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BIOLOGY:
AS SCIENTIFIC INQUIRY
Sixth
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Unit One
Introduction
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TEXT AND
LABORATORY
MANUAL
Biology:
As Scientific Inquiry
UNIT I: INTRODUCTION
(7
SIXTH EDITION
^ rv \d by:
RON THOM
High School Biology Teacher, Curriculum Writer, Science Workshop Provider & Consultant
Mercer Island, Washington
For additional copies and ordering information,
Contact:
Connecting Point NW
Number Six Lindley Road
Mercer Island, Washington 98040
(206) 230-8360 or (206)232-8042
Thompson Ron @ mac .com
www.BioInquiry.com
Copyright © 2007
Connecting Point and Ron Thompson
ISBN 0-14-891940-2
All rights reserved:
This publication, or parts thereof, may not be reproduced in any form by photographic, electronic, electrostatic, mechanical
or any other method, for any use, including information storage and retrieval, without written permission from the copyright
owners. For conditions of use and permission to use materials contained herein, apply to:
Ron Thompson, Connecting
Point, Number Six Lindley Road, Mercer Island, WA 98040. ThompsonRon@mac.com
fjf
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ACKNOWLEDGMENTS
Each of the following used Biology: As Scientific Inquiry during the early
years of its development. Their suggestions were incorporated into the
present curriculum. The author acknowledges the following educators
and students for their valuable contributions.
Dave Ainsworth
Biology Teacher and Dir. of Curriculum
Sammamish High School
Bellevue, WA
Sherry Stuber
Science Department
Sammamish High School
Bellevue, WA
Ron Bielka
Biology Students
1991- 97
Bellevue Public Schools
Bellevue, WA
Science Department, retired
Sammamish High School
Bellevue, WA
Loren Rood
Science Department, retired
Sammamish High School
Bellevue, WA
EDITED BY
Ann Maxine Thompson
Biology: As Scientific Inquiry originated in Believue Public Schools.
Major funding for the Fourth Edition was provided by the United States Department of
Education, Christa McAuliffe Fellowship program, 1990-91.
Funding for revisions for the Fifth Edition was provided by the National Science
Foundation Presidential Award Grant program, 1993.
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Biology: As Scientific Inquiry
TABLE OF CONTENTS FOR ALL 8 UNITS
Unit I An Introduction to Biology & the Scientific Method
%
Chapter 1 THE NATURE OF BIOLOGY
Page 1
1 -1
1-2
1-3
1-4
Page 2
Page 4
Page 5
Page 7
A Note from the Author
What is Biology?
Characteristics of Life
Safety Rules
Chapter 2 TOOLS OF THE BIOLOGIST
Page 1 0
2-1 Laboratory Investigation:
Can You Catch a Fish on a Moonbeam?
2-2 How to Use This Manual
2-3 Laboratory Investigation: How to Use the Binocular Stereoscope
2-4 Laboratory Investigation: The Compound Microscope
2-5 Laboratory Investigation: How to Make a Wet Mount
2-6 Electron Microscope
2-7 Other Tools
2-8 The Metric System
2-9 How to Read and Construct a Graph
2-10 Graphing Application
Page 1 1
Page 14
Page 18
Page 23
Page 32
Page 34
Page 35
Page 36
Page 38
Page 54
Chapter 3 THE ULTIMATE TOOL: THE SCIENTIFIC METHOD
Page 55
3-1
3-2
3-3
3-4
3-5
3-6
3-7
Page 56
Page 60
Page 61
Page 67
Page 77
Page 82
Page 84
Laboratory Investigation: Graphing Frog Respiration
The Importance of the Scientific Method
NutraSweet and the Scientific Process
The Scientific Process: Step-by-Step
The Role of Variables in Applying the Scientific Method ...
Science and Technology
Cooperative Learning Activity: Variables
Unit II
)
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Cells and Cell Processes
Chapter 4 CELLS
Page 1
4-1 Laboratory Investigation: Investigating Cell Variety
4-2 Cell Theory
4-3 Cell Structure (Continued)
4-4 In-Depth Enrichment on Cell Structures
4-5 Creating a Cell Model
Page 2
Pages
Page 1 0
Page 14
Page 16
Biology: AS Scientific Inquiry Table of Contents
page i
© Connecting Point
Chapters B A S I C CHEMISTRY
Page17
5-1
5-2
5-3
5-4
5-5
5-6
5-7
Page 18
Page21
Page 29
Page 31
Page 34
Page 39
5-8
5-9
5-10
5-11
5-12
5-13
5-14
5-15
5-16
5-17
Matter and Energy:
The Structure of the Atom
Are Atom Diagrams Really Accurate?
Laboratory Investigation: "Don't Confuse Me with the Facts."
Joseph Priestley's Experiments with Mice, Candles, and a Mint Plant
Laboratory Investigation: The Chemistry of Combustion
Summary of the Cyclic Nature of the Scientific
Process and Continued Inquiry
Laboratory Investigation: Compounds, Molecules and Atoms
From Priestley to Present Day: Elements, Compounds & Mixtures
Molecules and Atoms
In-Depth Enrichment: Details of Atomic Structure
In-Depth Enrichment: Using the Periodic Chart
Ions: The Charged Particles of the Universe
Chemical Bonding
Chemical Reactions
Acids and Bases
In-Depth Enrichment: Acid-Base Dynamics
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Page 51
Page 53
Page 59
Page 64
Page 65
Page68
Page 70
Page75
Page 78
Page 81
Page 82
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Chapters COMPOUNDS IN LIVING THINGS
Page 8 5
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6-1
6-2
6-3
Page 86
Page 86
Page 88
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Introduction
Carbohydrates
Proteins, Fats and Macromolecule Reactions
.^k. £3
Chapter? RESPIRATION AND PHOTOSYNTHESIS
7-1
7-2
7-3
7-4
7-5
7-6
7-7
Laboratory Investigation:
Can You Design an Experiment to Test a Hypothesis?
How Plants and Animals Obtain Energy: An Introduction
Laboratory Investigation:
The Chemistry of Respiration and Photosynthesis
Respiration and Energy Transfer
In-Depth Enrichment: ATP, the Energy Storage Units of the Cell
Photosynthesis: The Prime Energy-Capturing Reaction for Life on Earth
In-Depth Enrichment: Details of Photosynthesis
Page91
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Page 92
Page 97
Page 99
Page 112
Page 113
Page 11 7
Page 11 9
Chapters M E M B R A N E S A N D MOLECULES
Page 123
8-1
8-2
8-3
8-4
8-5
8-6
8-7
Page 124
Page 130
Page 136
Page 138
Page 142
Page 145
Page 146
Laboratory Investigation: How Do Molecules Enter Cells?
Diffusion
Details on Cell Membranes
Laboratory Investigation: Osmosis
Osmosis: How Does it Work?
Lab Investigation: An Application of Osmosis in Plant Cells
Cooperative Learning Review Activity
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Biology: As Scientific Inquiry Table of Contents
page ii
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Chapters E N Z Y M E S
Page 1 47
9-1
9-2
9-3
9-4
Page 1 48
Page 1 52
Page 1 56
Page 1 6 1
Organizing Data Helps in Solving Problems
Laboratory Investigation: Enzyme Action
Enzyme Structure and Function
Cooperative Learning Review Activity on Enzyme Function
Appendix
Appendix
Appendix
Appendix
A
B
C
D
Unit III
Basic Chemistry Definitions
Lab Activity 5-4 Follow-up
Cooperative Learning Guidelines
Periodic Table
A1
A3
A6
A8
Animal and Human Processes
Chapter 10 SINGLE-CELLED PROT1STS
Page 1
10-1
10-2
10-3
10-4
Page 2
Page 10
Page 11
Page 1 6
Laboratory Investigation: Paramecium
ProtistsasaGroup
AnimallikeProtists: TheCiliates
The Flagellates and Sarcondines
Chapter11 DIGESTION
Page21
11 -1
11-2
11-3
11-4
11-5
11-6
11-7
Page 20
Page 30
Page 32
Page 37
Page 39
Page 44
Laboratory Investigation: Frog Dissection
Animal Systems
Human Digestion
Details of Human Digestion
Laboratory Investigation Digestion of Fat
Factors Affecting Enzyme Action -A Math-Science Interdisciplinary ActivityLaboratory Investigation: Determining the Amount of Energy
in Food (-A Math-Science Interdisciplinary Activity-)
11-8 Calorie Mathematics -A Math-Science Interdisciplinary Activity11-9 Calories, Weight Loss and Weight Gain
-A Math-Science Interdisciplinary Activity11-10 Laboratory Investigation Hydra and Planaria
11-11 Digestion in Other Animals
Page 55
Page 57
Page 59
Chapter 12 CIRCULATION
Page 6 6
12-1 Laboratory Investigation:
The Effects of Nicotine and Alcohol on Capillaries
12-2 Introduction to the Human Circulatory System
12-3 The Human Heart
12-4 Blood Vessels and Gas Exchange
12-5 HeartAttack
12-6 Blood and Blood Cells
Page 67
Page 70
Page 72
Page 75
Page77
Page 80
12-7 Blood Pressure
Page 82
12-8 Circulation in Other Animals
Page 83
Biology: As Scientific Inquiry Table of Contents
page iii
Page 50
Page 54
Chapter 13 R E S P I R A T I O N
PageSS
13-1 Laboratory Investigation: Animal Respiration
13-2 Human Respiration
13-3 Gas Exchange and Respiration in Other Animals
Page 86
Page 93
Page 97
Chapter 14 T H E N E R V O U S S Y S T E M
Page 101
14-1
14-2
14-3
14-4
14-5
14-6
14-7
14-8
14-9
14-10
Page 1 02
Page 104
Page 1 06
Page 107
Page 112
Page121
Page 122
Page 1 23
Page 1 25
Page 128
The Two Main Parts of the Human Nervous System
The Human Brain
In-Depth Enrichment: The Thalamus and Hypothalamus
The Peripheral Nervous System
Laboratory Investigation: The Human Nervous System
SensesoftheSkin
The Human Eye and Sight
The Human Ear and Hearing
An Inquiry into Heart Rate Regulation
Nervous Systems in Other Animals
Chapter 15 THE E X C R E T O R Y S Y S T E M
Page 131
15-1 The Human Excretory System
15-2 Excretion in Other Animals
Page 1 32
Page 1 34
Chapter 16 THE S K E L E T A L A N D MUSCULAR S Y S T E M S
Page 1 37
16-1
16-2
16-3
16-4
Page138
Page 142
Page 143
Page 145
The Human Skeletal System
Laboratory Investigation: A Study of Living Muscles
The Muscular System
Skeletal and Muscular Systems in Other Animals
Chapter 17 R E V I E W O F ANIMAL AND HUMAN P R O C E S S E S
Unit IV Plant
Page 148
Processes
ChapteMS G R E E N P L A N T S : P R O D U C E R S O F FOOD
Page 1
18-1 Introduction to unit
18-2 Lab Investigation: An Inquiry on Light, Leaves and Starch
18-3 Lab Procedure: Starch Test for Leaves
Page2
Page 4
Page 9
18-4 Leaves and Photosynthesis
Page 1 0
18-5 Lab Investigation: An Inquiry on Chlorophyll, Leaves and Starch
18-6 Structure and Function of Chlorophyll
Page 1 3
Page 14
Chapter 19 THE LEAF: SITE O F P H O T O S Y N T H E S I S
Page 1 6
19-1 Laboratory Investigation: How Does Carbon Dioxide Enter a Leaf?
19-2 Laboratory Investigation: How is the Structure of a Leaf
Related to its Function?
19-3 Light and Photosynthesis
19-4 The Leaf and Photosynthesis
Page 1 7
Page 25
Page 34
Page 38
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Biology: As Scientific Inquiry Table of Contents
page iv
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Chapter 20 T H E R O O T
Page41
20-1 Prelab for Root Investigations 20-2 and 20-3
20-2 Laboratory Investigation:
Page 42
The Root: A Study in Structure and Function
Page 46
20-3 Laboratory Investigation: Cross Section of a Root
20-4 The Root: A Vital Contact with the Soil
Page 48
Page 51
Chapter 21 S T E M S
Page 5 6
21 -1 Stem Structure and Function
Page 57
21-2 Laboratory Investigation: The Architecture of the Stem
Page61
21-3 An Inquiry: Where Does the Mass of a Growing Tree Come From?
Page62
Chapter22
Page64
W A T E R MOVEMENT IN PLANTS
22-1 Laboratory Investigation: Water Transport: Problem & Experimental Design
22-2 How Water Moves Against the Force of Gravity
Page 65
Page 68
Chapter 23 PLANT V A R I A T I O N
Page 7 1
23-1 A Little About Plant Classification
23-2 Unit Summary
Page 72
Page74
Unit V Reproduction and
Development
Chapter 24 SEXUAL AND ASEXUAL REPRODUCTION:
AN INTRODUCTION
Page 1
24-1 Introduction to Reproduction
24-2 Sexual Reproduction
24-3 Asexual Reproduction
Page 2
Pages
Page 5
Chapter 25 SEXUAL REPRODUCTION IN PLANTS
Page 7
25-1 Laboratory Investigation:
Reproduction in Flowering Plants
25-2 Flowers and Reproduction
25-3 Cones and Reproduction
Page 8
Page 1 3
Page 16
Chapter 26 PLANT EMBRYOLOGY: S E E D S & FRUITS
Page 1 8
26-1 Laboratory Investigation:
Plant Embryo Development: The Seed
26-2 Seed and Fruit Formation
Page 19
Page 23
Chapter 27 HUMAN AND MAMMALIAN REPRODUCTION
Page27
27-1 Human Sexual Reproduction
27-2 Methods of Birth Control
27-3 Hormonal Control of the Female Reproductive Cycle: An Inquiry
Page 28
Page 35
Page 41
Biology: As Scientific Inquiry Table of Contents
page v
Chapter 28 REPRODUCTION IN OTHER ORGANISMS
Page 4 7
28-1 Reproduction in Single-celled Protists
28-2 External Fertilization
28-3 Internal Fertilization
Page 48
Page 4 9
Page 51
Chapter 29 E M B R Y O L O G Y : ANIMAL DEVELOPMENT
Page 5 4
29-1
29-2
29-3
29-4
29-5
29-6
29-7
Page 55
Page 58
Page 59
Page 68
Page 70
Page 72
Page 73
The Human Fetus
Bird Embryos
Laboratory Investigation: Chick Embryology
Amphibian and Fish Embryos
Internal versus External Development
General Embryology
Birth
Chapter30 CELL REPRODUCTION
Page75
30-1
30-2
30-3
30-4
30-5
Page 76
Page 78
Page 80
Page 81
Page 83
Review of Cell Structures Related to Cell Division
Cell Division: Mitosis
Laboratory Investigation: Cell Division by Mitosis
Cancer and Tumors: Diseases of Cell Division
Cell Division: Meiosis
Chapter31 LIFE C O M E S FROM LIFE: O R DOES IT?
Unit VI
Page87
Genetics
Chapter 3 2 INTRODUCTION TO GENETICS AND PROBABILITY
Page 1
32-1 Introduction to Genetics
32-2 Laboratory Investigation: Coins, Dice and Cards:
What Do They Have to Do with Genetics?
32-3 GregorMendel
Page 2
Chapter3 3 APPLYING THE PRINCIPLES O F G E N E T I C S
Page 13
33-1 Laboratory Investigation: Using PokerChipsto
Understand Hybrid Crosses
33-2 A Programmed Introduction to Genetics
33-3 Introduction to Solving Hybrid Cross Problems
33-4 A Review of Hybrid Cross Problems
33-5 Hybrid Cross Problem Set
Page 14
Page 21
Page 27
Page 31
Page 32
Chapter 3 4 CHROMOSOMES, GENES AND INHERITANCE
Page 3 3
34-1
34-2
34-3
34-4
34-5
Page 34
Page 38
Page 41
Page 49
Page 50
Laboratory Investigation: Human Heredity
Chromosomes and Genes
Sex Linked Traits
Sample Sex-Linked and Blood Type Problems
Sex-Linked and Blood Type Problem Set
Page 3
Page8
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Biology: As Scientific Inquiry Table of Contents
page vi
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Chapter 3 5 CHROMOSOMES AND DIMYBRID C R O S S E S
Page 5 2
35-1 Meiosis: Sex Cell Formation with Two Traits
35-2 Laboratory Investigation: Dihybrid Cross Lab Activity
35-3 DihybridCross ProblemSet
Page 53
Page 56
Page61
Chapter 3 6 THE CHEMICAL STRUCTURE O F THE GENE: DNA
Page 6 2
36-1 Introduction
36-2 The Double Helix
36-3 Laboratory Investigation: DNA Replication
Page 63
Page 64
Page 70
Chapters? HOW TH E GENE O P E R A T E S : THE GENETIC CODE
Page 7 2
37-1
37-2
37-3
37-4
Page73
Page 75
Page 77
Page 78
Cloning
Genes Form Enzymes which Produce Traits
Science Fiction or Reality
The Genetic Code and Enzyme Function
Chapter 3 8 GENETIC ENGINEERING
Page 8 6
38-1 Laboratory Investigation: Gene Splicing
38-2 Recombinant DNA
38-3 Genetics Review
Page 94
Page 95
Page 97
Unit VII Classification and Evolution
Chapter39
Pagel
CLASSIFICATION S Y S T E M S
39-1 Laboratory Investigation: Animal Classification
39-2 The Need for Classification
39-3 Introduction to Biological Classification
Page 2
Page 4
Pages
C h a p t e r 4 0 THE ANIMAL KINGDOM
Page 8
40-1
40-2
40-3
40-4
40-5
40-6
40-7
Phylum: Porifera (The Sponges)
Phylum: Cnidaria (hydra, jellyfish, sea anemones)
Phylum: Platyhelminthes (Flatworms)
Phylum: Nematoda (Roundworms)
Phylum: Annelida (Segmented worms)
Phylum: Molluska (Clams, snails, octopus, etc)
Phylum: Arthropoda (Insects, crabs and relatives)
40-8
Phylum; Echinodermata (Starfish and relatives)
40-9 Phylum: Chordata
Page 9
Page 10
Page 12
Page 13
Page 14
Page 15
Page 17
Page 19
Page 21
C h a p t e r 4 1 V E R T E B R A T E S : C H O R D A T E S WITH B A C K B O N E S
Page 2 2
41-1
41-2
41-3
41 -4
41 -5
41-6
41-7
Page 23
Page 24
Page 24
Page 25
Page 26
Page 27
Page 27
Chordata: An Overview of Vertebrate Classes
Class Chondrichthyes: Sharks
Class Osteichthyes: Boney Fish
Class Amphibia: Frogs and Salamanders
Class Reptilia: Snakes, Turtles and Lizards
Class Aves: Birds
Class Mammalia: Humans and other Mammals
Biology: As Scientific Inquiry Table of Contents
page vn
C h a p t e r 4 2 THE PLANT KINGDOM
Page30
42-1 Overview of the Plant Kingdom
42-2 Non-Vascular Plants
42-3 Vascular Plants (Phylum: Tracheophyta)
Page 31
Page 32
Page 34
Chapter 4 3 C H A R L E S DARWIN AND T H E T H E O R Y O F EVOLUTION
Page 3 7
43-1 The Theory of Evolution: An Introduction
43-2 Darwin's Theory
Page 38
Page 41
Chapter44
Page44
N A T U R A L SELECTION
44-1 Laboratory Investigation: Natural Selection Simulation
44-2 Natural Selection and Evolution
44-3 Mutation and Natural Selection
Page 45
Page 50
Page 52
Chapter 4 5 EVOLUTION AND THE EVIDENCE
Page 5 5
45-1
45-2
45-3
45-4
45-5
Page 56
Page57
Page 59
Page 60
Page 63
Review of Sequence of Animal Evolution
Fossils
Punctuated Equilibria
Homology
Dating Fossils
U n i t VIII Ecology
Chapter46 ECOSYSTEMS
Page 1
46-1 Feeding Relationships
46-2 Ecosystems
46-3 Laboratory Investigation: Creating a Model Ecosystem
Page 2
PageS
Page 7
Chapter 4 7 FLOW O F ENERGY
Page 1 2
47-1 Laboratory Investigation: Food Webs and Energy Relationships
47-2 Ecological Pyramids
Page 13
Page 1 7
Chapter4 8 BIOMES AND ECOSYSTEM C Y C L E S
Page 20
48-1 Self-Guided Field Trip
48-2 Ecological Succession
48-4 Laboratory Investigation Demonstration: A Self-Contained Ecosystem
48-5 Ecosystem Cycles
Page 21
Page 26
Page 27
Page 31
Page 32
C h a p t e r 4 9 POPULATION DYNAMICS
Page 3 4
49-1
49-2
49-3
49-4
Page 35
Page 37
Page 38
48-3 The Earth's Biomes
Laboratory Investigation: Population Dynamics in Model Ecosystems
Population Dynamics
Population Growth
An Interdisciplinary Math-Science Lab Investigation:
Estimating Population Size
49-5 Optional Enrichment Lab Investigation: Yeast Population Growth
Biology: As Scientific Inquiry Table of Contents
page vtn
Page 44
Page 46
49-6
49-7
49-8
49-9
Limits to Population Growth
Population Growth Computer Simulation
Human Population Growth
Population Density and Stress: An Interdisciplinary Video and Discussion
Page 49
Page 50
Page 52
Page 58
Chapters 0 HUMAN IMPACT ON THE BIOSPHERE
Page54
50-1
50-2
50-3
50-4
50-5
Page 55
Page 59
Page 62
Page 69
50-6
50-7
50-8
50-9
Pollution and What You Can Do
Laboratory Investigation: The Effects of Pollution on a Model Ecosystem
County Council Simulation (interdisciplinary))
Natural Resources and What You Can Do
Laboratory Investigation:
Determining the Amount of Energy in Different Fuels measure
Energy Resources and What You Can Do
Laboratory Investigation: Solar Energy
Jobs vs Environment: A Case Study
A Final Word about Ecology
Appendix A
Optional Interdisciplinary Thoreau and Haiku
Poetry for 4 8-1 Self-Guided Fie Id Trip
Biology: As Scientific Inquiry Table of Contents
page ix
Page 72
Page 74
Page 76
Page 78
Page 79
Pages 1
UNIT I
Introduction to Biology
and the Scientific Method
Chapter 1
The Nature of Biology
Chapter 2
Tools of the Biologist
Chapter 3
The Ultimate Tool:
The Scientific Process
CHAPTER
THE NATURE OF BIOLOGY
V.4
1-1 A Note from the Author
1-2 What is Biology?
1-3 Characteristics of Life
1-4 Safety Rules
Ch. 1 The Nature of Biology
Page 2
Page 4
Page 5
Page 7
Chapter 1
9\[ature
most Beautifui thing -we can experience is the, mysterious,
ft is the source of ai£ true art and science'
'Einstein
1-1 A Note to the Student from the Author
You are about to embark upon a 36 week course of study in biology that will
change the way you view the world in which we live. Our world is filled with an
incredible array of living things, including our own species. For thousands of years,
man has been intrigued by the exploration of the natural world. We know more about
the living creatures that inhabit our planet today than at any other time. I want you to
share in the excitement of uncovering and understanding the processes that take place
in living systems. I also want you to share in how these facts were discovered through
the use of the scientific inquiry process. Many science textbooks do a good job in
presenting the facts and concepts that make up our understanding of today's modern
science. Most textbooks do not give students the opportunity to experience the
process by which these facts are discovered. You will, therefore, find that many of the
activities in this manual will stress the use of the scientific process. A major goal of this
course is to provide you with the opportunity to function in the laboratory as a true
scientist. You will solve problems by designing and performing original experiments,
and collecting and interpreting data. In the process you will not only become a
problem solver, but will discover some exciting things about how your body and those
of other living organisms operate. I think you will enjoy these materials and hope that
you will help us refine them for future use.
Problem-Solving in Science: Why Learn It?
The problem solving process is also called the scientific method. Most
of the facts that we find in textbooks are a product of this method. Science is the
PROCESS of uncovering these facts as well as the facts and concepts themselves.
Learning the facts in a science course, without learning the process by which they
were discovered, would be like taking an art course to learn to do art and instead just
looking at the completed art work of others. If you don't have the chance to produce art
work yourself, you will not have a good understanding of what art is all about. Looking
at and studying the great works of art is important and we can learn from them, just as
Ch. 1 The Nature of Biology
a
we can learn from looking at experiments planned by scientists and studying facts
discovered by someone else. But that's not all a science student should do. Therefore,
in this course you will do some problem-solving of your own in the laboratory. By'
the end of the year you will thoroughly know how to use each step in the scientific
process to solve a laboratory problem. After all, that's what science is all about.
What you learn about problem-solving can be applied to non-science areas as well.
You will find that it is fun to discover new things. And that's just what you will do.
We Elicit Your Help
This publication is stored by computer. This provides us with the opportunity to
make changes in the text or graphic portions of this manual.
If you notice an area in the manual where information or instructions are not clear,
notify your teacher who will pass along your suggestions for changes. These changes
will be made in later printings for future groups of students. Past students have made
numerous recommendations for change in earlier editions of this publication. Your
suggestions will be appreciated and welcomed.
This Text is Different
You will find that this text is different from others you have used. Interesting lab
activities are usually scheduled to introduce you to concepts you will later read about
and talk about in class. The chapters are written so that you can frequently interact with
what you read or do in the lab. As you read the next section, read it with a pen or
pencil in hand and answer any questions on your own paper as you
encounter them.
I know that you will appreciate the time you spend
in the laboratory. Here you will be able to observe laboratory science
first-hand. You will see and handle the living materials that you will later read about
and study. You will be impressed by the beauty and highly organized structure found
in all living things. I hope you will be challenged and successful in your study of
biology.
The author,
%pn Thompson
Ch. 1 The Nature of Biology
1-2 What is Biology?
Question 1; In your opinion, what things are studied in a biology course?
Objective
You will be expected to describe what is studied in biology as compared to other
classes such as physics and geology.
What is studied
of the word biology.
Therefore, biology is
things: plants, animals
in a biology course? One way to find out is to examine the origin
Bio- means "life." The suffix -ology, means "the study of."
the study of life. More accurately, biology is the study of living
and microorganisms.
Question 2: What are some other words that contain either the prefix bio- or the suffix
-ology?
The study of living creatures is extremely fascinating. They can be beautiful in
color and form. They are incredibly adapted to their environments and exhibit unusual
and elaborate behavior. And you will be privileged to be able to study how they work
on the inside. You will observe elegant processes that occur in no other settings in quite
the same way as they do in living creatures.
Biologists have uncovered most of what they know by using the scientific
inquiry method. You will use the scientific method to discover many facts that make
up the science of biology.
What qualifies something as living? Is a seed alive? Is seaweed, found floating
on the surface of a bay, alive? Is wood alive? Is dried grass, mold, a tomato from the
supermarket or a mushroom alive? What characteristics qualify something as living?
The following news item provides a perspective on this question:
"Mystery Purple Blobs From Outer Space? "
Some years ago, the Seattle Times reported a bizarre occurrence that happened
in Texas. The headline read, "Mystery Purple Blobs From Outer Space? " One
morning, a Mrs. Sybil Christian found two slimy purple blobs in her front yard. "It looked
like smooth purple whipped cream," she said. "I called my husband over and neighbors
came over and 1 stuck this stick into the object. It went in easily, very easily. I punctured
it."
Officials from NASA and the local Natural Science Museum examined the blobs
Ch. 1 The Nature of Biology
*
4
4
.
and said they could be exotic meteorites from outer space. No one knows for sure and
they can't say from where they might have originated.
"We could make a science-fiction thriller out of this," said the curator of the
museum. You can just imagine the little green men coming out." Other authorities don't
believe the meteorite theory. "Later the color changed to a brownish red and the
phenomenon has become a greater puzzle." Could the blobs be living protoplasm?
How would you go about deciding if the purple blobs were alive?
Most biologists agree about the general characteristics required for life. There is
some disagreement about certain specifics. A generally accepted list of qualities of life
found in all living things is covered in the next topic.
1-3 Characteristics of Life
Question 1:
In your opinion, what qualities distinguish living things from non-living
things? To answer this question, make a list of the qualities that living
things possess.
Biologists are in general agreement about the characteristics found in living
organisms. (An organism is a term biologists use to refer to any living creature.) Living
organisms have the following characteristics:
Objective
You will be expected to list the characteristics of living things. You should
understand how these characteristics differ from those of non-living things.
1. All living organisms have an organized structure.
Plants, animals and microorganisms are composed of cells. Cells are highly
organized units that you will study in the next unit. Viruses are not made up of cells,
but are made of protein and nucleic acid molecules arranged in a highly organized
manner.
2. Living organisms have the ability to reproduce.
Members of each species can make copies of themselves. If this were not so, the
species would eventually cease to exist.
3. Living organisms have the ability to carry out metabolism.
Hours after an animal dies, we say it is no longer alive. What has changed?
UJHflT'S
THE
DIFFERENCE?
Ch. 1 The Nature of Biology
The answer is that a dead animal can no longer metabolize. Metabolism is a term
that scientists use to refer to all of the various chemical reactions that organisms are
responsible for carrying out. Living things use nutrients to obtain energy or they
absorb light energy. Animals and many microorganisms break down food
molecules to obtain energy for life processes. Animals use energy to move, breathe,
excrete and perform other important cellular functions.
Plants and certain
microorganisms absorb the energy from the sun and use it to make essential
materials for cells.
4. Living organisms require water.
Living things are made up mostly of water. Many organisms are over 90% water.
Hundreds of chemical reactions need to take place in order for life processes to
occur and water is needed to provide a medium in which the molecules can react. In
water, different molecules can move around and come into contact with others in
order to react. These metabolic reactions occur in the cytoplasm of cells. Cytoplasm
is mostly water and will be studied shortly in greater detail.
5. Living organisms grow and develop.
Living things use substances from their environment for growth.
undergo change as they grow.
They usually
Question 2: A salt crystal placed in super-saturated salt water will grow in size. Does
this mean that the salt crystal is alive? Explain.
6. Living organisms respond to their environment.
Movement:
Animals move about in their environment to find food and interact
with other organisms. Some plants can be observed to initiate
movement but most plants move so slowly that they appear to live
a completely motionless existence.
Stimuli and response:
Living organisms respond to the various stimuli in their
environments. They might respond to light, temperature changes,
gravity, moisture levels, chemical and other physical stimuli.
4
Something to Think About
Life Depends Upon Death
^
That's right. Life depends upon the death of other creatures. In order for
humans to live, they need food. Our food comes from animals and plants or animal
and plant products in the case of some processed foods. We do not often think of
our lives depending upon the death of cows, chickens, sheep, fish, crabs, clams,
and a large variety of plants. Some animals depend only upon other animals for
food. They are called carnivores. Certain animals eat only plants. They are
herbivores. Animals that eat both plants and animals as we do, are referred to as
omnivores. By the end of an average American male's life, he will have eaten the ^fe
following: six cows, 1872 pounds of fish, 30,000 pounds of wheat, 26,400 pounds of
4
q
Ch. 1 The Nature of Biology
4
^
:*
vegetables and 2,600 pounds of miscellaneous animals and grains
Question 3 List the characteristics that distinguish a living organism from non-living
things.
Question 4: Define metabolism and give an example.
Question 5: Is a block of wood alive? Explain.
Question 6: Bean seeds can sit on a shelf for decades and not change. Are they alive?
Explain.
Question 7: Is a supermarket tomato alive or no longer living? Explain.
Question 8: How is water required for life?
Question 9: If you could take one of the "mystery purple blobs" described in the news
article to a biology laboratory, what are some of the tests you would need
to make to determine if the" blob" was alive?
1-4 Safety Rules
Question 1: Have you been in a science class, shop class or PE class when someone
was injured? Explain.
Objective
You should understand the following 13 rules and apply them when in the
classroom and laboratory.
Many chemical solutions and reagents used in biology can stain or burn your skin or
eyes. It is therefore important to carefully follow our labratory safety rules. Science
students in various school districts in this state have been seriously injured due to the
careless handling of lab materials. Some have lost an eye. Others have been seriously
burned or injured in other ways. Please read and apply the following rules so that you
will not be injured in any way:
Ch. 1 The Nature of Biology
<s
RULE 1: Never touch chemicals or solutions that are set-up in the front of the room for
demonstration purposes. Some chemicals leak out of the bottles and touching
them can cause skin burns or eye damage.
RULE 2: Never touch other chemicals or solutions sitting elsewhere in the lab for the
same reason.
RULE 3: Handle only those chemicals provided to you at your own tables for that day's
work. Handle those chemicals carefully. If you should spill anything, call your
teacher immediately. If you accidently get any solutions on you, CALL YOUR
TEACHER IMMEDIATELY.
RULE 4: Never put chemicals or even water on your skin or on another person. The
water containers could have small amounts of acid, base, or caustic chemicals
that could irritate the skin or eyes. Labels could come off of caustic chemical
solutions and you might think that they are harmless water.
RULE 5: Always pick up dropper bottles by the main body of the bottle and never by the
lid or stopper.
RULE 6: Keep your hands away from your eyes and do not eat while working in lab.
RULE 7: Do not wear coats in lab. Bulky clothing could cause spills.
RULE 8: Take particular care when using flames or hotplates. Keep papers and all
liquids away from the flame. Some liquids are flammable.
RULE 9: Conduct yourself in an orderly manner in lab. Never grab or horse around in
lab since it could cause a serious accident.
RULE 10: Follow all directions and safety cautions in all lab instructions.
RULE 11: Handle razor blades, scalpels and knives carefully.
yourself.
Ch. 1 The Nature of Biology
Never cut toward
RULE 12: Use hot pads or metal tongs when handling hot glassware to avoid burning
yourself. Keep your hands off the burners of hot plates even if they appear to
be off.
RULE 13: Handle living specimens carefully so as not to injure them.
We want you to be aware of these precautions so that you do not injure yourself or
others.
Ch. 1 The Nature of Biology
CHAPTER
TOOLS OF THE BIOLOGIST
Laboratory Investigation:
Can You Catch a Fish on a Moonbeam?
How to Use This Manual
Laboratory Investigation:
How to Use the Binocular Stereoscope
Laboratory Investigation:
The Compound Microscope
Laboratory Investigation:
How to Make a Wet Mount
Electron Microscope
Other Tools
The Metric System
How to Read and Construct a Graph
Graphing Application
Ch 2 Tools of the Biologist
10
Page 11
Page 14
Page 19
Page 25
Page 34
Page 36
Page 37
Page 38
Page 40
Page 56
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Chapter 2
of the
2-1 Laboratory Investigation
Can You Catch a Fish on a Moonbeam?
Objective
0
You will be expected to experimentally determine if a fishing lure will emit light
as advertised under conditions in which it would be used.
PRELAB:
If unopened packages of glow-sticks are at your table:
Open the two packages at your table and bend the flexible plastic glow-stick until you
feel the fine glass tube inside break. K£* You should notice the stick begin to glow.
Shake it back and forth. If it has not begun to glow, bend it a little more.
If the packages have already been opened:
If the glow-sticks at your table already glow, the students before you have opened
them and you may proceed to the next step. Quite an amazing reaction is taking place
within the glow-stick. When the thin glass vial containing a chemical catalyst was
broken, the chemical mixed with the chemical outside the glass vial and the two
chemicals reacted together to produce light. Similar reactions occur in glow worms,
fireflies, and in certain algae and other living plants and animals.
The room lights will need to be turned off for this experiment. After the lights are out,
see if you can use the glow-stick to enable you to read the following instructions.
Question 1: Can you read the instructions with the aid of the glow-stick? Explain.
Work as a team at your table and set up two beakers of water; set up one at about 45
degrees C. and another at about 22 degrees C. (room temperature). Use tap water
and a thermometer to create 22 degree water. Obtain warm tap water for the 45
degree temperature.
You should have two glow-sticks at each table. Place one into the room temperature
water and one into the warm water.
Ch 2: Tools of the Biologist
11
Cp © 1999, Do not reproduce
Question 2: After one or two minutes, describe your observations for each stick.
Now remove the sticks from both beakers, dry them and set them on the table and wait one
to two minutes and then answer question 3. fa
Question 3: What did you observe happening as the two sticks changed back to room
temperature while on the table?
Question 4: What appears to be the relationship between the amount of light given off by a
glow-stick and temperature?
INVESTIGATION PROCEDURE:
In this investigation you will work as a team at your table; however, each student is to write
his or her own report. Feel free to discuss answers but put written responses into your own
words.
PROBLEM TO BE SOLVED
What affect does temperature have on the
amount of light given off from a glow-stick?
Copy the problem in the box above into your lab report. Label it "Problem to be solved" fa
HYPOTHESIS:
Write a hypothesis for the question in the above box. A hypothesis is a
possible answer to a question. Your hypothesis should describe the
relationship between temperature and the amount of light given off by the
glow stick, fa
EXPERIMENTAL
PLAN
After the heading, "EXPERIMENTAL PLAN" in your report, write a detailed
plan for how you will set up an experiment to test your hypothesis. Be sure to
set up a control beaker and an experimental beaker. Have your teacher
approve your plan before you go on.
fa
THE
EXPERIMENT
Your control should be a beaker with water at about 22-24 degrees C (room
temperature). Place one glow-stick into this beaker. The control beaker
containing the glow-stick should remain on the table for the duration of the
experiment.
Ch 2: Tools of the Biologist
12
Cp © 1999, Do not reproduce
A
Set up any other beakers based upon your experimental plan and reuse the
glow-stick each time. Wait at least two minutes before recording the results.
t&>
Question 5: What is the purpose of the control beaker?
DATA (RESULTS OF THE
EXPERIMENT)
Place these results after the heading "DATA" on you lab report.
*&
Record the results obtained in a neat data chart as follows:
You might use a system of stars to illustrate brightness. For example, ***** = brightest.
Use *, **, *** and **** to correspond to different degrees of brightness between
maximum and minimum. >&
Temperature
Brightness
37
27
17
10
etc.
ANALYSIS, INTERPRETATIONS AND
CONCLUSIONS:
Question 6: What does the additional data collected tell you about the relationship
between temperature and the amount of light produced in this reaction?
Question 7: At about what temperature did you observe the least light emitted?
CONCLUSION
REGARDING HYPOTHESIS:
Question 8: How close was your hypothesis to being correct? Explain.
These glow-sticks have been advertised for use as fishing lures. Your teacher may have a
copy of one of these advertisements. The ad explains how the stick will glow in water and
attract fish. Many of the rivers commonly fished in Washington State are between 2
degrees C. and 6 degrees C.
Question 9: Will the glow stick be an effective lure in water this cold? Explain.
Question 10: In your opinion and based upon your data, how warm does the water need to
be to cause the glow-stick to give off enough light to attract fish?
Your teacher may have you place the sticks in the refrigerator for the next class to use.
Ch 2: Tools of the Biologist
13
Connecting Point: © 1999, Do not reproduce
2-2 How to Use the Programmed Format in This
Manual
4
4
4
4
4
4
4
Many activities in this manual were designed for
student interaction. They are not meant to be read
passively. This curriculum is quite different from
• those used elsewhere in the nation. Instructions on
how to use this manual are important. What you
learn in this course will depend upon whether you
know how to read and use this manual correctly.
How to Read a Laboratory Activity
In the past we have found that students lost their places in the lab manual while
performing a given laboratory task. We also found that they did not read far enough
before performing the described task and, therefore, had difficulty with it. To solve this
problem, the author has inserted a symbol like this [
], at appropriate places in lab
activities. This tells the student to stop reading at this point and perform the task
described. When you have completed the task, return to the [
] and continue
reading. Read until you encounter another [
].
Try the above procedure with the material below:
DO NOT WRITE ON ANY OF THE PAGES IN THIS MANUAL.
[
Take out a piece of your own notebook paper upon which to write your answers.
] Begin the program below. [
]
How to Read a Programmed Reading or Programmed Lab Activity
Programmed reading or programmed lab activities are designed to give you
immediate feedback about your answers. You will find this extremely helpful.
Programmed activities ask the student questions. The student writes a response. Next
the student reads the correct answer provided and compares his or her answer to the
correct one.
1. Here's how it works. In the section of a programmed reading activity you will
find a question and sometimes instructions or related factual information. Write the
answers to these questions on a separate piece of paper. Number each answer. For
example: Up to this point, on this page, how many small [
] symbols can you count?
(Place answer number and answer on your own paper.)
Before you read question 2, note that the correct answer to question 1 is just
below the line.
1. 6
Tools of the Biologist
(Be sure you counted the "[
14
]" in question 1.)
'^P
I
2. The [
] symbols will help you to keep your place while doing complicated lab
experiments. Past experience has shown that not paying close attention to the [
]
symbols causes confusion in following lab directions.
It's important to not look at the answers prior to reading and answering each
question. For this reason, use the paper upon which you are writing your answers, to
cover the answers that follow. The best way to do this is to line up the top of your
answer sheet with the line below the question you are working on. Find the line at
the bottom of this question frame and do this now. [
] Each time you move to the
next question frame, move the paper down to the next line, but not further. Answer
the next question on your own paper and then read the answer and proceed to the
next question frame,
Students should sometimes not pay attention to the [
]'s or should skip some
printed material because they will be able to move faster through the reading. (True or
False?)
2. False
When you find that you have written an incorrect or partially incorrect answer, correct
the answer on your paper. This will help you to immediately learn from your
mistakes.
Frames like this one will contain no questions. You will be asked to, "Proceed to
the next frame." In this case, simply move your answer sheet down to the next frame.
"Proceed to the next frame."
4. Some questions will require a lengthy response, like the following one. After reading
most programs, you will take a quiz that will evaluate your understanding of the
material. If your quiz score is too low, your teacher may ask you to reread the
program or may ask you to read some related material and take the quiz again.
Some unwise students feel that they can do better if they read the correct answer
before they write in their own answer. This is not true and would be, in a sense,
cheating. Educators have conducted studies to determine which educational
methods work best. They find that students who read the answers without trying to
write their own answer first, do not learn as well as those who attempt writing their
own answer and then reading the answer provided.
Write out a plan for an experiment using a class of 30 students as your
subjects. The experiment should be planned to determine if reading the answers
before attempting to write an answer will affect what students learn. (Hint: You can
Tools of the Biologist
15
divide the 30 students into groups and try a different approach with each group.)
4. First divide the class into two equal groups.
Instruct one group to read the program in the correct manner
as described.
Have the students in the other group cheat on the
program by reading the answers before writing one of their
own.
Next, have each group take a test to determine which
group learned the material best.
Finally, compare the test results of the two groups to see
which group did the better.
5. Experiments similar to the one described above have been done at various
universities. The results show that the group that looks at the answers before writing
down their own answer has significantly lower test scores than the group that reads
the program in the correct manner.
We will expect you to "play the game" correctly. It will produce greater
understanding, satisfaction and higher grades.
•
Q
—
'
•
m
If you don't know the answer to a question, commit yourself in some way. Write ^^ €
down some answer. A wrong answer is better than no answer. In this way, you can
(
learn from your mistakes. If your answer was wrong, put a line through it, and place
m
the correct answer nearby. These answers will not be handed in or graded, so don't
worry that you will be penalized for having wrong answers. You won't. Your grade
on this type of activity will result from the quiz you will take when you finish the
activity. Strive to understand why you got any answer wrong by rereading the
previous information. If you can't understand why your answer is wrong, stop and
GET HELP from your teacher. Don't go on.
Answer the next question: Should a student read the provided answer before or
after he or she writes his own answer?
5. Before
6. If you are reading this part and did not ask your teacher for clarification on the
answer to #5, which was purposely incorrect, you are developing a bad habit. We're
just checking to see if you would ask for help with the incorrect answer that was
<
printed for #5! The correct answer should be "after you have first written your
<
own answer." Remember, when you don't understand an answer, be sure to ask
^
for help.
£;
(
I
Tools of the Biologist
16
|
When a student uses a program correctly, mistakes are not learned. The problem with
many textbook question and answer assignments is that students can complete them
and learn some wrong or incomplete concepts. Programmed reading and lab activities
allow one to correct wrong responses or modify slightly incorrect ones before going on.
A programmed reading also provides you with an opportunity to interact with the
printed page in an active way. This produces better understanding, greater retention
and less chance of distraction. Go on to the next frame.
7. List the advantages of using a programmed reading as compared to reading a text
book.
7. One learns less incorrect information by the time one finishes.
Allows one to correct wrong or slightly incorrect responses
Requires interaction with the printed page in an active way Produces
better understanding
Produces greater retention
There is less chance of distraction
(Your answers may not be worded exactly as those shown in the
programs. Compare your answers by looking for the same meaning
but not necessarily the exact same words.)
8. All of the material you will be reading in biology will not be from "programmed
readings." Many of the biology reading and lab activities are of the usual format. It will
be easy to tell as you begin. Simply look for the horizontal lines and provided answers.
Each main topic or activity in the manual has a clear statement of the objective near
the beginning of the topic. The following is how the objective for this topic would
appear:
Objective
You should know how this manual is different from other biology texts and
understand how you will benefit by using it correctly.
You no doubt recall seeing similar objective statements in Chapter 1.
Have a good year.
Ch 2: Tools of the Biologist
17
Cp © 1999, Do not reproduce
2-3
Laboratory Investigation
How to Use the Binocular Stereoscope
Objective ——^————i^—_
You will be expected to understand and
demonstrate how to use the binocular
stereoscope.
You will notice that the binocular stereoscope has 2
e y e p i e c e s , thus the name - bi (two) n
ocular(eyepiece) stereo(depth) scope. When
two eyepieces are present, the view will be in stereo
vision which will allow one to sense depth.
This microscope operates quite differently from the monocularfone eyepiece)
compound microscope. !t is much easier to operate once you have learned the few
simple instructions that follow. It is usually used when you do not need as much
magnification as the compound microscope provides or when looking at objects through
which fight cannot easily pass.
There are different types of stereoscopes. The picture below shows the SUBSTAGE
LIGHT VERSION. If you have this type, it will have a large base containing a light and
will be connected to an electric cord. See drawing below.
eyepiece lenses
(ocular lenses)
A ^eyepiece ring
adjustment
focus adjustment
light, overhead
arm—-
SUBSTAGE LIGHT VERSION
If you have no light in the base and no electric cord connected to the thin base, you
have what's called the SEPARATE LIGHT SOURCE VERSION shown on the next
page.
Tools of the Biologist
18
m
m
m
A separate lamp is needed to provide
light as shown at the right.
1. What type of stereoscope do you
have at your table?
SEPARATE LIGHT VERSION
You will find a variety of materials in your tray for examination. DO NOT use the
microscope to examine these materials until you have gone through the procedures on
the next few pages. Your viewing of these items will be successful only when you have
learned the unique features of each type of microscope.
Look back at the drawing on the first page, you should be able to find most of the parts
labeled. Find these labeled parts on your own stereoscope.
OPERATING PROCEDURE FOR BOTH TYPES OF MICROSCOPE:
Clean the eyepiece lenses with lens tissue. [
] NEVER REMOVE THE EYEPIECES
FROM ANY OF THE MICROSCOPES IN THE LAB. THIS INCLUDES THE COMPOUND
MICROSCOPE. Do not tip the scope, since the eyepieces can fall out and break.
Always carry any microscope with two hands.
All focusing is done with the single focus adjustment knob. Place a piece of
cheesecloth on the stage of your stereoscope and turn on the light. [ J Find
the focus knob and focus on the white threads of the cloth. [
] Find and examine the
objective lens. It is actually 2 lenses in one. To change the objective lens, rotate the
lens unit, [
] Every time it is rotated, be sure the lens clicks in place or comes to a full
stop before trying to see through the eyepiece. Try it. [
] To determine the objective
lens power, look on the side of the objective lens to see which number (2X, 4X, etc) is
facing away from the arm of the microscope. You will have to turn the stereoscope
around to clearly see these magnification numbers on the objective lens.
Be careful. [
]
2. What are the two objective lens magnification powers printed on your stereoscope's
objective lens? (This is the number of times the objective lens magnifies in each
position.)
Rotate the objective lens so that the lowest power is in place and examine the cloth.
" Next rotate the objective lens so that the highest power is in place.
3. Draw a careful sketch of four to six strands of the cloth. Show detail and make your
drawing at least 2 inches by 2 inches.
4. What number (lens power) do you find on each eyepiece lens unit? (This is the
Tools of the Biologist
number of times the eyepiece lens magnifies.)
The TOTAL MAGNIFICATION seen by the eye is calculated by multiplying the
eyepiece lens power times the objective lens power for the position of the objective
lens in use.
5. Place the lowest objective lens power in place and examine the cheese cloth again.
[
] Calculate the TOTAL MAGNIFICATION at which you are seeing the cloth
fibers?
6. Now rotate the objective lens to the highest power and look again. [
[
]
Refocus.
] What is the TOTAL MAGNIFICATION at which you are now seeing the
cloth?
7. What is the maximum magnification power that can be obtained with this binocular
stereoscope?
Notice that the two ocular lenses (eyepiece lenses) can be moved closer together or
farther apart, depending on the distance between the user's eyes. [
] Adjust this for
your eyes. [
]
8. Examine the two eyepieces. Is one eyepiece tube different from the other in any
way? If so, how?
If there is no difference, see if there is a stereoscope at your table with a different
eyepiece. [
j If your scope, or one at your table, has an additional focus for one
eyepiece, it will look something like that shown at the arrow in the photograph on page
one. This is called the eyepiece focus ring. If you have one at your table, look into
the eyepiece and rotate this eyepiece focus ring to focus. [
] This focus
adjustment is for adjusting the scope for any visual loss that one may have in one eye or
the other. To set this focus correctly, look into the eyepiece that does not have a focus
adjustment on it and focus with the focus knob on the arm of the scope while the other
eye is closed. [____] Now look into the other eyepiece and close the other eye. Now
focus with the eyepiece focus ring. [
] The eyepieces should now be adjusted for
your eyes. From now on only focus with the focus knob on the arm of the
microscope. [
] Examine the pond water by focusing at different levels. [
]
Each type of stereoscope operates somewhat differently. If you have the S U B S T A G E
LIGHT VERSION {with cord attached) continue reading below. If you have the
SEPARATE LIGHT VERSION, skip over the next part for now to the section titled
"SEPARATE LIGHT VERSION" [
]
SUBSTAGE LIGHT VERSION
Examine the switch on the stage of the stereoscope. While not looking through the
eyepieces, notice which light goes on in different locations when the switch is placed in
different positions. [
]
Ch 2 Tools of the Biologist
20
9. Explain the three different ways the cheesecloth can be illuminated (lighted) for each
switch position.
The overhead only lighting position is used when one is examining specimens through
which light cannot pass from below. Light from below is best for transparent materials.
Light from both sources is for transparent material when light from above and below are
both helpful.
View the cheesecloth on high power for the next question. [
]
10. Try all three lighting positions to determine which one seems best for the
cheesecloth. Which lighting position seems best to you?
Trade with a student who has a microscope without a substage light so you can do the
section that follows. [
] If you have already done the next section, continue where it
says "PERFORM THE FOLLOWING WITH EITHER TYPE OF STEREOSCOPE," below.
SEPARATE LIGHT SOURCE VERSION
You should have a white or black circular plate in the stage of this type of stereoscope.
Remove it by loosening a lock screw in the stage. [
] Turn it over and notice that one
side is black and the other side is white. Examine the cloth with both the black side and
the white side up.
11. Which side, black or white seems best for the cheesecloth? Why?
If you have not used the stereoscope with the substage light yet, change with a
student who has one and go back to page 20 and follow the procedure there for using
the substage light stereoscope then return to the section that follows.I
PERFORM THE FOLLOWING WITH EITHER TYPE OF STEREOSCOPE:
Place the dish of pond water onto the stage. [
table, dry it with a paper towel.
]
If any water spills on the stage or
Examine the pond water by focusing at different levels in the water first with low power
and then with high power.
12. You should notice a 3-dimensional effect, where a sense of depth is apparent when
using both eyes. Close one eye and look into the microscope. In what way is your
viewing different?
You should now be an expert at using the binocular stereoscope. It is fascinating to
examine a variety of materials with this microscope. Examine all of the items provided
in your tray. Also examine your finger nail and a coin, dollar bill, and strand of hair that
you can provide. Examine them in any order and draw a labeled drawing of at least 5 of
the materials viewed. Listed below are some of the items that may be in your tray for
Tools of the Biologist
21
microscope slide
the image 4 times larger
Vl
10X
eyepiece
lens
\t
source
4Xlow
power
objective
lens
pecimen
n slide to
be magnified
The above diagram is not drawn to scale and only shows how the image size is
and not how the paths of light actually are altered by the lens. If you wa
magnification with the objective lens than 4 X, a more powerful lens must be use
is a lot of trouble to unscrew one lens and replace it with a more powerful
microscope has been fitted with a revolving piece that holds 3 different objectiv
When you want greater magnification, rotate a more powerful objective lens int
too much light is coming through the stage and specimen, you can reduce the
light by making the hole smaller under the stage.
Cover the answers that follow with your notebook paper and proceed. [
answers on your own paper.
1. If a specimen is microscopic it cannot be seen with the unaided eye. Specim
to the unaided eye are called?
1. macroscopic
2. If the objective lens magnifies 5X, and the eyepiece magnifies 10X, thei
magnification at the eye will be?
2.
SOX (5X times 10X = SOX)
3. Find each labeled part in the following drawing on your microscope.
Ch. 2 Tools of the Biologist
24
© Connectii
eyepiece
coarse focus adjustment
revolving nosepiece
fine focus adjustment
Objective lenses
4X, 1 0 X & 4 0 X
arm
stage
diaphragm disk
mirror or light source
base
4. Cover the above labeled microscope diagram and write the names of each
microscope below. Write the letter and then the name.
-ite all
visible
4. For the correct answers, see question #3. Check each ans1
carefully and learn from any mistakes.
e total
5. What role does each part play? You already know the function of the eye piei
objective lens. Look at the eyepiece on your microscope. A number, followe
will tell you the magnification of the eyepiece lens. [
] What is its magnifica
Examine each objective lens and record the magnification power of each as fc
(You may find other numbers on the lenses. The magnification # is usual!
by an X.)
What is the magnification marked on the low power objective?
What is the magnification marked on the medium power objective?
What is the magnification marked on the high power objective?
int
Tools of the Biologist
25
5. Eye piece = 10X, Low = 4X, Medium = 10X High = 40X. Be sure
you have seen these numbers on the sides of each lens. (You
may have a microscope with objective lenses that have different
magnifications powers than the typical 4-10-40X)
6. Rotate the revolving nosepiece to see how each objective lens locks or snaps into place
when it is lined up with the tube. [_ J What is the relationship between the length of
each objective and the magnification power on each lens?
6. The longer the objective lens, the greater the power.
_
7. Swing the 10X objective into place. [_
this objective in place?
J What is the total magnification, at the eye, with
7. 1OX (10X times 1OX = 1 OOX) ( eyepiece x objective)
8. Swing the 40X objective into place. { ___ 1 Now what total magnification would be
obtained at the eye?
8. 400X
(10X
times 40X = 400X)
Turn the coarse adjustment knob and notice that this raises and lowers the tube. [
]
This coarse adjustment serves as an approximate focus. Now turn the fine adjustment
knob. You will probably not be able to see the tube move but it does. The movement is too
slight for you to notice. Look on the right side of the microscope arm between the fine and
coarse adjustment knobs. You will see a white mark on the base between two black
marks on the tube ratchet. (Some microscopes may not have these marks.) Turn the fine
adjustment knob many times as you watch these marks.
9. What happens to the marks as you turn the adjustment knob and what does this indicate?
9. You should be able to see the tube move as evidenced by the two
black marks moving with respect to the white mark. (Try it again if
you did not see it)
10. Center the white mark between the two black marks. [ _ ] This should be one of the
first things you do before using the microscope each lab day. If you forget to do this, you
may not be able to focus on high power.
Tools of the Biologist
26
i
<
*
*
The functions of the other parts of the microscope will be explained as you set up and
use the microscope in the next section.
HOW
SETTING UP THE
PART 11
TO USE THE C O M P O U N D MICROSCOPE
MICROSCOPE:
1. Set the microscope in front of you on the table so that the arm is toward you. [
1 Be
sure that the base of the microscope is no closer than 3 inches to the edge of the table.
2. Verify that the position of the white mark is midway between the 2 black marks on the
side of the arm.
3. If your microscope has a mirror, position the table lamp behind the microscope so the
light will strike the mirror. . [
] Adjust the lamp fittings so that the light is close to the
table. {
1 Move the lamp back so the lamp is about 10 inches from the mirror and turn
it on. [
1 If the lamp is closer than 10 inches, the heat from the bulb may cause water
onj3_sl{de to evaporate, killing the organisms you intend to view.
^
RIGHT WAY - The light hits the
mirror and does not shine in the
eye.
e
WRONG WAY - The cover over
the light bulb is not tilted to
keep light from shining in the
eye.
4.
If you have a sub-stage light instead of a mirror, simply turn on the sub-stage light.
[
] You will be required to know how to operate both kinds of microscopes.
5.
Crank the tube to its highest position. [
1 Clean the eye piece and the 10X and the
40x objective lenses with LENS TISSUE only. [
1 Notice the 4X lens is recessed so
you can't clean it. [
1 Be sure that you use only lens tissue for this because other kinds
of tissue may scratch the lens. The lenses of a microscope are about half the price of the
microscope. So take care of them. The total cost of this type of microscope is over
$100.00. When a lens is particularly dirty, use water on the lens tissue and dry the lens
thoroughly. Please do not use lens tissue to dry slides or cover slips.
Tools of the Biologist
e
WRONG WAY - Notice that
the light can't pass though
the metal stage and reflect
off the mirror.
27
6. Place the 4X objective in place and lower the tube until it stops.
7. Turn the microscope around and tilt back the arm as far as it will go. Examine the
diaphragm disk under the stage. [
] Rotate the disk so that each hole comes into
position under the hole in the stage. Notice that the disk must click into place in each of
these positions. The function of the diaphragm disk is to regulate the amount
of light that passes through the specimen. For maximum light, use the large
hole, etc. Place the largest hole in place and straighten up the scope and turn it around
to its normal position. [
] Keep the tube in the straight up position. If you tilt the tube
back while using the microscope liquid materials will run off the slide.
8. Skip this step if your microscope has a sub-stage light.
Look through the eyepiece and move the mirror until the field is as brightly illuminated
as possible. [
] (The "field" is a term that refers to the total circular area that one
sees when looking into a microscope.) This step is a very important one. Do not skip it
during future work with the microscope. The function of the mirror is to direct the light
up through the stage and through the microscope's lenses.
VIEWING
THE
SPECIMEN:
Step 1: Place your slide on the stage with the material to be magnified over the small
glass piece embedded in the stage. For today's exercise, use the prepared slide
in your tray. You will probably find it in a box. [ 1
The slide is marked "Allium root tip". This is an onion root tip. Place the slide on a
piece of white paper for a minute. [
] (You may have a substitute slide if
"Allium" is unavailable.)
11. How many small root tips can you count under the Allium slide's cover slip with your
unaided eye?
Place the slide back on the microscope so that one of the root tips is exactly centered over
the glass piece in the stage. [
] Place the left stage clip ONLY on the label of the slide.
Leave the right clip off the slide so that you can move the slide with your right thumb.
Step 2: Focus with the coarse adjustment on 4X. 4X is used to give the viewer an overall
view of the specimen. You cannot see much detail on low power. Draw what you
see an label it "Root tip on 4 X" -- (Draw the root tip at least 1 inch by 2 inches.)
The small dots you see are the nuclei of small, box-like cells. You will see more detail later.
The task at the moment is not to learn about ceils, but to learn how to use the microscope.
Focus the specimen as clearly as you can, then change to 10X. In doing so, don't raise the
tube. [
1 Focus first with the coarse adjustment and then with the fine adjustment. While
Tools of the Biologist
28
1
looking into the eyepiece, move the slide with your thumb. This procedure is called
"scanning". It gives you an overall picture of the specimen. Draw about 3 of the box-like
ceils that you can see on 10X. Make each cell at least 1 inch square. Label them "Root tips
on 10X" I 1
Once your microscope is set-up and working properly, it should not be moved. To see what
happens when the microscope is moved, rotate the base of your microscope slowly while
looking through the eyepiece. [
1
12. If you have a microscope with a mirror, explain what you observed when the
microscope was rotated.
Return the microscope to its original position. [
} If, while looking through the eyepiece,
you find that the light is too bright, or not bright enough, adjust the light by rotating the
diaphragm disk. NEVER CHANGE THE MIRROR TO CHANGE THE AMOUNT OF
LIGHT. Rotate the diaphragm disk through all five positions while looking through the
eyepiece.
13. Explain what happens.
Step 3: Focus as sharply as you can on 10X. [
] This step you just performed is very
important to do before shifting to 40X. If your microscope is not perfectly and
clearly focused on 10X, when you shift to 40X, you may hit the slide with the 40X
objective. Check the focus again and then shift to 40X but Do NOT RAISE THE
TUBE. [
1 You will see that the 40X objective comes very close to the slide.
(About a paper thickness away.) On 40X, FOCUS WITH THE FINE
ADJUSTMENT ONLY. NEVER USE THE COARSE ADJUSTMENT on
40x. The objective lenses on this microscope are "parfocal". This means that
when you shift from 4x to 10x or from 10X to 40X, the specimen will remain in
focus. You will have to adjust the fine focus slightly. This is particularly true with
40x. If you have to move the fine focus adjustment more than 1/2 turn on 40X,
then you have probably lost your specimen. NEVER GO FROM 4X to 40X.
Always proceed from 4X to 10X to 40X, in that order. Draw 2 or 3 boxlike cells as seen on 40X. Make each cell 1 inch square and show every bit of
detail you can see. Label the drawing "Root cells on 40X" [ 1
Scan the slide while using the 40X objective. [
]
Now rotate the 3 objectives and look into the eyepiece each time to determine how the light
varies with each objective lens. Match the following:
14. With the 4X objective in place, the brightness is
15. With the 10X objective in place, the brightness is
16. With the 40X objective in place, the brightness is
Tools of the Biologist
29
a. Lowest
b. Medium
c. Highest
In summary, the steps in setting up and viewing a specimen are as follows:
1. Position the microscope and lamp and turn on the light.
2. Clean lenses
3. Adjust the mirror (if your microscope has one) and light.
4. Center the white mark between the 2 black marks on the arm.
VIEWING THE SPECIMEN
1. Place the slide on the stage and examine under 4X. Focus with both adjustments.
2. Shift to 10X. Use coarse and fine adjustments to focus again.
3. Fine-focus for PERFECT clarity then switch to 40X. USE ONLY FINE ADJUSTMENT ON
40X.
Note: NEVER RAISE TUBE WHILE SHIFTING FROM 10X TO 40X.
If step 3 is not done exactly as described, you may hit the slide with the 40X objective and
break it.
PART III:
HOW TO CARE FOR THE MICROSCOPE
1. Always carry the microscope with both hands. Place one hand under the base and hold
the arm with the other.
2. Never carry two microscope at once. Never carry one microscope and a lamp.
3. Always carry the microscope upright. Don't tilt it. Some of the eyepieces may fall out the
tube if the microscope is tilted too far.
4. Keep lenses clean. Only use lens tissue. Never use any other kind of paper. Use
wet lens tissue on the 40X objective and then dry it with dry lens tissue. Use lens tissue
only for microscope lenses.
5. Keep stage clean. Wipe off any spilled water when working with liquids.
6. Always turn off the light when finished. This is particularly IMPORTANT with sub-stage
light microscopes.
7. Keep microscopes from getting too close to the edge of the table.
8. Never remove, or try to remove any lenses or other parts from the microscope. Students
are responsible for damage to the microscope and repairs are very expensive.
Tools of the Biologist
30
REVIEW:
17. Where can students look in this manual to determine what they will need to know on the
microscope quiz that follows this lab activity?
The objective statement at the beginning of this lab activity indicates that you will need to
know the names and functions of all microscope parts. Review the names and functions of
all parts. In addition, list the steps in order for setting up a specimen to view on 40X. Try to
do this from memory and then check the steps with those presented earlier.
When reviewing for any future quiz, you will always be able to determine what will be asked
by focusing on the objective statement at the beginning of each topic.
,— Objective —
N
m
ft
i
i
ft
ft
ft
ft
Tools of the Biologist
31
2-5 Laboratory Investigation
How to Make a Wet Mount
Now that you know how to use the microscope to view
a prepared slide with non-living material, you will need to
know how to prepare a slide for viewing living
microorganisms. The term MICROORGANISMS can best
be defined by breaking the word up into MICRO, which
means small, and ORGANISM which means any living
creature. MICROORGANISM, therefore, is defined as
any small living creature that requires the aid of a
microscope to see it clearly.
Objective
Demonstrate how to correctly make a wet mount of
a pond culture and show it to your teacher.
You should also be able to apply what you have learned about using the compound
microscope to view microorganisms on 4X, 10X and 40X. You should be able to neatly
draw some of the microorganisms you see. On your table is a supply of pond water
teeming with many microorganisms. Make a wet mount of this material as follows:
MAKING A WET MOUNT
1. Place a clear slide on the table. [
]
Using a medicine dropper, pick up some of
the debris on the bottom of the pond water culture dish and place 2 drops of this on
the slide
2. Place a plastic cover slip over the drop as shown in the steps drawn below:
2 small drops
Use a pencil to gently
lower the cover sli
Let the cover slip fall
GENTLY over the drops
Do not tap or press on
the cover slip.
The cover slip will be gently floating
on the drops of water. [
]
Did any water run out from the edge of the cover slip or are there any large air spaces
under the cover slip as shown below?
i c \g
Ch 2 Tools of the Biologist
air--
11
wrong
If water runs out from under the cover slip, you have too much water on the slide. If you
have an air space under the cover slip, you have not used enough water. In either case
start over. [
] When you have prepared a PERFECT wet mount, with no water
leaking out and with no air spaces, show your lab assistant or teacher and have him or
her O.K. your slide.'
3. Place the slide on the microscope stage and examine it using usual procedures. Do
not tilt your microscope back. This may cause the liquid to run out from under the cover
slip.)
Examine this material under 4x and 10x and scan the slide to see aJl parts of the 2
drops under the cover slip.
Pick a few interesting green algae or other pond microorganisms and examine them on
40x. Take about 5 minutes to look through different parts of the slide.
There are both microscopic plants (algae) and microscopic animals in this culture. First
you will need to identify which are plants and which are animals. In general the plants
(algae) are green. Some move, some don't. The animals move, and are not green. To
help you distinguish the algae from the animals, your teacher may put up labeled
drawings of some algae and animals that you will see. This will help you decide which
is plant and which is animal.
Draw and label two or three different plants that you can observe.
Draw and label two or three different animals that you observe. Although not totally
correct, for our purpose for this lab, if it's green label it a plant. If it's not green, label it
an animal.
Most of the algae and animals (protozoa) in this culture are single-celled. You will
also find a few multicellular organisms. Multicellular plants or animals are composed
of more than one cell. Locate a few multicellular organisms and draw and label them as
multiceliular algae or animals. [
]
Clean and dry all slides and cover slips when you have finished the lab.[
]
Ch 2 Tools of the Biologist
33
2-6 The Electron Microscope
Question 1: Excellent quality light microscopes can
magnify 1000 times. What do you
guess the maximum magnifying power
of an electron microscope to be?
Objective
Explain how the electron microscope
functions and how it is different from a
light microscope like those used in
class.
Microscopes, like those that you use in high
school biology, are called l i g h t
microscopes because they depend upon
light to create magnified images. The
electron
microscope
depends
upon
beams of electrons instead of light to produce
images. Because of the high cost per unit,
the electron microscope is usually used in
university and research settings. They are
large units costing hundreds of thousands of dollars and can produce photographs of
images many times the magnification of the light microscope.
Question 2: What was the highest possible magnification obtainable with your
compound light?
Question 3: In a light microscope, what part bends the fight to create the larger image?
A good quality compound light microscope can magnify up to 1000 times. The electron
microscope can magnify hundreds of thousands of times. It employs magnets to bend
the beams of electrons.
Elecron beam
(negative charge)
Enlarged
image on
screen
electron gun
Positive charged
magnets
In the transmission electron microscope, the electrons from a source below the
specimen, pass through the specimen as light does in a light microscope. The parallel
beams of electrons then pass between electromagnets. These positively charged
magnets pull the negatively charged electron beams further apart. When the more
Ch 2 Tools of the Biologist
34
separated beams of electrons strike the viewing screen, they create a pattern of the
image that is larger than the specimen. Magnification can be increased by increasing
the voltage to the electromagnets. Since electrons are much smaller than wavelengths
of light, smaller details can be viewed using the transmission electron microscope. For
this reason, the transmission electron microscope is commonly used to magnify the
interior of cells and cell structures.
The scanning electron microscope uses electrons in a different way to magnify an
object. It is used to observe the surface of the objects. Electrons are directed at the
surface of the object at an angle, creating a spectacular three-dimensional shadowed
effect. Both types of electron microscopes create images in black and white only.
Images can be viewed on a video screen or as a photograph.
2-7 Other Tools
The Computer
Computers are commonly used to gather and process
data from experiments in most disciplines of science.
You may have an opportunity to see how this is accomplished later in the course. Special probes, when connected to computers by wires, can measure temperature, light, moisture and other data. These probes sense
changing conditions in the organisms or containers in
which they are placed. The information is transferred
to a computer that is controlled by a computer program that processes, tabulates and
prints the data. A computer can also be used to process great volumes of experimental
data or other data that is entered using the keyboard.
Miscellaneous Laboratory Equipment
You will use a great variety of
laboratory
equipment
while
conducting various experiments
during the course. Your teacher
will review how to operate the
equipment just before you need to
use a specific piece of equipment.
Question 1: Explain how the transmission electron microscope works.
Question 2; How can a computer be used to make it easier to conduct experiments in
the laboratory?
Ch 2 Tools of the Biologist
2-8 The Metric System
Question 1: What is the difference between the English system and the metric system
of measurement?
Objective
List the basic unit of metric measurement for weight, length, volume and
temperature.
State the boiling and freezing points of water and body
temperature. Apply principles of conversion within the metric system.
Scientific measurements are usually made using the metric system. A short review
of metric facts most commonly used in biology follows:
Basic unit
Equivalences
Weight:
gram (g)
1 kilogram (kg) = 1000 grams
1 milligram (mg) = 1/1000 of a gram
Length
meter (m)
1 kilometer (Km) = 1000 meters
1 millimeter (mm) = 1/1000 of a meter
1 centimeter (cm) = 1/100 of a meter
Volume
Liter (L) or (I)
1 Liter (L) = 1000 milliliters
1 milliliter (mL or ml) = 1 cubic centimeter (cc)
1 mNliliter of water weighs 1 gram
Temperature
Celsius degree (C)
100 degrees C = 212 degrees F (boiling)
0 degrees C = 32 degrees F (freezing)
22 degrees C = 72 degrees F (room temp.)
37 degrees C = 98.6 degrees F (body temp.)
Question 2: What is body temperature in degrees C ?
Question 3: What is room temperature in degrees C ?
Question 4: Water freezes at what temperature in degrees C ?
Question 5: Water boils at what temperature in degrees C ?
Question 6: What is the basic metric unit for measuring weight?
Question 7: What is the basic metric unit for measuring temperature?
Question 8: What is the basic metric unit for measuring length?
Ch 2
Tools of the Biologist
36
© Connecting Point
Question 9: What is the basic metric unit for measuring volume?
Question 10: 1 Kg equals how many grams?
Question 11:1 Km equals how many meters?
Question 12: How many mm in 1 m?
Question 13: How many ml in 1 L?
Question 14: Solve the following conversions:
Copy the following and replace the "?" with the appropriate number.
1 kilometer = ? meters
7 km = ? m
200 mg = ? g
1 cubic centimeter of water = ? gram(s)
4.5 m = ? mm
0.33 m = ? mm
0.5 l _ = ? mL
120 ml_ = ? L
23 g = ? mg
Ch 2 Tools of the Biologist
37
© Connecting Point
2-9 How to Read and Construct a Graph
INTRODUCTION
A graph is a very useful way to communicate certain kinds of information. Throughout
the balance of your life, you will see graphs in newspapers, magazines and other
sources. Some of you will use graphs in your future occupations. Throughout this
course you will be given graphs to read and asked to construct graphs from the results
you collect in lab experiments. A graph can simplify otherwise complicated information.
A graph is a picture of what the data (experimental results) shows. This program will
teach you the correct procedures required to make and read graphs. Throughout the
year you will be asked to read and construct graphs of experimental data.
Objective
You will be expected to demonstrate on a quiz that you can construct and read a
line graph.
1. There are three main types of graphs used to portray data. Each is shown below:
B
transport
-ation
my
YEAR
YEAR
food
% Spent / yr.
Shown are a pie graph, a bar-graph and a line-graph. Which is which?
1. "A" is the bar-graph, "B" is the line-graph and "C" is the pie graph or
chart. For most of our work this year we will use the line graph. For
this reason, this program will deal with the line graph exclusively.
Ch 2
Toots of the Biologist
38
© Connecting Point
2. The graph always has a VERTICAL AXIS and a HORIZONTAL AXIS. The
VERTICAL AXIS is the line that goes up and down the page. The
HORIZONTAL AXIS goes across the paper from left to right.
vertical
axis
Horizontal
axis
(go on to next frame)
3. If units of time make up a part of the data, these units are always placed on the
horizontal axis. Place the label "time" on the correct axis below
3.
"time"
PART ONE:
HOW TO READ A GRAPH
Examine the following graph:
Elk Population in Olympic National Park
Number
PI
A
of elk
per
square
mile
*
*
*
1 97O
1 92O
*
1 9SO
o No. of Elk
The graph shows that there were about 15 or 16 elk per square mile in 1925. To verify
this, find 1925 on the horizontal axis and read up to the line and then over to the left to
the vertical axis line and read the number. See the above illustration. Note that 1925 is
not actually printed on the time axis but it is the mid-point between 1920 and 1930.
Ch 2
ft
Tools of the Biologist
39
© Connecting Point
4. How many elk were there per square mile in 1960?
4. about 40 elk
5. How many in 1970?
5. about 50 elk
6. Consider this question ; In what year were there 60 elk?
6. 1950
If you got it correct, go to frame #8 If
you missed it, read frame #7.
7. To answer this question, find 60 on the vertical axis and read over to the graph line
at the right where it touches the line representing 60 elk. Then move straight down to
the horizontal axis and read the date found there.
eo
V
40
• t^-
1940
7. ( Go on to frame #8)
8. During the 60 years that the elk were observed and counted, the lowest number of
elk were found during which year?
8. About 1920.
Ch 2
Tools of the Biologist
40
© Connecting Point
*
9. During the period from 1930 to 1935, the elk population
a. increased in number
b. decreased in number
c. stayed the same in number
d. had their pictures taken
*
9. "c".
stayed the same in number
10. This condition, when there is no increase or decrease and the line remains level, is
called a period of EQUILIBRIUM. This doesn't mean that no elk were born during
the five years. It means that the number born were EQUAL to the number that died
that year. Find another span of years on the graph where an EQUILIBRIUM exists.
10. From 1970 to 1980
11. During this time the population of elk leveled off at how many elk/square mile?
11. 50 elk/square mile (48 - 52 is acceptable)
12. A forest fire occurred sometime between 1920 & 1980. What year did this probably
happen? Explain why you selected the answer you did.
12. About 1950, because a sharp decrease is
shown at 1950 where the elk population dropped
from 60 to less than 40 in 1960.
13. After the fire, no hunting was allowed in this area for a 10 years. What happened to
the elk population 10 years following the fire?
13. It increased from 1960 to 1970.
1 4. The area was later opened to hunters again. What year do you estimate that the
hunting resumed?
Ch 2 Tools of the Biologist
41
© Connecting Point
14. About 1970 (Because the number of elk leveled off after that.)
15. World War II occurred from 1941-45. Because of the shortage of man power, no
counts were made during that period. Examine the graph and you will see no dots
during that time. Each dot represents an actual count at the year indicated. At what
year, prior to the war, was the last count made?
When did the counting resume after the war?
15. 1940, 1950
16. Note that even though no counts were actually made during the 1940's, one can
tell approximately how many elk were in the area in those years. For example, how
many elk were in the area in 1945?
16. About 46
(44 - 48 is acceptable)
17. Examine the following graph:
THE RELATIONSHIP OF ATTENDANCE TO SCHOOL PERFORMANCE
(A) 4,0
Grade
Point
Average
(GPA)
5
10
15
Number of Absences Each Semester
In this case, each dot represents a student. Each student's absence record was
compiled with his or her grade point average (GPA) at the end of the 1st semester of the
sophomore year. Then a dot was placed on the graph for each student.
For example, student "A" had how many absences per semester and what GPA?
Ch 2 Tools of the Biologist
42
© Connecting Point
17. 10 absences/semester and a GPA of about 2.1
or a C average.
18. Each dot is defined by two factors. What are they?
18. Number of absences and GPA
19. Examine the graph in frame 17 again and write a statement that sums up what this
data means. In other words, what interpretation can be made about the
relationship between GPA and school attendance?
19. The fewer the absences the higher the GPA and/or
the more a student is absent, the lower his/her grades will be.
20. With this kind of data, many dots result because of the large number of students
involved, and a line cannot be drawn that runs through every dot as was done in the
previous graph. In situations like this, a single line is drawn that represents an
average of all dots. This line runs through the middle of the dots with about as many
dots above as below the line at any one point.
If a line were placed on the graph below in accordance with the above principle,
describe how the line would look.
BACTERIA
GROWTH
3
5
900
800
700
600
0
1
2
4
Days
7
8
20.
Ch 2 Tools of the Biologist
43
© Connecting Point
21. The time on all graphs presented so far, increases from
a. right to left
b. left to right
21. "b"
left to right
22. Note that the numbers on the vertical axis of all graphs presented so far increase
from
a. bottom to top
b. top to bottom
22. a. bottom to top
23. Graphs are sometimes drawn with no numbers on their axes. Such a graph is
shown below. Notice you can still determine what the graph illustrates.
Number
of
mice
Time
Circle the appropriate words in the sentence below:
In this graph, the number of mice first (increases, decreases, remain the same) then
they (increase, decrease, level off) for a period and finally (increase, decrease, level
off) as time goes on.
23. Increase. Level off. Decrease
24. Examine the vertical axis of all graphs presented so far. Do they always start at
zero?
Ch 2 Tools of the Biologist
44
© Connecting Point
Do all horizontal axes start at 0?
This is important to remember. It will come in handy when you construct your own
graphs.
ft
ft
ft
ft
ft
24. No, no
25. Often data for 2 or more situations are placed on the same graph.
ANIMAL
POPULATIONS IN MT.
NATIONAL PARK
No. of
Animals
i1
per
RAINIER
p^
^^
\ f •**• , i * %'
,''
i
,.'
5-
, ..' ' '
Cougar 1
Deer
*-*,
10 acres
in Mt. R a i n i e rr
Nat. P a r k
For example:
k •»•* j?y r
i"
F r o g s ••
•.."
1 920
1940
1 960
1 980
YEAR
Answer the following from the graph
a. How many deer were there in 1955?
b. How many cougar were there in 1945?
c. How many frogs in 1968?
25. a. 8 deer (+or-1)
b. 13 cougar
c. 5 frogs
One has to be very careful to read to the correct
lines.
26. What is your guess as to why the number of deer dropped in 1935?
26. One possibility is that cougars were eating the deer.
27. Graph lines that show this kind of relationship to each other usually mean that one
is eating the other. Note that the lines for deer and cougar cross again in 1962.,
From 1955 to 1965 the cougar increased/decreased (select best answer) and the
Ch 2
Tools of the Biologist
45
© Connecting Point
deer increased/decreased (select best answer). Since deer don't eat cougar, what
is an explanation for the decrease in cougar and increase in deer during this
period?
27. cougar decreased
deer increased
Something must have caused the death of cougars
(maybe hunters). If so, fewer cougars would cause the
deer to increase since there were fewer cougars
to feed on the deer.
28. When a graph is composed of 2 or more lines, it's important to not mix up the lines.
One can easily make this error when the lines cross. Try to avoid this
common mistake.
You now know all you need to about how to read a line graph. An important thing to
remember is to study the entire graph before drawing conclusions or answering
questions.
Now that you can read line graphs, you will find that it will be easy to learn how to make
one. The following section will present the specific methods we want you to use in this
course whenever you need to make a line graph.
PART TWO:
HOW TO MAKE A LINE GRAPH
29. Let's assume that you want to construct a graph that shows how fast sunflower
plants grow during the summer. A gardener collected the following information:
Days
10
20
3 0 , 40
70
80
P l a n t height
in inches
6
12
17
44
5 0 60
24
84
The first step in constructing a graph is to place thehorizontal and vertical axes lines on
the graph paper. Then you must label the lines with the appropriate days and heights.
RULE #1: When placing the vertical and horizontal axes on a piece of graph paper.
be sure to leave at least 11/2 inches of space below the horizontal axis and to the left of
the vertical axis. This is so there will be enough room beside the axes to clearly place
the appropriate numbers and labels. In this course, it is necessary to make each graph
as large as possible. Small graphs are usually less accurate than larger ones.
Rule #2: Always attempt to make your graph fill the entire piece of graph paper.
On the separate piece of graph paper provided, use rule #1 and #2 to place your vertical
and horizontal axes on the graph paper.
Ch 2
Tools of the Biologist
46
© Connecting Point
graph
paper
ft
ft
ft
ft
ft
ft
30. It is important that both the horizontal and vertical axes are clearly labeled. Rule #3 :
Both axes must be labeled to indicate what the numbers on each axis represent.
When time is involved, it goes on the horizontal axis. Label both axes on your graph for
the data in frame 29 of this program.
_____
Plant
height
in
inches
Days
31. The next task in constructing a graph is to place the numbers on each axis. Before
we do this, consider the next rule in graphing. It's very important. Rule #4 : All
numbers on an axis should be spaced so that each equal space is equal to the
same span of numbers for that axis.
Which of the examples below are incorrect according to rule #4?
300
64
A
62
1 00
Z50
60
200
S 8
1 00
90
80
0
•>
5
1 0 2 0 2 5 30
c
B
20
40
60
0 2
4
6
8 10
31. Choices A & B are incorrect. ( Look each graph
over again if you did not get both answers.)
32. In frame 31, what is wrong with graph A?
Ch 2
Tools of the Biologist
47
Connecting Point
32. Graph A has a spacing error on the horizontal axis.
At the beginning and end of the axis, 1 space =
5 units. In the middle of the axis 1 space =10 units.
33A In frame 31, what is wrong with graph B ?
33. Graph B has a spacing error on the vertical axis.
On most of the axes, 1 space = 100 units. At one
spot on the axis, 1 space = 50 units. Each space
should equal the SAME number of units (rule #4).
Also note: that numbers need not start at zero
at the intersecting corner of the two axes.
34. The next step in constructing a graph involves the placement of the
appropriately spaced numbers on the two axes. In order to do this with your graph
paper, first count the number of spaces from the corner of the two axes to the top of
the vertical axis and to the far right side of the horizontal axes.
How many spaces are on the horizontal axis?
How many spaces are on the vertical axis?
34. The answer will depend upon which type of graph paper
you have. (Horizontal axis has about 50-54 spaces and
the vertical axis has about 70-75 and your answer to these
questions will depend on whether your two axes are
accurately placed at 1 1/2" from the edges of the
paper. 50 and 70 are good round numbers to use
and will leave some margin on the upper and right
edges of your graph.)
35. Now look back at the data we have to graph in frame #29.
Measurements were taken each day of growth up to the
day of growth. This is
called the RANGE. Days are to be placed on the
axis. Assume that there are
about 50 spaces on your graph on the horizontal axis and you need to place up to
84 days on this axis. We need to now figure out how many days will equal one
space. One way to do this is to divide 50 spaces into 84 days. What answer did
you get? (Carry out answer to nearest 1 /10)
35. 84th day, horizontal axis, 1.68 (or 1.7 days/space)
Ch 2 Tools of the Biologist
48
© Connecting Point
36. The next step is to round off your answer (1,68) to the nearest whole number. 1.68
rounded off to the nearest whole number is
36. 2.0
37. Each single space on the horizontal axis will be represented by how many days?
37. 2 days
38. Before you make the graph, let's try some other practice examples: Assuming 50
spaces exist on the horizontal axis, and that the plants grew for a period of 250
days, how many days would equal one space?
38. 5 days (250/50 = 5)
39. If the plants grew for a period of 980 days, how many days would equal one space?
39. 20 days
(980/50 =19.6 or if rounded off, then 20)
40. If the plants grew for a period of 25 days, how many days would equal one space?
40.
0.5 or 1/2 days (25/50 = .5 days/space)
Notice the answer in #40 is 1/2 day = 1 space, which is the same as 1 day = how many
spaces? In this case the horizontal axis would look like the following:
o
i
3
4
days
5
7
8
41. 2 spaces
Ch 2 Toots of the Biologist
49
© Connecting Point
42. Now look back at the data in frame (question) #29 again. Plant height increased
from 6 to how many inches? This is the RANGE for height. The height wiil go on
which axis? Check answer #34. How many spaces are on the vertical axis?
42. 60 inches, vertical axis, 70-75 spaces (This example)
43. Using the same procedure for determining the spacing on the time (horizontal) axis,
figure out how many spaces will equal how many inches on the horizontal axis for
plant height. (Assume 70 spaces on the vertical axis)
43. 1 space = 1 inch of plant height (60-6 = 54 inches, 70
spaces / 54 inches = 1.296 spaces / inch, or 1 space/in.
44. RULE #5: To determine how many numbers will be represented by one space on
either axis, divide the number for range) by the number of spaces on that axis or
vice versa and round off your answer to the nearest whole number.
Before you are asked to place the numbers on your graph, consider which of the
following two graphs look better and why.
75-!
74
73H
68
0
10
5 10 15 20 25 30 35
20
Which would be easiest to read?
44. Graph B (see explanation in rule 6 below)
45. RULE #6: Do not crowd numbers on an axis. This makes them hard to read. It's
not desirable to have a number on every line. Numbering by 5's. 10's or 100's often
produces the a graph that is the easiest to read.
Now use your graph paper and place the appropriate numbers on the horizontal and
vertical axes for the data in frame #29. Be sure to follow rules 5 & 6.
Ch 2
Tools of the Biologist
50
© Connecting Point
45. Other options are available for numbering as long as they meet the rules.
46. The next step is to place dots at the appropriate points on the graph.
Example:
Examine the data in frame #29 again. For every day a measurement was taken, a dot
can be placed at the appropriate spot for the height of the plant on that day. The first
measurement was taken on the 10th day. How high was the plant on the 10th day? To
place a point on the graph, find the vertical line for the 10th day and determine where
the horizontal line representing a height of 6 inches crosses the 10 day line. Place a
dot at that point
ill —
10 -
Place this dot
on your graph
5 -
0 - TTT
Days
Now follow the same procedure for placing the next dot. On the 20th day the
plant was how many inches high? Place the 2nd dot in its appropriate place on your
graph.
Continue placing dots for the remaining days that measurements were taken
in accordance with the measurements given in frame 29.
Now that you have all the dots in their appropriate places, connect the dots by
starting with the first dot and running a single line through each dot. Use some type of
straight-edge to make the line neat. You do not necessarily need to start the horisontal
and vertical axes at 0 as in the above example. Since there was no data between 0
and 10 days and between 0 and 6 inches, you could start at 6 on the vertical axis and
10 on the horizontal axis.
Rule #7: Place each dot, which is defined by 2 numbers, in its appropriate place
on the graph.
Rule #8: Connect the dots with a line that runs through each dot. Do not connect
the line to the lower left corner of the graph if there is no data requiring it. All graphs
have titles. You will need one for the graph you just completed. Before creating your
Ch2
Tools of the Biologist
51
© Connecting Point
own title, look back at the graphs in this program (2-9) and read their titles,
the title that you created at the top of your graph.
Now print
Rule #9 : Write a title that briefly describes the information graphed.
Graphs can be used to predict possible future trends. For example, you can use
your graph to predict how high the sunflower will be on the 88th day. To do this, place
a straight-edge on the top portion of the graph-line. Now draw a dotted line from the
end of your graph-line upward to the top of the paper. This dotted line represents future
probable growth. This assumes that the growth rate will be the same as between the
80th and the 84th day. To find the "probable" plant height at 88 days, find 88 on the
horizontal axis and place a piece of paper or straight-edge on 88 and run your eye up
the 88 line to where the dotted graph-line crosses the 88 line. Now read directly over to
the plant height axis. What height do you find?
In this manner you can predict the future. The plant height that you got, if you did
it correctly, should be close to seventy inches.
Rule #10: Graphs can be used to predict future trends by extending the graph-line
and reading the graph in the usual way. Notice that you can also reverse this process.
You should be able to answer the following question: On what day in the future will
the sunflower plant probably get to be about 70 inches? If you did this correctly, you
should have predicted that this would occur on about the 88th day.
A very relevant application of rule 10 can be used with the following graph:
Bacterial
Growth
5000
4000
Bacteria/
3000
mL of blood
2000
1000
4
6
Hours
8
after
It)
1 2 1 4
16
infection
When bacteria get into the blood when the skin is cut, they begin multiplying. Samples
of blood were taken over an 11 hour period and the number of bacteria were
determined for each mL of blood.
47.
How many bacteria per mL were present 10 hours after the infection began?
48. How many bacteria per mL were present 13 hours after the infection began?
Ch 2
Tools of the Biologist
52
© Connecting Point
49. How many bacteria per mL were present 16 hours after the infection began?
The predictions made for questions 48 & 49 are based upon the assumption that the
bacteria will continue to grow at the same rate. Various factors could affect the rate of
growth. One is the effect of the immune system upon bacterial growth. Never-the-less,
when asked to project the growth trends on a graph, the estimated slope of the
line is to be based upon the assumption that the rate is to continue as
measured previously. The projected trend will occur only if the same conditions
prevail.
REVIEW
To review, go back through this program and find RULE #1, and then copy all 10 rules
neatly on your own paper. [
]
Keep this for a reference for later. You will be making many graphs throughout this
course. When you turn in your manual as you finish this unit, be sure to keep this list of
10 rules "How to Make a Graph " in your notebook for use in remaining units.
Hand in the graph you made in this program on the date due.
Your teacher will announce the date of the quiz over this topic. On the quiz, you will be
expected to read graphs as well as to be able to construct a graph from data provided.
Ch 2
Tools of the Biologist
53
© Connecting Point
2-10 Graphing Application
Objective —
•
Apply the correct principles of graphing using the data that follows to
construct an accurate graph.
in order to practice your graphing skills, use the following data to construct a graph on
graph paper. The following chart shows the increase in population in a small western
town in Wyoming called Longhorn:
YEAR
1840
1850
1860
NUMBER
OF
PEOPLE
670
774
875
1880
1890
1900
1910 1930
1950
1068 1175 1180 1182 1379 1581
Notice that census counts were not available after the civil war in 1870, after World War
I in 1920 and prior to World War II in 1940.
After you complete your graph, answer the following on the back of your graph:
1. Predict what the population would be in 1960. (Assume the same growth rate since
1930.)
2. Even though counts were not made in 1870, 1920, and 1940, how many people
would you say were in Longhorn on those dates?
3. How many people were in Longhorn in 1845?
Ch 2
Tools of the Biologist
54
© Connecting Point
ft
i
ft
CHAPTER
»
»
J
9
3
THE ULTIMATE TOOL:
THE SCIENTIFIC METHOD
^
p
p
The important thing is not to stop questioning.
Curiosity has its own reason for existing.
One cannot hefp But Be in awe when he
p
contemp fates the mysteries of eternity, of fife,
P
P
P
P
of the m aroe fous structure of re afi ty.
It is enough if one tries merefy to comprehend
a fittfe of this mystery everyday.
J\[ever fose a hofy curiosity.
P ^^
Albert Einstein
P«>
P
P
P
P
P
P
p
.
*
P
P
P
P
_
3-1
3-2
3-3
3-4
3-5
3-6
3-7
Laboratory Investigation:
Graphing Frog Respiration
The Importance of the Scientific Method
NutraSweet and the Scientific Process
The Scientific Process: Step-by-Step
The Role of Variables in Applying the
Scientific Method to Solve a Lab Problem
Science and Technology
Cooperative Learning Activity: Variables
Page 56
Page 60
Page 61
Page 67
Page 77
Page 82
Page 84
^y
9
9
9
9
Ch.3 TheScientificMethod
55
©ConnectingPoint
Chapter 3
The Scientific *Me,tfioct
of science, is nothing more, than a refinement of everyday thinking'
Albert Einstein
3-1
Laboratory Investigation
Graphing Frog Respiration
(And Reviewing the Steps in the Scientific Process)
- Objective
—__«--—__^»_^__
Conduct an experiment to determine what affect
temperature has on the breathing rate of a frog.
Interpret the experimental results. List and
describe each step in the scientific process.
PRELAB
Examine the frog sitting in water at your table. Be sure to keep the lid on the container
so the frog does not get out. [
] Notice that you can observe the breathing rate by
watching the skin on the frog's throat. Each student at the table needs to check the clock
and count the number of breaths per minute. Compare your results with each other. If
the frog is moving around too much, count the number of breaths for one-half minute
and multiply by 2 to get the number of breaths per minute, (or count for 15 seconds and
multiply by 4)
1. How many breaths per minute did you personally count?
2. How many breaths per minute did each other person at your table count?
Ch. 3 The Scientific Method
In a few minutes you will be using the Celsius thermometer to measure the temperature
of the water in which the frog is sitting. Before doing this, there are some important
things you need to know about the Celsius scale and about using the thermometer. Do
not try to shake the mercury down in the thermometer as you would with one used to
check your temperature. Laboratory thermometers do not require this to get the mercury
to drop. The mercury in laboratory thermometers will automatically rise and fall as the
temperature changes. For this reason, do not take the thermometer out of a solution to
read it. The thermometer will immediately respond to the temperature of the air and
change its reading and you would record an incorrect temperature.
For your reference only:
0° C
= freezing point of water
22°-23° C = room temperature
37° C
= body temperature
100° C
= boiling point of water
m
m
p
*
m
•
m
3. Measure and record the temperature of the water in which the frog is sitting.
Experiment 1:
Recording breathing rate at room temperature.
Use the four breathing rates determined earlier and calculate the
average breathing rate. (If you didn't obtain four breathing rates
earlier, repeat the count for one minute as many times as
necessary.) Record the average in a chart like the following:
Temperature
INVESTIGATION
1st
count
4th
Average
2nd
3rd
count count count
PROCEDURE
PROBLEM:
What affect does varying the water temperature have on a frog's breathing
rate?
m
m
m
Identifying a scientific problem or question is the first step in the scientific method. This
step states a scientific problem in the form of a question that can be answered by
laboratory experimentation.
Write the heading "PROBLEM" on your paper and after the heading copy the problem
above in bold print.
HYPOTHESIS:
In this step the scientist offers a possible answer to the question or problem just
stated. This should be an answer that seems most logical at the moment. If you are not
sure, guess. Copy the heading "HYPOTHESIS" and write your own hypothesis for the
problem stated.
9
i
Ch. 3 The Scientific Method
57
EXPERIMENTAL
DESIGN:
In this step, the scientist or science student plans an experiment that will test the
hypothesis to see if it might be an appropriate answer to the question (problem). The
plan is a written detailed description of how an experiment is to be conducted. It usually
consists of a step-by-step procedure. Diagrams are often included to show the
experimental set-up. A statement about what results are to be observed and recorded is
included. The experimental design usually has two parts; the CONTROL SET-UP
and THE EXPERIMENTAL SET-UP
Place the heading "EXPERIMENTAL DESIGN" in your report, and then describe
your own personal experimental plan. [
] Read the next two sections before
beginning the experiment.
CONDUCT THE
EXPERIMENT:
Conduct the experiment as planned, taking into consideration the following:
1. Use ice to lower the water temperature and warmer tap water to raise the
temperature. Wait at least 2 minutes after changing the temperature so the frog's
body has a chance to change temperature also. Be sure the frog is in a bowl onehalf filled with water. No more, no less.
2. Count the frog's breathing rate for one full minute each time you count.
3. Make 4 counts for each temperature and record and average the 4 counts for each
temperature. Do this independently. Do not rely upon another student's counts.
Redo any counts that greatly differ from the others.
4. It's best to start with the lowest temperature first (5°C). Use ice to lower the
temperature of the water. Each time you try a new temperature, raise the previous
temperature by 5° C. Don't try to obtain temperatures of below 5° C. It's usually
difficult to do this. To raise the temperature, exchange the water for warmer tap water
if needed. Raise the temperature in 5° C increments until you get to 35° C. Do not
try a temperature above 35° C.
5. It's important to sit relatively still and move slowly so as not to frighten the frog.
Frightening the frog causes it to move around which increases its breathing rate.
6. Share all data you obtain with other at your table.
Place all temperatures, counts and count averages in a neat data chart. See the next
section for further information.
DATA:
(Recorded Results)
Record all results in a neat data chart similar to the
following:
Temperature
Ch. 3 The Scientific Method
1st
count
2nd
count
4th
3rd
Average
count count
t
Use the above data to construct a neat line graph where temperature is plotted on the
horizontal (x) axis and breathing rate on the vertical (y) axis. Start the graph as soon as
you get the first average. You can work on the graph while waiting for the frog to change
temperature. Then add to the graph as you obtain additional data from the 2nd through
the 4th count. Graph the averages ONLY for each temperature.
ANALYSIS AND INTERPRETATION OF RESULTS:
In this step, the scientist explains what the data means. He, or she,"interprets"
what would otherwise be obscure numbers or other scientific data. In this step, be sure
you can distinguish between data and interpretation of data. Students often mix up
these two steps. Another way to look at it is to realize that the DATA tells WHAT
HAPPENED and the interpretation tells us WHY IT HAPPENED.
Write the heading "INTERPRETATION OF DATA" next in your report. [
] Next write
your interpretation statement about the data. Whenever a graph is part of the data, the
easiest way to interpret the data is to write a sentence or two describing what the graph
means.
4. How does the breathing rate of the control frog compare with that of the experimental
frog?
CONCLUSION ABOUT THE HYPOTHESIS:
In this step, the scientist or student refers to the original hypothesis and writes one of
the following statements about the hypothesis:
-Hypothesis seems true or is supported by the data,
-Hypothesis seems false or is contradicted by the data,
-Can't determine if the hypothesis seems true or not (not supported by the
data).
Read the original hypothesis and compare it with your data and data interpretation
and decide which of the above concluding statements best fits the data obtained in the
experiment. [_ ] Place the heading, "CONCLUSION" on your paper, and write the
appropriate concluding statement about the hypothesis after that heading.
5. What are some of the variables in this experiment that, if not controlled, could cause a
different set of results?
Leave the frog in the covered container with all equipment on the table. Dry the table if
any water was spilled.
Ch. 3 The Scientific Method
59
3-2 The Importance of the Scientific Method
A curious mind
A quest ion
Creative thought
An experiment
A conclusion
New knowledge
Objective "
State why it is important to learn how
to solve problems.
This describes part of the problem solving sequence. It all starts with curiosity. Curious
people are fascinated with the world around them. This creates a heightened
awareness. It is hoped that this course will stimulate you to be more curious than you
have been about the world we live in.
Question 1: Select one or two possible careers you might pursue after graduation and
suggest how possessing problem-solving skills might help you in this area
of work.
A sound education should prepare each student to be a problem solver. Throughout
life, individuals encounter problems in their roles first as students, later as employees,
citizens, members of a family and as community members. Problem-solving skills are
needed as individuals make personal decisions. If you were only to emphasize the
learning of facts and concepts, you would find that much of your learning would later
become outdated in this world of rapid and unpredictable change. New information is
being discovered daily and this can cause previous concepts to become outdated. It is
important, therefore, that your education stresses methods for solving problems. There
will always be problems. No matter how much the world changes in the future, you can
count on having numerous problems to solve. Many people solve their problems
hastily, without proper consideration given to all aspects. This often results in
frustration. The methods for solving problems need to be learned. They don't come
naturally. This course is designed to teach you skills in problem-solving as well as
some basic biological concepts.
Question 2: State one of the main objectives of this course and why the author believes
this objective is important to stress in a high school biology course.
Experts in business, industry and education all emphasize the importance of problemsolving. They stress how it is necessary for the employee of the future to be able to
solve routine problems. Your training in this course will make you a more valued
employee and citizen.
Ch. 3 The Scientific Method
60
mm
3-3 NutraSweet and the Scientific Process
An Interdisciplinary Math-Biology Activity
Objective
m
m
m
m
On a quiz, you will be expected to:
1. List the steps of the scientific process in order
2. Describe what a scientist does in each step
3. Apply understanding of the process by interpreting data provided and stating
whether an hypothesis is supported or contradicted by the data.
An article in the Seattle Post Intelligencer on January 20, 1988, reported that the
use of diet sweeteners can cause a person to GAIN weight! If this is so, a lot of us are in
trouble. How could this be? The NutraSweet label says 1 calorie. How could a diet
sweetener, with almost no calories, cause weight gain? Or is this just publicity seeking?
Scientists were quoted as saying "NutraSweet increases one's desire for other high
calorie foods that increase weight." But, are these claims accurate? Fortunately, this
question can be answered scientifically. This reading will introduce you to the scientific
method. Examples of how such a question might be answered will be given in this
reading activity. You will learn and master the details of the scientific process in this
course and will apply your understanding by solving many problems in the laboratory.
You will operate much like a true scientist. You will identify lab problems and will
conduct experiments and gather the results. You will then use the results to formulate
tentative answers to the problems.
Let's look at each step in the scientific process. When you have completed this
reading activity, you should know the names of the major steps in the scientific process.
You should understand the definition of each step and be able to give an example for
each of the steps. Remember however, that this is an introduction to the scientific
problem-solving method. Much more detail will be presented later. You will use this
method throughout this course.
m
•
i
STEP ONE: THE PROBLEM
Most scientific investigations begin with a question or PROBLEM that can be
Ch, 3 The Scientific Method
61
answered in the lab or field. Our example of a PROBLEM statement, written as a
QUESTION is:
A
PROBLEM:
CAN THE REGULAR USE
"NutraSweet" CAUSE WEIGHT GAIN?
OF
THE
DIET
SWEETENER
Did you notice that this question is written in such a way that it might suggest a
possible experiment or two?
STEP TWO:
THE HYPOTHESIS
When we have a question, we like to answer it. That's what a hypothesis is. A
HYPOTHESIS is a possible answer to the question or problem. Some might respond
by saying, "I have no idea what the answers might be." That's O.K. Scientists usually
don't know the answers to the questions either. !f they knew, they wouldn't need to do
experiments to find out. It's very appropriate to offer our "best guess" as an answer. A
good definition for HYPOTHESIS is, therefore, a "possible" answer to the question
based upon any information we might process. Most people would offer the following
hypothesis for our problem:
HYPOTHESIS:
THE REGULAR USE OF THE DIET SWEETENER
NUTRASWEET WILL NOT CAUSE WEIGHT GAIN.
Question 1: What is an alternate hypothesis to the one provided in this reading activity? Place all answers
on your own paper.
STEP THREE:
EXPERIMENTAL DESIGN
In this step, the scientist or student carefully thinks through how an experiment
might be conducted that could provide results telling us if the hypothesis is a reasonable
answer to the question. Often the student (and scientist) must think through many ideas
about how to do the experiment. EXPERIMENTAL DESIGN is defined as a written
plan describing how to set up an experiment to determine the answer to the question.
Most experiments require at least one CONTROL GROUP set-up and at least one
EXPERIMENTAL GROUP set-up. It has been decided that it will be best to use mice for
this experiment since it is easier to control such factors as exercise and diet with caged
mice than it would be if humans were used.
EXPERIMENTAL
CONTROL
DESIGN
GROUP:
Set up 50 mice in identical separate cages
Provide unlimited water containing 10% sugar
mouse.
EXPERIMENTAL GROUP:
Set up 50 mice in identical separate cages
Provide unlimited water containing 10% (or
Ch. 3 The Scientific Method
62
under identical conditions.
and unlimited food for each
under identical conditions.
sweetening power of 10%
sugar solution) NutraSweet and unlimited food for each mouse.
^
™
Weigh each mouse at the start and record the weight for all mice in each group. Be sure
all mice in both groups are healthy and between 2 and 3 months old. For food, use the
same dog food pellets for all mice. Dry dog food pellets are nutritionally balanced and
are an excellent food source for mice. Run the experiment for 4 weeks. At the end of the
experiment, weigh each mouse in each group and record the weight.
STEP FOUR; PERFORM THE EXPERIMENT
Follow all steps in the experimental design.
Set up and conduct the experiment
EXACTLY AS PLANNED.
STEP FIVE.
DATA COLLECTION AND RECORDING
DATA is the term scientists use for results from an experiment. All DATA must be
observed or measured carefully and accurately. It's usually best if the data can be
placed in clear DATA TABLES or charts. An example of data that might be obtained in
this experiment, arranged in a data table follows:
mouse
#
1
2
3
4
etc.
50
Control Group (sugar, water and food)
weight at
weight 4
start
weeks later
210g
203g
187g
232g
212g
202g
197g
230g
+109
•29
197g
193g
-4q
Average change in weight:
Ch. 3 The Scientific Method
change in
weight
63
-19
+2g
Mouse
Experimental Group
weight at
start
1
2
3
4
etc.
50
fNutraSweet.water and food)
weight 4
change in
weeks later
weight
206 g
194 g
188 g
224 g
212 g
Averaae chanae
220 g
202 g
189 g
220 g
-
+14g
+8g
+19
•4g
-
234 g
+229
in weiaht
+42 a
The 2 grams increase in the control group is not much of an increase. One paper clip
weighs about 1 gram. The average increase in the experimental group is a very
significant increase.
Notice how the DATA TABLE shows all weights and the change in weight for each
mouse during the 4 weeks. Also note that the AVERAGE CHANGE IN WEIGHT was
calculated for each group. This calculation could actually be part of the next step. If the
data is numerical and if it can be placed in a line or bar graph, the appropriate graph
would be included in this step. It would not help us to graph this data.
STEP SIX:
ANALYZING AND INTERPRETING THE DATA
In this step, the science student must review the data and review the question in step
one. After careful and thoughtful examination of the experimental 'results, a statement of
INTERPRETATION of the DATA is formulated and written. An example of
ANALYSIS AND INTERPRETATION OF DATA for our experiment is as follows:
ANALYSIS AND INTERPRETATION
OF DATA:
The most significant parts of the data are the average changes of weight for each group,
Control Group
(water, sugar and food)
+2 gram average increase
in weight
Experimental Group
(water, NutraSweet and food)
+42 gram average increase
in weight
Interdisciplinary Math-Biology Topic
For all practical purposes, a change of 2 g is NOT a significant change. The average
mouse weighed about 200 g. 2 g/200 g =1/100 = 1% change. The increase of 42 g. is
42/200 = 21.0/100 = a 21.0% increase. The difference between the changes in the
experimental group and the control group is 21% - 1% = 20% difference between the
two groups. This difference is very significant and would not be due to chance alone.
Since the experimental group drank NutraSweet instead of sugar with its water, the best
Ch. 3 The Scientific Method
64
f
INTERPRETATION is: THE REGULAR USE OF NUTRASWEET CAUSES WEIGHT GAIN.
A COMMENT ABOUT SIGNIFICANT DIFFERENCES.
Professional scientists and researchers use complicated statistical formulas to tell
them if numerical differences are significant or not. You will not be asked to use or
understand these statistical procedures. For our purposes, use the following guideline:
If the difference between two groups is 3% or less, consider the two groups not
statistically different. They are "statistically the SAME." If the difference between two
groups is 20% or greater, then the groups are "significantly DIFFERENT." If the results
are between 3% and 19% we can't tell if the difference is real or due to chance. In
actual practice, these will vary depending upon the data.
STEP SEVEN...
CONCLUDING STATEMENT ABOUT THE HYPOTHESIS
In this step the student compares the hypothesis with the interpretation statement and
if the hypothesis and the interpretation statement A G R E E , it is said that the
HYPOTHESIS IS SUPPORTED bv the data. If the Hypothesis and the interpretation
statement DISAGREE it is said that the HYPOTHESIS IS CONTRADICTED bv the
data. If, after examining the data, one can neither determine if the data supports or
contradicts the hypothesis, it is said that the HYPOTHESIS WAS NOT SUPPORTED.
Students need to be careful here since HYPOTHESIS NOT SUPPORTED is easily
confused with HYPOTHESIS CONTRADICTED.
Students will have many later
opportunities to understand the difference.
In our experimental example, let's compare the hypothesis with our interpretation:
HYPOTHESIS: The regular use of the diet sweetener NutraSweet will NOT cause
weight gain.
INTERPRETATION: The Regular use of NutraSweet causes weight gain.
Since the hypothesis and the interpretation disagree, we say the HYPOTHESIS
IS CONTRADICTED.
It is important to remember that since this experiment was done with mice, our
interpretation and conclusion apply only to mice. Similar experiments would need to be
done with humans. Scientists assume that since humans and mice are both mammals,
they both would respond similarly in such experiments. This has often been the case in
other studies.
Question 2: If the control group had shown +1 g. average increase in weight and the experimental group
had shown a +2 g. average increase in weight, would this different data SUPPORT or
CONTRADICT the original hypothesis, "The regular use of the diet sweetener NutraSweet will
not cause weight gain?
Question 3: If the control group had shown 1.5 g. average increase in weight and the experimental group
had shown a 13.0 g. average increase in weight, and the mice at the start of the experiment
weighed an average of 100 g., what would the concluding statement about the original
hypothesis be?
Ch. 3 The Scientific Method
65
COMMENTS ABOUT CURRENT RESEARCH ON NUTRASWEET:
The actual research on this subject is limited. As of this writing, the conclusions
drawn about the research that is available seems to be controversial. The following is
an excerpt from the January 1988 Seattle PI article on this subject:
The Bitter Truth About Artificial Sweeteners," by Dr. Dennis W. Remington and nutritionist
Barbara W. Higa (Vitality House, $9.95), claims that sugar substitutes increase appetite
and exaggerate the preference for sweets. Restricting calories, as opposed to restricting
fats and low-nutrition foods, stimulates a starvation response that makes it harder to shed
pounds, authors say. The book goes on to make some pretty contentious claims such as:
Artificial sweeteners stimulate appetite and promote weight gain.
Remington and Higa contend that routine use of artificially sweetened products interferes
with the body's system for metabolizing sugars and causes some people to develop a
resistance to insulin, the hormone necessary for the proper metabolism of blood sugar.
This, the central premise of the book, has sparked a "battle of the studies" between
authors and artificial-sweetener manufacturers...
...Tordoff and Friedman found that rats fed saccharine-and-water solution ate more than a
control group, while rats fed sugar water ate less-at least for an hour or so...
... Blundell achieved a similar result with human subjects, feeding an aspartame (genetic
name of NutraSweet) solution, sugar solution and plain water and asking participants to
rate their hunger levels afterwards.
Tordoff cautioned against reading too much into these results. "My feeling is that
you're not going to see changes in body weight, because there are other regulatory
mechanisms relating to food intake which take over. But I do think available data
suggests that artificial sweeteners are not a panacea..."
... Another study cited by Remington and Higa involved 78,000 women who were
questioned about their habits in the course of a 1981 -1982 study for the American Cancer
Society. Among many other questions, the women were asked to give their present
weight, their weight the previous year, and whether or not they had been using artificial
sweeteners. Going back through the data, the researchers found a correlation between
artificial sweetener use and weight gain.
Moser says this study is suspect because the results are based on the women's
memories, which might have been fautty. Also not counted was the Catch-22 that people
with chronic weight problems are the most likely to use artificial sweeteners, and are also
the most likely to show a weight gain over a year's time.
Moser points to a series of studies that shows no relationship between hunger and
artificial sweeteners. Chief among these is work by Dr. George Blackburn at the Harvard
Medical School. A study partly funded by NutraSweet
... Blackburn himself has said the small sample size-59 subjects, 13 men and 46 womenprohibits any definitive conclusion...
... "There's one final way in which the authors say that artificial sweeteners cause weight
gain. They say some people use the calories "saved" to splurge on fattening foods. But
Moser protests that the fault here is not the Diet Coke and the hamburger but the person
who chooses to eat them."
Question 4: What is your personal reaction to this information that diet sweeteners may not prevent
weight gain and may possibly produce a weight increase?
Question 5: List the steps of the scientific process in order and then define each step in the process.
Question 6: What are the two groups that make up the experimental design?
Ch. 3 The Scientific Method
66
3-4 The Scientific Process: Step-by-Step
Objective
On a quiz, you will be expected to:
1. List the steps of the scientific process in order
2. Describe in detail, what a scientist does in each step
3. Apply understanding of the process by interpreting data provided and stating
whether a hypothesis is supported or contradicted by the data.
^
*&
^
«0
•0
—
^
«0»
By the time you complete this reading assignment you should understand the basic
aspects of the scientific inquiry process. Later activities will stress many of the details.
AN EXAMPLE PROBLEM
You will learn the scientific inquiry process best by performing your own experiments.
There will be plenty of time for this throughout the year. Before you begin, you will need
to know a few principles and definitions. Most of you have probably heard people say
that vitamin C can prevent colds. In fact, a popular book has been written about the
subject by Dr. Linus Pauling, a two time Nobel Prize winner. It is not our purpose to
decide whether vitamin C does or does not actually prevent colds. We do, however,
want to see how such a problem might be solved by using the scientific process. Our
scientific pursuit starts with a QUESTION or PROBLEM.
PROBLEM (OR QUESTION):
CAN VITAMIN C PREVENT COLDS IN
HUMANS?
The problem selected is one that will not require much previous knowledge of biological
concepts. The next step is to formulate a possible answer to this question. Such a
possible answer is called a HYPOTHESIS. A hypothesis is also sometimes referred to
as "an educated guess". This is a valuable way to describe a hypothesis because it
stresses the important point that this "possible answer" should be an educated answer.
It is not to be a wild guess. When formulating hypotheses, consider all that you know
from past experience, from reading and from any other sources. Our problem has two or
maybe three different "possible answers". Each one can be considered a separate
hypothesis. Possible answers are: I) Vitamin C can prevent colds. 2) Vitamin C cannot
prevent colds 3) Vitamin C may at certain times prevent colds, and at other times not
prevent them. When formulating hypotheses, it is best to consider all the possible
hypotheses that might seem reasonable. It is often a good idea to make a list of the
various hypotheses under consideration.
Note the different spelling used for the word "hypothesis" reflect whether it is singular or plural. Hypothesis is
singular. Hypotheses is plural.
Question 1: What is the next step in solving this problem?
If you answered this question by saying that experimentation is needed, then you are
Ch. 3 The Scientific Method
67
correct. You, in fact, may have explained how to do this. If you did explain an
experiment that would tell you the answer to this problem, compare the following
procedure with your answer to see how well you understand the scientific process. An
experiment "tests" a hypothesis. We must first select ONE of the three hypotheses to
"test". The general rule used to select the first hypothesis for testing is to pick the one
that has, in your mind, the greatest chance of being the correct answer. For sake of.
discussion, the author picks the following hypothesis for testing.
HYPOTHESIS:
(To be tested)
VITAMIN C CANNOT PREVENT COLDS IN HUMANS.
Notice that a hypothesis is stated in such a
way that the statement sounds as if it is factual.
We know that it is not factual, but it is stated in
these definite terms.
A hypothesis by
definition, is not a factual statement. A
hypothesis is a possible answer to a
question. It's a "belief" and remains to be
tested for its reliability. In order to develop an
experiment that will test this hypothesis, the
hypothesis is often rewritten in what is called
the "if-then" form.
SAME HYPOTHESIS:
IN IF-THEN FORM
IF Vitamin C has no effect in preventing colds,
THEN when Vitamin C is given to large
numbers of people, just as many will catch
colds as those not given vitamin C.
Since you will be asked to write many hypotheses in if-then form throughout this course,
it is important to understand how each component of the hypothesis is determined.
Let's analyze the above if-then hypothesis. One component of the hypothesis follows
the IF and two components follow the THEN. Diagrammed as follows, the blank
spaces show the separate components:
IF
THEN
Notice that the statement that follows the IF is our possible answer to the problem. It is
our guess, our belief or our hypothesis as stated at the top of this page. Our
hypothesis is that "Vitamin C has no effect in preventing colds." The two components
that follow the THEN part of the hypothesis are as follows: an experiment (when Vitamin
C is given to large numbers of people), and the result expected from this experiment,
assuming the IF part of the hypothesis is true (they will still catch cold). The following
summarizes the if-then format:
Ch. 3 The Scientific Method
t
IF hypothesis. THEN experiment, predicted results of experiment.
The if-then hypothesis states a possible answer to the "question", an experiment that will
test this possible answer or belief, and the predicted results of that experiment if the IF
portion of the hypothesis is true. The if-then format is actually saying "IF such and such
is true, THEN when we do a certain experiment, such and such will follow as results".
After stating a hypothesis in the appropriate if-then form, one is ready to begin
considering some of the details of the experiment. These "details" of the experiment are
referred to as the EXPERIMENTAL DESIGN. Before a discussion of the experimental
design, it's important for you to know that the above example of the if-then hypothesis is
an over-simplification. For example, can you see that it would be important to the
experiment, to use two groups of people? One group would be given vitamin C and the
other group would not be given vitamin C. The if-then hypothesis at the top of the next
page takes this and one other factor into account. Examine it carefully.
IF-THEN
HYPOTHESIS
(REVISED):
IF vitamin C has no effect in preventing colds, THEN when vitamin C is regularly given
to one of two groups of people, identical in all other respects, the group that receives the
vitamin C will have about the same number of colds as the group that does not take
vitamin C.
Question 2: Why is it necessary for the two groups of people to be the same in all
other respects as stated in the above hypothesis?
Question 3: Why is it important to give the vitamin C to relatively large numbers of
people rather than just one or a few people?
Since there are two ways to write a hypothesis, the if-then form and the straight single
statement form, it is important that you know which form to use when you are asked to
write a hypothesis throughout this course, if you are asked to simply to write a
hypothesis, put it in the "simple single statement form". Use the "if-then form"
only when asked to put your hypothesis in the "if-then" form.
Question 4: For review, what component of the if-then form follows the IF and what
two components follow the THEN part of the hypothesis?
Question 5: Consider the following PROBLEM: Do lettuce seeds require light in
order to germinate? (The term germinate refers to the sprouting of a seed into seedling
or young plant.) Write at least two different simple hypotheses for this problem.
Question 6: Write the two hypotheses developed in question 5 in if-then form.
Now you should be ready to consider some of the aspects of planning and setting up
the appropriate experiment.
Ch. 3 The Scientific Method
69
EXPERIMENTAL
DESIGN:
In this step the scientist creates a written plan for conducting an experiment
that will test the hypothesis. With our vitamin C problem and hypothesis, we know
that we will need two groups of people. We will give vitamin C to one group and not to
the other. This much of the experiment is provided in the if-then hypothesis. The if-then
t form tells us only the main parts of the experiment.
Some of the details of the
Experiment are still to be worked out. For example, how much vitamin C should be
^n to each person? For how long a period of time should the vitamin be taken? How
^e going to try to set up the experiment so the group not taking the vitamin C does
\ehow get above average amounts of vitamin C in their daily meals? The
nt must be planned to take these questions and others into account. If we give
min C, we may obtain different results than we would have if we had given
\3f the vitamin to each person. We would then come to the wrong
"'ding the effect of vitamin C on cold prevention. If the subjects in your
'° vitamin for less than a year, the results may not be valid because
^ly one to two colds each year. How many people should be used
Answer to this question is, the more people you have in each
qu
^ur results. A certain minimum number is essential. This
test
^
it experiments, but in general, this minimum number of
out 50, and 75 to 100 is better.
hypot
"the "if-t
worked out and stated clearly in the written
9riment's report. Some experiments require more
SAME
IF Vitamin
THEN
numbers of
colds as thos<
Since you will, bl
it is important t<
Let's analyze the|
the IF and two a
spaces show the se"|
two groups in our vitamin C experiment.
'oerimental treatment" (in this case, the
'P. The group that will not receive the
The CONTROL group will serve as
'ost every experiment that you will
"hese two groups make-up what
hat you developed for
'heses, consist of two
IF
Notice that the stateme
^
our guess, our belief
hypothesis is that "Vitamf
that follow the THEN part
C is given to large number
assuming the IF part of the
summarizes the if-then formal
Ch. 3 The Scientific Method
/ntrol group and
of the experiment.
EXPERIMENTAL
RESULTS (Also called DATA, or OBSERVATIONS):
The experimental results are the observable things that happen in the
experiment. This includes the results obtained for each person, plant or other thing, in
each of the groups of the experimental design. It is usually best to try to tabulate data in
chart form. Such a chart for our vitamin C experiment might include the name of the
persons in each group along one side of the chart and the amount of vitamin given, the
times vitamin was taken, the number of colds per year, the duration of each cold, along
the other side of the chart. Charts allow for quick and easy viewing of the collected data.
(The term data refers to all of the observed and recorded results in an experiments.) In
this section of the report no conclusions or interpretations of the data are to be included.
If the data can be expressed in a graph, this graph should be included in this part of the
report. Graphs and charts should be neat and clearly labeled. Graphs will show any
trends that might exist in the data. After all the result have been tabulated, the next step
is to interpret this data.
INTERPRETATION OF
RESULTS:
In this part of the report, the experimenter explains what the data means. He or
she looks back over all of the recorded results charts and graphs and explains what the
graphs and charts show. Sometimes these interpretations are very obvious, and at
other times, the interpretations are not quite so obvious. The interpretation is the
answer to the problem based upon the experimental results. Any additional
discussion of the results or of the experiment belongs in this section of the experiment's
report. The next step in our procedure is the conclusion.
CONCLUSION:
In this course, the conclusion will always be a statement about the validity of the original
hypothesis. There are only three possible conclusions regarding the hypothesis. These
are I) HYPOTHESIS SUPPORTED, 2} HYPOTHESIS NOT SUPPORTED and 3)
HYPOTHESIS CONTRADICTED. One of these three conclusions is selected according
to the following criteria:
HYPOTHESIS SUPPORTED: The data supports the original hypothesis. The data
is in agreement with the hypothesis statement. The hypothesis "seems to be"
true. It is important to note that one does not say that the hypothesis is "true", or that the
hypothesis is "proved". One experiment never proves a hypothesis. The results of ONE
experiment might SUPPORT a hypothesis, but never proves that it is true. Many
experiments of various types are required before one can be reasonably certain about a
particular hypothesis. Many scientists feel that experiments, no matter how many, never
completely prove any statement. Additional experiments just pile up additional
evidence for that particular statement. It is for this reason that it is best to select one of
the above concluding statements and forget using the word "proved".
HYPOTHESIS
CONTRADICTED:
Ch. 3 Thg Scientific Method
In this case, the interpretation of the data
71
does NOT agree with what the hypothesis statement is saying.
HYPOTHESIS NOT SUPPORTED: It is sometimes difficult for some students to ^
distinguish between this conclusion and the hypothesis contradicted conclusion. Some
examples will help. To say that a hypothesis is NOT SUPPORTED is to say that the
hypothesis is neither supported nor contradicted. This conclusion is often used
when something has gone wrong in the experiment. This conclusion is used when, by
examining the data, one cannot determine if the hypothesis "seems true" or
"not true". When this conclusion is selected, it usually means that the experiment
should be repeated, possibly with a change in the experimental design.
In review:
HYPOTHESIS SUPPORTED: The data says the hypothesis "seems true". The data
is in agreement with the hypothesis. The data supports the hypothesis. The hypothesis
is also supported when the results in the THEN part of the if-then hypothesis occurs as
predicted.
HYPOTHESIS CONTRADICTED:
and in fact is contradicted.
The data says that the hypothesis "seems false"
HYPOTHESIS NOT SUPPORTED: We cannot tell, by the data, if the hypothesis
"seems true" or "seems to be not true." We just don't know. The experiment should be
repeated.
Let's look at some actual examples. Consider the following four possible and different
results that could be obtained in our Vitamin C experiment:
Situation A:
Situation B:
Control group
72 colds per year
per 100 people
Control group
74 colds per year
per 100 people
Experimental group
71 colds per year
per 100 people
Experimental group
23 colds per year
per 100 people
Ch. 3 The Scientific Method
72
A
Situation C:
Situation D:
Control group
70 colds per year
per 100 people
Control group
50 colds per year
per 100 people
Experimental group
95 colds per year
per 100 people
Experimental group
42 colds per year
per 100 people
(It was found
that the
control group
got extra
exercise and
some extra
vit. C in their
meals.)
Question 9: Select one of the three possible conclusions for each of the 4 different
situations above for the hypothesis "VITAMIN C CANNOT PREVENT COLDS IN
HUMANS."
In some of the reading activities of this type, you will notice that the answers are
sometimes given to you after you have had a chance to respond to the question
yourself. This will be done immediately when it is of extreme importance to be aware of
the correct answer right away. This will usually be done in those reading activities
which are followed by a quiz, as is this one. Checking your answers with the stated
answers gives you a chance to see if you are understanding the material. Check your
answers to question 9 with those that follow:
In situation A, the hypothesis is supported because as many people got colds that took
vitamin C as did not take the vitamin and this means the vitamin had no effect in
preventing colds as the hypothesis said.
In situation B the hypothesis is contradicted because this data shows that the group that
had taken the vitamin had fewer colds. In other words, the vitamin prevented colds. The
hypothesis says that the vitamin will not prevent colds. The data says the opposite, and
this contradicts the hypothesis.
In situation C the hypothesis is supported because the group that took the vitamin did
not have fewer colds (colds were not prevented), and this is what the hypothesis says.
The hypothesis says that the vitamin will not prevent colds. The hypothesis is supported
even though it appears that the vitamin, in this case, seems to increase the number of
colds. This point should be described in the interpretation of data.
In situation D, the hypothesis is not supported. This is mainly due to the fact that
something went wrong in the experiment. This means that we can't tell if the hypothesis
is supported or contradicted and we therefore conclude that the hypothesis is NOT
SUPPORTED. Our experimental design required that the control group gets no extra
amount of vitamin C. One group was not to get more exercise than the other since this
might affect the general health of those in that group. Because the experimental design
was not followed, the results are not valid and the hypothesis is not supported. Even if
the experimental design was followed it should be noted that the difference between 42
and 50 is not very great. This again means that we "can't tell" if the hypothesis is really
Ch. 3 The Scientific Method
73
supported or contradicted so in this case we conclude that the hypothesis is NOT
SUPPORTED. Study any answers that you got wrong in question 9. If you got all of
them correct, then continue. If you got any wrong, change your answers and then
continue. Consider the following hypothesis:
HYPOTHESIS:
GERMINATE.
LETTUCE
SEEDS
REQUIRE
LIGHT
IN
ORDER
TO
Question 10: Write a conclusion for each of the 5 different situations shown in the
chart on the next page that shows various possible results that might be obtained in an
experiment to test the above hypothesis.
EXPERIMENTAL
RESULTS:
Group One
% of seeds germinating
while seeds were in the
light.
Group Two
% of seeds germinating
while seeds were in
the dark.
Situation A
87%
86%
Situation B
86%
4%
Situation C
0%
0%
Situation D
4%
81%
Situation E
88%
74%
Be sure you have selected a
conclusion for each situation in the
chart before you go on. [
] When
you have done this and written your
answers on paper, check your
answers with the following: Situation
A - contradicted, because the data
shows that seeds do NOT require
light.
The hypothesis says the
opposite and is therefore a
contradiction.
In situation B the
hypothesis is supported because the
data says exactly what the hypothesis
says. In situation C, the hypothesis is
not supported because something
j
went wrong with the experiment. No
seeds grew at all and we therefore can't tell if the hypothesis is supported or
contradicted. In situation E, the hypothesis is also not supported. The difference
Ch. 3 The Scientific Method
74
between the % that germinated in the light and the % that germinated in the dark is not
that great. In this case we can't really tell if light is required. When we can't tell if light is
required or not, our conclusion should be NOT SUPPORTED. In situation D the
hypothesis is contradicted because the seeds germinated without light.
Question 11: Which group, in the above experiment, is the control group, and which
is the experimental group?
If you have answered these questions correctly, you have indicated that the seeds in the
light make up the experimental group. The experimental group is the one that gets the
treatment for the factor mentioned in the hypothesis (light). The seeds in the dark, are
the control group. The control group is the group that does not receive the treatment
(light). The control group will serve as a comparison.
Before we leave the vitamin C problem, it is important that you understand that the
author is not suggesting, in any way, that you take vitamin C to prevent colds. A great
number of medical doctors and other authorities in this field say that it is not necessary
to take any extra vitamin C and that most people get enough vitamin C in their normal
diets. Some doctors have made the statement that extra large doses of this vitamin may
in fact, be harmful. Whether large amounts of vitamin C are harmful is not yet known. It
has been shown to cause problems in some people. For this reason, many doctors
advise against large doses of this vitamin. More research is needed on the subject. In
fact, experiments like those referred to in this reading, on a large scale, would provide
valuable data. In the meantime, this remains a controversial subject with some noted
authorities, like Dr. Linus Pauling, saying that large doses of vitamin C prevent and even
cure colds, while other equally noted authorities, say there is no good scientific
evidence to support this hypothesis. This controversy will one day be solved by the very
inquiry process that you are learning. Would you be interested in organizing the
experiments?
Question 12: List each of the steps in the scientific inquiry process in order. Also
provide a one or two sentence description of each step. (In most cases, the main
description for each step is in bold print throughout this activity.)
What is a THEORY and How is it Different from a Hypothesis?
A theory is very different from a hypothesis. Unfortunately, the word "theory" is often
used when the writer or speaker should have used the word "hypothesis." This error is
frequently made in newspapers and in conversation. A hypothesis is a possible answer
to a question. Some hypotheses have not yet been tested by experimentation. These
hypotheses have no data at all to indicate that they are correct or incorrect. Other
hypotheses may have been tested by only two or three experiments. Such a hypothesis
might be considered "supported" by limited data from a few experiments but the
statement is not yet accepted as a probable description of reality.
A theory, on the other hand, is accepted as a highly probable description of reality.
Data from many hundreds of experiments are used as evidence to support a theory. An
Ch. 3 The Scientific Method
75
example of such a theory is The Atomic Theory. The Atomic Theory describes the
detailed structure of the atom and how the atom is expected to interact with other atoms.
Hundreds of experiments in physics and chemistry support the current Atomic Theory. A
theory is a much more certain statement than a hypothesis. A theory is not a fact.
When evidence that contradicts an established theory is obtained, the theory must be
revised.
Least Certain
Untested
Hypothesis
*- Most Certain
^ Tested
Hypothesis
^ Theory
^ Fact
Question 13: What qualifies a statement as a theory and not a hypothesis?
Review
You should now be ready for a quiz over this topic. To find out what will be on the quiz,
refer back to the objective statement at the beginning of 3-4. The objective states what
you should review for the quiz. When you begin your review, get into the habit of
referring back to the objective statement about the quiz at the beginning of each topic.
Ch. 3 The Scientific Method
76
3-5 The Role of Variables in Applying the Scientific
Method to Solve Laboratory Problems
Objective
You will be expected to:
1. List the steps in the scientific process
2. Understand how to design an experiment containing an experimental and control group
3. Be able to define and identify different kinds of variables in an experiment
1. Can an experiment, properly designed according to the steps in the scientific method,
"prove" a hypothesis to be true? Explain your answer.
Review the steps in the scientific method below and pay particular attention to the role
variables play in an experiment.
PROBLEM
The PROBLEM is a question to be answered in the lab. Example;
Does the color of light affect plant growth?
OBTAIN ADDITIONAL INFORMATION
Complex problems often require additional information before the investigator can
formulate an intelligent hypothesis or design an appropriate experiment. If needed, this
information can be obtained by reading general background sources or by reading related
research conducted on the topic. Example for the above problem:
Determine what colors of light are in sunlight. Determine if colored cellophane can be
used to create the different colors present in sunlight.
HYPOTHESIS
An hypothesis is a possible answer to the question that began the investigation. Example
(simple hypothesis): Plants grow best in green light. An hypothesis can also be stated
in "if-then" form, which briefly describes an experiment and the predicted results that must
occur if the hypotheses is to be supported.
DESIGN AN EXPERIMENT
To test your hypothesis in the lab, remember to have an experimental and a control
group. When appropriate, make a rough sketch of how the two groups will be set up. An
appropriate example will be provided after the following paragraph on VARIABLES.
VARIABLES
Variables are conditions that are likely to change (or vary) in an experiment. Some
variables should differ between the experimental and the control group and some should
remain the same. Examples of variables for the above hypothesis are: water, fertilizer,
soil type, color of light, temperature and plant height. Some variables can be manipulated
Ch. 3 The Scientific Method
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(changed), others should be held constant. While still others may change as they
respond to changes in another variable that is manipulated.
2. For the hypothesis, Plants grow best in green light, which variable (water, fertilizer,
soil type, color of light, temperature or plant height) should be manipulated (changed)
in the experiment?
This variable is called the manipulated variable or the experimental variable and will be
the variable that is to differ between the experimental and the control groups.
3. Which variable (water, fertilizer, soil type, color of light, temperature or plant height)
might respond (or change) as a result of changing the "manipulated variable?"
This variable is called the responding variable. The responding variable will be
observed or measured and will make up the data in our experiment.
4. Which variables (water, fertilizer, soil type, color of light, temperature or plant height)
need to be kept constant (not allowed to change) in an experiment designed to test
the above hypothesis?
These variables are called controlled variables. They are factors that, if allowed to differ
between the control and experimental groups, could affect the results of the experiment in
an undesirable way.
5. Describe how you would set up an experiment to test the above hypothesis. Be sure
to have an experimental group and a control group. Identify the following variables
in your experimental design: manipulated variable, responding variable and
controlled variables.
We can think of LIVING SYSTEMS using the terms, inputs, outputs, transfers and
transformations. This will allow us to investigate cause and effect relationships and
determine what factors might be influencing a system. Examine the following model of
such a system for plants below;
PLANT SYSTEM
Manipulated Varia1
Processes of
plant
photosynthesis
INPUT
Controlled Variables
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t
i
p
p
r
In the plant system model, manipulating the color of light is the INPUT into the PLANT
SYSTEM that causes changes in the responding variable. The observable response
plant growth, is the OUTPUT from the system. If all of the controlled variables such as
temperature, soil, fertilizer and water amounts are kept constant, then the manipulated
variable (a selected color of light) caused the changes seen in the responding variable
(increased plant height). We can then conclude that the selected color of light somehow
transforms something in the plant system into new plant material by transferring the
light through the system.
This same SYSTEM MODEL can be modified to investigate the effects of some of the
other variables upon the system. For example, if we wanted to know what affect
manipulating the temperature would have upon the system, we would change the
manipulated variable to temperature and keep the light and other controlled variables the
same. We would still measure the same responding variable (plant height).
An essential rule in setting up an investigation is to allow ONE and ONLY ONE variable
to differ between the experimental and the control groups. When this is done, and all
other variables are held constant, then the response (increases in plant height) must be
due to the changes in the manipulated variable. Thus, any changes in height must be
due to the changes in temperature (the manipulated variable). This kind of experiment is
called a controlled experiment. Examine the following diagram:
EXPERIMENTAL DESIGN
CONTROL GROUP
EXPERIMENTAL GROUP
15°C
25° C
30° C
20° C (room temnerature)
40° C
Manipulated variable (temperature)
Controlled variables: Plants in both groups will be grown in natural sunlight, receive the
same amounts of water and fertilizer and be planted in the same type of soil. Many plants
must be grown and monitored for each temperature.
DATA
The height of all plants (responding variable) should be measured regularly and
organized into a neat data chart. Calculate the average height increase for all plants
grown at each temperature. Graph the average increase in height for each temperature.
Ch. 3 The Scientific Method
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INTERPRETATION
Write a statement that explains what the graphed data means. State what affect the
temperature had upon the height of the plants.
CONCLUSION
After reading the hypothesis and comparing it to your interpretation, your conclusion
should state whether the hypothesis is supported or contradicted by the data.
Assume you obtained the following data from the experiment on plants described above:
40 cm Average
Increase
In plant
height
30cm20 cm 10cm0 cm Oc
10C
20C
30°
40°
50C
Temperature in decrees C.
6. If you began with the hypothesis, Plants increase in height as the temperature
increases, provide an interpretation and conclusion for the data in the graph above.
A Comment on Terminology
It is important to note that some texts and other scientific sources you may read will use
different terminology for some of the variables we have been studying. For example, the
manipulated variable or experimental variable is also known as the independent variable
because it is independent of any of the other variables. The responding variable is also
known as the dependent variable, because it is effected or dependent upon the
manipulated (or independent) variable. Biology: As Scientific Inquiry will rarely use the
expressions dependent and independent variables.
7. Reread the objective at the beginning of this topic and write a paragraph that
illustrates that you understand the 3 objectives listed.
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I
Review:
PROBLEM
HYPOTHESIS
EXPERIMENTAL DESIGN
EXPERIMENTAL GROUP
CONTROL GROUP
Only ONE variable, the manipulated variable, (or experimental variable)
can differ between the two groups.
Be sure all controlled variables are identified and kept constant.
DATA
Observe and record the results (responding variable) obtained for both groups.
When appropriate, create charts and graphs for numerical data.
INTERPRETATION
Explain what the data means in plain English.
CONCLUSION
State whether the results support or contradict the hypothesis.
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3-6 Science and Technology
1. In your opinion, how are science and technology different?
— Objective
You will be expected to describe the difference between science and
technology.
How Is science different from technology?
Science
As you learned from the last two topics,
science is an inquiry process where the
objective is to find out what was previously
unknown about the world in which we live.
Through use of the scientific process, new
discoveries are made.
The problem
under study is identified. A hypothesis is
formed and experiment is designed to test
the hypothesis.
The experiment is
conducted
and
data
gathered.
Interpretations are made about the data
and conclusions are formed. The scientific
process is also used to verify previously
discovered
information.
Scientific
research falls under the category of
science.
Sometimes research is called
"pure science."
I
2. State a problem, in question form, that a research scientist might try to solve in the
lab.
Continued on the next page
Chapter 3 The Scientific Method
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Technology
In technology, scientific principles are applied to
solve technical problems or develop a new product
or improve an old product. An engineer uses the
principles of physics to design and build a new
airplane or missile. The creation of a new computer
involves the application of scientific principles to
design and build this new technological tool.
Sometimes engineers are called "applied scientists."
Engineers do not usually perform experiments to
discover new information as would a research
scientist. When an engineer performs experiments,
he or she is operating as a scientist and not an
engineer.
3.
Describe an area of technology or a technological application problem that an
engineer might work on in the lab.
4. Do you think the Boeing Company employs more scientists or engineers? Explain.
5. In the laboratory, a woman designs and builds a new microscope that makes use of
sound waves to create an image. Is this science or technology? Give a reason for
your answer.
6. In the laboratory, a doctor does an experiment that shows for the first time that the
chemical el-dopa, can reduce a patient's seizures. Is this science or technology?
Give a reason for your answer.
7. Using a wind tunnel, a Boeing engineer does an experiment confirming that
Einstein's General Theory of Relativity is correct. Is this science or technology?
Give your reason for your answer.
8. Is a family doctor practicing science or technology when she is examining and
treating patients? Explain your choice.
9. How do the drawings on this and the previous page illustrate the difference between
science and technology?
Chapter 3 The Scientific Method
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3-7
Cooperative Learning Activity: Variables
In your assigned cooperative teams, (probably your lab table teams) perform the following
activity as a group, but prepare individual answers to questions 5-6 at end of the activity.
Materials needed per team:
3 5X7 inch cards (substitute 3X5 cards if 5X7 cards are not available)
2 Felt-tip markers (other writing instruments are acceptable)
4-5 3"X3" post-its (notebook paper cut into 3"X3" squares can be substituted)
1. Along the top or each 5X7 card, in capital letters, write the name of a different
VARIABLE category (MANIPULATED VARIABLE, RESPONDING VARIABLE or
CONTROLLED VARIABLES). See the diagram in 3 below:
2,, Write the name of a single "specific variable" (frog's breathing rate, temperature, amount
of food eaten or amount of light) on each of four post-its.
3. Arrange the three VARIABLE cards at one edge of your table, so all can read them.
MANIPULATED VARIABLE
RESPONDING VARIABLE
CONTROLLED VARIABLES
4. Consider the following three hypotheses and place the "specific variable(s)" post-its on the
appropriate 5X7 VARIABLE card for each different hypothesis below. Answer question 5
as you do this.
Hypothesis I: Increasing temperatures increase a frog's breathing. (See lab 3-1 if
needed)
RESP3NDING VARIABLE
MAN PULATED VARIABLE
:ONTROLLED VARIABLES
appropriate
appropriate
appropriate
Etc.
Hypothesis II: : Increasing amounts of light decrease a frog's breathing rate.
Hypothesis III: An increase in food has no effect upon the frog's breathing rate.
5. Make a list showing which "specific variables" you placed in each "VARIABLE category" for
each hypothesis.
6. Which "specific variable" remained in the same VARIABLE category for all 3 hypotheses?
This procedure (using cards and post-its) can be used to help you design experiments to test
many other hypotheses in the units to follow. Keep the 5X7 VARIABLE category cards for
use later. Discard the post-its. The "specific variables" will be different for differing
hypotheses.
Ch. 3 The Scientific Method
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