
1. Make sure you have a clear, clean, dry, flat
work surface for the microscope. If the
microscope has a plug, position the
microscope so that it is close to the outlet.
2. Use two hands to carry the instrument - one
hand on the base and the other on the arm.
l. Use lens paper to clean the lenses. Never
touch the lenses with your fingers.
4. Rotate the revolving nosepiece until the lowpower lens clicks into place.
5. View the microscope from the side. Turn the
coarse adjustment knob until the low-power
Figure 1.7 The coarse adjustment knob moves the
stage up or down.
revolving nosepiece until the medium-power
lens clicks into place.
11. Use the fine adjustment knob to sharpen the
Image.
12. View an object and at the same time move
the slide left, then right, then up, and then
down. Describe what happens to the image.
1l. Refer to Drawing Hints in Toolkit 9 to help you
draw and label the Images YOLi see under the
microscope. Draw sketches of two of the
specimens you viewed. How are they the
same 7 How are they different?
Figure 1.8 The fine adjustment knob brings the
object into sharper focus.
Cel ls are the basic un its of al l l iving things.
15
I
r
cp
Practise Your Skills
1. In your own words, restate th three key
ideas about ce ll theory.
2. Create a chart listing the names of the
parts of a ill1cfoscope on the left-hand side
and the functions of each part on the
right-hand side. Your chart should have
13 rows.
5. Write up the procedure for bringing a
microscope from fhe storage area to your
work space and setting it up.
6. The student in the photo below is using a
microscope safely. Name three things she
is doing correctly.
3 . In )70Ur own words, define a compound
light microscope.
r
,. Y Ir In pr
n
4. Your classmate is viewing a sample
using high p wer and is about to refocus
using the coarse adjustment knob. What
would you recommend your classmate
do and why?
For more questions, go to ScienceSource.
A7
Thinking about Science, Technology, and Society
~
The Importance of Technology in Science
Most technologies are developed to answer a
Consider This
specific need, but they often lead to more
With a classmate or as a whole class, discuss
questions, more studies, and whole new areas
these questions.
of knowledge. This is the case with the use of
2. Do you think it would have been possible
lenses to create microscopes.
to know that living thin gs are made of cells
if microscopes had not been developed?
What to Do
1. Compare the difference
16
In
the detail you
Explain your thinking.
observed while viewing the microscope
3. Do you think that scientific discoveries
slide with your unaided eye and Viewing
always require the invention of new
the slide under the microscope.
technologies 7 Explain your reasoning.
UNIT A
Cells
Here is a summary of w hat you will learn in this section:
•
•
Plant and animal ce ll structures are called organelles.
Plant and animal cell s perform some similar function s, such as converting energy and getting rid of
wastes.
• Plant cells perform a unique function, which is using energy from the sun to convert carbon dioxide
and water into food.
When you first learned to classify living things, the easiest
ones to classify were likely the members of the plant kingdom
and the members of the animal kingdom. Think of the main
differences between plants and animals that you observed and
that h lped you decide wh ich category the organism belonged
t . Scientists decide which is which by dividing organisms into
those that can make their own food (plants) (Fi 6 ure 1.9) and
those that must consume other living things in order to get the
nutrients they need (animals).
This difference between pla nts and animals is reflected in
the structure of their cells. Plant and animal cells have some
similar specialized parts that do the same job. Plant cells also
have some unique parts that allow them to transform the Sun's
energy into food in the form of sugars .
Figure 1.9 Pla nts have cel ls with
special parts that enable them to
use energy from the Sun to produce
food.
What is the magnification?
The size of a red blood cell is about 0.007 mm.
A liver cel l is about 0.02 mm. The point of a
ballpoint pen is about 0.2 mm. The head of a
pin is about 1 mm.
Consider This
3. When you are looking at a magnified
image, is it important to know the
magnification? Exp lain you r answer.
What to Do
1. List which of the above items you cou ld
see with your unaided eyes.
2 . Compare the actual size of a red blood cel l
with the image shown in Figure 1.10.
Estimate how many times it has been
magnified.
Figure 1.10
Red blood cells
Cell s are t he basic units of all living things.
17
Parts of Plant and Animal Cells
Figure 1.11 Photograph of a plant
cell taken through a microscope. It
shows chloropl
sts
(green),
cytopla m, vacuo les (large yellow
areas), and the cell wa ll, among
other structures.
All plant and animal cells contain a jelly-like material called
cytoplasm in which the parts of a cell float. To keep the
cytoplasm together, cells possess a thin covering caU d a cell
membrane. The cell membrane acts like a security guard,
allowing only certain materials in or out. Floating in the
cytoplasm are structures (parts) called organelles. Organelles
are tiny parts within the cell that have special functions that
help the cell survive, grow, and reproduce. Most organelles are
contained inside a membrane of their own. Organelle
membranes keep different parts of the cell separate from one
another.
P
t
igures 1.11 and l.12 show various organelles an d structures
typical of plant cells.
nucleus A large organelle
t hat is easy to see under
magnificat ion . It controls
th e activities of t he cell ,
such as growth.
endoplasmic reticulum
A folded organelle t hat
makes proteins .
Goigi apparatus
A f olded organelle
cell w all Fou nd in plant
cells but not in animal
cells The rigi d struct ure
th at surroun ds t he cell
membrane It provides the
cell with strength and
support. Material s pass in
or out of th e cell through
pores in the cell wall.
tha t com bines prote in s made
by th e endoplasm ic ret icu lu m
and delivers them to the rest
of the cell and ou tsi de th e cell .
~
mitochondria The
powerhouses of the cell .
These orga nell es break down
fo od particles and release t heir
stored energy. The ce ll uses
this energy to f uel all of Its
activities. M it ochondri are
surrounded by a membran e.
vacuole A large, sac- li ke
organelle t ha t stores excess
food, w aste, and other
substances . Each v cu ole is
surrounded by a membrane .
cytoplasm Jelly-like material
th at fills the ce ll and surrounds
the organelles. Food and
oxygen move thro ugh
the cytoplasm t o the
organelles.
Figure 1.12 This is
18
UNIT A
a representation
Cells
cell membrane The t hin
covering t hat holds the
cytopl asm and the
organelles inside th e cell
and controls the passage
of material s in or out of
th e cell.
chloroplasts M em brane -bound
orga nelles that cont ai n a green
subst ance (p igment) called
chlorophyll. In a process called
photosynthesis, chlorophyll uses
the Sun's energy t o co ver ca rbon
diox ide an d w ater int o sug ar (food)
and oxygen. Chloroplasts are found
in pl ant cells b ut no t in animal cells.
of the key parts of
a plant cell
rib osomes Tin y
organelles that help make
proteins . There are many
of these organelles in the
cytoplasm .
It does not rep res ent all plant cells.
nim I Cell
Figure 1.13 Photograph of an
animal cell taken through a
microscope The nucleus (pink)
takes up most of th e cell. Outside
the nucleus is the cell cytoplasm
(gre en) The brown bodies at the
top of the cell are m itochondria. Th e
cell is surrounded by a cell
membrane.
Figures 1. 13 and 1.14 show that animal cells
have many of the same organell that pla nt
cells have. Compare the two diagrams and
note any similarities or differences.
cell membrane The thin
cove ring that su rrou nds
t he organelles inside the
cell and controls th e
passage of mat erials III or
out of th e cell . The cell
membrane is t he oute r
boundary of an an imal cell .
Iysosomes Th ese organelles
break down food and digest
w astes .
cytoplasm Jelly· llke
matecial that fills th e ce ll
and surro unds the
organelles Food and
oxyg en move th ro ugh
the cytop lasm to th e
organelles.
nucleus A large organel le
th at is easy to see under
magnification. It controls
the activities of t he ce ll,
such as growth
mitochondria The
powerhouses of the cell.
These organelles break
down food pa rticles and
release their stored energy.
The cell uses t his energy to
fuel all of its act iviti es. The
num ber of mito ch ondria
varies accordin g t o the
function of th e ce ll .
ribosomes Tin organelles
th at help make protein s
There are many of
t hese orga nell s in t he
cytop lasm.
Goigi apparatus
A f olded orga nelle that
combines protein s made by
th e endopl smic reticulum
and delivers them to t he
rest of th e cell and ou tside
the cell .
Figure 1.14 This is a representati on of th
re present all animal cells.
vacuoles Sac-l ike
organelles that store excess
food, waste, and other
substances. Anima l
cel ls have several small
vacuoles.
endoplasmic reticulum
A folded organelle t hat
makes proteins .
key pa rts of an animal cell. It does not
Using Headings
Textbook headings are specifically organized to
headings as well as the different ways they are
guide a reader's understanding of th e
presented. Think about colour, type size, and
information and indicate which topics are
other conventions used to highlight these
connected or related. As you read to th e end of
headings. How does the visual presentation of
section 1.2, pay special attention to the
the head ings help you as a reader? Use the
headings and subheadings presented on these
headings on th ese pages to explain the
pages. In your notes, make a list of th ese
connections among these topics.
Cells are the bas ic units of all living things.
19
Special Technologies for Studying
Plant and Animal Cells
Biologists are not th e only
scienti sts who use microscopes.
Earth scientists such as geologists
also use them. Fi nd out what a
geologist uses a microscope for.
Begin your research at
ScienceSou rce.
When you first looked at cells under a microscope, you were
likely looking at prepared slides, and the cells had been stained
with a dye such as iodin e. The cells and their organelles do not
have much colOluing, so light passes through them. Without
colour or contrast, the organelles are difficult to see. Stains make
some organelles visible ( 'igures l.15 and l.16). All of the ce11s
shown in photographs in this text are micrographs of stained
cells. Micrographs are photographs taken with a microscope.
T he preparation of a specimen (sample) for viewing under
the microscope involves a variety of steps that depend on the
type of specimen. Typically, a very thin slice of the specimen is
obtained without damaging the cells. Next, the specimen must
be mounted on a slIde.
Finally, the cells are stained. Researchers usually choose the
type of stain best suited to the cell they are examining. For
example, some stains are best for observing blood or bone
marrow. Others are for distinguishing cells from surrounding
tissues or to make carbohydrates visible.
Stains must be handl ed with car e because some are toxic
8.nd others can damage the eyes . T he most common stains for
student purposes are:
• food colouri ng , which is non-toxic
• iodine, which is used to detect the presence of starch
• methylene blue, wh ich is used on animal cells to make
the nucleus visible
•
•
•
..
•
•
• ••
•
•
•
•
Figure 1.15 These liver cells were stained in order to revea l
Figure 1.16 A stain was used in this sa mple to revea l the
the organelles.
presence of cancer cells.
20
UNI T A
Cells
Building a Cell
3. Consider options for material s that will best
To design and construct a model of a plant or
animal cell
represent the organelle.
4. Select the best building materials and
construct your model.
building materials such as recycled objects
OR
food items such as pasta or breakfast
cereal that resemble the organelles they
are representing.
5. Add the material you used to represent each
organelle to the chart you created in step 2.
6. Justify your choice of materials.
7. What part of your model best represents an
organelle? Explain your reasoning.
1. Choose the type of cell you will construct.
2. List the organelles to be represented and the
8. If you had more tim e or different materials,
what would you change in your model? How?
function of each one in a chart.
Preparing Dry Mount Slides
3. Hold a cover slip very carefully by its edges,
To learn how to correctly prepare dry mount slides
of a variety of non-living things
and gently place it over the threads.
4. View the threads under the microscope using
the medium-power lens.
compound light microscope
microscope slides and cover slips
tweezers
threads from different fabrics
other samples (e.g, hair, salt)
5. With your teacher's permission, make dry
mount slides of other samples, such as hair or
salt.
6. Draw and label a sketch of the threads you
saw
1. Choose a few strands of thread from the fabric
sa mples provided.
7. Cha llenge your lab partn er to figure out what
fabriC sample the thread on your dry mount
came from.
2. Place the thread s at the centre of a clean,
dry slide
8. Repeat steps 6 and 7 for the other specimens.
Cells are t he basic units of ar l li ving t hings.
21
Preparing Wet Mount Slides
>
::\.
....
<
....
Prepared microscope slides are conveni ent to use,
~
but in order to view your ch oice of specimens, you
need to prepare your own slid es. In order to vi ew
living or moving objects, you must prepare a wet
mount.
4. Use tweezers to place the "e" right side up on
the drop of water.
5. Hold the cover slip very carefully by its edges,
at an angle of about 45° to the surface of the
slide. Gently lower the cover slip over the
sam ple. If any air bubbles get trapped,
carefully move the cover slip with your filnger
To learn how to correctly prepare wet mount slides
to free them ..
of a variety of objects
6. View th e sample under the microscope. Start
with low power and then move to medium
power.
co mpound light microscope
microscope slides
cover slips
tweezers
7. Make a wet mount of homogenized milk, and
view it under medium power.
8. Get permission from your teacher to make
medicine dropper
wet and dry mount slides of other samples,
water
su ch as pond water.
a newspaper
homogenized m ilk
skim milk (optional)
other samples (e.g., pond water)
9. Draw a sketch of the specimens you viewed.
Give your sketch a name and a date.
10. Challenge your lab partner to figul'e out what
your sketch represents.
1. Obtain a clean, dry microscope slide and
cover slip. Place the slide In front of you.
2. Carefully cut a lowercase "e" from the
newspaper.
3. Use the medicine dropper to place 1 or 2 drops
of water in the middle of the microscope slide.
Figure 1.17
22
UNIT A
Cells
11 . There are many white blobs visible on the wet
m ount of homogen ized milk. What might
these be! Test your theory by making a wet
mount slide of skim milk. Draw alld label a
sketch comparing both milk samples.
12. Why do you think it was important to get rid of
any air bubbles!
r
C"p
ct Y
tP
1. Prepare a chart listing the organeUes of a
3 . When would you use a dry mount to view
a specimen under a microscope? When
would yo u use a we t mount?
4. What is a micrograph?
I
5. Plant and animal cells have some of the
same types of organelles. List these
organelles, and explain why you think
this is the case.
plant cell and their functions. Label the
columns in your chart and give your chart
a name.
2. Prepare a chart listing the organelles of an
animal cell and their fun ctions. Label the
col umns in your chart and give your chart
a name.
r
6. Plant cells have some organelles that are
different from those found in animal ce11s.
List these organelles, and explain why
you think these organelles are needed.
ill
7.
have obtained specimens of a piece of
meteorite and water from the pond it
landed in. Describe the procedure for
preparing to view each of them under a
microscope that has been set up.
YOLl
_~
For more questions, go to ScienceSource.
A13
Thinking about Science, Technology, and Society
~
uPerfecting" Plants
Farmers have saved seeds for crops almost
farmers will always buy seeds from the
since the beginning of agriculture. They have
company that paid for the research.
also experimented with breeding plants in the
hope of developing better ones.
SCientists began to assist farmers, and in
Canada, research studies led to the
development of wheat that could grow In our
Consider This
With a classmate or as a whole cla ss, discuss
these questions.
1. Companies are usually allowed to own the
climate. This success enabl ed Canadian farmers
to become major produ cers of wh eat, an
technology they invent. Should companies
be able to own technologies that relate to
important part of Canada's economy.
living things 7 Explain your reasoning.
SCientists are now able to breed plants that
resist insects or can grow better in more
challenging conditions. Som etimes the seeds of
those plants are engineered so that they cannot
develop Into new plants. This ensures that
2. If scientists can change plant cells to
improve the world's supply of food,
should they be allowed to do so? Who
should decide 7
Ce ll s are the bas ic un its of all l ivi ng things.
23
Here is a summary of what you will learn in this section:
• The cell membran e can control the substances that move into or out of a cell because the
membrane is se le ctively perm eable.
•
Diffusion is a process wh ere substances in areas of high concentration move to area s of
low concentration.
• Osmosis is a special type of diffusion involving water and a selectively permeable membrane.
Figure 1.18 On a windy, rainy day
only th e right type of Jacket will keep
the wearer warm and dry.
';\,Then it is wet and windy outside, you need to wear a jacket
that keeps the rain and cold air away from your body. A
clothing designer must choose from the few fabrics that have
the right properties for a wet-weather jacket. If the jacket is
made of cotton, you will be wet and cold. Cotton is permeable,
which means water and air can pass through it easily.
If the jacket is made of a plastic material, you may still be
wet and perhaps cold. Plastic is impermeable. Although rain
cannot pass through it, you will get hot and sweaty because the
air heated by your body cannot escape through the plastic. Then
the moisture in the heated air will condense on the inside of the
jacket and conduct heat away from your body. T he best jacket
material keeps the rain out but lets some water vapour pass
through. Such material is selectively permeable (Figure 1.18).
Selective permeability refers to the property of a barrier that
allows only certain substances to pass through it.
Finding Buried Treasure
A sieve is an example of a selectively permeable
Consider This
membrane. It allows some items to pass
through it while other items cannot.
If you lost your ring in a pail of sand, you
could use a soil sieve or a kitchen sieve to
UNIT A
sand to find your ring, what is the most
important quality of the selectively
permeable membrane you are using7
retrieve it.
24
1. If you were using a sieve to sift through
Cells
Cells and Permeability
The cell walls and membranes you see in Figures 1. 19a and
1.19b below are sel ctively permeable. Each structure functions
as a barrier that separates the inside of a cell from the outside
environment and keeps the cell intact. In addition, these
selectively permeab1e cell structures allow certain substances,
such as water, oxygen, carbon dioxide, carbohydrates, and waste
created within the cell, to pass through it. Large molecules that
may harm the cell are blocked by the membrane or cell wall.
Withou t selective permeability, the celI would be sealed. It
would be unable to access the supply of materials the
organelles need to carry out cell activities, and the cell would
be unable to get rid of the wastes generated by its activities.
Instead, every cell in your body (and in every other organism)
is bringing water, food, and gases in and removing wastes at
every moment of the day.
This movement of substances into and out of a cell is called
cellular transport. Cellular transport involves several
differen t processes. Diffusion and osmosis are two types of
cellular tran sport processes.
(b)
(a)
Figure 1.1 9 Both plant (a) and
an imal (b) cells have selectively
permea ble mem branes and wa lls
(in the case of pla nt cells).
Substances such as air and water
move into the celi s and waste
moves out of the cell s.
ClieCKpdifit' ,;;u;r='=-~ ~ ,. _- ~':
J
~~_
j
',,'
-tl -
•• 1
1-.
Build a Mind Map
A mind map is an excellent tool to help you
Begin by wr,iting "cellular transport" in the
remember what you are reading. In the
centre of a piece of paper. Then build your
information that follows, you will be Introduced
understanding about the key ideas of diffusion
to two different forms of cellular transport -
and osmosis. Note definitions, functions, and
diffusion and osmosis. Create a mini-mind map
examples of the two forms of transport as you
to help you summarize their roles in ensuring
read through the rest of this section,
the survival of a cell.
Ce lls are t he bas ic uni ts of ali living tlli ngs.
25
i fusio
Figure 1.20 The smok from this fire moves thro gh the
air by diffus ion, dispersing its particles evenly throughout
the air.
•
solute pa rticles
•
water particles
Diffusion is the movement of particles fro m an
area where there are many of them (a higher
concentratio n) to an adjoining area where there
are few of them (a low r concentration) (Figure
1.20). Diffusion continues until bo th areas have
the same number (concentration) of particles
(Figure 1. 21) .
Diffusion happens all around you. Diffusion
occurs \\ hen you place a tea b ag into boiling
water to make tea. Diffus ion is at work when
you can smell the aroma of pizza coming from
the kitchen. Everything you can smell is because
of diffusion. Diffusion causes the fragrance of
cologne or perfume to spread through a room. A
classroom is usually not a good place to wear
these products because of the effectiven ess of
diffusion in such a small pace, and because some
people are very sensitive to fragrances.
For a cell, diffusion is how resources such as
oxygen are transported (moved) into it through
its selectively permeable membrane. When the
concentration of oxygen is lower inside a cell
than it is outside the cen oxygen diffuses into the
ce1l, where it is used by the mitochondria. As the
oxygen is used to produce energy, more will
diffu 'e into the cell to keep the concen tration
almost the same inside and ou tside the cell.
solid barrier
..·..........
. . .. . ...
...
·.:........
.:........-....
-·.......
: ........
..: .. .......:
start
~
Figure 1 .21 The proc ss of diffusion
26
UNIT A
Cells
solute particles diffusing water particles diffu sing
finish
.
mos.
Osmosis is a special kind of
se lectively permeable membrane
diffusion that involves only the
w ater particles
movement of water through a
solute particles
selectively permeable membrane
(Figure 1.22). T he
concentration of water inside a
cell must stay fairly constant,
and therefore water diffuses into
and out of cells continuously.
Osmosis (this movement of
Figure 1.22 During osmosis, water moves fro m an area of higher concentration of
water in to and out of cells) is
water to an area of lower concentration of water through a se t ctivel y permeable
vital to the cens' surviva1.
memb rane. In the diagram. th e water particles move fro m left to right
The process of osmosis also
depends on the difference in the
concentration of particles. In the case of cells, if the
concentration of water particles inside the cell is higher than it
is outside the cell, water will move out of the cen by osmosis. If
the concentration of water particles outside the cell is higher,
Bottled water is not pure water. It
the water particles will move into the cell.
has dissolved substances in it Find
If you let the soil around the plant dry out, the plant would
out more about th ese substa nces
begin to droop as the concentration of water particles inside
and how th ey may help your cells
to
function pro perly. Report back to
the cell dropped. With no water in the soil, there is no water to
your cl ass. Begin your research at
move into the cells. If you examined the cells in the stem, they
Sci ence Source.
would look shru nken. T he cell walls wo uld not be rigid, giving
the plant a \vilted
appearance. Th is process
is easies t to detect in
plants (Figure 1.23).
If you were to look at
one of the cells in the stem
of a firm plan t under the
microscope, you would see
that it has a very ful1
shape. The cell has so
mu ch water in it that if
the thick cell wall were
removed, the cell would
Figure 1.23 Osmosis is involved in giving plants the rigidity they need to reach up for
burst.
sunlight. Compare the drawing of a cell in a wilted plant (left) to the one in th e healthy
~.
plant
Cel ls are the
b aS IC
units of al l l iving things
27
Evaluallng procedures
• DraWing conclusions
Diffusion Detective
During diffusion, molecules move random ly as
J. Carefu lly hold the food colounng container
they shift from a high co ncentration to a low
5 mm above the surface of th e water In the
conce ntration . This activity w ill allow you to
first container, and gently add 3 to 5 drops to
obse rve diffusion .
the surface of the water.
4. Use the medicine dropper to carefully add 3
to 5 drops of vegetable oil to the surface of
Do all liquids diffuse in the sam e
ay?
the wa ter in th e second container.
5. Carefully lower the tea bag into the third
conta in er.
3 clea n 400-m L beakers or clear glass
con tainers
water
electric kettle
food colounng
vegetabl e oil
tea bag
6. Do not bum p or move th e containers or
agitate, swirl, or stir the liquid inside the m.
7. Observe what happens over a 5-min period.
8. Draw and label a series of diagrams that
reco rds what happened In each container.
medicine dropper
9. Compare your observations with those of a
cla ssma te. In one sentence, describe the
pattern of movement you observed for each
of the substances added to the water.
10. Did you observe any differences in the way
the substan ces moved in the water? Suggest
an explanation
11. Do you think the activity was a fair test to
co mpare the diffusion of different substances?
Explain why or why not.
Figure 1.24 Get as close to the surface as possible (within
5 mm) before adding the substance to the water.
1. Add approxim ately 300 mL of water to two of
the containers
2. Add approximl'tely 300 m L of boiling water to
the third container. Be ca reful with the hot
water. It can sca ld yO l .
28
UNIT A
Ce l ls
12. If n cessary, suggest how the activity could be
cha nged to make it a fair test.
13. What factors, if any, do you thin k might affect
diffusi on?
Predicting
Observing and Recording
Food for Thought
4. Create a chart to record your observations. In
How will plain water and a sa ltwater solution affect
your chart, record the shape of each food
plant cells 7
item, what it fe els like, and what it looks like.
Add 1 carrot, 1 celery stick, and 1 raisin to
each of your bea kers.
two 400-mL beakers
5. Cover each beaker with a piece of pla stic food
water
wrap. Predict what will happen to each food
2 pieces of each food carrot, celery stalk,
item in each beaker. Create a chart to record
raisin
your prediction s.
spoon
salt
plastic food w rap
6. Let the beakers sit for a day or less.
7. Record your observations In your chart.
nalyzin
nd Inter retin
8. How did the plain water and the saltwater
1. Fi ll each beaker w ith 300 mL of water.
solution affect th e food items7
2 . Label one beaker A and the other beaker B.
3. Add salt to beaker B and stir. Continue to add
sa lt until no more w ill dissolve (a small pile
9. Compare yo ur predictions to your resu lts.
Discuss any differences.
will remain on the bottom no matter how
much you sti r) .
10. Use words and pi ctures to show how osmosis
occurred in this activity.
11. Should you store plant-based foods in plain
water or a sa ltwater solution 7 Explain yo ur
reasoning.
Figure 1.25
Cells are th e basic un its of all living things.
29
p
'I
1. Define the term "permeable" in your mvn
words.
2. Use the term "concentration ' in a
sentence about liquids that conveys its
mean ing.
3. List three examples of a selectively
permeable material or item. Explain
where it is found or used and vvhy a
selectively permeable material is needed.
4 . If ou wrap fresh celery in foil, it will stay
cnmchy when you store it in the
refrigerator. Explain why you think this
happens.
Practise Your Skills
5. You need to put a new roof on your
hOllse. Describe how you would test
possible materials for permeability. What
would be the criteria for Sllccess?
For more questions, go to ScienceSource.
A18 Thinking about Science, Technology, and Society
~
The Artificial Kidney
Your kidneys help filter waste materials out of
Consider This
your blood. If they become da maged, you may
need to have your blood filtered artifiCia lly. This
With a cla ssmate or as a whole class, discuss
process is called dialysis.
Dialysis works by using the principles of
diffusion and osmosIs. Tubing hooks the patient
up to a machine, known as a dialyzer, and blood
is pumped from one of the patient's arteries into
the dialyzer (Figure 1.26). This blood is rich in
waste materials.
The compa rtment in the dialyzer is divided by
a selectively permeable membran e. A special
dialysis fluid, called dia lysate, flows through the
dialyzer on the other side of the membrane.
This system can filter the waste materials from
the patient's blood. The clean blood IS returned
to the body by being pumped into a vei n.
Figure 1.26 Pa ients with damaged kidneys need regular dialysis
treatment
30
UN IT A
Ce lls
the following questions.
1. A dialysis treatment can take from three to
five hours and must be done three or four
times a week. Every year, another 2000
Ontarians require dialysis. Should those
who can afford it be asked to contribute to
the cost! Explain your reasoning.
2. A kidney tran splant is an alternative to
dialysis. Should people be encouraged to
donate their organs for transplant! Explain
your reasoning.
Solving the Mystery of
s
Figure 1.28 A skin cell seen under
a compound light microscope
Figure 1.29 Skin cells seen
under a scanning electron
microscope
organelles such as th e nucleus or mitochondria
(Figure 1.28). Nor could they see tiny viruses. In
order to see that level of detail, scientists
needed microscopes that could magnify objects
by 10 OOOx or more.
An electron microscope uses a focussed
beam of electrons Instead of light to create an
image of a specimen. Magnetic lenses help
contain and focus the beam. The interactions of
the electrons and the specimen are
transformed Into an Image (Figure 1.29).
Since the mid- 1960s, when sca nning electron
microscopes became more widely available,
there have been a number of breakthroughs in
the study of viruses. In addition to solVing the
Figure 1.27 Transmission electron microscope
mystery of how West Nile virus IS transmitted,
researchers have studied everything from the
Viruses are extremely tiny agents that cause
common cold to the outbreak of SARS (severe
infection. They are smaller than bactena, and
acute respirato ry syndrome) .
they are unable to grow or reproduce on their
own Instead, they must Invade a living cell.
They use the resources of the cell to develop
and multiply.
Researchers did not see viruses until after the
Q estion
1. A compound light microscope costs
hundreds of dollars, depending on the
model. An electron microscope can cost
electron microscope was developed In the late
hundreds of thousands of dollars,
1930s (Figure 1.27). Compound light
dependmg on the technology supplied With
microscopes are limited to magnifications of
it. Should governments provide funds for
500x or 1000x. Th iS level of magnification did
researchers to acquire specialized electron
not allow researchers to see the details inSide
microscopes I Explain your reasoning.
Ce ll s are the bas ic un its of all living thi ngs .
31
1 . \\l here is the diaphragm located on a microscope? Explain
vvhat it is used for.
2. (a) Identify the type
of cell in the
diagram shown
here, and nam e
all numbered
Virts.
Reflect and Evaluate
Brain research indicates that
the brain is a pattern seeker.
As we read increasingly more
complex text, the brain tries to
draw on what it already
9
(b) Describe the
function of the
part numbered
1, 3, 5, and 6.
8
4
3. Compare and
contrast the
processes of osmosis and diffusion. Give an example of each.
knows about how the text
works in order to understand
new information.
With a partner, develop a
chart to list the text features
related to scientific vocabulary
that you have encountered in
chapter 1. What is the
purpose of each of these text
features? How does each
feature help you as a reader?
What other text features did
you encounter in chapter 17
Include them in your chart.
32
UNIT A
4. Your teach er has given yo u a sample of soil to examine.
Would yo u use a dry mount or a wet mount to examine it?
E plain your reasoning.
5. If you were looking at a cell specimen through a microscope,
how could you tell that the cells belonged to 1:1 plant?
6. Use the term "selectively permeable" in a sentence that
demonstrates its mea ning.
rt Your Under
In
7. What would happen if cell membranes suddenly became
permeable instea d of selectively permeable? Could cells
remain alive? Explain your thinking.
ACHIEVEMENT CHART CATEGO RIES
Knowledge and underslanding
Thinking and investigation
Communication
App lication
8. What would be the impact on the environment if an artificial
virns that attacked and destroyed chloroplasts in plant cells
was accidently released by a research company?
9 . When you put the grocer ies away, you forgot to put the celery
in the refrigerator. When you found it on the counter, it was
soft and Limp. I. .low could osmosis help the celery? Explain
what you would do and why it would work.
Cells are the basic unit of life,
and it is im portant to
understa nd w hat th ey look
li ke and how they function.
Make a list of the key features
of plant and ani mal cells and
describe their fu nction.
o
10. Describe the steps involved in preparing a wet mount of a
specImen .
11. You have mounted your specimen on the stage of the
microscope. Describe the process of focussing the lens on the
specnnen.
12. Describe the steps involved in making a drawing of what you
se under a microscope.
13. List three safety steps you mnst follow when carrying a
mIcroscope.
A19
Thinking about Science, Technology, and Society
~
Reverse Osmosis
During osmosis, water moves across a
holes of the selectively permeable membrane.
selectively permeable membrane from an area
They move to the high water concentration side,
of high water concentration to an area of low
and the salt is left behind.
water concentration. In other words, pure
(100 percent) water will move across a
Consider This
selectively permeable membrane to water that
With a classmate or as a whole class, discuss
has dissolved substances in it like salt.
these questions.
During reverse osmosis, water particles are
forced to move in the opposite direction - from
1. How could this technology be used by
shipwreck victims on an island in the ocean?
a low concentration to a high one. High
pressure is applied to the low water
2. If viruses are smaller than salt molecules, is
concentration (usually saltwater) side, and the
this filtering method 100 percent safe 7
water particles there are forced through the tiny
Explain your reasoning.
Cells are the basi c units of all l iving th ings.
33
In this chapter, you wi ll :
• examine unicellular and multicellular organisms
• explain cell specialization
• describe plant and anima l cell processes
In this chapter, you will
• demonstrate the proper use of a microscope
• observe and draw orga nisms observed under a
microscope
Living things include unicellular and multicellular
organisms. Understanding cellular processes
helps us to understand how every organism on
Earth - fro m an amoeba to us to a blue wha le meets its basic needs
Reading and Interpreting
Graphical Text
Writers use graphical text forms such as
pictures, diagrams, and charts to
communicate information in a concise and
visual way. Complex ideas and concepts can
sometimes be com municated more easily in
a picture or diagram. These visual elements
provide important clues to the main ideas and
concepts in the written text.
Take a "picture walk" through chapter 2. Use
what you see to write a prediction about th e
main idea of this chapter. Consider how most
of these pictures are simi lar to each other but
different from pictures you saw in chapter 1.
Key Terms
• unicellular
• multicellular
• specialized cells
• cell division
Figure 2.1 Blue whales sustain themselves by
eating huge quantities of zooplankton.
he blue \' rhal is the largest type of animal on Earth
(Figure 2.1). It can gww to be about 25 m long. An adult
often weighs more than 150 tonnes. The whale feeds on
zooplankton, vvhich is one of the smal1est animals on Earth.
The blue whale and zooplankton are just two of the estimated
1.75 million different kinds of living things found on Earth. All
living things, vvhether they are plants, animals, fungi, protists,
or type of bacteria, are made of cell . It is the activities of cells
that allow each living thing to meet its basic needs.
The obvious structures of the living things you see around
you - jaws, teeth, eyes, limbs, and wings or fins; leaves, stems,
or roots - may appear to be the means of meeting basic needs .
In fact, these structures are working together to supply the
organism's cells with the water, oxygen, and nutrients that the
cells need to carry out their activities.
The visible structures of organisms may look very different.
TIley make it possible for the organism to get what it needs to
live from its environment. They also ensure that the necessities
of life are processed to get to the cells. The real work of
survival happens within the cells.
T
36
UNIT A
Cell s
The co-ordinated activity involved in getting the oxygen,
water, and nutrients to the cells happens without any
awareness on the part of the organism. This is true when these
activities take place in your own body. While you may taste the
food you eat, or notice that the water you drink is hot or cold,
yo u rarely breathe consciously. Once the oxygen, water, and
food are inside your body, the various parts of your body take
care of the processing. You are unlikely to notice any of this
activity unless something goes wrong. Yet withou t it, you
would not be able to survive.
Meeting Basic Needs for Survival
Living things must perform certain functions in
order to stay alive. These functions may include
4. Compa re your chart with one prepared by a
classmate.
moving, responding to stimu li, gathering food,
taking in oxygen, and building a home.
5. Did your cla ssmate list functions that you did
not! Wh ich ones 7
To decide what structure each organism uses to
6. Which functions did most people name 7
perform the activities that keep it alive
7. Did each organism shown have a structure for
each of the functions you Iisted 7
pen and paper
p
1. Prepare a chart with five columns.
2. Down the left-hand column, list the functions
that living organisms perform in order to
Figure 2.2 Microorgan ism
Figure 2.3 Plant
Figure 2.4 Mammal
Figu re 2.5 Fish
survive. Name the organisms shown on the
right in the headings for the rema ining
columns. (Note: A microorganism is an
organism that can only be seen with a
microscope.)
3. Fill in your chart to indicate which structure
you think each organism uses to perform each
function . (Some functions may not be
applicable.)
Cel lu lar processes sustain living th ings.
37
Here is a summary of what you will learn in this section:
•
Unicel lular organisms are essential for the continuance of life on Earth.
•
Unicellular and multicellular organisms carry out many of th e same activities to meet their basic needs.
•
Unicellular organisms are varied in structu res and adaptation s.
Figure 2.6 Phytoplankton are
unicellula r organisms that supply
most of Earth's oxygen.
Unicellular organisms are living things made of a single cell.
They arc usually smaller than a speck of du st, and they live
everyvvhcre that can susta in life: in water, in soil, and in or on
multicellubr organisms . T here are millions of species.
Scientists believe these organisms could have been on Eari h for
as long as :3 (; billion year .
While som unicellular organisms , such as some forms of
bacteria, are harmful, many more are essential for life on Earth
to continue. Phytoplankton are unicellular organisms that live
in the oceans (Figure 2.6). T hey contain chlorophyll to convert
the Sun's energy into food . Phytoplankton provide most of the
oxygen in Earth's atmosphere and are the founda tion of the
ocean food chain.
Unicellular decomposers, such as bacteria, are another
group of single-celled organisms that are essential for life on
Earth. Th ey complet the cycling of matter by converting
nitrogen in soil into a form of n itrogen that can u pport plan t
life and the terrestrial food chains.
What is going on in the composter?
Have you ever looked inside a com poster after
C 'd
r hi
the decomposers have been at work for a
With a cla ssmate or as a whole class, discuss
while? What did it look like in there, and how
did it smell? Did you turn away in disgust7 Or
the following questions.
were
YOLi
fascinated7
2. List the basic needs of decomposers. Are
these needs the same or different from
What to Do
1. List the conditions decomposers need to
do their work.
38
UNIT A
Cells
the basic needs of other living things7
3. What should be done with the contents of
a com poster? Explain your reasoning.
A Single Cell Is a Living Thing
Most unicellular organisms, such as the diatom, paramecium
(pI. para mecia) and the amoeba, are microscopic, although
some can be seen with the unaided eye. Diatoms (Figure 2.7)
live inside glass-like shells, which they make themselves. Like
plants, diatoms make their food through photosynthesis.
It is often assumed that unicellular organisms are simple
because of their simple structure. And yet, they perform the
same basic activities that complex plant and animal organisms
perform . They move, eat, respond to stimuli, reproduce, and
expel waste that results fro m cellular activity.
D
a
.
n ms
Dve
Unicellul ar organisms move in a variety of ways. Paramecia
have cilia, which are tiny hairs that act like oars and propel
the organism along (Figure 2.8). E. coli bacteria move by
rotating or lashing a flagellum that looks a bit like a tail
(Figure 2.9). These organisms "swim" along. An amoeba
moves by changing shape and forcing its cytoplasm into
extensions called pseudopods.
Figure 2.8 Para mecia are un icellular
organisms that use cilia to propel themselves.
Figure 2.7 Diatoms are unicellular
organisms. They live in lakes,
oceans, and moist soil and are an
important part of the food chain .
WORDS MATTER
Pseudopod comes fro m two Greek
words. Pseudes means "false " and
pous means "faa!." So pseudopod
means" false faa!."
Figure 2.9 E coli are unicellular organisms
that move by lashing a flagellum.
Visualizing with Combination Notes
Taking notes while reading is a good way to
top two-thirds of the page, record key
check understanding and clarify thinking. The
information as you read ''The Amoeba" Use the
"combination notes" strategy allows you to
right side to visually display your understanding
record information in a variety of ways, including
in pictures, diagrams, or a web. Use the bottom
visually. Draw a line two-thirds of the way down
one-third of the page to record summaries of
the middle of your page. On the left side of the
main concepts.
Cellular pro cesses sustain li vi ng t hi ngs.
39
he Amoeba
Figure 2.10 Coloured scanning
micrograph of Amoeba proteus, one
of the largest species o f am oebas
Diatoms, paramecia, and bacteria
are examples of unicellular
organisms. Choose two types of
unicellular organisms, and find out
how they obtain and digest their
food. Prepare a chart comparing the
two processes. Begin your research
at ScienceSource.
D o not mistake the microscopic amoeba for a mere blob. It is a
fascinating organism. Amoebas thrive in water-based
environments and are found in both fresh and salt water. They
can also live in wet, decaying vegetation on the forest floor, in
wet soil, or in other living organisms (including humans).
There are many, many species of amoebas (Figure 2.10). Most
are harmless to humans, but some cause disease.
Amoebas have many of the characteristics typical of animal
cells. The body is surrounded by a selectively permeable cell
membrane. Commonly visible organelles include one or more
nuclei (depending on the species), cytoplasm, food vacuoles,
and a special vacuole that pumps water out of the cell to
prevent it from bursting. Water enters the amoeba by osmosis.
Oxygen diffuses into the organism, and carbon dioxide waste
diffuses out of the organism.
Amoebas can be carnivores, herbivores, or omnivores.
Despite their usual microscopic size, amoebas are predators they prey upon organisms such as algae and bacteria. The
amoeba's hunting skills are based on its ability to change shape,
a result of having a very soft cell membrane and cytoplasm.
(T he word "amoeba" comes from the Greek word for change.)
The organism changes shape as it moves and captures prey
(Figure 2.11).
As the amoeba completes the capture of its prey, the food it
has engulfed becomes a vacuole. Chemicals called enzymes
digest the food, the nutrients are absorbed by the organism,
and the vacuole disappears. Waste products are eliminated
through the cell membrane.
Figure 2.11 Wh en food is detected nearby, an amoeba exten ds pseudopods to capture it
These images show an amoeba (a) surrounding and th en (b) engulfing its prey.
40
UNIT A
Cells
ObservIng
Cornrnunlca tlng
Observing Unicellular Organisms
NOTE: If the organisms In yo ur sample are
moving too quickly for you to observe them,
What cell structures can be seen under a
compound light microscope7
use the medicine dropper to add a tiny
amount (less than a drop) of methyl cellulose.
This will thicken the water. Do not touch the
Ipment
sample or the methyl cellulose during this
microscope
procedure
microscope slides
cover slips
6. If yo u are not successful in locating amoebas,
medicine dropper
parameCia, or diatoms, use the prepared
pond water sample (supplied by your
slides to view these microorganisms.
teacher)
7. Prepare a draWing of one of the organisms
small jar
yo u observe. Indica te the shape, relative size,
methyl cellu lose (optional)
colour, and any cell structu res that you can
prepared slides of amoebas (optional)
see. Label your drawing. I\lote the
magnification you are uSing.
CAUTION: Handle microorganisms with care. Wear
safety gloves. wash your hands thoroughly aher the
activity. and dispose of the specimens as instructed by
your teacher.
8. If you are observing pond water, describe how
your organism moves.
9. If yo u used the methyl cellulose, what Impact
did it have on the specimens in you r sample7
1. Turn to Toolkit 9 to review how to set up and
use a microscope.
2. Prepare a wet mount sl ide of the pond water.
10. You have made drawings of your observations.
Do you think words would be a better way to
communicate your observatlons7 Explain your
3. Set your slide up on the microscope stage,
and use the low-power objective lens to
reasoning.
observe your sam ple.
4. View the slide systematically for evidence of
unicellular organisms.
5. Switch to the med ium-power lens. Concentrate
on what you are observing, and keep your
F
11. What cell structures did yo u see7
12. Did all of the organisms you saw move in the
same way7 Describe any differences.
sample In focu s. Try the high-power lens.
Figure 2.12 Iways wear
safety gloves when
working with
microorganisms.
Cellular processes sustain living things,
41
K
rljY"]
1. Explain why something with only one cen
can be considered to be an organism .
2 . Name three unicellular organism '.
5. Describe
things that would happen in
an ecosystem if there were no unicellular
organi 111 .
1:',,\'0
3. Name three ways in vvhich unicellular
organisms can move. Describe one of
them.
6. Describe three things you should do when
handling microorganisms.
4. Where did the amoeba's name come
from? Explain why it was given that
name.
7. Explain how you would prepare a drop of
v\ a ter containing an amoeba for viewing
under a microscope.
For more questions, go to ScienceSource.
A24 Thinking about Science, Technology, and Society
ft
Cooking and Freezing
Unicellular organisms such as bacteria th nve
In
Consider This
warm temperatures and moist onditions. These
With a classmate or as a whole class, discuss
conditions are ideal for composting; however,
they must be avoided when preserving, storing,
the following.
or preparing food. Past and present
technologies for the preservation and storage of
food focus on creating conditions that are cold
and/or dry. Cooking raises the Internal
temperature of foods high enough to kill
microorganisms
What to Do
3. Explain how each of the preserving
techniques ensures that the food will not
contain harmful microorganisms.
4. How do the guidelines for handling food
help to ensure that food is free of
microorganisms that could contaminate it7
5. What do you think would happen if we did
not have these guidelines 7
1. Research one of the following technologies
to find out how It preserves food.
(a) air drying of foods such as fish
(b) canning of foods such as vegetables
(c) freezing of foods such as meat
2. Review Health Canada's guideli nes for the
safe handling of food.
42
UNIT A
Ce lls
Figure 2.13 Dryi ng racks are a traditional way
of preserving fish.
Here is a summary of what you will learn in this section:
• Diffusion and osmosis limit the size of cells.
• Multicellular orga nisms use specialized cells to ca rry out activities to meet basic needs.
• Specialized cells in multicellular organisms interact with and depend on other sp cialized ce lls
You have seen how an amoeba captures a meal. T hink of how
the frog in Figure 2.14 does it. Unicellular organisms rely on
one cell to perform all the functions that meet their basic
ne ds. Multicellular organisms rely on a variety of types of
cells to perform cellular fun ctions. These types of cells are
called specialized cells. T hey perform specific functions, such
as digestion or movement. They must interact with other types
of cells in the organ ism in order to carry out their tasks
successfully.
Specialized cells in various parts of the frog - including
eyes, muscles, and tongue - must work in perfect coordination in order to capture an insect for dinner. The average
frog performs this task many times each day. Once the frog
catches the insect, the cells in the frog's digestive system take
over, extracting the nu trients and expelling cell ular vvastes.
Figure 2.14 The specia lized cells ill
a frog v\lark together to help the
organism catch a meal
Specialized Structures to Do Specialized Jobs
Takin g in air in order to get oxygen is a function
th at all terrestrial animals must perform. Look at
Figures 2 .1 5- 2. 17 to see if the structures they
use are very similar or very different.
Figure 2. 16
Consider This
Figure 2.15
1. What key tasks related to getting oxygen
into an organism are accom pli sh ed by the
noses yo u see?
2. Do you think the structures you see are the
same or different? Explain your reason ing.
Figure 2.17
Cellular processes sustain liVing things.
43
More Cells for Bigger Organisms
Figure 2.18 Acetobu/ono IS one of
the world's largest un icellular
orga nisms
Figure 2.19 Multicell ular organisms
have a va riety of specialized cells.
T h ere are a few unicellular organisms that are so big you can
see them with your unaided eye. One of the members of the
algae family, Acewbularia, can grow to be 5 to 7 cm in diameter
(Figure 2.18). Some amoebas may reach 1 cm, but unicellular
organisms are usually microorganisms.
U oicell ular organisms are usually micro-sized because
cellular activities are performed most efficiently at that size.
The limitation is related to the processes of diffusion and
osmosis. The processes that deliver gases and water to cells
and remove vvastes are effective across very short distances.
For example, an oxygen particle can diffuse over a distance of
0.01 mm in a fraction of a second. To diffuse over a distance
of 1 mm would take 100 times as long.
This large increusc in distance is because in a bigger cell,
even though the surface area of the selectively permeable cell
membrane would increase as the cell's size increased, the cell's
volume would increase even more. You can imagine the same
principle on a bigger scale if you picture the difference between
a golf ball and a beach ball. The distance to the middle of the
golf ball is many times shorter th an the distance to the middle
of the beach ball. For a cell to be bigger in the same proportion,
gases and water would have to travel much farther to reach all
of the organelles in the cytoplasm . If a unicellular organism
were many times bigger than 1 mm, diffusion and osmosis
could take several minu tes instead of fractions of a second.
This increase in volume as a cell grows is why the
organelles in a huge cell would have trouble accessing the
resources they need. Larger living thin gs tend to be made up of
more than one cell. In an organism made up of dozens,
thousands, or even millions or trillions of cells, diffusion and
osmosis can still happen in fracti n s of a second. The trillions
of tiny cells that make up your body are very efficient units
when it comes to getting resources to the organelles.
In a community, some people grow foo d; others deliver it. Some
people protect the community from danger, and others help to
clean up. One person is not skilled enough to do all of the
44
UNIT A
Cells
different jobs expertly. Nor could one person meet all of the
demands of a community.
The same is true for multicellular organisms. One type of
cell cannot do all of the different jobs in a complex organism.
In the same way that a community needs specialists, multicellu1ar
organisms are made up of specialized cells rather than cells that
are exactly the same. While the specialized cells have the same
kinds of organelles as other plant or animal cel1s, the organelles
may be better adapted to performing the cell's tasks.
Specialized Animal Cells
The number of types of cells in a multicellu1ar organism
depends on the complexity of the organism. The hydra is a
simple m ulticellular organism (Figure 2.20). It has "skin" cells
on the outside an d digestive cells on the inside. The skin cells
protect the insides from the outside environment and act as
"gatekeepers" to control the substances that can get into and
out of the organism in the same way that the cell membrane
protects a cell.
A complex organism such as a human has hundreds of
different types of cells. We have types of cells that function as
protection and gatekeepers (Figure 2.21, skin cells), and cells
responsible for digestion. We have cel1s that make up bones and
cel1s that specialize in converting lots of energy (muscle cells)
(Figures 2.22 and 2.23). Humans also have cells that are primarily
for transmitting electrical impulses (nerve and brain cells)
(Figures 2.24 and 2.25)' Eyes have special cells that detect light.
Blood cells transport oxygen and cany away wastes of cellu1ar
processes. Storage cells keep unused energy on hand in the form of
fat, to be released and burned when the need arises (Figure 2.26).
Figure 2.21 Human skins cells make up
the largest organ in th e human body.
Figure 2.22 Huma n bone cells make up
th e stru dure that supports the body
Figure 2.20 The hydra is a simple
multicellular organi sm. Hydras are
best viewed under a microscope.
Figure 2.23 Human muscle cel ls have
more mitochondria than other cells, so they
can transform more energy.
Cel lu lar processes susta in li ving things.
45
Figure 2.24 Hum an nerve ce lls transmit
Figure 2.25 Human brain cel ls receive
e lectrical imp ulses alo ng pathwa s to the
and transmit electrica l Impulses
brain .
Figure 2.26 Human fat cell s store ene rgy
in he form of fat, whi ch ca n be accessed
and burned when resources f or fue l
are low
A26 Learning Checkpoint
Explaining the Size
1. III your own words, explain why diffusion and osmosis limit the size of cells.
2. In your own words, explain why multicellular organisms have specialized cells.
Plants and animals have celis with
the special job of defending the
organism against invaders. In
humans, these cells work in the
immune system. Four of these
types ot cells are cal led killer T celi s,
helper T cells, memory T cel ls, and
antibodies. Find out what Job two of
these types of cells do and how
they do it. Report back to the class
Begin your research at
ScienceSource.
Specialized Plant Cells
Multicellular plants also have specialized cells. Some transform
the Sun's energy into sugars. These ce1ls are found primarily in
the leaves (Figure 2.27). The job of cells in the stem is
primarily to transport food and water to the rest of the plant,
store some food, and support the plant (Figure 2.28). The cells
in the roots store food, absorb water from the soil, and
transport \vater and nu t rients to the stem (Figure 2.29).
Figure 2.27 These leaf cells contain
Figure 2.28 Th e ce lls in a plant stem
chlo ro plasts, hich convert the Sun's
energy into food.
transport water and materials throughout
Figure 2.29 The cells in a plant root absorb
water and nutrients fro m the soil and
th e plant.
transport these resources to the stem.
46
UNIT A
Cells
Observing
Communicating
~
Observing Multicellular Organisms
n
....
....<
<"+
NOTE: If the organisms in you r sample are
moving too quickly for you to observe them,
use the medicine dropper to add a tiny
amount (less than a drop) of methyl cellulose.
This wi ll thicken the wa ter. Do not touch th e
sampl e or the methyl cellulose dUring this
procedure.
<"+
'<
What mu lticell ular organisms can be seen under a
compound light microscope7
.ipment
microscope
microscope slides
cover slips
mediCine dropper
pon d water sample (supp lied by your
teacher)
small jar
methyl cellulose (optional)
prepared slides of hydras (optional)
CAUTION: Handle microorganisms with care. Wear
safety gloves, wash your hands thoroughly after the
activity, and dispose of the specimens as instructed by
your teacher.
6. If you are not successful in locating a hydra,
use the prepared slides to view these
microorganisms
7. Prepare a drawing of the multicellular
organisms you observe. Indicate the shape,
relative size, colour, and any cell structures
that you observe. Label your drawing. Note
the magnification you are using.
8. If you are observing pond water, describe how
the organisms move.
9 . How many different organisms did you see in
your sample 7
1. Turn to Tool kit 9 to review how to set up and
use a microscope.
2. Prepare a wet mount slide of the pond water.
3. Set your slide up on th e microscope stage,
and use the low-power objective lens to
observe your sample.
4. View the slide systematically for evidence of
mu lticell ular organisms.
10. Describe the steps you must follow to observe
a pond water sa mple with a compound light
microscope
F
11. Were the organisms you observed plants or
animals 7 Justify yo ur rea soning.
5. Switch to the medium-power lens. Concentrate
on wh at you are observing, and keep your
sample in focu s. Try th e high-power lens.
Figure 2.30 Pond water can
supply a number of multicellular
organisms
Cellular processes sustain li ving things .
47
SKILLS YOU WILL USE
Deslgmng an experimental
procedure
• Designing a fair lest
Cells and Solutions
10. Share and compare your deSign and results
How will the cells in an onion membrane respond
with your classmates. How were they simllar7
to pure water, salt water, and vinegar?
How were they different7
e ign and Conduct Y ur
1. Make a hypothesis. Refer to Toolkit 2 for help
with this procedure.
2. DeCide what materials and equipment you will
need to test your hypothesis. For example
(a) List the lab equipment yo u wil l require to
make your observations.
(b) List the materia ls such as samples or
solutions you wi ll require.
3. Plan the steps in your procedure. Include any
safety precautions.
Figure 2.31 Peel off a single layer of an onion
membrane.
4. Write up your procedure. Include steps to
ensure that It wil l be a fair test of yo ur
hypothesis. Explain how yo u wi ll document
yo ur results.
5. Ask a classmate to read the procedure and ask
about any steps that are not clear. Show your
revised procedure to your teacher.
6. Carry out your investigation . Refer to Toolkit 9
to review how to set up and use a
microscope Refer to "Preparing an On ion
1. Select a clean glass slide and cover slip.
2. Carefully remove a piece of thin, semitransparent membrane from between
two inner layers of the onion.
3. Pick up the m embrane With the
Membrane" in the next column for tips on
tweezers. Take the microscrope slide,
handling your sample.
an d hold it at a 45° angl e Carefu lly
7. Compare your results with your hypotheSIS.
Did your results support your hypothesis 7 If
not, what possible reasons might there be 7
8 . Was your investigation a fair test7 Justify your
drape the membrane onto the middle
of the slide. AVOid trapping air bubbles
between the membrane and the slide.
4. After you have applied the solution, pick
up the cover slip and slowly lower it
answer.
over the membrane specimen. Avoid
9. Was you r procedure comp lete 7 How wou ld
yo u change it if yo u were gomg to do the
investigation again7
48
UNIT A
Cells
trapping air bubbles between the cover
slip and the specimen.
'iP
f\/
1. Name five different types of cells that can
be found in the human body.
2 . Name three different types of plant cells,
and describe their key functions.
3 . Explain why a tiny cell is a more efficient
basic unit of life than a large ce11.
C
'lP("
VOL
4. What are the advantages of having
specialized cells? Are there any
disadvantages? Explain your answer.
p
5. Describe the steps to be followed to make
a drawing of organisms observed under a
microscope.
For more questions, go to ScienceSoufce.
A29 Thinking about Science, Technology, and Society
_~
~
Water for Cells
Two-thirds of the average human body is water.
Consider This
Close to 70 percent of that water is inside the
With a classmate or as a whole class, discuss
body's cells, 20 percent is in the space
th e following questions.
surrounding the cells, and the rema inder is in
the bloodstream. The water moves into and out
of cells as necessary through osmosis.
When your body is properly hydrated, it has
enough water to maintain cellular activities.
When the body does not have enough water, it
is dehydrated. Making sure that your body has
enough water is one way to keep your body
cells healthy
What to Do
consume daily. Ca lculate the average.
5. Compi le a list of the first three ingredients
in fluids commonly consumed to find out
what is being consumed along with water.
6. Suggest ways in which people are most
likely to become dehydrated and what
steps can be taken to avoid dehydration.
7. Some people think that bottled water is
1. Ca lculate the amount of fluids that you
consume
4. Compa re th e amount of fluids you each
In
one day.
bad for the environment. They are
concerned about the waste of water in
unfinished bottles and the plastic bottles
2. List the fluids you consume regularly.
Check the ingredient lists of your favourite
that end up in landfil l sites. Suggest ways
to meet the body's water needs without
commercial drinks, and compile a list of
creating enVIronmental problems.
the first three ingredients.
3. Research the most common effects of
dehydration Start your research at
ScienceSource.
Cellular processes sustain living things.
49
Here is a summary of w hat you will learn in this section:
• Cellu lar processes are conti nuous.
• The conversion and tra nsport of energy are key cellular processes.
• Cells are repl aced through the process of cell division.
Figure 2.32 When yeast interacts
with sliga r, it prod uces carbon
dioxide as a waste product
Whether you are awake or asleep, sitting watching a show or
playin cf soccer, your cells are busy places. Just like a busy factory,
materials are arriving i.n your cells, being used in production,
and the waste and final products are being transported out.
The materials entering a cell through diffusion and osmosis
and other transport mechanisms are raw materials to be used
by the various organelles . Those organelles are breaking
materials dO'wl1 to convert energy, transporting energy,
building proteins, and sending chemical messages.
Cells also expel waste products. While a tiny cell regularly
emits a tiny amount of wa te, an organism with a trillion cells
finds itself with a lot of waste in its system.
Yeast in Action
Yeast is a unicellular fungus used in the
preparation of baked goods. Its dr'ied form is
mixed with warm water and sugar and added to
What to Do
1. Inflate a balloon several times to stretch it
out. Set it aside.
flour to make Irght-textured breads and cakes.
How does this work? Yeast cells consume
sugar and use the starches in flour to make
more sugar. They generate carbon dioxide as a
waste product during the process (Figure 2.32).
The gas is trapped in the dough, creating smal l
bubbles. The carbon dioxide is eliminated
during baking} and the final product is filled with
small pockets of air.
You can test for yeast in action.
2. Pour 250 ml of warm water into a
SOO-ml recyclable water bottle. Add one
package of baker's yeast and about 30 ml
of granulated sugar. Swirl the mixture.
3. Stretch the balloon over' the mouth of the
bottle.
U
4 . What change drd you see in the balloon?
What is causing this change?
50
UNIT A
Cells
IM~L:==~~~===:~
________________________________
~
~ L~~~
Visualizing the Cell as a Factory or a City
Visualizing as you read helps you use experiences,
could be represented by a part in a factory or a
senses, and prior knowledge to better understand
city. Draw your cell as a factory or city. Use a
what you are reading. As you read pages 51 and
legend to ident'ify organelles and their visual
52, note the different organelles and their
counterparts, and explain the workings of your
specialized jobs in cells.
cell factory or cell City to a partner. What other
metaphors could you create for a cell7
Using the metaphor "the cell is a factory" or "the
cell is a city," visualize how each part of a cell
Transforming Energy
All c Hular activities such as growth, repair, and reproduction
need energy. Mitochondria provide energy for the cell by
transforming oxygen and sugar (food) into carbon dioxide and
water. T his process is called cellular respiration, which
occurs in both plant and animal cells.
In plan t cens, chloroplasts produce the sugar needed by the
mitochondria in a process called photosynthesis. In
photosynthesi s, the chlorophyll in chloroplasts captures the
Sun's energy so the chloroplast can convert carbon dioxide and
water into sugar and oxygen. In this way, energy is transformed
fro m sun ligh t into sugar in plants (photosynthesis) and then
sugar is con sumed to release useable energy in both plant and
animal cel1s (cellular respiration).
Figure 2.33 This pa ramecium has
ingested (eaten) two sma ller
organisms, called euglena. The
green uglena are visible inside the
para mecium near the bottom of the
micrograph Thro ugh the process of
digestion, the paramecium extracts
suga rs produced in the chloropla sts
of the euglena and provides th em to
its own mitochondria for energy
production.
Processing and Transporting Materials
What happens when water, gases, and nutrients enter cells
through the cell membrane? Ma terials move through the
cytoplasm to the various organelles. T he endoplasmic
reticulu m makes proteins from raw materials that come in to
the cell and passes them to th e Golgi apparatus. T he Golgi
apparatus processes protein molecules and secretes them
outside the cell to be used elsewhere in the organism.
Lysosomes break down food and digest wastes. All of this
cellula.:: activi ty is controlled by the nucleus.
Cellul ar proce sses sustain li Vi ng things.
51
Reproducing
Using your muscles fre quently all d
with increased Intensity wi ll
illCrease the nu mber of
mitochondria in you r m uscl e cell s.
Fin d ou t more about how using
your m uscles will increa se your
abi lity to tra nsform energy. Begi n
yo ur resea rch at ScienceSou rce.
Cells have a lifespan - amoebas live for approximately two
days. Human brain cells live between 30 and 50 years. Human
red blood cells live for 120 days. Skin cells live for 20 days.
What does this mean? In the case of your skin, it means that
your skin cells are replaced approximately every 20 days.
In fact, in the average human body, with its several hundred
trillion cells, approximately three billion cells die every day.
Cells die because they have been damaged, because they have
not received enough water or food, or because they have
reached the end of their lifespan. Given these losses, you might
expect that multicellular organisms are constantly shrin king.
T his does not happen, however, because before the cells die,
they create a replacement for themselves through cell division.
During cell division, cells split in half to form tVilO smaller
cells. The nucleus splits into two first. The rest of the cell
then divides .
Cell division is easiest to see in a unicellular organism.
Figure 2.34, below, shows the process. First, the cell's nucleus
splits in two. Then the membrane begins to pinch near the
middle to divide the cytoplasm, including its organelles , and
ensure that each new cell has a nu cleus. The two new cells are
identical. The same process occurs in the cells of your body.
Figure 2.34 First, the nucleus divides into two. Th en the cell mem brane pinch es to divide
th e cytoplasm Two new, identical cells result from ce ll division.
52
UNI T A
Cells
In the case of a plant cell, instead of pinching
in half after the nucleus divides, a new cell plate
develops across the cell to create a neyv cell wall
between the two nuclei (Figure 2.35).
Figure 2.35 Plant cells divide by developing a new cell wall.
Modelling Diffusion
3. Submerge the bag with the cornstarch solution
To model the diffUSion of molecules through a
in th e iodine water bath . Keep the twist tie
selectively perm eable membran e
above the level of the liquid. Leave the bag in
the bath for approximately 10 min.
4. Remove the bag from the iodine bath, taking
600-mL beaker
2S0-mL beaker
water
cornstarch
measuring spoons
non-resea lable plastic sandwich bag
care not to drip the Iodine solution onto
clothes or other surfaces.
5. Observe the cornstarch solution in the bag.
6. Follow your teacher's Instructions in cleaning
up everything you used.
twist tie
iodine
7. What colour was the cornstarch solution at the
beginning of the activity7 What colour was the
CAUTION: Iodine wil l stain skin and clothing .
cornstarch solution at the end of the activity7
8. What colour was the iodine bath at the
1. Put approximately 200 mL of water in the
large beaker. Add about 10 drops of iodine,
and set the beake r aside. Note the colour of
the solution.
2. Put approximately 100 mL of water in the
smaller beaker. Measure 2 tablespoons of
cornstarch into the water and mix It thoroughly.
Pour the solution Into the bag. Seal it with a
beginning of the activity? What colour was the
Iodine bath after the bag with the cornstarch
sol:ution was submel·ged in it 7
9. Did the cornstarch diffuse out of the bag into
the iodine solution? How do you know 7
10. Did the iodine diffuse through the bag into the
cornstarch soluti on 7 How do you kllow 7
11. Explain your results.
twist ti e. Note the colour of the solution.
Cellular processes sustai n living things .
53
1.
arne three cellular processes.
2 . What time of the day or night is best for
cellular activities?
3 . Describe the process of cell division in
your own word '.
4 . Name three reason s why cells die.
c
v
r
ndin
5. Explain how cell division is linked to cell
theory.
6. This is a
picture of a
plant celi.
Describe \vhat
is happening
in this picture.
p
7. Explai n how building a model can help
you understand scientific processes.
For more questions, go to Science Source.
A33 Thinking about Science, Technology, and Society
~
Helping Cells, Harming Cells
Hea lthy human ce lls divide to produce new
What to Do
cells on a regular basis. When cancer develops,
Go to ScienceSource to research the topics in
cells are dividing uncontrol la bly, and the body is
steps 1 and 2.
harmed. Some cancers are hard to detect and
result in premature death.
Finding technology to stop the cancer process
is a goa l of cancer research. Current treatment IS
based on two key therapies : chemotherapy and
1. Fi nd out how the two therapies wo rk, and
write an explanation of each in terms of
what you know about cells.
2. Fi nd out and describe the effect of each of
radiation therapy (Figure 2.37). Both therapies
the two therapies on cancer cells and on
are expensive.
hea lthy ce lls.
Consider This
With a classmate or as a w hole class, discuss
the follOWing points.
3. Use what you know about ce lls and
cel lular processes to explain how cancer
patients can recover from these therapies.
4. As the number of cases of cancer increases,
54
Figure 2.37 Radiation therapy can harm both
how can society make sure that all patients
cancer cells and healthy cells.
can get the treatment they need 7
UN IT A
Cells
_~
~_~cience ~DJachnoJogY-!-L"L...L.-~~....IL......IL-~~___
icrobiologists at Work
Cree s in Mic ob" 01
The study of microbiology has expanded
steadi ly since the 1930s and has become
increasingly specialized. There are now a variety
of careers in a variety of fields.
• Bacteriologists study bacteria .
· Environmental microbiologists study
Figu re 2.36 Microbiologists study cells and c lIula r
microorganisms in the environment.
processes, as well as other microorganisms.
• Food microbiologists study microorganisms
Many early researchers studying "things too
small to be seen with the unaided eye" were
inspired by a desire to understand what caused
disease. The earliest suggestion that
microorganisms were a factor was pub lished in
that spoil food and cause illness.
• Industrial microbiologists study
microorganisms in order to make useful
prod ucts (biotechnology).
1835 after a study of fungi affecting silkworms.
The theory that germs were responsible for
· Medical microbiologists are doctors
many illnesses was being discussed by 1847.
• Microbial epidemiologists study the role
Louis Pasteur published the theory in 1857.
As the germ theory gained acceptance, the
medical profession began to change their
practices to Include more attention to
clean liness and steri lization. Many more of their
studying diseases caused by microbes.
of microorganisms in illnesses and health.
• Mycologists study fungi.
• Protozoologists study protists.
• Virologists study viruses.
patients survived as a result
Th
Ie of I pro
d echnology
German electrica l engineer Ernst Ruska
constructed the first electron microscope in
1931. Since Ruska's innovation, microscopes
and techniques for studying cells have become
more advanced . At the same time, the
discoveries by microbiologists have become
increasingly influential in the way diseases are
diagnosed and treated .
Q estions
1. Research a career in microbiology. Start
your reseach at ScienceSource.
2. Prepare a report that Includes the following
information:
(a) the education required
(b) a place of work
(c) a description of possible main duties
(d) a recent important discovery in the field
Cellu lar processes sustain living things.
55
,
,r
~
'------------- , · +U~
Reflect and Evaluate
The study of science is often a
study of similarities and
differences or comparisons
and contrasts. A study of
1 . Define the term' ce ll specialization" in your own words.
2. How do diffusion and osmosis belp amoebas survive?
3. Hm· do diffusion and osmosis limit the size of a cell?
4. Explain \-vhy visible structures , such as fins, beaks, and tail s,
look so differ nt on different organisms.
5. Unicellular organisms move in many djfferent ways. Use
\'lords and pictures to explain how each of the following
organisms moves:
ecosystems, for example, is
about biotic and abiotic
factors. A study of fluids can
be about fast or slow, thick or
(a) para mecium
thin . This study of cells is
(b) E. coli bacteria
about same or different,
(c) amoeba
unicellular or multicellular,
plants or animals.
r
Research tells us that our
brains work in the same way.
They store information based
on similarities and retrieve
information based on
differences.
With a partner summarize
what you have learned from
this chapter in the form of a
5-4-3-2- 1 organizer.
List:
• 5 new learnings
• 4 similarities and
differences between plant
and an imal! cells
• 3 key differences between
unicellul ar and multicellular
orga nisms
• 2 ways visualization helps
you as a reader
•
1 question you still have
56
UNIT A
6. Phytopla nkton are unicellular organisms th at live in the
ocean. How is their existence important to yo ur survival?
7. A unicellular organ ism is a living thing that meets all of its
basic needs \'lith just one cell. A multicellular organism can
require up to several trillion cells to do the same thing. Which
one do yo u consider to be more advanced? Explain your
reasol11ng.
8. Y u need to collect a live sa mple of an amoeba for study in
class. Where would b e th best natural enviro nment to collect
this sa mple'? Why?
p
Skills
9. What is the correct proced ure for handling a sample of pond
water?
10. Some algae reproduce every 24 hours if conditions are ideal.
If it takes 15 days for the algae to h alf-fill a pond, how long
wil1 it take to fill the whole pond? What assump tion did you
make in order for th is to happen? How likely is this to occur?
Explain yo ur reason ing.
ACHIEVE MENT CHART CATE GO RIES
Knowledge and understanding
Thinking and investigation
Communication
App lication
11. You are examining a sample of pond water, and you notice
organisms passing through your field of view. You are out of
methyl cel1u10se, so your teacher suggests making a new wet
mount and adding a few threads of cotton from a cotton ball
to the slide before adding the cover slip . What effect will this
have?
12 . Sean and Krista were working on the Modelling Diffusion
activity (A32) in class. They observed no change in the
cornstarch solution. Suggest and explain two possible reasons
why this might have happened .
Review the list of key features
and functions that you made
at the end of Chapter 1. Use
the list to make notes on the
cellular processes you learned
about in this chapter.
Remember to include
diffusion and osmosis.
A34 Thinking about Science, Technology, and Society
~
Protecting Cells in the Environment
Synthetic chemicals are chemicals that are
produced in a laboratory. SynthetiC chemicals
are used for cleaning, preserving, and decorating
as well as for fuel ling our machines. Think of the
bleaches, soaps of all kinds, hair gels, make-up,
polishes, perfumes, varnishes, paints, gasoline,
and oil yo u use or come into contact with
during your regular activities. SynthetiC
medicines help treat illnesses. All of these
synthetic matel'ials are helpful to society.
Many of the chemicals that make up these
materials have entered the soil and water
systems and are now found in the cells of
plants and animals. Some synthetic chemicals
are suspected of disrupting cell processes in
one of two ways either by causi ng
uncontrollable cell reproduction (cancer) or by
interfering with the reproductive processes of
organisms and causing sterility or physical
deformities
What to Do
1. Create a two-column chart. In the first
column, list the synthetic chemicals and
medicines you have used or have been in
contact with in the pa st week.
2. In the second colum n, note how the
materials are disposed of. For example, are
they thrown In the garbage or put into the
water system 7
Consider This
With a classmate or as a whole class, discuss
these questions.
3. Do yo u think new chemicals should be
made available for use before their effects
on cells are known 7 Explain your
reasonillg.
4. Many people think that the disposal of
chemicals should be regulated carefully.
Suggest ways in which this could be done.
Cellular processes sustain living things.
57