Botany 101 Lab Manual
Tacoma Community
College
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Biology Laboratory: Safety, Procedures, Emergencies
1. No open food or drink is permitted in the lab at any time, whether a lab is in progress or not. No
eating, drinking, chewing of gum or tobacco is permitted. Never taste anything at all while in the
lab rooms.
2. Know the locations of the eye wash and shower stations, fire alarm, fire extinguisher, first aid kit,
and emergency exits.
3. Safety instructions are given at the beginning of each lab period. Always arrive on time so that you
know what you are supposed to do and are informed of any specific safety concerns or safety
equipment associated with the day’s lab activity.
4. Wear any required personal protective equipment (lab coat, apron, goggles, etc).
5. Stash book bags safely so that they won’t trip people.
6. Report all illnesses, injuries, breakages, or spills to your laboratory instructor immediately.
7. Clean broken glass (glass that is not contaminated with any chemical reagents, blood, or bacteria)
can be swept up using the dust pan and placed in the broken glass container. If the glass is
contaminated in any way, keep the area clear to prevent tripping or laceration hazards, and consult
your instructor for proper disposal guidance. A broken glass flow-chart is available in the lab to
help you decide what to do.
8. Notify your instructor if any of the equipment is faulty.
9. Clean up your entire work area before leaving. Put away all equipment and supplies in their original
places. Disinfect your work surface if the lab activity involved any infectious materials.
10. Use the appropriate waste containers provided for any infectious or hazardous materials used in lab.
11. Safety information about hazardous chemicals used in the lab activities can be found in the Material
Safety Data Sheets (MSDS), located in the Right-to-Know Binder in the safety station. We (faculty
and students) should be fully aware of the properties of the chemicals we are using. Please use the
MSDSs. If you cannot find the MSDS for the reagent you are using in lab, inform your instructor.
They are also relatively easy to find online. A keyword example is “Sodium Chloride MSDS.”
12. Use caution with the lab chairs. Because they are on casters, the can roll away when you are
standing at your workstation. Make sure your chair is where you expect it to be before sitting down.
Do not use your chair as a means of moving from one part of the lab to the other.
13. Wash your hands before leaving the lab room.
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Laboratory 1: Pea Lab - Principles of the Scientific Method
Adapted by permission from Steve Brumbaugh from the Green River Biology Lab Manual
Perspectives
Biology is a dynamic field of study whose aim is to unravel the mysteries of life itself. Throughout
history, humans have been curious about the world around them. Through the millennia people have
observed the natural world and have asked, “why?” Those that have advanced our biological knowledge
the most, whether the great scientists of the centuries before us, such as Robert Hooke (discovered cells in
1665) and Charles Darwin (co-developer of the theory of evolution by natural selection in 1859), or
modern molecular biologists such as James Watson and Francis Crick (discovered the structure of DNA in
1953), have certain traits in common. They have inquiring minds, great powers of observation, and they
use a systematic approach to answer the questions that intrigue them, the scientific method, which is
similar to you.
In this course you will have ample opportunity to develop your scientific skills. The weekly
laboratory exercises are designed not only to stimulate your curiosity and heighten your powers of
observation, but also to introduce you to and allow you to practice the scientific method. This laboratory
activity will allow you to practice the scientific method as you study the factors that influence your pulse
and level of physical fitness or the Fibonacci Series and the Fibonacci Ratio (sometimes called the Golden
Ratio). Let’s first learn a bit about the scientific method in more detail.
Scientific Method
The scientific method is neither complicated nor intimidating, nor is it unique to science. It is a
powerful tool of logic that can be employed any time a problem or question about the world around us
arises. In fact, we all use the principles of the scientific method daily to solve problems that pop up, but
we do it so quickly and automatically that we are not conscious of the methodology. In brief, the
scientific method consists of
 Observing natural phenomena
 Asking a question based on one’s observations
 Constructing a hypothesis to answer the question
 Testing the hypothesis with experiments or pertinent observations
 Drawing conclusions about the hypothesis based on the data resulting from the experiments or
pertinent observation
 Publishing results (hopefully in a scientific journal!)
Observations
The scientific method begins with careful observation. An investigator may make observations from
nature or from the written work of other investigators, which are published in books or research articles in
scientific journals, available in the storehouses of human knowledge, libraries.
Let’s use the following example as we progress through the steps of the scientific method. Suppose
that over the last couple of years you have been observing the beautiful fall colors of the leaves on the
vine maples that grow in your yard, on campus, and in the forests in the Cascade Mountains. You note
that their leaves turn from green to yellow to orange to red as the weather turns progressively colder and
the days get shorter and shorter. However, the leaves do not always go through their color changes on
exactly the same days each year.
Questions
It is essential that the question asked is a scientific question. I.e. The question must be testable,
definable, measurable and controllable. For example, one would have a tough time trying to test the
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following question; “Did a supernatural force such as God create all life on earth?” Moreover, since the
concept of God has many different meanings and definitions, it is difficult to define what is a God. Since
this question is not a scientific question, and hence not testable, the courts of the United States have ruled
that “creation science” should not be taught in science classes as has been demanded by various groups in
this country. However, that’s not to say that God did not create life, it’s just not testable, but rather, a
matter of faith.
Now, back to the vine maple example...Being a curious and inquisitive person you ask, “What’s
causing or stimulating the vine maple’s leaves to change color?”
Hypotheses
The next step in the scientific method is to make a hypothesis, a tentative answer to the question that
you have asked. A hypothesis is an educated guess that is based on your observations. It’s a trial solution
to your question that you will test through experimentation. Hypotheses are often stated as “If... then...”
statements.
Now back to the vine maples. You have noted that vine maples change color in the fall on
approximately the same dates each year, but this varies by a week or two each year. You hypothesize,
since air temperature is not constant each year in the fall, the progressively cooler days in fall are
responsible for stimulating the color changes. Therefore, you develop and wish to test the following
hypothesis: If progressively cooler temperatures are responsible for stimulating the color changes in the
leaves of vine maples, then vine maples placed in a artificially cooled growth-house should go through the
same color changes as would the vine maples in nature, even if the length of day/night are held constant
via artificial lighting.
Testing Hypotheses via Experiments or by Pertinent Observations
The next step of the scientific method is to design an experiment or make pertinent observations to test
the hypothesis. In any experiment there are three kinds of variables.
 Independent variable: The independent variable is the single condition (variable) that is
manipulated to see what impact it has on a dependent variable (measured factor). The independent
variable is the factor that causes the dependent variable to change. E.g. the temperatures the trees are
exposed to is the independent variable in the vine maple example. The independent variable is the
factor (i.e. experimental condition) you manipulate and test in an experiment. A great challenge
when designing an experiment is to be certain that only one independent variable is responsible for
the outcome of an experiment. As we shall see, there are often many factors (known as controlled
variables) that influence the outcome of an investigation. We attempt, but not always successfully,
to keep all of the controlled variables constant and change only one factor, the independent variable
or controlled treatment, when conducting an experiment.
 Dependent Variable: The thing measured, counted, or observed in an experiment. E.g. the color of
leaves is the dependent variable in the vine maple example.
 Controlled Variables: These are the variables that are kept constant during an experiment. It is
assumed that the selected independent variable is the only factor affecting the dependent variable.
This can only be true if all other variables are controlled (i.e. held constant). In the vine maple
example: species of vine maple, age and health of the trees used, length of day, environmental
conditions such as humidity, watering regime, fertilizer, etc. It is quite common for different
researchers, or for that matter, the same researcher, to get different and conflicting results while
conducting what they think is the very same experiment. Why? They were unable to keep all
conditions identical, that is, they were unable to control all controlled variables.
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In an experiment of classical design, the individuals under study are divided into two groups: an
experimental group that is exposed to the independent variable (e.g. the group of trees that are exposed to
the varying temperatures), and a control group that is not. The control group would be exposed to the
identical conditions as the experimental group, but the control group would not be exposed to the
independent variable (e.g. The control group of vine maples would be kept at a constant temperature,
everything else would remain identical.)
Sometimes the best test of a hypothesis is not an actual experiment, but pertinent observations. One of
the most important principles of biology, Darwin’s theory of natural selection, was developed and
supported by his extensive observations of the natural world. Since Darwin’s publication of his theory, a
multitude of experiments and repeated observation of the natural world continue to support Darwin’s
theory.
An important hypothesis may become a theory after it stands up consistently to repeat testing by other
researchers. A scientific theory is a hypothesis that has yet to be falsified and has stood the test of time.
Hypotheses and theories can only be supported, but cannot be proved true by experimentation and careful
observation. It is impossible to prove a hypothesis or theory to be true since it takes an infinite number of
experiments to do this, but it only takes one experiment to disprove a hypothesis or a theory. Scientific
knowledge is dynamic, forever changing and evolving as more and more is learned.
Conclusion
Making conclusions is the next step in the scientific method. You use the results and/or pertinent
observations to test your hypothesis. However, you can never completely accept or reject a hypothesis.
All that one can do is state the probability that one is correct or incorrect. Scientists use the branch of
mathematics called statistics to quantify this probability. Later in the quarter you will use a statistical test
called the Chi-square test to determine the probability that your hypothesis in a fly breeding experiment is
correct.
Publication in a Scientific Journal
Finally, if the fruits of your scientific labor were thought to be of interest and of value to your peers in
the scientific community, then your work would be submitted as an article for publication in a scientific
journal. The goal of the scientific community is to be both cooperative as well as competitive. Research
articles both share knowledge and provide enough information so that the results of experiments or
pertinent observations described by those articles may be repeated and tested by others. It is just as
important to expose the mistakes of others, as it is to praise their knowledge.
Exercise: Applying the Scientific Method
This lab is an opportunity to enhance your understanding and appreciation of the scientific method
process in a semi-structured situation similar to that used by researchers in their work.
Teams of students should carry out the activities in this lab. The division of labor is the responsibility
of the team. The success of the group depends on the careful and conscientious effort of each person.
This dependence on others is also characteristic of research and many other aspects of life (as you may
already know).
The work required for this lab spans two to four weeks depending on a number of factors. Your
instructor will explain the methods of storage for your experimental set-ups, and how to arrange for the
use of the rooms and greenhouse to do your work.
Pre-lab Assignment
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Before coming to lab carefully read the previous pages on the scientific method (Lab 1) and the pages
of the exercise then answer the pre-lab questions. Be prepared to hand in your responses to the pre-lab
questions at the start of lab.
Goals of this Lab Exercise
 To understand the mechanisms used in the scientific method
 Design an experiment and carry out the steps of a scientific experiment
 To work cooperatively in establishing a protocol for a scientific experiment
Introduction
In its simplest form, an experiment involves a check or control group compared with an experimental
or test group. The control is held under constant conditions while the test group is exposed to the affects
of various factors, one at a time. Any changes that occur in the test group, but not in the control group,
are assumed to be the result of the condition that is changed. Each treatment, including the control,
should be replicated, and the replicate organisms should be carefully distributed so that no individuals
being treated will be favored more than others. In the activity that follows, you will investigate a small
portion of a problem in biology that lends itself very neatly to the experimental method. It is concerned
with coordination of growth and development in plants by chemical regulators called hormones. A
disease of rice plants results in overly rapid growth of seedlings. The seedlings become tall and weak and
finally fall over. Scientists found that a fungus caused the disease. Japanese scientists were able to
produce symptoms of the disease with cell-free extracts of the fungus. From the extracts they isolated a
substance, named gibberellin, which was shown to be the active agent causing the disease. Later research
revealed that gibberellins are produced naturally by plants and are involved with regulating stem growth
and other processes.
In this project you will study the affect of gibberellic acid on pea plants whose genetic constitution
(genotype) for the trait of height is dwarf. The expression of a genotype is termed a phenotype. The
purpose of this lab is to determine whether the dwarf phenotype can be modified by the application of
gibberellic acid to these plants.
Materials (per group of four students)
20 Little Marvel pea seeds and 2 flower pots
Growth medium (vermiculite in greenhouse)
Atomizer containing gibberellic acid solution
Atomizer of de-ionized water
Procedure
Each team should decide on its organization, discuss the problem/hypothesis, and plan the experiment.
Gather the materials needed and begin the activity. Prepare your seeds planting by following the
following method.
1. Seed Preparation - Place 20 pea seeds in a beaker and cover them with tap water so that the water
level is about 2 cm above the level of the pea seeds. Label the beaker with team identification and
date. Place it in a dark cupboard in the biology lab and let the pea seeds soak overnight (i.e. 12-24
hours). The soaked seeds should now be planted as directed below.
2. After the seeds have soaked overnight take them to the greenhouse. Prepare two 15-cm flowerpots
by adding a growth medium (vermiculite) to each. The containers should be about 3/4 full.
Moisten the medium. In each pot, place the soaked seeds and fill to the brim the pots with more
vermiculate and moisten. Label each pot with team identification and date and keep them in the
greenhouse. Keep the medium moist, but not soggy wet.
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3. When the seedlings are 2-3 cm high measure their height in millimeters. This is done by
measuring the distance from the growth medium surface to the tip of the shoot apex. Measure
each seedling and record your data. These lengths are the initial measurements. Hormonal
treatment of the plants follows immediately! Do the hormonal treatment outside of the
greenhouse!
4. Using a hand atomizer (found in the refrigerator at the back of the lab room) containing gibberelic
acid spray the plants of one pot as this will be your experimental group. Spray the other potted
plants with the deionized water atomizer. This is the control group. Since some of the spray for
the experimental treatment may drift, do all spraying outside of the greenhouse. Spray the plants
until the leaves and shoot apex are wet enough to form droplets which will almost run off, but do
not permit appreciable amounts to drop onto the growing medium. The spray treatment is done
ONLY one time. Label each pot as “control” or “experimental.” Be sure that both of the pots are
exposed to similar light conditions. Keep the growth medium of both pots uniformly moist, but do
not spray water over the plants themselves. Keep both pots in the greenhouse.
Measurement Option 1:
1. Optimally it would be best to start this part of the experiment on a Monday, and then continue
making measurements for the rest of the week, Tuesday - Friday, and then make the last
measurements on the following Monday.
2. Measure the pea plant growth in each pot for five days (not counting weekends) from the time you
first spray with the gibberelic acid and de-ionized water. When you measure record the heights of
the plants in each pot, take note of the general health (leaf/stem color and stem diameter) and
appearance of the plants, and record the data on Table 1. In addition, on the last day, measure an
inter-node length (Figure 1,) on each plant and count the number of leaves produced on each plant
in both the experimental and control groups. As the plants grow tall, it may be necessary to place
stakes in the pots and tie the plants loosely to them.
3. At the conclusion of the activity, CLEAN UP all materials and equipment. Empty the used
vermiculite into the appropriate container in greenhouse.
4. Answer the questions on the Report Sheet and hand in at the next laboratory period.
Figure 1 Plant Anatomy This drawing is to be used to guide the measurement of the inter-node length.
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Control
Date:
Initial height (mm)
Health of plants
Date:
Height (mm)
Health of plants
Date:
Height (mm)
Health of plants
Date:
Height (mm)
Health of plants
Date:
Height (mm)
Health of plants
Date:
Height (mm)
Health of plants
Date:
Height (mm)
Health of plants
Date:
Height (mm)
Health of plants
Experimental
Inter-node Length
(mm)
# of leaves
Table 1 Pea Lab Data Table
plants.
Use this table to record you raw measurement data and a description of the health of the
Miscellaneous, Observations, Information, and Notes
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Page to be used for Biological Doodling
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Report Sheet
Pea Lab Exercise
Name
Group Names
.
.
.
.
.
Answer the following question based on your pea lab observations: The major question asked in this
lab is “Can the phenotype of a genetically dwarf pea plant be altered by the addition of a plant hormone
called gibberellic acid?”
1. Write a hypothesis using the “If .... Then” format for this experiment.
2. On your fifth day of observations calculate and list the average internode lengths of the
experimental and control plants. Include units of measure.
Control average inter-node lengths = _________________
Experimental average inter-node lengths = ____________
3. On your fifth day of observation calculate the average number of leaves in the experimental and
control groups and list them below.
Control average number of leaves = ________________
Experimental average number of leaves = ____________
4. Prepare a graph of the average daily heights for both the experimental and control groups.
Properly title and label your graph (Appendix A). Place average height on the vertical axis and
time on the horizontal axis. Graph both sets of data on the same graph by using different colors
and a key. Attach this graph to your lab.
5. What correlation(s) did you observe between number of leaves, internode length, and plant height?
6. List at least two observations of similarities and/or differences in the general growth of the
experimental and control plants other than the observations recorded in questions 2-4 above.
7. List at least three possible sources of error that may have influenced the data you collected.
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8. Suggest one additional experiment that would provide more valid data or show other pertinent
results. Be specific!!!
9. Did you confirm your hypothesis?
YES
/
NO
(Circle One)
10. Can the phenotype of a genotypically dwarf pea plant be changed? Explain and support your
answer by using specific numerical examples from the data collected.
11. According to this investigation which component of an organism’s life is more influential on its
phenotype; its genetic make-up or the surrounding environmental influences? Explain using your
data and/or observations to support your response.
12. If you were given the opportunity to apply gibberellic acid to your vegetable garden would you do
so? Use your data and/or observations to support your response.
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Pre-Lab Report Sheet
Pea Lab Exercise
Name_________________________________
Note:
Answer the following six questions before coming to lab, but after having read
the previous pages of this handout!
1. What is gibberellic acid?
2. Define the following:
phenotype-
genotype-
3. Write a hypothesis using the "If .... Then" format for this experiment.
4. What is the independent variable of the pea experiment?
5. What is the dependent variable of the pea experiment?
6. Name at least three variables that you will be controlling in the pea experiment?
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Lab 2: Identifying Organic Compounds in Plants
Name________________________
Names of Group members___________________________________________
Introduction: This lab will introduce some simple qualitative methods for identifying basic types of
organic compounds. Read through the lab, and the chapter on organic molecules in your book, and then
answer the prelab questions at the end of the lab
I. Carbohydrates
Ia. Simple Sugars
The basic formula for simple sugars is (CH2O)n: where “n” is three or some greater number. For some of
the most common sugars n = 6 and, hence, their formula is C6H12O6. Sugars with this formula include
both glucose and fructose. Both of these sugars react with Benedict’s solution as do all simple” sugars.
Procedure (work in pairs):
1. Take 5 ml of dilute honey and add 1 ml of Benedict’s solution in a test tube. Heat this tube in beaker of
boiling water. What do you observe?
_____________________________________________________________________________________
_____________________________________
This is a positive test for simple sugars such as glucose and fructose.
2. Repeat this test using a solution of sucrose (table sugar). Do you get a positive reaction?
________________________________________________________
3. Again add 5 ml of distilled water to a test tube. Place a piece of apple into the tube and crush it with a
stirring rod. Pour the water into a clean test tube and test with Benedict’s. Does apple have simple sugars?
_______________________________________________________
Discussion: The sugars in honey and apple are both monosaccharides. Given that honey is simply nectar
gathered from flowers, what is the function of the sugars in nectar and fruit (how do they help the plant to
survive to reproduce)?
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________
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Table sugar is processed from stems of the grass, sugar cane. Chemically it is the disaccharide, sucrose.
Each molecule of sucrose consists of one glucose and one fructose bound together. With this chemical
bond, electrons are not available to reduce the copper ion in Benedict’s solution, hence, the negative
reaction. Sucrose is the sugar transported by the phloem of plants. Speculate about why it may be adaptive
for plants to produce monosaccharides in fruits and flowers, but transport sugars in their tissues in the
form of a disaccharide.
_____________________________________________________________________________________
_____________________________________________________________________________________
___
Ib. Starches are long chains of the simple sugar glucose. Starch is easily identified using a solution of
iodine and potassium iodide (I2KI).
1. Fill a test tube one third full of distilled water, and add 2 drops of starch suspension. Swirl the tube and
add one drop of I2KI. This result is diagnostic for the presence of starch.
2. Cut a thin slice of potato and make a wet mount using distilled water. Observe the tissues at 400x and
make a drawing. Remove the slide. Put a drop of I2KI on one edge of the cover slip and blot water from
the other edge using tissue paper. Put the slide back under the microscope and observe any changes. Draw
the stained tissue.
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Unstained
Stained
3. Working with your partner take a precut corn grain and treat the cut surface with I2KI. Specifically
what tissue of the grain tests positive for starch?__________________________
- Save this corn section for reference in “Part III”.
II. Lipids
Lipids are not one chemical class of molecules like carbohydrates. However, all lipids are nonpolar: they
do not mix in water and they will dissolve certain nonpolar substances that will not dissolve in water.
Triglycerides, phospholipids, waxes, and steroids are all examples of lipids. In this exercise we will
consider only the triglycerides, which are commonly known as fats and oils.
Procedure: Take a piece of peanut seed, cut a thin slice and make a wet mount of the tissue. Observe the
tissue under both low and high power. Now add I2KI
as described previously and observe the distribution of starch in the tissue. Add Sudan IV stain to your
wet mount using the same procedure previously described for adding I2KI to a wet mount. This stain is
nonpolar and will move into the lipid droplets residing in the tissue.
Discussion:
Can you think of why it may be more adaptive for a plant to store food in the form of oils in a seed than in
a tuber?
_____________________________________________________________________________________
_______________________
Why don’t animals lay down long-term energy stores in the form of starch?
_____________________________________________________________________________________
_______________________
Do animals ever lay down energy stores in the form of starch?
_____________________________________________________________________________________
_______________________
III. Proteins
From your text you know that proteins are polymers of amino acids. The general formula of an amino acid
is given below:
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There are twenty different amino acids found in living systems. Each of these has adifferent “R” group. A
huge number of proteins can be formed using different combinations of these twenty. One test for proteins
uses concentrated nitric acid. The acid reacts with the “R’ groups of certain amino acids.
III. Identifying Protein in a Corn Grain (work in pairs).
Procedure: Observe the corn kernel you tested earlier with I2KI. Note where starch is located. Take
another dry corn kernel that has been cut longitudinally, and place it in a petri dish. Add two drops of
concentrated nitric acid to the cut surface of the half-kernel: be careful not to breathe the fumes!!! Wait
three minutes and check for a yellowish coloration indicative of proteins. Compounds other than proteins
will turn yellow after this treatment. To specifically test for the presence of proteins, add two drops of
concentrated ammonium hydroxide to the yellowish tissue. Proteins should turn orange after this check
step.
WARNING: Both nitric acid and ammonium hydroxide are extremely caustic. Protect your eyes!
Use safety glasses while working with the reagents, and avoid rubbing your eyes after using them
until after you rinse your hands. Avoid breathing the fumes of either.
Questions and Speculation for Discussion:
In what tissue is starch concentrated?
_____________________________________________________________________________________
______________________
In which tissue is protein concentrated?
_____________________________________________________________________________________
_______________________
Why are starch and protein located in different regions of a corn kernel?
_____________________________________________________________________________________
_______________________
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Prelab Questions for Lab 2: Identifying Organic Compounds in Plants
Name_____________________________________
These questions must be answered from the lab introduction materials and turned in at the beginning of
lab.
1. What are the four main groups of biological macromolecules?
2. What is the monomer (building block) for each of these groups?
3. What monomers make up the polysaccharide starch?
4. I2KI is used to test the presence of which molecule?
5. Benedict’s test is used to test the presence of which molecule?
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Laboratory 3: Microscopy, Cell Structure and Function
Prelab Report Sheet
Name _____________________________
Directions: Read ALL parts of the lab first, in order to write the best, most correct answer to each
of the following questions
1. What is the function of the iris diaphragm?
2. What is the magnification of the low power objective? The medium power? The high power?
3. Describe cell theory
4. What is the difference between a prokaryotic cell and a eukaryotic cell?
5. What are the four categories of organelles?
6. To what Eukaryotic Kingdom does an amoeba belong?
7. How does an amoeba accomplish movement?
8. What four kinds of human cells will we be observing in lab?
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Parts of the Swift M5 Microscope
Ocular lens (10X)
Headpiece
Objectives –5X (red),
10X(yellow), 40X(blue),
100X(white)
Condenser Lens –
focuses the light from the
source. The blue filter is
attached to the bottom of
the lens, beneath the iris
diaphragm.
Arm
Iris Diaphragm
Lever – controls
the light that enters
the condenser.
Coarse Focus
Fine Focus
Condenser Lens
Control – Raises
and lowers
condenser lens
Mechanical Stage
Control – moves the slide
Forward, back, left, and
right
Light Source
Mechanical Stage
– holds the slide, is
moved with the
mechanical stage
control
Power Switch
Light Intensity
Control
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Microscopy
Purpose
This lab is designed to give the student a basic understanding of microscopy, and introduce proper
techniques for using a compound, light microscope. The primary objectives of this lab are for the student
to:
- Understand the importance of microscopy in viewing individual cells.
- Identify the parts of a compound light microscope and their function.
- Demonstrate and practice proper techniques for use and care of a compound light microscope.
- Make a wet mount slide preparation.
- Discriminate differences in specimen depth.
- Learn & demonstrate proper technique for presentation of illustrations of microscopic
specimens.
Background
I. Visualization of Small Specimens.
The basic unit of life and the smallest hierarchical level that can be considered alive is the cell. All
living things, simple or complex, are made of cells and much has been learned through their analysis. The
human eye is able to resolve objects less than a millimeter (1.0 mm) in size, but not much smaller than
that. Although there are some cells that can be observed with the naked eye (human egg cell, squid giant
axons, etc.) most cells are too small to be viewed without assistance. Today, in order to visualize small
specimens such as individual cells, a light microscope is most commonly used. The first light
microscopes were invented in the 17th century AD by Anton Von Leeuwenhoek, Von Leeuwenhoek was
able to achieve a magnification of approximately 270X. The invention of the light microscope opened up
a new world for biologists to study, and the field of Microbiology was born. Today’s modern light
microscopes are capable of magnifying images over 1000X, enough to clearly see even some of the
smallest cells.
Exercises:
I.
Using the Swift M5 Microscope
Carrying the Microscope:
1. Always use two hands, one of which should support the base while the other holds the arm of the
microscope. Microscopes contain delicate optical structures that could be damaged through
impact. Thus, be very careful and gentle when setting down the scope and moving it.
Setting Up:
2. The eyepieces (oculars), condenser lens, and light source should be clean and dust-free. You may
want to wipe these surfaces with a lens-grade Kim Wipe prior to using the microscope.
3. Ensure that the lowest power (red) objective is pointing at the stage before placing your slide on
the stage.
Ocular Lens Distance and Focusing: Preventing Eye Strain, Headaches, and Dizziness
4. Place your slide on the stage so that the light shines through it. Look at the stage, not through the
eyepieces. Use the mechanical stage controls to position your slide.
5. Move the Iris Diaphragm Lever to the left and use the condenser lens knob to raise the condenser
lens to the highest position possible, which should be immediately beneath the slide.
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6. Turn on the microscope and use the rheostat wheel on the front of the stage to adjust the light so
that it is not too bright or dim – go for what is comfortable for your eyes.
7. Look through the eyepieces- don’t worry about focusing yet. What do you see? Two circles, one
blurry circle, or one clear circle? Do not worry about whether you can see the slide clearly – all
you should be focusing on right now is the circle – if you see two circles, you need to push your
eyepieces together a bit. If you see a blurry circle, you need to widen them. When you find the
right distance for your eyes, look at where the dial is between the eyepieces. You can select the
best distance for you using that number whenever you need to use your microscope for the rest of
the quarter.
8. Finally, set the ocular lens focus. Bring the object into focus using the coarse focus knob and then
the fine focus knob. Look through the right eyepiece with your right eye – close your left eye.
Use the fine focus to make the image as sharp as possible. Now look through the left eyepiece
with your left eye and close your right eye. If the image is blurry in any way, sharpen it by
rotating the left eyepiece clockwise or counterclockwise.
Measuring Field of View
9. With each slide, ALWAYS start with the low power (4X, red) objective. With the 4X objective,
you may start with the coarse focus knob and then use the fine focus knob to sharpen the image.
10. Next, look at the slide with the medium power (10X, yellow) objective. The objectives should be
parfocal, which means that you should only need to use the fine focus knob. Note how the
objectives increase in length with magnification power. The coarse focus moves the stage up and
down, and you may run the slide into the objective if you use coarse focus with the longer
objectives.
11. Finally, look at the slide with the high power (40X, blue) objective. Again, only use the fine focus
knob – you can turn it in either direction to sharpen the image. If the image does not become clear
in a couple rotations in one direction, you should probably rotate the focus knob in the other
direction.
The Condenser Lens and Iris Diaphragm
12. When you are viewing a slide, experiment with the positioning of the condenser lens and the iris
diaphragm lever. Find the knob that raises and lowers the condenser lens under the left-hand side
of the stage. You should not loosen the condenser lens with the pins that are used to hold it under
the stage. When you lower the condenser lens at high power, it will sharpen the image. For
scanning and low power, it is best to keep the condenser lens in the highest position possible.
13. The iris diaphragm controls how much light passes through the slide to the objectives. View your
slide with the lever in various positions – far left, middle, far right, and see how it changes the
image that you see. You should not use the lever to control the actual light level. For this, use the
rheostat dial on the front of the base.
Troubleshooting
“The light doesn’t work”
 Ensure that the worktable is plugged in – the worktables should be plugged into overhead electrical
outlets. If your table is not plugged in, it won’t have power.
 Ensure that your power cord is properly inserted into the base. The power cords are removable and
sometimes come loose.
 Ensure that the rheostat is not dialed all the way down.
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
If you have tried all of the above, and the light still does not work, notify your instructor. The
lightbulb, power cord, or fuse may need to be replaced. Your instructor may have you use a different
microscope for the time being. If your instructor is unable to repair the microscope, the lab technician
should be notified.
“I cannot see anything.”
 Ensure that the scanning (4x, red) objective is fully locked into place.
 Make sure the light is on.
 Make sure your slide is centered properly and not upside down.
 Check the condenser to make sure the iris diaphragm lever is set to the left.
 You will need to use the coarse adjustment knob to raise the stage so that the slide is quite close to
the objective before an image can be seen.
 If you have tried all the above and still cannot see anything, notify your instructor. You may be
directed to put away your microscope and use a different one. In this case, the lab technician
should be notified.
“The image is blurry.”
 First, make sure you followed all of the focusing steps described in steps 2 through 11.
 CLEAN EVERYTHING. Clean the ocular lenses, the light source, the condenser lens, the
objective, and the slide. DO NOT REMOVE ANYTHING. You should be able to clean the
objective without removing it. Make sure the slide is not upside down!
 If you’ve tried all of the above, and the image is still not sharp, please notify your instructor. Your
instructor may attempt further cleaning or direct you to put the microscope away and use a
different one. The lab technician should be notified in this case.
Putting the Microscope Away
1. Select the scanning (4x, red) objective, and remove your slide from the stage.
2. If you used methylene blue or any wet mounts, gently wipe the high power (40x, blue) objective
with a dry lens tissue. If it is clean and dry, use the same tissue to wipe the eyepieces and stage. If
you see fluid or stain on the tissue, use a small amount of lens cleaner to wipe the objective. Then
wipe the eyepieces and stage.
3. Center the mechanical stage so none of the gearing is hanging out on the side. The electrical cord
should be bound with the velcro strap.
4. Carry the microscope properly and place it in the appropriately numbered space in the cabinet with
the arm facing outward. When the arm is facing outward, the number is visible, and the scope is
more easily retrieved from the cabinet.
Parking Tickets
5. If you put away your microscope improperly, the next user may write up a ticket and attach it to
your microscope.
6. If you find something wrong with your microscope, notify your instructor. If it was put away
improperly, you can write a ticket, and attach it to the arm so that it is visible from outside the
cabinet. Your microscope will probably be used by at least 10 other students this quarter. The
purpose of the tickets is to foster awareness for proper handling and use of the microscopes. They
are very expensive, useful tools for your learning and should be respected as such. Some
faculty may deduct points for improper handling of the microscopes.
25
Cell Structure & Function Lab Procedure
Purpose
This lab is designed to give the student a basic understanding of cell structure and function. The
primary objectives of this lab are for the student to:
- Appreciate the importance of cytology in scientific study.
- Understand the close relationship between structure & function as it applies to cells.
- Understand the structural and evolutionary differences between prokaryotic and Eukaryotic
cells
- Identify organelles & structures common to most cells and their functions.
- Identify the three bacterial cell shapes.
- Observe and discriminate between prokaryotic and eukaryotic cells
- Observe a typical plant cell & identify any confidently observable organelles and/or structures.
- Observe a typical Protist cell & identify any confidently observable organelles and/or
structures.
- Observe 4 examples of animal (human) cells and describe how the structure of the cell
facilitates its function.
- Demonstrate proper techniques for presentation of illustrations of microscopic specimens.
Background
I. Introduction
Recall the cell theory, which states that all living things are composed of cells and that the cell is
the smallest level of organization that can be considered to be alive. There are two primary types of cells:
Prokaryotic and Eukaryotic. Eukaryotic (eu = true; karyon = kernel) cells have evolved many specialized
internal structures called organelles (“little organs”). Most organelles are membranous, though a few are
not. Organelles provide separate areas or compartments for all of the different reactions and processes
that are required to maintain a living cell/organism. Organelles fall into 4 basic categories: manufacture
(endoplasmic reticulum, golgi apparatus), breakdown (lysosomes), energy processing (mitochondria) &
support (cell membrane, cilia, flagella). All plant and animal cells are Eukaryotic. Prokaryotic (pro =
before) cells are the more primitive type, and their most distinguishing feature is the lack of a nucleus
(and all other membranous organelles). In bacteria and other prokaryotic cells, the DNA and other
molecules are free floating in the cytoplasm.
II. Eukaryotic Cell Structures & Their Functions
The following is a list of cell structures and their functions. You should be able to identify these
structures on a diagram or model and know what their functions are.
Cell Membrane – The cell membrane makes up the outer edge of the cell (in animal cells)
and controls the movement of substances into and out of the cell. Typically
composed of a phospholipid bi-layer with other types of molecules imbedded in
it.
Cell Wall – Found in plant cells, fungal cells, some protist cells, and bacterial cells, cell
walls are thick, fibrous walls enclosing the cell membrane. Plant cell walls are
made of cellulose, providing support and protection for plant cells.
Cytoplasm – The region of the cell between the cell membrane and the nucleus. Contains
liquid cytosol, organelles, & the cytoskeleton.
Cytosol – The fluid (sometimes jelly-like) portion of the cytoplasm.
Cytoskeleton – Interconnected system of fibers, tubules & filaments that provide support
and allow for movement.
26
Nucleus – The genetic control center of the cell, it directs all cellular activities. Contains
the DNA, nucleoplasm (like cytoplasm but in the nucleus), and the nucleolus.
Nucleolus – Smaller spherical structure located within the nucleus, it is the site of
ribosome production.
Nuclear Envelope/Membrane – A bi-layered membrane surrounding the nucleus.
Contains numerous (nuclear) pores to allow for passage of molecules into and out
of the nucleus.
Ribosomes – Composed of DNA, RNA and protein, ribosomes are the site of protein
synthesis. Can be free floating in the cytoplasm or attached to rough endoplasmic
reticulum (ER).
Rough Endoplasmic Reticulum – Rough ER is a continuous series of membranous
channels that contains ribosomes on its surface. The ribosomes give it a rough
appearance, hence the name. Rough ER is involved in synthesis of proteins.
Smooth ER – Smooth ER is also an interconnected series of channels, but does not
contain ribosomes on its surface. Smooth ER is involved in lipid synthesis.
Golgi Apparatus – The golgi apparatus is a series of flattened membranous sacs (like a
stack of pancakes) that is responsible for concentrating, packaging and transport
of proteins. Finished proteins are packaged in secratory vesicles for transport. I
like to think of golgi as “cellular UPS.”
Lysosomes – Lysosomes (lyse = to burst) are smaller membranous sacs filled with
digestive enzymes. They are responsible for breakdown of particles ingested (by
endocytosis) and breakdown/recycling of old, worn-out organelles.
Vesicles – Small membranous sacs used to transport substances into and out of the cell.
Vacuoles – Large membranous bags within plant and animal cells, vacuoles have
generalized functions like storage of water & sometimes chemicals & growth (via
water absorption).
Chloroplasts – Found only in plant cells, chloroplasts are membranous organelles that are
the site of photosynthesis. They are responsible for the green color of plants.
Mitochondria – These “sausage-shaped” membranous organelles are responsible for ATP
(energy) synthesis and are often referred to as the “powerhouse” of the cell.
Centrosome – Non-membranous structure composed of 2 tubular centrioles that pull
chromosomes (DNA) to opposite ends of the cell during cell replication.
Cilia & Flagella – Both are tubular extensions of the plasma membrane that aid in
movement by beating. Flagella are longer, most often occur singly, and are used
to propel a single cell (gametes) through water. Cilia are shorter and more
numerous. In single celled organisms cilia are often used to propel the cell
through water. In multi-cellular organisms, they are often used to propel fluids or
mucous through the organism.
Laboratory Exercises
I. Prokaryotic Cells – Kingdom Eubacteria
There are 3 primary types of bacterial cells, which are differentiated based upon their shape. A
bacillus (pl. bacilli) is rod-shaped, a coccus (pl. cocci) is spherical and a cell that is spiral shaped is called
a spirellum (pl. spirelli). Observe the demonstration microscopes containing examples of each bacterial
cell type and make a drawing of each type on your report sheet (you only need to draw a few individuals
of each type – you do not need to draw the entire field of view).
27
II. Eukaryotic Cells – Kingdom Protista: Amoeba
You are going to examine living Amoeba for this exercise and you will be required to make a wet
mount of the Amoeba. Living Amoebae have no specific shape, and their shape is almost always
changing. Amoebae move by extending a portion of their cell membrane and increasing the size of the
extension by filling it with cytoplasm. These extensions of the cell membrane are called pseudopods
(sing. pseudopod). The procedure for making the Amoeba wet mount slide is as follows.
1) Obtain a clean glass slide and cover slip.
2) Place a drop of water from the amoeba sample onto the center of the slide (HINT: if
you take your sample from the bottom of the container, you are more likely to get an
amoeba in your sample.
3) Place the cover slip over the drop of water
4) Observe the Amoeba wet mount at 400X and make a drawing on your results sheet
labeling what parts you can.
5) When you are finished with the wet mount, place the slide and coverslip in the used
slides container. When you are finished using your microscope, remember to put it
away properly. Do not leave any slides on the stage of your microscope.
IV. Eukaryotic Cells – Kingdoms Plantae and Animalia – Review of Diffusion and Osmosis
The purpose of this part is to demonstrate the action of a “living” semi-permeable cell membrane.
How do things pass through a cells membrane? What precautions must a cell take to ensure homeostasis
and maintain functions, while still being an active vibrant cell? You will view plant and animal cells in
three different kinds of solutions: pure water (Solution A), 10% NaCl (table salt, Solution B), and 0.09%
NaCl (Physiological saline, Solution C). Think of how the principles demonstrated here can be applied to
the normal and abnormal environments cells can find themselves involved with and yet still can maintain
their lives. Remember to formulate hypotheses for each situation in the following part of this exercise.
Work as a team – one half of the group should share the work on the exercise with the blood cells
while the other half works on the exercise with the elodea leaves. Share your observations and
allow all of your team members to view your slides.
Procedure: Red Blood Cells and Osmosis
1. Write down a hypothesis for what you expect to happen to the blood cells in each of the solutions A,
B, and C on the report sheet.
2. Label four microscope slides A, B, C, and D.
3. Place a drop of blood on slide D with a cover slip and observe the shape of the red blood cells.
Record you observations in the Report Sheet in Table 3
4. Place a drop of solution A on slide A and a drop of sheep’s blood about ½ cm away from solution
Add a cover slip over the two drops. View the slide under the microscope and find the area where the
two solutions meet. Record your observations in Table 3.
5. Repeat step 4 for solutions B and C.
6. Place your slides in the used slide container.
7. Answer questions on the report sheet.
Procedure: Plant cells and Osmosis
1. Write down a hypothesis for what you expect to happen to the elodea cells in each of the conditions
A, B, and C as used in the procedure above
2. Place an Elodea leaf with a drop of water on a microscope slide, and add a cover slip. Place slide on
a microscope stage and observe the shape of the cells and record your observations in Table 4 of the
Report Sheet.
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3. Follow steps 3 through 6 above substituting Elodea in place of the sheep’s blood, and answer the
questions in the report sheet..
V. Human Tissues
Recall that there is an extremely intimate connection between structure and function. This is true
at all levels of organization, but it is extremely striking at the cellular level (remember that structure
determines function, change the structure and you change the function). Complex multicellular
organisms have developed differentiation of cells based upon their function. Cells that do a particular
function have a structure that best allows them to do that function. In this exercise you will be looking at
the following cell types (the number in parentheses is the total magnification under which you are to view
each specimen): Blood (1000X), Neurons (400X), Sperm (1000X), Skeletal Muscle (400X). All of these
slides are professionally prepared and require no preparation. The two slides to be observed at 1000X
(sperm and blood) are on demonstration microscopes. Make a drawing of each cell type on your results
sheet labeling what structures you can.
29
Name ______________________ Names of Group members___________________________________
Section ______________________
Report Sheet
Cell Structure & Function
I. Prokaryotic Cells – Kingdom Eubacteria
________________________
________X
________________________
________X
________________________
________X
____________
What structure is most obviously lacking in prokaryotic cells?
What structure is found in both plant and bacterial cells but not animal cells?
___________
II. Eukaryotic Cells – Kingdom Protista: Amoeba
________________________
________X
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Your drawing of the amoeba may look different than your partners. Why is this ok?
___________
What are the cytoplasmic extensions called that Amoebae use to move called?
___________
III. Eukaryotic Cells – Osmosis and Diffusion through a living membrane
Condition
D (blood only)
Appearance and Condition of Red Blood Cells
A
Deionized water
B
10% NaCl
C
0.09% NaCl (Saline)
Table 3 RBC Data Observations of the potential changes in cell structure of Red Blood Cells in test solutions.
1. Write a hypothesis for each of the conditions using your experiences with non-living membranes.
2. Which of the three solutions was hyper-tonic to the red blood cells? Explain your answer.
3. Which of the three solutions was hypo-tonic to the red blood cells? Explain your answer.
4. Which of the three solutions was isotonic to the red blood cells? Explain your answer.
5. What conditions within the human body might lead to results similar to those you experienced here?
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Condition
A
Appearance and Condition of Elodea Cells
Deionized water
B
10% NaCl
C
0.09% NaCl (Saline)
Table 4 Elodea Data Observations of the potential changes in cell structure in Elodea Cells in test solutions.
6. Write a hypothesis for each of the conditions using your experiences with non-living membranes.
7. Which of the three solutions was hyper-tonic to the Elodea cells? Explain your answer.
8. Which of the three solutions was hypo-tonic to the Elodea cells? Explain your answer.
9. Which of the three solutions is isotonic to the Elodea cells? Explain your answer.
10. Would you expect pond water to be isotonic, hypo-tonic, or hyper-tonic to Elodea cells and why?
___________
In which organelles does this process go on? ___________
What is the pigment molecule required for this process? ___________
What is the process called by which plants turn light into energy?
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Give two examples of structures/organelles that are found in plant cells but not in animal
___________
What substance are plant cell walls made of? ___________
cells.
___________
IV. Eukaryotic Cells – Kingdom Animalia: Human Tissues
Label the following structures on the animal cell diagram below: nuclear membrane, nucleolus,
chromatin, nuclear pore, rough endoplasmic reticulum, ribosomes, smooth endoplasmic reticulum,
mitochondrion, golgi apparatus, lysosome, plasma membrane, vesicle, centrosome (centrioles), spindle
fibers, cilia.
33
Draw and label each of the 4 human tissues you viewed in the circles below. Next to each
drawing, generally describe how the cells’ structure might facilitate its function.
_________________
_________________
_________________
_________________
_________________
_________________
_________________
________________________
________X
_________________
_________________
_________________
_________________
_________________
_________________
_________________
________________________
________X
_________________
_________________
_________________
_________________
_________________
_________________
_________________
________________________
________X
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Lab 4: Plant Anatomy
Name________________________________
Pre-Lab #4
1. List three specialized cells of the epidermis
2. Where is the vascular cambium located and what is its function?
3. List three of the four primary functions of roots.
4. Where is the Casparian strip located and what is its function?
36
In-lab for Lab 4: Plant Anatomy
Name___________________________
Names of Lab Partners_____________________________________________________
Topic 1. The Plant Body
Introduction:
Plants are photosynthetic autotrophs which are also structurally complex. The tissues of higher plants
are organized into roots, stems, and leaves. These are the organs of the plant body. Together, the leaf and
the stem make up the shoot. Both leaves and stem are derived from growth of an apical bud. Each leaf
along the stem is associated with a bud, and these give rise to lateral branches. The upper angle formed by
the leaf and stem is called an axil. These buds are found in that location, and are called axillary buds.
1. Describe the functions of each of the 3 plant organs:
a. stems:
b. roots:
c. leaves:
Learning objectives:
Gross morphology - terms you will be required to know and be able to use
I. The Bean Seedling. Go to the side bench and carefully uproot a seedling growing in vermiculite. Label
the figure using the list of terms below:
Axillary Bud, Blade , Root System, Petiole, Root , Shoot System, Stem, Vein , Leaf, Cotyledon
37
II. Examples of Other Plants. Around the room are examples of plants with the following
characteristics. Write the name of the plant next to its leaf arrangement
Opposite leaves__________________________
Alternate leaves__________________________
Whorled Leaves _________________________
Compound Leaves________________________
Dormant Shoots: Morphology of a Woody Twig
Take a woody twig and carefully study it. Consider the following questions:
1. The twig is encased in a water-proof, air-tight covering (the bark). Can you discern any observable
structures in the bark that may be related to gas exchange?
2. Based on your observation of the dormant twig, were the leaves arranged in an opposite or alternate
fashion?
3. Speculate. Botanically, what are the bud scales?
4. Without looking at the cross section of the stem determine how many
years growth is represented by your twig.
Plant Primary Growth and Development
1. Examine a prepare slide of a leaf bud. Label the figure below
38
Discussion
1. Describe the changes in cell size and structure in the stem tip. Begin at the youngest cells at the
apex and continue to the xylem cells.
2. What is an apical meristem?
Examine a prepared slide of a stem cross section. Label the figure on the following page:
39
1. Were any epidermal trichomes present on the stem? yes or no (circle one)
2. Is there any evidence of and secondary growth?
3. What is the function of xylem? of phloem?
Lab Study B Roots
Examine a prepared slide of a root cross-section
c. label the figure on the following page:
40
1. Note that the epidermis of the root lacks a cuticle. Can you explain why this might be
advantageous?
Leaves
Procedure: Examine a prepared slide of a leaf cross-section
Observe the structure of cells in the central midvein. Is the xylem or phloem on the top half? (circle one)
41
c. Observe the distribution of stomata on the upper & lower epidermis. Where are they more abundant?
(circle one) Why?
Cell Structure of Tissues Produced by Secondary Growth
Look at the cross-cut of tree. Locate the heartwood, sapwood, and cork. Count the number of annual
rings. When you have done all of this, call your instructor over for initials here_________________.
Now examine a prepared slide of a woody stem cross-section under your microscope.
1. Based on your observations of the woody stem, does xylem or phloem provide structural support
for trees? (circle one)
42
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43
Lab 5: DNA, Miotosis and Karyotyping
Pre-Lab Report Sheet
Name _____________________
Lab Section
.
Mitosis & Karyotyping Exercise
1. Using your text, outline the steps or phases of mitosis by describing the major events of each phase of
the process.
2. Cite reasons why cells would undergo mitosis and how does mitosis fit in with the cell cycle.
3. Suggest how the use of stains could be applied to reveal other cellular processes such as
photosynthesis, cellular respiration, or meiosis?
4. During which phase of mitosis are chromosomes harvested for karyotyping and why?
44
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45
Perspectives
In the late 1800’s new techniques to visualize cellular structure exploded with the discovery of vital
stains and dyes. Most plant cells were fairly easy to visualize since most contain pigment molecules for
photosynthesis, but animal cells were another matter. When viewed under a microscope lens sub-cellular
structures, called organelles, were seen as simply the grainy consistency of the cytoplasm. When
scientists would apply different pigments harvested from different plants the graininess took on a distinct
form. Organelles could now be distinguished and studied as separate structures. Differences in cellular
function could be attributed to the number and types of organelles found in various cells. By the end on
the century scientist were using not only pigments from plants to stain cells, but were beginning to use
heavy metals linked to pigments to further delineate structure. Dyes and stains became almost as an
important discovery as the light microscope.
The new technology of stains allowed a number of scientists to peer into cells like they could not have
done before their advent. One scientist, Walter Flemming, noted in salamander ovary cells that dark
staining condensations appeared within the nucleus. These condensations were then separated toward
opposite poles of the cell (“Dance of the Bodies”) just prior to the cell splitting into two new cells. He
eloquently described and named the process called mitosis.
Today’s technology in the field of genetics and how genes affect the phenotype of an individual
started over 140 years ago with the work of Gregor Mendel. His work with pea plants set the stage for
how chromosomes are sorted and passed from generation to generation. In the early part of the 1900’s
another geneticist, Thomas Morgan, working with fruit flies (Drosophila melangastor) developed a
technique that allowed him to visualize the structure of chromosomes. This technique harvested
chromosomes from cells arrested in pro-metaphase of mitosis, after being treated with colchicine, stained
the chromosomes with a vital stain, and then matched the chromosomes based on staining patterns and
size. This technique is called karyotyping and is used today to show the potential for genetic
abnormalities within the genome of an individual. The specificity of the technique has been refined
through the use of more specific stains (spectral analysis) which adhere to specific sites within the DNA
molecules to further highlight the differences between chromosomes.
Introduction
In the following activity you will play the role of a cytogenetic technician and complete the
karyotype for three patients, then use these karyotypes to evaluate and diagnose each patient. Be careful!
The emotional and physical well being of each patient is in your hands……or almost in your hands!
Part 1 On-line karyotyping
1. Go to the Biology Project at: http://www.biology.arizona.edu/
2. Scroll down and click on “Human Biology”.
3. Scroll down to “Activities” and then click on “Web Karyotyping”.
4. Read the introduction and then complete the assignment as described. Record your responses on
Table 1 of the Report Sheet.
5. Go to: http://www.google.com
6. Search for a karyotyping website and answer the questions of page 103.
Part 2 On-line Onion Root Tips: Phases of the Cell Cycle
This activity is a digital version of a classic microscope lab. You will classify cells from the tip of an
onion root into the appropriate phases of the cell cycle, and then count up the cells found in each phase.
You can use those numbers to predict how much time a dividing cell spends in each phase. In the process
46
of doing this you will become familiar with the cell cycle and the process of mitosis and its stages, which
are, oddly enough, the major goals of this activity!
1. Go back to the Biology Project at: http://www.biology.arizona.edu/
2. Scroll down and click on “Cell Biology”.
3. Scroll down to “Activities” and then click on “On-line Onion Root Tips: Phases of the Cell
Cycle”.
4. Read the introductory pages (about 3 total) and then complete the assignment as described.
Record your responses in Table 2 on the Report Sheet.
47
Assignment Sheet
Name
______________
.
Group members______________________________
Mitosis & Karyotyping
Part 1: Web Karyotyping Data
Patient
Notation
Diagnosis
A
B
C
Table 1 Web Karyotyping Data Information in this table shows the results of a web karyotyping exercise.
Internet Search
URL of Site: http://
.
Title of Site:
.
Describe an interesting thing you learned at this site:
Part 2: On-line Onion Root Tips: Phases of the Cell Cycle
Interphase
Prophase
Metaphase
Anaphase
Number
of Cells
Percent of
Cells
Telophase
Total
36
100%
Table 2 Mitotic and Cell Cycle Data Information in this table shows the results of an On-line Onion Root Tips: Phases of
the Cell Cycle.
What can be concluded from the data collected above as it relates to cells in the cell cycle?
48
Lab 6: Pigments in Photosynthesis
Part A. Introduction
Living organisms are made up of cells that require a constant supply of energy to grow, reproduce and
heal. The sun is the ultimate source of energy; the source of energy that runs the universe and supplies the
initial energy. Green plants absorb that light energy from the sun and convert it into a sugar (food) called
glucose through a process called photosynthesis. Photosynthesis occurs in any plant tissue, bacteria or
protist that contains chloroplasts. The leaf is the primary focus (although some plants like cacti use their
stems to photosynthesize) of photosynthesis. After the glucose is made, it is joined with other glucose
molecules to form disaccharides and polysaccharides (complex carbohydrates) and stored in the cell.
Starch is a polysaccharide and is the primary form of storage in plants.
The photosynthetic process is one of the most important chemical processes on earth! Without it, living
organisms could not harvest the energy from the sun and we would have no stored energy that can be
broken down to run our cellular processes. The process takes carbon dioxide, combines it with water to
form glucose (a simple sugar/carbohydrate--monosaccharide), oxygen and water. The ‘waste’ product is
oxygen though some oxygen is used in cellular respiration.
1. Write the complete, balanced formula for photosynthesis. Circle the reactants and underline the
products.

Part B: Testing a Simple Hypothesis using I2KI (work in pairs).
At the side bench is a variety of Coleus with variegated leaves. There are two obvious pigments to be
found in various regions of its leaves:
- Chlorophyll in the areas colored green, and
- Anthocyanin in the areas colored red.
- Note that here is also a region of overlap.
Take a leaf from the plant. Note where chlorophyll and anthocyanin are present. Because chlorophyll is
not found everywhere in the leaf, we can use the leaf toevaluate whether chlorophyll is necessary for
photosynthesis. To do so,however, we require a method for determining photosynthetic activity. One
approach is to consider where in the leaf starch forms. If photosynthesis occurs more rapidly than the
photosynthate can be transported out, leaves tend to convert photosynthate into starch. As we have a
means for determining the presence of starch, we have everything we need to conduct a simple
experiment to evaluate the hypothesis: Chlorophyll is necessary for photosynthesis.
Procedure:
1. Take a leaf and draw it. Clearly indicate where chlorophyll and anthocyanin are located and where they
overlap.
2. Boil the leaf in water to remove the water soluble anthocyanin pigment. Make a second drawing clearly
showing where the chlorophyll is located.
3. Boil the leaf in alcohol to remove the chlorophyll pigmentation.
4. Carefully place the bleached and brittle leaf on a watch glass and flood it with I2KI.
5. Again draw the leaf clearly indicating where the purple stained starch is located.
49
Drawing 1
Drawing 2
Drawing 3
Untreated leaf
Anthocyanin removed
Stained with I2KI
Discussion:
Are your results consistent with the hypothesis? Explain.
________________________________________________________________
Consider a second hypothesis: Anthocyanin is necessary for photosynthesis.
Do your results support that statement? Explain.
Can you reject the second hypothesis? Explain.
Have you “proved” the first hypothesis? Explain.
50
51
Lab 7 : Plant Diversity I: Nonvascular Plants and Seedless
Vascular Plants
Name_______________________ Names of Group members__________________________________
The Bryophytes
Plants are eukaryotic, photosynthetic organisms with chlorophylls a and b, xanthophylls and
carotenoids. Plants have cell walls with cellulose, and store food as starch localized in plastids. As is
found in the charophycean green algae, cytokinesis is accomplished by means of a phragmoplast. As we
learn more about the green algae and the plants, it is becoming clear that plants are a phylogenetic group
within the green algae adapted for life on land. Plants are more structurally complex than the green algae.
This is certainly due to the environmental pressures associated with life on land. The most structurally
simple plants have a sterile jacket of cells (dermal tissue) surrounding the sexual structures protecting
their gametes from dehydration. Eggs are contained in an archegonium, and developing sperm in an
antheridium (these have been lost in some of the more structurally complex lineages of plants). The
vascular plants have tissues specialized for the transport of water and photosynthate, which allow them to
tap underground water and mineral resources and to support themselves in competition for light. All
plants have a life cycle called alternation of generations, in which gametes are always produced by
mitosis, and spores are always produced by meiosis. All plants have embryos. The embryo is an early
sporophytic (diploid) stage that is nourished by the gametophytic generation.
The Bryophytes: Bryophytes are simply the plants without xylem and phloem. Mosses do have cells
specialized for the movement of water and photosynthate, which may be homologous to xylem and
phloem of vascular plants. The three phylogenetic groups of non-vascular plants are unique among living
plants in that the dominant generation is the gametophyte. In each case, the sporophyte is dependent on
the gametophyte for survival for the duration of its life’s span.
Domain: Eukarya - Organisms with nucleated cells
Kingdom: Plantae
Phylum: Hepatophyta (Liverworts)
Genus: Marchantia
Phylum: Anthocerophyta (Hornworts)
Phylum: Bryophyta (Mosses)
Part I: Phlyum Hepatophyta (Liverworts).
Structurally this is the simplest phylum of plants. The group lacks vascular tissues and stomata (there are
air pores, but these are not associated with guard cells). As with the other bryophytes, the gametophytic
generation is the dominant generation being free-living and photosynthetic. The sporophytes are both
totally dependent on the gametophyte for survival, and, inconspicuous. The tissues of the gametophyte
are undifferentiated. A body composed of simple, undifferentiated tissues, like those of liverworts, is
termed a thallus. Fertilization results in the formation of a diploid cell called a zygote. The zygote
resides inside the base of the archegonium where the zygote undergoes mitosis and grows into a
multicellular diploid embryo. The mature sporophyte mostly consists of one large sporangium which
produces spores by meiosis.
Observation of Marchantia.
Observe the Marchantia culture at the front of the room, and take a petri dish of Marchantia to your seat.
The non-reproductive portion of the plant grows firmly attached to its substrate. The main, green leafy
structure is called the thallus.
52
Draw a picture of Marchantia below, labeling all of the following: thallus, rhizoids, antheridia,
archegonia
1. Is the plant you observed the gametophyte or the sporophyte? (circle one)
Observe a gemma cup under a dissecting scope.
2. Are the gemmae responsible for asexual or sexual reproduction? Explain.
3. Why are these plants, like most bryophytes, restricted to moist habitats, and why are they always
small?
Sexual Structures.
Observe the elevated umbrella-like structures growing from the thallus, and note that there are two types.
One has spokes radiating from the stalk like the ribs of an umbrella, the other has a stalk terminating in a
disc. The structure with the spokes is an archegoniophore and bears archegonia.
The structure with the disc is an antheridiophore and bears antheridia. In each case, these structures are
made up of gametophyte tissue.
The Sporophyte of Marchantia.
The sporophyte develops while surrounded and nourished by the tissues of the gametophyte. This is a
fundamental characteristic of all plants. However, in the non-vascular plants, the sporophyte never
becomes independent from the gametophyte. The mature sporophytes of Marchantia can be found
hanging from the older archegoniophores.
Part II: Phylum Antocerophyta (Hornworts).
This group is superficially similar to the liverworts. Like liverworts, there is little tissue differentiation in
the gametophyte. The thin thallus grows in contact with the substrate. The cellular structure is different,
however. Indeed hornwort cells are uniquely different from all other plant cells. Typically plant cells have
numerous, disk-shaped chloroplasts. Hornwort cells have one, central, algal-like chloroplast. Also, unlike
liverworts, the hornworts have stomata. The sporophytes of the hornworts have guard cells associated
with the openings in its surface layer of tissues. This marks these openings as being true stomata.
Obtain a slide of a hornwort cell and draw a picture below. Also draw a picture of the overall hornwort
plant:
53
Part III: Phylum Bryophyta (Mosses)
Of all the non-vascular plants, the mosses have the clearest affinity to the vascular plants. Mosses have
specialized cells that conduct water, and others that conduct photosynthate. Further, these cells appear to
be homologous to similar tissues in the vascular plants. Unlike the vascular plants, in the mosses, the
gametophytic generation is the dominate generation, the sporophyte being dependent all its life on the
gametophyte for survival. The mosses also have disc shaped chloroplasts and have stomata.
View the Colonies on Demonstration
Of all the non-vascular plants, these are the ones, undoubtedly, with which you are most familiar. Mosses
grow everywhere where there is moisture to support them. Most mosses are very similar in form. Most
have gametophytes consisting of a central axis with leaf-like structures attached. The structures that
appear to be sporangia are actually the sporophyte generation.
Draw any moss on demonstration with sporophytes. Label both gametophyte
and sporophyte.
Review the structures and processes observed and then label the moss life cycle diagram below. Using
colored pencils or pens, indicate if structures are haploid or diploid, and circle the processes of mitosis &
meiosis.
54
Answer the following about the moss life cycle:
1. Are the spores produced by the moss sporophyte formed by mitosis or meiosis? (circle one) Are
they haploid or diploid? (circle one)
2. Do the spores belong to the gametophyte or sporophyte generation? (circle one)
3. Are the gametes haploid or diploid? (circle one) Are they produced by meiosis or mitosis?
(circle one)
4. Is the dominant generation for the bryophytes the gametophyte or the sporophyte? (circle one)
5. Can you suggest any ecological roles for bryophytes? (hint: the answer is not: “no”)
6. What feature of the life cycle differs for bryophytes compared with all other land plants?
7. How does moss get up on your roof?
55
Prepared Slides of Mnium Archegonia and Antheridia.
Mnium moss has separate male and female gametophytes. The antheridia on the male plants are clustered
into “splash platforms”. Take the slide labeled “Mnium: Antheridium” and place the slide under your
microscope and observe the antheridia.
Draw an antheridium here:
Take the slide labeled “Mnium Archegonium” and place the slide under your microscope and observe the
archegonia. Make a composite drawing of an archegonium below and label the egg:
Part IV: Phylum Pteridophyta – (The Ferns and Their Relatives)
Domain: Eukarya
Kingdom: Plantae
Phylum Lycophyta (spike mosses, club mosses, and quillworts)
Phylum: Pteridophyta (whisk ferns, horsetails, and ferns)
** Since the plants in Phylum Lycophyta are mostly extinct, we will not deal with them in today’s
lab.
Phylum Pteridophyta – the Ferns.
Ferns are a major phylogenetic group of plants consisting of several different orders in the phylum
Pteridophyta. They are widespread and ecologically important. Fern sporophytes are structurally complex
and typically have true stems, roots and leaves. The gametophytes we will see in lab are very small and
are bisexual).
Ia. The Sporophyte.
Observe the living and pressed sporophytes in the room. Identify the stems, leaves, and sori (clusters of
sporangium). Sketch the overall structure of the whisk fern, horsetail, and fern below. Label structures
where appropriate:
1. Are there any true leaves on the whisk fern?______ On the horsetails?______
2. Are sporangia present on the whisk fern? ______On the horsetails? _______
On the ferns?______
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3. Are the spores in the sporangia produced by mitosis or meiosis? (circle one)
4. Are the sporangia haploid or diploid? (circle one) Think about which generation produces them.
5. Once dispersed, will these spores produce the gametophyte or sporophyte generation? (circle
one)
Fern Life Cycle
Review the structures and processes observed, and then label the stages of the fern sexual
reproduction outlined in Figure 15.6 on the next page. Using colored pencils or pens, circle those
parts of the life cycle that are haploid and those that are diploid. Circle the processes of mitosis
and meiosis.
1.
2.
3.
4.
Are the spores produced by the fern sporophyte formed by mitosis or meiosis? (circle one)
Are the gametes produced by meiosis or mitosis? (circle one)
Is the dominant generation for the fern the gametophyte or sporophyte? (circle one)
Can you suggest any ecological role for ferns?
Ib. The Gametophyte.
Now take the prepared slide of a whole-mounted gametophyte and look for gametangia. Archegonia can
be found near the notch and antheridia will be found scattered across the whole thallus. The archegonium
is embedded in the tissue of the gametophyte. To observe the egg you must focus carefully.
Draw the entire gametophyte at 40x. Label archegonia and antheridia.
57
Name______________________________________
PreLab for Plant Diversity I: Non-Vascular and Vascular Seedless plants
1. Mosses belong to the seedless non-vascular plant group. What does “non-vascular” mean?
2. Define spores and gametes. What is the difference between the two?
3. How does the life cycle of a bryophyte differ from all other land plants?
4. What is the name of the liverwort that we will see in today’s lab? (scientific name)
5. Which is bigger: a fern sporophyte or a fern gametophyte?
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59
Lab 8 Plant Diversity II: Seed plants and Flowering
plants
Name_________________________________
Names of Group
members_____________________________________________________________
Seed Plants: The Gymnosperms
Domain Eukarya
Kingdom Plantae
Phylum Coniferophyta (The Conifers)
Genus Pinus
Phylum Cycadophyta (The Cycads)
Phylum Ginkophyta (The Ginkgoes)
Phylum Gnetophyta (The Vessel Bearing Gymnosperms)
Seed Plants: An Overview of Terms
The remaining five phyla of plants, are all seed plants. Seeds contain young sporophytes
(embryos). In all cases, the gametophyte generation is still there, but is either hidden by
sporophytic tissues or dramatically reduced. Our knowledge of the life cycles of non-seed
plants provides us with a perspective about the evolution and life cycles of the seed
plants. All seed plants are heterosporous, which means that they produce separate male
and female spore in separate male and female sporagnia. A Seed is a mature ovule
(female gametophyte) bearing a young sporophyte (an embryo) complete with food
storage tissue covered by a seed coat derived from integuments.
The Gymnosperms
Gymnosperms are simply seed plants that are not angiosperms. This means that they are
grouped by what they don’t have. Gymnosperms do not bear fruits and their seeds are not
enclosed. ‘Gymnosperm’ literally means naked-seeded as their seeds are not enclosed in
fruits. There are four phyla of gymnosperms.
I. Coniferophyta (The Conifers).
Conifers are seed plants all of which have woody stems. Their life cycle does not include
motile sperm. The sperm nuclei are carried all the way to the egg by the pollen tube.
While absent in the yews, the most distinctive feature of the group is the compound
ovulate cone, consisting of a central stem bearing seed-scale complexes. Each seed scale
complex consists of a modified leaf in which the ovules develop. Conifers include many
commercially and ecologically important species. These include the pines, spruces,
hemlocks, douglas fir, junipers, cedars and all three genera of the redwoods. Conifers are
among the world’s largest, tallest and oldest trees. Observe the examples of conifers on
display.
What economically important products are derived from
Conifers?________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Ib. Life Cycle of the Genus Pinus
Observe the living Pinus leaves on display. How many needles are in each
bundle?_____________
Use the key provided to determine which species of pine tree this
is___________________________
In conifers, male cones are borne for only a matter of days or weeks and are then shed. In
Pinus the male cones are borne in clusters and emerge with the new spring growth of the
lower branches.
Studying the Details of the Male Cone
Take the prepared slide labelled, “Pinus Male Strobilus”. Draw what you see below, and
label the microsporangia and pollen grains.
The Male gametophyte (Pollen Grain)
In all seed plants the male gametophyte is greatly reduced. For fertilization to occur the
male gametophyte must be physically carried to the ovule. This event is pollination and
in pine is accomplished by the wind. Examine a prepared slide of a pollen grain and
draw it below. Label the tube cell and the generative cell.
What possible survival advantage could be provided by the “Mickey Mouse” ears?
The tube cell will germinate into the pollen tube which will grow up through the neck of
the archegonium to an egg. After pollination the generative cell will divide to form two
sperm nuclei. Both of these nuclei will be delivered to the egg nucleus via the pollen
tube.
Megasporangiate Stages
In conifers female cones persist through the year and their presence give rise to the
common name of the group. In Pinus the female cone emerges with the new spring
61
growth of the upper branches. Female cones typically emerge in May and do not reach
maturity where they disperse seed until the fall of the following year!
What are two ways in which pine seeds might be
dispersed?_______________________________________________________________
________________________________________________________________________
Studying the Details of the Female Cone
Observe the prepared slide through your
microscope. Identify the sterile bracts labelled “A”,
and the seed scales labelled “B” on the next page. A
sterile bract with its associated seed scale is a seed
scale complex.
Dissection of a Female Cone:
Takethis cone and pull it apart using your fingers. Share
the pieces with those at your table. Everyone should
then dissect out one seed-scale complex. Use a
dissecting microscope! Lay it flat and observe the
ovules. How many ovules are there on each seed-scale?
Flip over the seed-scale and observe the sterile bract.
Draw each view of one seed-scale complex. Label seed-scale, ovules, and sterile bract.
Studying the Details of the Ovule
Take the prepared slide labeled “Pine female strobilus”and use 400x to study details of
the ovule. Look for an ovule with a huge cell in the center. This cell will undergo
meiosis to produce four female spores. In Pinus, only one female spore will go on to
produce a female gametophyte. The tissue in which this cell is embedded is the female
sporangium. The female gametophyte will undergo_______________ to produce an
egg. After pollination, the sperm will fertilize the egg.
II. Phylum Cycadophyta (The Cycads).
Cycads are a group of seed plants with non-woody secondary growth. Plants are
dioecious. What does this
mean?__________________________________________________
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Foliage is similar to a palm tree. Cycads have flagellated sperm carried to the
archegonium by means of the pollen tube. This group was more important ecologically in
the past than in the present. Today the group consists of only three families of plants.
Cycads are extensively planted in tropical and subtropical areas as ornamentals. Observe
the examples of cycads and draw a rough sketch of one here below:
III. Phylum Ginkgophyta (The Ginkgos).
Ginkgos are seed plants with woody secondary growth and distinctive fan shaped leaves.
They are also dioecious. Female ovules mature into a stinking fruit-like seed. Ginkgo
has flagellated sperm! The group was more important ecologically in the past than in the
present. Today the phylum includes one species, Ginkgo biloba, which is extensively
planted as a street tree. Observe the demonstration materials of Ginkgo biloba on the side
bench. Ginkgo is used by some people as an herbal supplement
for_____________________________________________________________________
________________________________________________________________________
_______________________
IV. Phylum Gnetophyta (Vessel-Bearing Gymnosperms).
This is a peculiar group consisting of only three genera (plural of Genus) that are
radically different in shape and form from each other. These plants are dioecious. Even
though these three genera don’t look similar, they are thought to be a true evolutionary
group of plants.
Label each figure with the appropriate genus name (Ephedra, Gnetum,
Welwitschia):
Genus: ____________________
63
Genus: ____________________
Genus: ____________________
The Angiosperms
Domain Eukarya
Kingdom Plantae
Phylum Anthophyta (The Flowering Plants)
The angiosperms are the most abundant and diverse group of plants on Earth.
Angiosperms were the last major group of plants to appear in the geologic record.. The
group diversified explosively. All sexually reproducing flowering plants have flowers.
The general rule is that the flower is a shoot consisting of four types of modified leaves,
sepals, petals, stamens, and carpels. However, there are major groups of flowering
plants that have flowers without petals or sepals. Examples include the oaks and birches.
It is not clear whether these trees descended from plants that never had petals and sepals,
or if their floral structure has become reduced as an adaptation to wind pollination. The
grasses are another group adapted to wind pollination. Their flowers typically have only
stamens and carpels. In the case of the grasses it is clear that their flowers represent a
reduction in complexity from ancestors that did have petals and sepals.
Defining characteristics: All angiosperms have carpels. The carpel is a female
sporangium that bears and encloses ovules. After pollination, carpels mature to form
fruits. All angiosperms undergo double fertilization. The male gametophyte (pollen
grain) produces two sperm nuclei which are delivered to the female gametophyte via the
pollen tube. One fertilizes the egg to produce a zygote. The other undergoes fusion with
the two nuclei of the central cell of the female gametophyte giving rise to a type of
nutritive tissue called endosperm.
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I. Flowers
A flower is A determinately growthed shoot that typically includes four tiers of modified
leaves: The calyx made up of sepals, the corolla made up of petals, the androecium
made up of stamens, and the gynecium made up of carpels. A flower is complete if it
contains all four tiers of modified leaves. A flower is incomplete if it does not have all
four tiers of modified leaves.
Closely examine (pull apart and slice open) a big real flower locating all the parts. Sketch
it below and label all the parts: stigma, style, ovary, anther, filament, petals, sepals
Grass flowers have most of the parts too but they are modified. Using the poster for
help, label the following grass flower parts: (if real grass flowers are available, be sure to
look for the dangling male parts and feathery female parts.)
.
e) Pollen: look at all the different shapes and sizes! Draw your favorite here:
*f) How come...
- “a daisy is not “a flower”?
- some flowers stink like rotting meat?
65
- some flowers make sweet nectar?
- some orchid flowers are shaped like female wasps?
- some flowers are small, un-noticeable, and scent-free like alders and grass?
Take five different flowers to your table and fill in the table below. Use the attached keys
at the end of this lab to help you determine the shape of the corolla, landing platforms,
and predicted pollinators.
Flower #
Features
1
2
3
4
5
# of petals
# of sepals
parts absent
color
scent (y/n)
nectar (y/n)
shape of corolla
(tubular,star,
etc.)
special features
(landing
platform,
guidelines,
nectar spur,
etc.)
predicted
pollinator
Dichotomous Key to Pollinators
Flower Characteristics Method of Pollination
1A. Sepals and petals reduced or inconspicuous. Feathery or large stigma. Flower has no
odor.
Wind
1B. Sepals and/or petals large and easy to identify. Stigma is not feathery.
The flower may or may not have an odor.
2A. Sepals and petals are white or not very colorful (greenish or burgundy).
Flowers have a distinct odor.
 Odor is strong, heavy and sweet.
Moth
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 Odor is strong, smelling of fruit or fermented fruit. The flower parts and
pedicel are strong.
Bat
 Odor similar to sweat, feces or rotting meat.
Fly
2B. Sepals and/or petals are colored. The odor may or may not be present.
 Flower shape is regular or irregular, but not tubular.
• Flower shape irregular. Sepals or petals
are blue, yellow or orange. The petal is
well-suited to serve as a landing platform.
There may be dark lines on the petals.
Odor is sweet and fragrant………………………………………..Bee
• Flower shape is regular. The odor is
fruity, spicy sweet or meat-like.
Beetle
 Flower is tube-shaped.
• Strong, sweet odor
Butterfly
• Little or no odor. The flower is typically red.
Hummingbird
II. Fruits
These enclose the mature seeds and are derived from the ovary of the pistil. These may
be fleshy, or hard. If hard they may be dehiscent or indehiscent. Fruits are ripened
ovaries. One of the definitive characters of the angiosperms is that the ovules are
encased. Fruits always serve to protect the maturing ovules/seeds. However, a great deal
of variation exists in the angiosperms in regards to the nature of the mature fruit.
Berries: Some fruits become totally fleshy. These fruits are berries. Many unrelated
plants have fruits that are berries. In regards to fruit-type a great deal of convergent
evolution has occurred.
Drupes: Fruits that have a fleshy outer and a stony inner part are drupes. “Stone fruits”
are drupes, and include cherries, peaches, plums, apricots and nectarines. All are
members of the genus Prunus in the family Rosaceae. Other plants bear drupes as well
but are unrelated.. This is another example of convergent evolution.
Pomes: Pomes are a type of fruit borne by one taxonomic group within the rose family
including apple, pear, hawthorne and quince. In pomes the sepal, petal and stamen tissues
have become fused to the ovary resulting in an inferior ovary. Pomes, like berries, are
fleshy, but the tissues surrounding the ovary contribute the bulk of the flesh of the mature
fruit.
Follicles: Follicles are dehiscent dry fruits derived from a simple carpel that opens along
one side. The one obvious example familiar to many people are milkweed fruits.
Legumes: Like pomes this fruit type is associated with a taxonomic group - the bean
family (Fabaceae). This fruit is derived from one carpel that opens along two sides. Note
that peanuts are not dehiscent but are still considered to belegumes.
Capsules: A capsule is any dehiscent fruit derived from a compound ovary.
Grains, Nuts, Achenes: These are all examples of fruits that are non dehiscent and
develop into a hard or stony tissue surrounding the seed. Grains are the fruits of grasses
(Poaceae). The carpel develops into a hard layer tightly fused to the seed coat. This
covering is the bran stripped from the wheat kernel.
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Nuts are fruits where the carpel becomes completely stony. Many fruits considered to be
nuts, however, are actually drupes such as walnut, almond and coconut. Acorns are true
nuts.
Achenes are hard fruits but not stony. An examples is sunflower “seed”. Some achenes
are winged and these are termed samaras.
Aggregate Fruits: Some flowers have multiple pistils. Their fruits develop into
aggregates of simple fruits all attached to the receptacle of the flower. These simple fruits
themselves can be berries, drupes, follicles or nuts. Observe the examples of these fruits
at the front. Classify which simple fruit type develops from each individual ovary. Note
that strawberry is also an accessory fruit because the fleshy tissue is not derived from the
ovary. For strawberry list both the fruit type of each individual ovary, and the floral part
that becomes fleshy.
Multiple Fruits: Some plants have fruits that develop from whole inflorescences - from
flower stalks
Lab Study D. Fruits and Dispersal- grocery store botany!
Examine six different fruit types and fill in the table below. Use the key below and
pictures provided. Make sure to take both dry and fleshy fruits. Feel free to cut the fruits
open.
Fruit #
Fruit type
Dispersal method
1
2
3
4
5
6
Dichotomous Key to Fruits
Fruit Characteristics
Fruit Type
Dry fruits at maturity (one ovary)
> Fruit with one seed
- Ovary wall and seed coat are fused …………………………………..Achene
- Ovary wall is hard or woody but can be separated
from the seed.
Nut
> Fruits with two to many seeds
- Ovary several cavities when cut in cross section and
several to many seeds.
Capsule
- Ovary with one cavity
+ Mature ovary opens along both sides
Legume
+ Mature ovary opens along one side.
Follicle
Fleshy Fruits (one ovary)
> Ovary with one seed. The seed is surrounded by a vary hard
stone (outer covering of the seed is formed from the inner ovary
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wall)
> Ovary with many seeds. There is no “stone”
- All of mature ovary tissue is soft and fleshy and the
surrounding flower tissue does not develop into fruit.
- Fleshy fruit develops in part from the surrounding
tissue of the flower (base of sepals and petals). The
ovary wall is seen as a “core” surrounding the seeds.
Compound fleshy fruits (more than one ovary)
- Fruit formed from single flowers that have multiple
carpels which are not joined together
- Fruit formed from from a cluster of flowers (called
an inflorescence). Each flower produces a fruit, but
these mature into a single mass
Drupe
Berry
Pome
Aggregate fruit
Multiple fruit
Adapted from http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookDiversity_6.html
And Investigating Biology Lab Manual, Morgan and Carter 2005.
Supermarket BotanyShoot Systems - Stems, Buds and Leaves
Cabbage. A single compact shoot: Leaves are curled over the apical meristem to form a
head. Longitudinal sections show buds in the axils of leaves. Head lettuce shows a similar
morphology. Note that commercial cabbage and lettuce were bred for this heading
quality. Wild cabbage and lettuce show normal stem elongation.
Brussels sprouts. Same species as cabbage: bred for its compact and edible lateral buds.
Kohlrabi. Same species as cabbage: central stalk serves as a fleshy storage organ.
Broccoli and Cauliflower. Same species as cabbage: bred for compact edible flower
heads.
Artichokes. Another edible inflorescence: artichokes are composites similar to a giant
thistle; edible
parts are bracts and receptacles.
Onions. These are bulbs that consist of tightly arranged layers of starchy- succulent
leaves which are connected by a short stem; longitudinal sections show the shoot tip(s).
Potato. An underground stem modified for storage with no leaves called a tuber. Eyes are
buds from which above ground shoots grow. Potato tubers form at the ends or sides of
rhizomes (you might wish to draw a diagram of a mature plant showing the three shoot
types - aerial, rhizome, tuber).
Celery. These stalks are enlarged succulent petioles whoes blades are much reduced.
Commercial celery was also bred for non-elongation of central stem. Rhubarb is another
example of a plant bred for edible petioles.
Root Systems
Carrots. This is a tap root with parenchyma predominating in the secondary xylem and
phloem tissues.
Sweet Potato. Another root modified for storage but, unlike carrot, cambia form around
vessels in the secondary xylem.
Beets. A tap root modified for storage. Secondary growth takes place in a series of
cambia. These form from the inside to the outside with the most recent cambium (the
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outer one) being functional. These cambia give the root its characteristic pattern of
concentric rings in cross-section.
Fruits
Tomato. This fruit develops from a single, fertilized flower the ovary of which becomes
greatly enlarged. It is technically a berry.
Cucumber and Squash. Both are berries in the cucumber family. Each develops from a
single flower. In cross-section one has an air space, the other is solid and succulent.
Pineapple. A multiple fruit developing from an entire stalk of fertilized flowers: The
receptacle and the ovaries are enlarged and fleshy. A longitudinal-section shows the
entire stalk and the positions of individual fruits.
Questions for review
1. Plants have evolved a number of characteristics that attract animals and ensure
pollination, but what are the benefits to animals in this relationship?
2. Complete following table
Features
Moss
gametophyte or
sporophyte
dominant?
vascular tissue?
(y/n)
seeds? (y/n)
fruits? (y/n)
water required for
fertilization? (y/n)
pollen grain? (y/n)
Fern
Conifer
Flowering plant
4. Your neighbor’s vegetable garden is being attacked by Japanese beetles, so she dusts
her garden with an insecticide. Now, to her dismay, she realizes that the beans and
squash are no longer producing. Explain to your neighbor the relationship among
flowers, fruits (vegetables, in the gardening language), and insects.
Seeds. Look at soaked bean and corn seeds and/or posters.
a) Look at a real corn kernel...the embryo is the white leaf-like thing you can see beneath
the skin. i) How many embryos per seed?
b) What was the purpose of the long tube, called corn silk,
which was attached to each corn seed?
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c) Open a bean or peanut seed and find the embryo.
Sketch and label its seed coat, leaves, cotyledon food,
and the scar where it attached to its fruit:
*d) List at least 8-10 FOODS which are made from seeds:
*e) Which is higher in calories per ounce (on average): foods from seeds or veggie?
Why?
ETHNOBOTANICAL OBJECTS
Ethno = ethnic/cultural and so these are plant items used by people for various
purposes.Look at each specimen. What is the “useful” product? What part of the plant
does it come from? Look at the list below. Can you spot the correct category? Write
down the product. (see examples below)
A. whole plants: embryo, seedling, or young sprouts:
B. roots or derived from roots: --e.g. sweet potatoes (often called yams incorrectly)
C. stems, stalks, and trunks:
i. whole stem or their internal fibers: --e.g. linen from the flax plant
ii. underground stems= tubers and rhizomes:
-- e.g. real, tropical, yams
iii. xylem and phloem fluids (sugary water)
iv. wound-healing and pathogen-killing latexes and resins:
D. leaves including leaf stalks (petioles and leaf buds: --e.g., celery stalk= leaf stalk
-- e.g. blue indigo dye from
leaves
E. Flowers, flower parts, or unopened flower buds:
F. fruits/pods (including their seeds) or things derived from fruits:
G. seeds (apart from their fruits):
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Prelab For Plant Diversity II: Gymnosperms and Angiosperms
Name________________________________________
1. Describe three ways in which Gymnosperms are different from Angiosperms
2. List four features of flowers that attract pollinators.
3. From what part of the flower does the fruit develop? ______________________
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73
Name_______________________________
Group members________________________________________________________
Lab 10: Local plant diversity/ taxonomy
Place the 25 plant samples on your lab desk and use your dichotomous key given to
properly name each of the plants. Once you have correctly identified your 25
plants, go the the UW herbarium website at
http://biology.burke.washington.edu/herbarium/imagecollection.php to verify that
your plant is correct. Copy down the general species description
Plant name
Family
General description
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
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20
21
22
23
24
25
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Lab: The Tacoma Nature Center and Preserve at Snake Lake
Name: _____________________________
Meet in the parking lot of the Nature Center at Snake Lake. It is one mile
east of TCC on South 19th street at the corner of Tyler/Stevens (kittycorner from Fred Meyers). Parking is accessed from Tyler street, not S
19th.
We will start behind the building (nearest 19th st) near the inflow by the
information signs.
Snake Lake is a 54-acre nature preserve that consists of open water, forested hillsides and
an urban wetland. Snake Lake is named for its long, narrow shape--not its abundance of
reptiles! The preserve provides habitat for nesting, rearing, foraging and resting of many
different bird, mammal, reptile and amphibian animals. Remember as with any nature
preserve or park--stay on the trails, take out only (and everything) what you take in, and
don’t feed the animal.
 While waiting for everyone to get to Snake Lake, look at the interpretive sign on the
south side of the parking lot. Name three species of native plants and animals found at
Snake Lake
A. Plants
B. Animals
1.
1.
2.
2.
3.
3.
How many species of mammals are found at Snake Lake?
Birds?
c) What is a “riparian” community? (listen)
d) What is the difference between an “ecosystem” and a “community”? (p
433)
1. I can think of a few reasons why this habitat is so great for wildlife
a
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i) Who are the autotrophic producers here? List as many different plant
species as you can recognize:
ii) By what process are they producing biomass?
iii) What factors make this exceptionally great for producers?
b) high species diversity of producers which lead to...
i) high species diversity of heterotrophs - What kinds do you see here
today?
ii) and contributes to seasonal variation in foods (like what do we see today?)
iii) and structural complexity (which means what? why is this important?)
3. Communities with high species diversify are great places for studying
ecological relationships. (p 436)
a) Give examples we see today of “mutualism”.
b) Give examples of relationships we don’t see but presume are also here:
c) Do you see relationships that might be “commensal”?
d) Examples of “parasitism”?
4. When ecologists do research on communities, one thing that is important
is how much food is available to the animals throughout the year or from one
77
year to the next. The “food” or “biomass” (leaves, roots, fruits etc.) is
made of molecules. It can be measured in two ways:
- the volume or mass of the stuff;
- the energy released when the stuff is consumed or burned (calories);
Understand and explain why is there always WAY more mass/calories of
plants than animals. The same principle explains why top carnivores like
hawks are rarer than the herbivores like mice. This is often called the “10%
RULE” and it is way most environmentalists try not to eat meat. Understand
the connection?
5. Has this community always looked the same? Of course not! Disturbance
has occurred here. The change in a community over time is called
____________
a) Primary succession is when.....
When or how did that happen here?
b) What is secondary succession and when/how did that happen here?
6. These nature areas are great for helping clean up pollution and stabilizing
the atmosphere.
a) How is Snake Lake and its surrounding communities helping reduce global
warming?
c) How might the lake be helping reduce “eutrophication” of the stream that
drains the nature area? (listen for the term “bioremediation”)
d) Heavy metal and toxin burial:
78
7. We severely damage natural areas, especially wetlands, in many ways, such
as:
a) acid rain: (explain what is caused from, and what it is, why it hurts)
b) Street run off contains many bad things such as:
c) Nonnative invasive species such as...
Post 1 (wetland loop):
What is a wetland?
What role do the plants have in the filter process?
Post 2(wetland loop):
What is the name of the common wetland tree here?
Make a quick sketch of one leaf:
Post 3 (wetland loop):
The boxes in the trees are for wood ducks. What time of year would be best for spotting
babies? Why?
How do you tell a sword fern from a bracken fern?
Post 4(wetland loop): Skip
79
Post 5(wetland loop):
Name the berries!
What color berries are usually poisonous?
What color is usually safe?
Post 6(wetland loop): First bridge
Turtles are cold-blooded animals. What does that mean? How do they keep warm?
When referring to sexual dimorphism of mallards, which sex is drab colored?
Post 1 (History loop): skip
Post 2: (History loop):
What did native American tribes use the wetlands for?
Post 3: (History loop): Skip
Post 4: (History loop):
What is special about Fireweed (Epilobium augustifolium)?
Post 5: (History loop):
Hwy 16 (built in 1972). Second bridge
What are the larvae of dragonflies called?
Why do adult dragonflies hang around wet spots?
Post 6: (History loop): Other side of the bridge
What is the name of the large native trees with shredding bark?
What is an interesting fact about this tree?
Post 7: (History loop): Skip
Post 8: (History loop):
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What do you think happened here?
Backtrack to the forest loop
Post 8 (Forest Loop):
What do you think happened to this tree?
Post 7: (Forest Loop):
How do you tell a Douglas Fir from any other tree?
What will eventually happen to the Douglas Fir trees and why?
Post 6: (Forest Loop): Skip
Post 5: (Forest Loop):
What is the relationship between closed or open canopies and the amount of understory?
Post 4: (Forest Loop):
What is the name of the tall trees here?
Post 3: (Forest Loop):
What is a snag?
Post 2: (Forest Loop):
What is a moss? A lichen?
How do you tell the difference between moss and lichen?
Post 1: (Forest Loop): skip
Post 8 (Wetland Loop)
What is a nurse log?
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Post 9: (Wetland Loop) Ants!
What do the ants eat?
Post 10: (Wetland Loop)
What happened in this area about 13,000 years ago that formed the land into depressions
called kettles?
Post 11/12: (Wetland Loop) Skip
Final Interpretive sign
Inflow:
Where does the water in Snake Lake come from?
What is the difference between point and non-point source pollution?
What can you do to help the water quality of Snake Lake?
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Lab 8: Forest Ecology Field Walk
Prelab assignment: Read the paper entitled: “Great Bear Rainforest: The Coastal
Temperate Rainforests of British Columbia” and briefly answer the following questions:
1. What is the definition of a coastal temperate rainforest?
2. What did the First Nations tribes use the Western Red Cedar Tree for?
3. Describe the relationship between mycorrhizal fungi, trees, and squirrels.
4. Why are salmon so important?
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5. How does clear-cutting affect Salmon?
6. What is a snag? A nurse log?
7. After reviewing the entire article, list ten species of plants and ten species of
animals.
85
Great Bear Rainforest
The Coastal Temperature
Rainforests of British Columbia
The defining characteristics of temperate
rainforests are: they exist between 32 and 60
degrees latitude in areas with moderate climates
and few temperature extremes; receive at least 192
centimetres (80 inches) of rain every year; have a
high frequency of clouds and fog, and are located
very close to both mountains and oceans. These
conditions are found in small geographic regions on
the west coasts of North America, New Zealand,
Tasmania, Chile, Argentina, Japan, northern
Europe, Turkey, Russia and the Republic of Georgia
(Kellogg 1992) (Redman and Taylor 1997).
Defining Temperate Rainforests
Worldwide temperate rainforests are not distinguished by the species of
plants and animals that live in them but rather by similarities in climate and
geography. For instance, the Chilean temperate rainforest is dominated by
deciduous trees whereas most of the trees in the rainforest in British
Columbia are evergreens. (Wolf and Beebe 1991).
What all temperate rainforests share is a unique
set of environmental characteristics. The most
important of these is they only exist in places
where high mountain ranges loom over the sea
(Kellogg, 1992). Moisture-laden clouds moving
inland immediately hit these mountains, forcing
the clouds up into cooler air, and causing their
stored water to condense and fall to the earth.
Photo: Ian McAllister
In other words, the ocean and the mountains
put the rain in the rainforest and together they
shape every aspect of the temperate rainforest environment (Cannings and
Cannings 1996) (Schoonmaker, Von Hagen and Wolf 1997).
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Physical Characteristics: The Temperate
Rainforest in British Columbia
BC's coast is a rugged, stunning archipelago consisting of countless
windswept islands of all sizes and shapes. Here, the temperate rainforest is
nestled between the coastal mountains and the ocean, on the western edge
of the Canadian province. It originally blanketed 6.5 million hectares
(16,250,000 acres) of land, covering the entire coastline, and extending as
much as 150 kilometres (94 miles) inland, on the steep slopes of wild river
valleys (Beebe and Wolf 1991). Twenty-five species of evergreen trees
flourish in the coastal rainforest, the most common of which is western
hemlock (Pojar, Klinka and Demarchi 1991). Hemlocks dominate the low to
middle
elevation forest west of the
Coast Mountains and extend
inland on the valleys of every
river flowing into the Pacific
Ocean. Less common Douglasfir trees dominate forests on
the east side of Vancouver
Island, the Gulf Islands and
some parts of the southern
mainland. Today, most of the
original Douglas-fir forests
have been replaced by human
settlements, and the few
ancient groves that do remain
are isolated reminders of the
In the secluded
rainforest of
Canada's northwest coast live the
Kermode bear,a
population of
black bears in
which one in ten is
white. The only
Kermode or Spirit
bear habitat on
earth is on BC's mid- and north-coast.
Photo: Ian McAllister
past (Young 1985).
Another common species of tree in BC's rainforest is western redcedar. These
statuesque trees commonly reach 70 metres (250 feet) in height and have
trunks that are three metres (10 feet) or more in diameter. Redcedars thrive
in permanently drenched valley bottoms and in other wet sites, of which
there are many in coastal BC. (Alaback and Pojar 1997). Western hemlocks,
western redcedars and Douglas-firs are joined on the outer coast by Sitka
spruce and shore pine to form a lush towering forest with thickets of bigleaved maple (Alaback and Pojar 1997). Sitka spruce grow best in the rich
soils of river valleys, estuaries and on the exposed coastline (Cannings and
Cannings 1996). They are able to thrive beside the ocean because they are
tolerant of salt spray and thus provide a living shield for less hardy trees and
plants. Ancient Sitka spruce trees rank with western redcedar and Douglas-fir
as Canada's biggest trees and can live for up to 800 years (Kavanagh 1993).
87
About 100 species of vertebrates depend on BC's ancient rainforest to
live (Bunnell and Chan-McLeod n.d.). The most common large
mammals are black-tailed deer, black bear, grizzly bear, gray wolf and
mountain goats. (Henderson, Bindernagel and Blood 1996).
As one moves north up the coast, and the climate becomes cooler and wetter, Sitka
spruce trees become more numerous and Douglas-fir fades out (Alaback and Pojar 1997).
Bogs dominate much of the northern coastal fringe, and many of the outer islands are
carpeted with muskeg. In these areas, the trees remain short and scraggy despite being
hundreds of years old. In other, better drained areas, groves of huge trees flourish,
creating a diverse tapestry (Young 1985).
Weather greatly influences the ecological character of BC's rainforest. In
winter months, storm clouds gather water over the ocean and soak the
forests with almost constant rain. In summer months, warm ocean air meets
cold coastal waters and creates dense layers of fog which moisten rainforest
plants, while long periods of bright sunshine provide welcome nourishment
(Redman and Taylor 1997).
BIOMASS is the total weight of every living thing
in the forest. BC's rainforest has more biomass than
any other forest on earth, including tropical
rainforests
(Beebe and Wolf 1991).
Natural History of BC's Temperate Rainforest
The natural history of coastal British Columbia began 2,000,000 years ago
with the dawn of the Pleistocene Epoch or Age of Glaciers. The Pleistocene
Epoch was characterized by alternating cold and warm periods. During the
cold periods, vast sheets of ice flowed over North America, sculpting the face
of the continent we know today (Cannings and Cannings 1996).
The last ice age formed in the mountain tops 50,000 years ago, in an age in
which woolly mammoths, short-faced bears, muskox and bison roamed the
coast. Twenty-five thousand years later, the ice emerged from the mountains
and covered the area. For the following 15,000 years, glaciers carved
mountains, changed the course of rivers, dug out lakes and ploughed fjords
through solid rock. The recent evolutionary history of BC's rainforest began
10,000 years ago when the glaciers melted for the final time (Cannings and
Cannings 1996).
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The ancestors of the plants and animals living in today's rainforest survived
the ice age in warmer regions to the north and south of coastal British
Columbia. Lichen were the first life form to grow on the barren rock after the
ice retreated. The lichen then produced acid which eroded tiny cracks in the
rocks in which mosses could grow. The mosses supplied food and water for
grasses and ferns, which grew, died and decayed, providing debris which
mixed with rock fragments and formed soil (Young 1985). Grasses and ferns
also provided food for bison which began to roam the south coast of British
Columbia once again (Cannings and Cannings 1996).
Biodiversity
Biodiversity, or biological diversity, is literally the diversity of
life. The term encompasses nature's diversity at the genetic,
species and ecosystem levels. Today most of the planet's
ecosystems are under increasing pressure to supply goods
and services to humanity, and as a result are losing
biological diversity. As species and ecosystems disappear,
the life support systems of the planet are threatened.
An apt analogy for this problem is a man prying rivets out of
the wing of an airplane so that he can sell the rivets - he
sees no reason to worry about the consequences of his
action since he has already removed numerous rivets from
the wing with no ill effect (World Resources Institute, 1989).
The long term health of species and ecosystems is dependent
on the protection of large, contiguous areas from overexploitation.
Alder and lodgepole pine forests were the first to grow in the newly formed soil, as they
were suited to the climate of the time, which was drier and cooler than it is today. Rotting
dead wood, supplied by these initial forests, gradually enriched the soil until it could
support evergreen trees. Eventually, Sitka spruce and mountain hemlocks were able to
thrive on the coast. The climate also gradually warmed, enabling Douglas-fir trees to
grow and replace the initial forests. All of these trees continued to die and decay, and
therefore supply the organic matter and nutrients needed to build forest soils (Cannings
and Cannings 1996).
Five thousand years after the ice retreated, enough soil had accumulated to
support extensive areas of western redcedar and western hemlock. As the
climate became moister and cooler, these trees gradually began to dominate
89
the landscape. Twenty centuries passed and the rainforest of today finally
took shape (Young 1985).
Coastal islands were revegetated by wind borne seeds often carried by birds
flying to occupy their new island homes. Many mammals did not migrate to
the coastal islands but those that did, such as black bears, evolved in small
isolated communities. As a result of being on an isolated island, many of
these animals now have different physical characteristics than their mainland
cousins. Some, such as the Vancouver Island marmot, are now considered a
separate species from their ancestors. Scientists have identified sub-species
of mammals, fish and birds on Haida Gwaii, (Queen Charlotte Islands), that
do not exist anywhere else on the coast, including the worldճ largest
subspecies of black bear. In fact, Haida Gwaii is home to so many of these
unique island sub-species that it is some-times called the Galapagos of
Canada (Cannings and Cannings 1996).
First Nations
Indigenous cultures and the rainforest evolved together in coastal British
Columbia in the
millennia following the last ice age. The forest
and the sea shaped the culture of coastal First
Nations, and their resource use in turn
influenced the character of the forest.
When the first European explorers arrived in BC,
coastal indigenous people enjoyed one of the
most affluent and sophisticated societies in
North America. They lived in huge wooden
Photo: Ian McAllister
houses, had complex social hierarchies, intricate
systems of land ownership and resource
management, dramatic ceremonies, superb art forms and rich oral histories.
The sculptures and paintings of BC's coastal First Nations are now recognized
as one of the world's great art traditions (Suttles and Ames 1997).
Before European colonization, the basic social unit of coastal First Nations
was the local group with its house site or sites, resource sites, and origin
myth. Although each group was basically autonomous, they were linked to
other groups (in what today are referred to as tribes)
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Many species of rainforest birds and fish move back
and forth between the forest and the sea and are
dependent on both for their survival. Some birds
nest and breed in fresh water lakes and then hunt in
coastal estuaries and tidal flats (Henderson,
Bindernagel and Blood 1996). Many other animals,
such as mink, river otters, bats, Pacific giant
salamanders and tailed frogs depend on the close
juxtaposition of aquatic and forest environments for
their habitat needs (Bunnell and Chan-McLeod
n.d.).
through marriage, kinship,
and participation in
ceremonial systems (Suttles
and Ames 1997). All groups
participated in extensive
sharing, trading and raiding
networks throughout what is
today coastal British
Columbia, Alaska,
Washington, Oregon and
California (Heiltsuk Cultural
Education Centre 1989).
The unusual diversity and abundance of fish, shellfish, wildlife and forest
plants in the North American rainforest enabled coastal First Nations to
become some of the largest hunter gatherer societies on earth. Several
hundred thousand indigenous people lived on the west coast of North
America, surviving by foraging for fish, game and wild plants (Kellogg 1995).
The most important tree in First Nations' culture was western redcedar.
Cultures based on this tree developed on the coast when redcedar began to
grow in the rainforest 5,000 years ago. BC's indigenous people used cedar
wood, bark, branches and roots to produce an amazing variety of products.
Their houses were constructed with massive redcedar posts, beams and
planks. They carried water in water-tight cedar boxes, wore long robes made
from cedar bark, carved cedar totem poles, and traveled in dug out cedar
canoes (Young 1985).
Anthropologists believe that the complexity of BC's coastal First Nations'
culture was made possible by the rich rainforest environment. The natural
abundance of the forest and sea enabled people to sustain themselves and
produce surplus food which gave them the leisure time necessary to devise
social hierarchies, patronize the arts and conduct lavish ceremonies. Taking
advantage of this abundance required sophisticated ecological knowledge and
resource management skills (Suttles and Ames 1997).
The languages, art and irreplaceable legacy of First Nations' cultural
knowledge of the environment is being lost faster than the plant and animals
species of the rainforest. Forty-four of the 68 languages believed to have
been spoken on the North American west coast are now extinct or spoken by
fewer than 10 individuals. Today, First Nations populations are a fraction of
their former size. However, with remarkable tenacity, many First Nations
have sustained the integrity of their traditions in the face of overwhelming
pressure (Kellogg 1995).
91
Anthropologists believe that the complexity of BC's coastal First
Nations' cultures was made possible by the rich rainforest
environment. The natural abundance of the forest and sea enabled
people to sustain themselves and produce surplus food which gave
them the leisure time necessary to devise social hierarchies, patronize
the arts and conduct lavish ceremonies. Taking advantage of this
abundance required sophisticated ecological knowledge and resource
management skills (Suttles and Ames 1997).
Ecology of the Coastal
Temperate Rainforests of
British Columbia
In some areas of coastal BC, rain or snow falls on more than half of
the days of a year (Redman and Taylor, 1997). The west coast of
Vancouver Island and Haida Gwaii (Queen Charlotte Islands) are the
wettest places in North America (Cannings and Cannings,1996).
Clayoquot Sound, on Vancouver Island, receives up to 330 centimetres
(130 inches) of rain a year, while the west coast of Haida Gwaii may
receive up to 457 centimetres (180 inches) (Young 1985).
Countless complex and unique ecological processes take place in ancient
forests, most of which we do not fully understand (Crow 1990). There are
several defining characteristics of ancient temperate rainforests on the west
coast of North America. They contain many different kinds of trees of all ages
but most of which are between 250 and 1000 years old (Bunnell and ChanMcLeod n.d.).
Both understory plants and small trees thrive beneath gaps in the forest
canopy. Pounded by centuries of wind and rain, the canopies of ancient
rainforests are rugged and uneven with many broken tree tops, and the
upper branches of ancient trees are often covered with thick layers of moss
and lichen. The diversity of lichen begins to increase when a forest is 150
years old and continues to increase until the forest is 350 years old. For this
92
reason, lichen, perhaps more than any other group of organisms, are prime
indicators of very old forests (Cannings and Cannings 1996).
Water
The North American temperate rainforest is located on the eastern edge of
the Pacific Ocean, the largest body of water in the world. The forest and the
sea are intimately connected in this unique ecosystem. Ocean winds and rain
influence the character and species distribution of the trees, plants and
animals that reside in the rainforest. Rivers and streams carry fresh water
and nutrient-rich organic debris to the coast, replenishing the ocean waters
and endowing them with essential nutrients. Trees and plants supply organic
debris by shedding their leaves or needles, or by falling into the water after
they die (Maser and Sedell 1994) (Cannings and Cannings 1996).
The nutrients and organic debris carried through the forest in rivers
concentrate near the shore, creating estuaries which are one of the most
biologically-rich environments on earth (Cannings and Cannings 1996).
Shellfish such as mussels, clams and crabs break down the organic debris,
thus adding even more nutrients to the estuary and marine environment
(Kellogg 1992).
BC's estuaries are globally important habitats for fish, shorebirds and
waterfowl. Some species of salmon spawn in estuaries while others stop to
feed there during their migration to the ocean (Nehlsen and Lichatowich
1997). Migrating birds such as ducks, geese and swans travel from Siberia,
Alaska and other parts of western Canada every fall to reap the bountiful
harvest of seaweed and salt marsh plants (Cannings and Cannings 1996).
Many coastal birds, such as the rare trumpeter swan, depend on the
sheltered waters of rainforest estuaries for winter refuge (Bunnell and ChanMcLeod n.d.).
Plants and animals in other coastal areas also depend on the forest for their
sustenance. Shallow tidal zones are home to over 600 different kinds of
seaweed which are nourished by the water flowing from the forest. The
seaweed in turn shelters over 70 species of sea star, a greater diversity than
on any coast in the world. The coastal rainforest also nourishes underwater
kelp forests dominated by giant kelp and bull kelp. These kelp beds provide
food and shelter to hundreds of species, such as sea otters. Rivers and
streams also transport nutrients to needy plants throughout the forest
(Cannings and Cannings 1996). In addition, organic debris generated from
the stream-side vegetation feeds everything that lives in the stream, from
bacteria and fungi to insects and fish (Sedell 1990).
Despite the importance of streams and rivers, they are only one part of the
system that controls the movement of water and nutrients in the forest. The
forest canopy also plays an important role by catching snow and rain and
93
then releasing it slowly to the ground, thus preventing floods and landslides
(Franklin 1994). Thick beds of moss, which cover the ground like giant
sponges, help canopies moderate water flows by absorbing and filtering
excess moisture. When water does reach the forest floor, it is channelled
down the sides of steep rainforest valleys, through a maze of dead, hollow
underground tree roots, thus preventing winter storms from washing away
forest soils (Beebe and Wolf 1991).
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Pacific Salmon
Five species of
Pacific salmon
(plus steelhead)
live in the
waters of the
coastal
temperate rainforest and adjacent
landscapes. Nearly all of the streams, rivers
and estuaries in the bioregion, extending
from northern California to Alaska, are (or
were) part of the salmon's extended home.
Salmon begin their lives in rainforest
streams, large rivers and in coastal
estuaries and then migrate to the sea. They
remain in the ocean for one to five years
and then return to the streams of their birth
to spawn (Nehlsen and Lichatowich 1997).
Salmon are a key component of the
rainforest ecology. Returning salmon
substantially enrich carbon and nitrogen
cycles in the vicinity of spawning areas and
at least 22 forest and sea mammals and
birds feed on salmon (including bears,
eagles, orcas and sea lions). Salmon also
play an important role in human societies.
They have been a dominant part of the
culture and diet of coastal indigenous
people for thousands of years. Today, they
are also of great economic and cultural
importance to non-Native communities
(Nehlsen and Lichatowich 1997).
Healthy, multi-aged forests play a critical
role in stream health and salmon survival.
Streamside tree cover provides shade in
summer, keeping salmon stream
temperatures cool and ensuring salmon,
which cannot tolerate high water
temperatures, survive the drier, hot
summer months.
Clearcutting, particularly on steep slopes,
can have a significant negative impact on
fish and fish habitat. Landslides due to
unstable slopes or poor road-building can
cause debris to bury the gravel spawning
beds in streams, smothering salmon eggs.
Without the forest root systems to regulate
water flow into salmon streams, torrents
can wash away gravel spawning beds.
A report from the Bolle Center for Forest
Ecosystem Management details these 95
problems: "Logging in numerous small
streams in the Queen Charlotte Islands
Soil
The soil in BC's temperate
rainforest is maintained by a
continual accumulation and
decomposition of organic
debris such as twigs, logs,
flowers and animal feces and
carcasses. Trees, plants and
animals provide an endless
supply of this debris and thus
protect, nourish and replenish
the shallow layers of organic
soil. The debris is continually
eaten by a host of bacteria,
fungi and algae, causing it to
decompose and release stored
nutrients such as potassium,
nitrogen and phosphorus that
trees need to survive (Norse
1990).
A constant supply of organic debris
is essential in wet climates because
nutrients are washed out of the soil
very quickly by rains (Pojar, Klinka
and Demarchi 1991). Trees in BC's
rainforest get almost all of their
nutrients from a shallow layer of
organic soil near the surface of the
forest floor (Cannings and Cannings 1996).
In a shovel full of rainforest soil there are kilometres of thin threads of
mycelia, the root-like threads of fungi, which evergreen trees need to stay
healthy. The most important of these fungi are mycorrhizal fungi. Mycorrhizal
fungi form mutually beneficial relationships with tree roots, helping them
extract nutrients from the soil and resist disease (Hammond 1991).
By attaching themselves to the tips of roots and reaching out into the soil to
absorb nutrient-rich water from a much larger area than the tree could on its
own, the fungi gather phosphorous and 'trade' it to the roots for carbon.
Mycorrhizal fungi also strengthen the immune systems of trees and produce
growth-regulating chemicals which help trees live longer, healthier lives. An
ancient Douglas-fir may have up to 40 different kinds of these fungi attached
to its root system at all times (Pielou 1996).
Mycorrhizal fungi are found primarily in mushrooms which grow both above
and below the ground and are spread through the forest by the wind and in
the feces of small animals. Underground mushrooms are called truffles and
are abundant in and around big dead trees (Maser 1994). Their odour is
irresistible to small animals such as flying squirrels, voles, chipmunks and
deer mice. These animals dig up the truffles, eat them and then deposit
spores full of mycorrhizal fungi throughout the forest in their droppings
(Cannings and Cannings 1996) (Hammond 1991).
For this reason, many of the giant trees in ancient forests are dependent on
animal droppings and mushrooms (Maser 1994). The fungi in turn depend on
sugars produced by the trees for their survival. When trees are removed
from the forest, the mycorrhizal fungi and other soil organisms begin to die.
When soil organisms die, the soil's ability to store water and nutrients
decreases and gradually the soil becomes inhospitable for all but a few
opportunistic plants (Perry 1990, 1994).
Trees
The size and shape of a tree is determined by its genetic make up, but its
growth is effected by environmental factors such as moisture, light and
competition from other trees (Kavanagh 1993). Short, mild winters,
combined with an abundance of moisture and ample sunlight, create perfect
conditions for huge plant growth in coastal British Columbia (Alaback and
Pojar 1997).
At every point from below ground to 200 feet in the air, trees stretch out
their surfaces to receive what the sky and earth have to offer. A tree is like a
vast collection system, gleaning light from the palest winter sun and
moisture from the thinnest fog (Kelly and Braasch 1988). There are up to 60
million needles on a single ancient tree with a cumulative weight of 200
96
kilograms (440 pounds). If these needles were spread out on the ground,
they would cover a surface area of 10 football fields (Waring 1979) (Maser
1989).
Needles are so well adapted to combing moisture from fog and mist that
approximately one quarter of the annual moisture in the rainforest comes
from water dripping off the needles of trees (Kelly and Braasch 1988). For
this reason, forested land is believed to collect and return to the air at least
10 times as much moisture as bare, deforested land, and twice as much
moisture as land covered by plants other than trees (Young 1985).
One ancient tree also supports thousands of smaller specialized plants,
insects and animals. The huge upper branches of old trees are covered with
debris, moss, lichen and organic soil which is often several inches thick and
supports entire communities of small mammals and birds. Some animals,
such as the tree vole, spend their entire lives in the top of an old tree. Tree
voles survive by eating needles, licking them for water and using them to
build their nests (Kelly and Braasch 1988).
The Life of Dead Trees
When trees die it is usually a result of an accumulation of injuries caused by
lightening, wind and fire, or disease and insect infestation. Once dead, trees
either get blown to the ground or remain standing. Either way, big, old, dead
trees are a very important part of the rainforest (Maser 1989, 1994).
Trees that remain standing after they die are called snags. Snags may stand
erect for up to 200 years. In the first six years of a snag's existence, beetles
chew tunnels throughout the outer layers of wood and introduce wooddecaying fungi and bacteria with their feces. Woodpeckers feed on the
beetles and the tree's branches begin to fall off. Bats use the spaces under
the loose bark of the snag for roosting and rearing their young (Maser 1989).
During the ensuing decades, the snag's wood softens enough for cavitynesting birds to excavate new residences. Only ancient trees grow big
enough to accommodate these birds. These cavities, when vacated by their
initial residents, provide other birds and small mammals with warm winter
and cool summer homes, giving them the temperature stability they need to
survive (Maser 1989).
As more decades pass, the snag shrinks in height and width, and after a half
century, only the largest branches remain attached to the trunk. When the
branches fall off, sunlight is able to reach the forest floor, allowing species of
plants and trees that need light to grow. As decades turn into centuries,
trees and shrubs begin to grow on the snag, using its soft nutrient-rich wood
as soil (Maser 1989).
97
When an ancient tree dies and falls to the ground, it starts ecological
processes which may continue for more than four centuries. As with snags,
beetles enter the downed logs first and introduce fungi and bacteria which
further the processes of decay. The beetles are quickly followed by mites,
termites and carpenter ants which hollow out galleries that salamanders,
spiders and newts use to hunt for food. These teeming populations of insects
become food for birds and mammals (Kelly and Braasch 1988). Eventually,
winter wrens, marten and bears may nest or den in the upturned roots or
hollows of fallen trees (Bunnell and Chan-McLeod n.d).
Tree seedlings germinate on dead trees because the dead trees' spongy,
nutrient-rich wood provides an ideal nursery. As decades pass, a small
number of trees grow to maturity with their exposed roots hugging the nurse
log. Eventually the nurse log completely disappears, leaving the trees it
nurturedstanding on stilts. As the tree decomposes it releases its stored
nutrients back into the forest floor, which is why the area between the soil
and the bottom of a log is the most nutrient-rich place in the forest (Maser
1989, 1994).
Under the Trees
Plants in BC's rainforest often form a nearly impenetrable thicket under the
towering ancient trees. This jungle of shrubs and tree seedlings is collectively
referred to as understory. A rich and complex understory is an important part
of a healthy natural forest.
Understory plants have diverse habitat needs, some requiring constant sun,
others needing constant shade, some liking swampy areas, while others
prefer dry places (Alaback and Pojar 1997) Dense salmonberry thickets
thrive in areas with rich soils and lots of light. The leathery, evergreen leaves
and small bell-shaped flowers of salal bushes are familiar to anyone who has
visited the rainforest in BC. Salal grows in dry areas and thrives on poor soil.
Red huckleberry grows best on fallen logs and is seeded through bird
droppings. Huge skunk cabbages grow in very wet, nutrient rich sites and fill
the air with their pungent, skunky odour in early spring (Cannings and
Cannings, 1996). The only BC plant with bigger leaves than skunk cabbage is
devil's club, whose infamous prickly leaves can be up to 46 cm (18 inches)
across (Young, 1985).
However, nothing characterizes BC's rainforest more than the abundant
waist-high thickets of ferns. The most common types are deer, sword,
bracken and small licorice ferns which grow in living tree trunks. Understory
plants provide food for insects, animals and in some cases humans.
Disturbance and Succession
98
Forests are continually modifying themselves. The basic pattern by which
forests alter and recreate themselves are called disturbance and succession.
Forests everywhere have a history of disturbance of one kind or another.
Some disturbances are quite mild, such as a single tree or clump of trees
falling over after they have been hit by lightening. Other disturbances can be
catastrophic, such as when a fire destroys large areas of forest. Natural
disturbances are a normal and necessary part of the ecology of all forests
(Perry 1990, 1994).
Different forest types are adapted to specific kinds of disturbances (Perry
1990, 1994). Small disturbances are common and beneficial in BC's
rainforest. For example, in coastal British Columbia trees are easily blown
over, as they get their nutrients near the surface of the soil and therefore
have shallow roots (Bunnell and Chan-McLeod n.d.). These small
disturbances allow light to penetrate the forest canopy and nourish plants on
the forest floor, and create nurse logs which enable many different kinds of
trees to grow (Franklin 1994).
Huge winds, like hurricanes, are uncommon in coastal British Columbia and
the constant moisture helps prevent fire. Therefore, unlike most forest types,
large disturbances are uncommon (Kellogg, 1992). On the very rare occasion
when large scale disturbances do occur, they neither kill all of the trees nor
remove the wood. Even large, very hot fires leave pockets of unharmed trees
(Bunnell and Chan-McLeod n.d.).
Industrial foresters often claim that clearcutting mimics natural disturbances
in BC's rainforest. However, a natural opening in these rainforests is
generally less than two tree lengths in diameter, unlike clearcuts (Meidinger
and Pojar, eds. 1991).
Succession is the long-term survival pattern of forests. It is the process
whereby the forest vegetation adjusts to ensure that the landscape remains
alive after a disturbance. For example, after a landslide, a diverse mixture of
shrubs, herbs and pioneer species of trees will begin to grow. Pioneer species
of trees are those which can only grow in exposed conditions and therefore
are the first to reforest a disturbed landscape. Red alder is the most common
pioneer tree species in British Columbia. Pioneer species are important
because they replace nitrogen in the soil and provide new forest cover
(Young, 1985).
In the rainforest, once red alder is in place, western hemlock will slowly start
to grow. After pioneer species have reestablished a forest, their dead leaves
and trunks start to decompose and rebuild the soil so that the trees that are
to dominate the landscape over the long-term are able to grow again (Young,
1985).
99
Industrial foresters, anxious to have commercially valuable trees grow
sooner, often try to kill pioneer species of trees with fires or herbicides.
Creatures of the Rainforest
The most varied forest habitat in Canada is in coastal BC. The massive size of
the trees, the hospitable climate, and disparate landforms, including islands,
plains, estuaries, streams, lakes, lush forest and mountain peaks, provide
suitable homes to one of the most diverse populations of animals in the
northern hemisphere (Bunnell and Chan-McLeod n.d.).
Many rainforest creatures depend on the specific ecological characteristics of
the ancient rainforest to survive. One such creature is the pileated
woodpecker which is the largest species of woodpecker in the rainforest,
growing up to 46 centimetres (18 inches) long. These woodpeckers build
their nests by hollowing cavities in ancient trees. After they leave, their
abandoned homes are used by many other creatures, including tree
swallows, chickadees, bushy tailed woodrats, martens, bats and owls (Maser
1989).
100
Grizzly Bear
Historically,
grizzly bears
roamed more
places in the
world than any
other kind of
bear, finding
wild homes in
Europe, Asia,
North Africa
and North
America.
Today, there are very few wild areas left on
earth big enough to sustain a population of
grizzly bears. European grizzlies are barely
surviving in small, isolated pockets in
Scandinavia, have been completely
extirpated from all but a few places in
western Asia and are extinct in Africa, and
only have healthy populations in Russia.
The grizzly population in North America has
decreased by half in the last century and 99
per cent of their habitat has been destroyed
in the United States south of the Canadian
border (MacHutchon, Himmer, Bryden
1993).
The rainforest on the central and north
coasts of British Columbia is one of the very
few remaining wild places in the world big
enough to support a healthy population of
grizzly bears. Half of Canada's grizzlies
make their homes on BC's coast and have
evolved there for a millennia in the ancient
rainforest. Grizzly bears are prominent in
the stories, songs and dances of coastal
First Nations, who regard these bears as
healers (Ministry of Environment, Lands and
Parks 1995). The traditional wisdom of the
Nuxalk First Nation tells that bears know
which roots and herbs to seek when they
are injured or sick.
Grizzly bears thrive in the most productive
parts of the ancient rainforest. Scientific
studies demonstrate that they spend most
of their time on low elevation mountain
slopes, the bottoms of river valleys, 101
floodplains, wetlands and in estuaries,
gorging themselves on berries, devil's club,
clams, salmon and colonies of insects in
Coastal BC and southeast Alaska
are also home to the largest
population of bald eagles in the
world. These massive birds rely on
many types of huge ancient trees to
build their nests. Marbled murrelets
are another species of bird that can
only live in ancient rainforests.
Murrelets are characterized by their
short wings which they use to
propel themselves under-water in
pursuit of fish (Maser 1989). Pairs
of murrelets spend most of their
lives in the sea but the females fly
inland up to 64 kilometres (40
miles) to nest. They lay a single egg
in a shallow depression in the moss
on branches of trees that must be at
least 60 metres (200 feet) tall. These
birds are now classified as
threatened with extinction because
clearcut logging is reducing their
old-growth nesting habitat
(Henderson, Bindernagel and Blood
1996).
Northern flying squirrels are
another creature which can
only live in ancient forests.
These squirrels make their
homes in any cavity large
enough to accommodate them,
usually preferring those
abandoned by woodpeckers.
Northern flying squirrels are
most abundant in areas that
have large numbers of slowly
decomposing old trees, as they
feed mainly on truffles. They
also depend on gaps in the
forest canopy, as they hunt for
food by jumping out of trees
and gliding through the forest
from one tree to another
(Maser 1989) (Cannings and
Cannings 1996).
One ancient tree in BC's rainforest may be so large and structurally complex
that it can provide breeding habitat for several different bird or mammal
species. In a single ancient Sitka spruce, brown creepers might live under the
bark three metres (10 feet) off the ground, a pileated woodpecker may have
its nest in a cavity 15 metres (49.5 feet) from the forest floor and a marbled
murrelet may lay her egg on a tree limb 40 metres (132 feet) off the ground.
If these creatures are unlucky a predator such as a red squirrel or a marten
may also have a home in the tree (Bunnell and Chan-McLeod, n.d.).
The Pacific giant salamander, the largest salamander in Canada, is one of
many amphibians that can only live in the ancient rainforest. They share
streams with tailed frogs and are also eaten by them. Tailed frogs are the
most primitive frogs in North America and have evolved to breed in cold,
swift rainforest streams. Their tadpoles have sucker devices that enable them
to adhere to rocks (Maser 1989). Tailed frogs are classified as vulnerable to
extinction by the government of BC, primarily due to the destruction of
stream habitat caused by clearcut logging.
Some mammals that live in alpine areas in warmer months migrate to
rainforest valleys during the winter (Bunnell and Chan-McLeod n.d.). Blacktailed deer and Roosevelt elk survive winter months by finding shelter in
ancient forests and eating lichen and needles which grow on old trees.
Clearcutting is causing serious declines in the populations of these animals
on northern Vancouver Island (Young 1985).
Mountain goats spend most of their lives in alpine areas but ancient forests provide them
with necessary protection from cold temperatures and heavy winter snowfall. Like the
deer, they also depend on needles and lichen for food during harsh winter months.
Wolves spend their winters in the forest, hunting the deer and goats (Henderson,
Bindernagel and Blood 1996).
Appendix A: Criteria for Graphing Scientific Data
Often the first step in analyzing the results of an experiment is the presentation of the
data in the form of a graph. A graph is a visual representation of the data, which assists
in bringing out and finding the possible relationship(s) between the independent and
dependent variables. Examination of a graph makes it much easier to see the effect the
independent variable has on the dependent variable(s).
Accurate and clearly constructed graphs will assist in the interpretation and
communication of your data, and when presenting a well-documented argument
supporting or falsifying your hypothesis in the final steps of a scientific investigation.
All graphs should be easy to interpret and labeled fully. The following guidelines will
help you construct a proper graph.
Graphing tips
1) Use graph paper of a high quality.
2) A ruler should be used to draw axes and to plot data neatly and accurately.
102
3) Always graph the independent variable on the x-axis (horizontal axis), and the
dependent variable on the y-axis (vertical axis).
4) The scales of the axes should be adjusted so that the graph fills the page as much
as possible. The axes often, but not always, start at zero. Choose your intervals
and scales to maximize the use of the graph paper. Intervals should be logically
spaced and easy to interpret when analyzing the graph (e.g. intervals of 1’s, 5’s, or
10’s are easily interpreted, but non-integer intervals (e.g. 3.25’s, 2.33’s, etc.) are
not. To avoid producing a graph with a lot of wasted space a discontinuous scale
is recommended for one or both scales if the first data point is a large number.
Simply add two tic marks between the zero and your lowest number on one or
both axes to show that the scale has changed.
5) Label both axes to indicate the variable and the units of measure. Write the
specific name of the variable. Do not label the axes as the dependent variable and
independent variable. Include a legend if different colors are used to indicate
different aspects of the experiment.
6) Graphs (along with drawings, and diagrams) are called figures and are numbered
consecutively throughout a lab report or scientific paper. Each figure is given a
number, a title that describes contents, and an informative sentence giving enough
information for the figure to be understandable apart from the text (e.g. Figure 1.
Temperature and Leaf Color Change. The relationship between the change in
vine maple leaf color and changes in ambient temperature). Generally, this
information is placed below the figure or graph.
7) Choose the type of graph that best presents your data. Line and bar graphs are the
most common. The choice of graph type depends on the nature of the variable
being graphed.
Line Graphs are used to graph data that only involves continuous variables. A
continuous variable is capable of having values over a continuous range (i.e. anywhere
between those that were measured in the experiment). For example, pulse rate,
temperature, time, concentration, pH, etc. are all examples of continuous variables. See
figure 1 on the next page.
Making Line Graphs
1) Plot data as separate points. Make each point as fine as possible and then
surround each data point with a small circle. If more than one set of data is
plotted on the same graph, distinguish each set by using circles, boxes, triangles,
etc.
2) Generally, do not connect the data points dot to dot. Draw smooth curves, or if
there appears to be a linear relationship between the two variables, draw a line of
best fit.
3) If more than one set of data is plotted on a graph, provide a key of legend to
indicate identify each set. Label the graph as a figure, give it an informative title,
and a descriptive sentence.
103
Rate of lactose digestion
(mg lactose/min.)
20.0
15.0
10.0
5.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
pH of solution
Figure 1. pH effects on lactase. Note that a line graph was used to graph the data
because both variables, pH and the rate of digestion, are continuous variables.
Bar Graphs are used if the data involves a discrete variable (non-continuous
variable). A discrete variable, unlike a continuous variable, cannot have intermediate
values between those measured. For example, a bar graph (Figure 2, below) would be
used to plot the data in an experiment involving the determination of chlorophyll
concentration (chlorophyll concentration is a continuous variable) found in the leaves of
different tree species (The discrete variable is the species of tree). Bar graphs are
constructed using the same principles as for line graphs, except that the vertical bars are
drawn in a series along the horizontal axis (i.e. x-axis). In the example below, a bar
graph was used to graph the data because tree species is a discrete variable since it is
impossible to have a value or species between those used.
Chlorophyll concentration
(mg / gram of leaf )
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
Dogwood
Vine Maple
Red Alder
Figure 2. Chlorophyll Concentrations. The chlorophyll concentrations were
measured mg/grams of leaf in the leaves of three tree species.
104