Duckweed LabAn Experimental Study of Population Growth Introd.docx

Duckweed Lab:
An Experimental Study of Population Growth
Introduction (3/2 or 3/3)
How populations change over time, using genetics, allows us to
understand how microevolution works. To understand the
ecology of a population, we need to know how they grow or
decline. There are two components that need to be considered in
studying population growth. First is the data collection.
Gathering data on an existing population and documenting the
number of births and deaths can give us a picture of what is
actually going on in the population. We can see if the
population is growing or shrinking. The second component is
using the data to model and predict how the population will
grow or shrink in the future. Thus, understanding population
growth has important implications in terms of conservation and
management.
How a population grows or declines can easily be determined by
counting the number of births and deaths in a given time. This
can be determined by using the following equation:
∆�
∆� = � − �
Where DN/Dt is the change in population size (N) over a given
time (t). B is the number of births and D is the number of
deaths, which is easy enough. However, this information is
limited. It can only tell us what is going on now (what we are
actually observing and what has occurred in the past), but it will
not allow us to predict what will happen in the future. To be
able to do this, we need to determine the birth and death rates
per capita (or per individual). The per capita birth and death
rates are symbolized by b and d, respectively. These rates are
multiplied by the population number (N) because birth and
death relies on how many individuals are in a population. Thus,
the equation above can be modified to the following equation:
∆�

∆� =��−��
Now, the above formula can be simplified if we assume r to
equal b – d as the per capita growth rate. Additionally, it would
be helpful if we can determine the growth rate in very short
time frames. This is because populations fluctuate regularly
such that the growth rate in the first year may not the same as
the growth rate in the second year. Thus, we can further modify
the above equation to the following:
��
�� = ��
Let’s assume, in a population, that the same amount of
individuals are born (b) and die (d). This means that r = 0. If r =
0, then 0 * N is 0. This means that the population is not
growing, and whatever N was will stay the same. If we assume
that there are more individuals dying than are being born, this
means that r < 0 (some negative number). This means that the
population will decline. For example, if the birth rate is 0.5 and
the death rate is 1, this will result in r being -0.5. This means
that in a population of 100, dN/dt = -0.5 * 100 = -50, which
leads to the population decreasing in size by 50 individuals (100
– 50 = 50). In contrast, if the birth rate is greater than
BIOL251 Spring 2020 Updated 12/03/20 Alejandrino 1
Duckweed Lab:
the death rate, r > 0. This will result in the population growing
in size. If we were to graph this population over time, we would
get a J-shaped curve (or an exponential growth curve). This
usually happens when a population is just starting out.
However, as the population increases, the curve tends to level
out. This is largely because resources become limiting, but
other ecological factors can apply. When this occurs, the graph
will be S-shaped, which is a logistic growth curve. The
population has reached its carrying capacity, which is
designated by K. We incorporate K to the above equation in the
following way:
�� −� ��=��+ � -

Now, how do we determine what K is? K can be estimated from
the data collected. If we observe that the population is no longer
increasing or decreasing, the number of individuals in that
population is K; the population has stabilized and reached its
carrying capacity. Once we have all these information, we can
use them to predict whether a population is decreasing,
growing, or has stabilized. For the most part, ecologists are not
worried about the latter two scenarios. What concerns ecologists
mainly are the decreases in population size. If these patterns are
observed, ecologists need to start thinking about conserving and
managing the population so that it does not die out.
In this lab, we will model the growth curve of duckweed
(Lemna minor), to determine what factors are necessary for its
success. Duckweed is an excellent organism to examine growth
because it is relatively easy to grow in a short amount of time.
It is an angiosperm, but its main mode of propagation is
asexual. New individuals (thallus) emerge out of existing
individuals, which eventually break off and create other
individuals. At some point, the population will reach its
carrying capacity and we can determine what the factors are that
limit its growth.
For this experiment, we will set up duckweed in two conditions:
the first will consist of duckweed growing in distilled water and
the second will consist of duckweed growing in distilled water
with fertilizer. We will grow our duckweed populations for
about a month, counting individuals twice a week. Based on this
experiment setup, start thinking about what your biological
hypothesis might be.
Materials
· lab coats
· gloves
· plastic cups (x7)
· labeling tape
· marker
· distilled water
· fertilizer

· disposable pipette
· duckweed
· toothpick
BIOL251 Spring 2020
Updated 12/03/20 Alejandrino 2
Methods
Duckweed Lab:
1. Form a group of either three (3) or four (4) individuals.
2. Wear lab coats and gloves.
3. For the labeling, be sure to use the labeling tape so that we
can use the cups more than
once.
1. Label three (3) of your cups with “A,” “B,” and “C.” These
will represent the
control or distilled water treatments.
2. Label three (3) of your cups with “D,” “E,” and “F.” These
will represent the
fertilizer treatment.
3. Label the last cup as the “counting cup.”
4. Except for the counting cup, fill the cups with 200 ml of
distilled water and use a marker to indicate the water level on
the outside of the cup.
5. For the three (3) fertilizer cups, add five (5) drops of liquid
fertilizer using the disposable pipette. The fertilizer tends to
settle, so you might want to shake the container, keeping in
mind that the lid is on tight (note: the fertilizer smells really
bad and you don’t want to get it on you).
6. Except for the counting cup, add 15 individuals of duckweed
to the cups using a toothpick. If a thallus is white, it is dead.
Try not to put them in the cups. If they are attached to a green
individual, you can put them in the cup, but don’t count them.
“Baby” thalli do not count unless they are about half the size of
an “adult.”
7. Set your cups on a bench space along the side or back of the

lab. In the counting cup, place your toothpick and disposable
pipette so that you can use them again.
8. In three days (outside of scheduled lab times), your group is
to count the number of thalli in each cup and record them in
Table 1. Remember to count only the green ones as the white
ones have died. You may take the dead ones out of the cups as
long as there is no live ones attached.
9. Once you have finished counting your duckweed, refill the
water up to the line you marked previously. Do not fertilize the
treatments. They will only be fertilized once a week i.e., your
scheduled lab day.
10. Continue this procedure for three weeks. Be sure you are
wearing close-toed shoes, long pants, gloves, and a lab coat
whenever you are working with your plants.
11. On the fourth week, count your duckweed populations one
last time and record them into Table 1.
Table 1: Data sheet for recording duckweed population growth.
A, B, and C represent the control or distilled water treatments,
while D, E, and F represent the fertilizer treatments. Twice a
week, count the number of individuals (N) in each cup and
record them below.
control or distilled water distilled water with fertilizer
GroupDayA B C D E F
0 3.5 7
Duckweed Lab:
10.5 14 17.5 21 24.5 28 K r
Data Calculations (3/30 or 3/31)
On 3/30 or 3/31, you will receive your group’s complete data
from your professor. Now, you need to estimate K (the carrying
capacity) and calculate r (the intrinsic rate of increase) for each
of your population.

12. K is estimated by averaging the last two or more counts
where the population has stopped growing and leveled off. If it
seems like the population has not leveled off, use the last count
as K. Do this for each of your population and record K into the
“Group Duckweed Data” Excel spreadsheet.
13. To calculate r, remember that the basic logistic population
growth equation is �� −�
��=��+ � -
If we solve for r, the equation can be rewritten as �=+��-+1-+
� -
or
�=+ ∆� -+ � - �∗ ∆� �−�
Remember that DN/Dt is the change in population size (N) over
a given time (t). Thus, we are multiplying it to the inverse of
the population size with respect to K. Now, r can be calculated
for multiple, specific time intervals and averaged (see Table 2).
Below are the detailed instructions to calculate r for one
population.
�� −�
Duckweed Lab:
1. Using Excel or some other spreadsheet program, create a
table similar to Table 2 for each of your populations. The first
column should be the days we collected data. For our lab, keep
in mind that we collected data every 3.5 days. To simplify the
work, assume that each 3.5-day interval is one (1) day. We can
make adjustments later by multiplying 1 day by 3.5.
2. N are the population (size) counts per day. You can copy
these over from the “Group Duckweed Data” Excel Spreadsheet.
3. DN represents the change in population size from the
previous day to the current day. You can think of this as
∆� = �0 − �012

where Nt is the current day and Nt-1 is the previous day. Enter
these differences
into the third column.
4. The fourth column is a division of DN from the third column
by the product of
the population from the previous day (Nt-1, second column) and
Dt, which is 1.
5. The fifth column incorporates the carrying capacity (K) that
you averaged for the population. K is divided by the difference
between K and the previous day’s population size (Nt-1). There
is no need to calculate the last row of the fifth
column because this usually results in a large number, which
can skew the data.
6. Finally, r (the intrinsic rate of increase, Column 6) is the
product of the fourth and fifth columns. At the bottom of the
column, average all the r values for the
population and enter it into your “Group Duckweed Data” Excel
spreadsheet.
7. Repeat this process for the rest of your group’s populations.
Table 2: An example for calculating r based on the data
collected, where Dt = 1 day and K = 337, which an average of
the population size from Day 3 through Day 6.
Day
0 1
2 3 4 5 6
N DN DN/(Nt-1*Dt) K/(K-Nt-1) r 15 - - - -
22 22-15=7 7/(15*1)=0.47 107 85 3.86
355 248 2.32
308 -47 -0.13
339 31 0.10
346 7 0.02 - -
0.47*1.05=0.49 1.07 4.13
337/(337- 15)=1.05

1.47 3.40 -18.72 2.48 11.62 1.17
r (average) 2.33
14. Once you have recorded all of your group’s populations’ K
and r, upload the completed
file into the Group Duckweed Data link on Moodle.
Statistical Analyses (4/6 or 4/7)
Thus far, each group has uploaded their completed duckweed
data onto Moodle. For statistical analyses, these data should be
compiled together and reorganized. As with the previous lab, I
have done the former but you have to do the latter. Before you
begin, download the Class
Duckweed Lab:
Duckweed Data Excel spreadsheet from Moodle. Also make sure
that K and r were calculated correctly.
15. First, calculate the average population of all groups’
Treatment 1 (all control; A, B, and C together) from the initial
day.
16. Then, repeat the process for each day of Treatment 1. You
should have a total of nine averages.
17. Do the same for Treatment 2 (fertilizer treatments or D, E,
and F together).
18. Then, graph the growth curve of Treatment 1 and Treatment
2 using the class averages. Remember which axis the
independent variable goes. The graph should have two growth
curves, which are Treatment 1 and Treatment 2 averages per
day.
19. Next, perform an ANOVA comparing K between the
treatments and construct a graph
that shows this comparison with the appropriate error bars.
20. Finally, perform an ANOVA comparing r between the
treatments and construct a graph
that shows this comparison with the appropriate error bars.

Specific requirements for the final paper
Introduction: Below is an outline of how the Introduction for
this paper should be organized and what information should be
included. Be sure to use scientific literature to support your
explanations.
· Start with a paragraph that broadly explains what the
experiment is about. What is the main idea of the experiment
and why is it important to test? Think about the big picture of
this second part of the class.
· The next paragraph should be about growth curves. Explain
what growth curves are and how they relate to the main idea of
the experiment.
· The third paragraph should introduce the experimental system.
Why is Lemna minor an ideal organism for the experiment?
What can it tell us about growth curves and the main idea? How
might the treatments affect the growth curves?
· The last paragraph should explain how experimenting on
Lemna minor will help us understand growth curves and the
main idea (What is your objective?). Don’t forget to include
your biological hypothesis and make sure your references in the
previous paragraphs back it up.
Results: Below is a list of specific figures that need to be
included in the final paper.
· A figure showing the class average growth curves of
Treatment 1 and 2.
· A figure comparing the class average of K between Treatment
1 and 2. Be sure to include
the appropriate error bars that match the results of the ANOVA.
· A figure comparing the class average of r between Treatment 1
and 2. Be sure to include
the appropriate error bars that match the results of the ANOVA.
Writing Guidelines and Rubric

BIOL/ENVS251 Spring 2020 Updated
20/02/20 Alejandrino 1
One of the major goals of the laboratory section of this course
is to develop scientific
writing skills. Students are required to write three (3) formal
laboratory reports. These formal
reports should follow the format of primary research papers
found in scientific journals. This
handout is a guideline describing the required structure for a
formal report with the rubric for
grading (Table 1).
Table 1: This is the general rubric used for evaluating formal
laboratory reports based on the
guidelines explained below. A detailed rubric follows the
guidelines (Table 2).
Item Percentage Value
Title 5
Abstract 15
Introduction 15
Methods 15
Results 15
Discussion 15
Literature Cited 10
Formatting 10
Total 100
Title
• The title must be descriptive and informative. You can try to
attract the reader’s attention,
but this can often result in a misleading statement. In comparing
the two titles below, the
first certainly grabs the reader’s attention, but is the ocean

really boiling? The second title
is more descriptive, informative, and accurate.
o “Boiling Sea Food: The Effects of Temperature and Salinity
on the Mass
Mortality of Pisaster ochraceus Along the California Coastline.”
o “Increased Ocean Temperature May Result in Mass Mortality
of Pisaster
ochraceus Along the California Coastline.”
• The title should also contain the major result, specifically
whether or not there is a
relationship between the independent and dependent variables
(or two independent
variables). The second title clearly states that an increase in
ocean temperature may result
in mass mortality. The first title vaguely describes some effect
of temperature and salinity
on mass mortality.
• Finally, the title should identify the focus species, if
applicable. In both titles, the species
is clearly identified.
• Below the title should be the author’s name, their institution,
and their institution’s
address.
• “García, S., Whittier College, Whittier, California 90608”
Abstract
An abstract is a concise summary of the paper. It should
provide all the relevant
information needed for the reader to understand the scope of the
study. Abstracts do not include

references and the best abstracts are written after all the other
parts of the paper have been
written. Abstracts should include the following:
• an orientation to the theme of the experiment; the general
purpose for conducting the
study
• the specific objective of the experiment with the hypotheses
• a description of the most important methods
• the specific results that addresses the hypotheses, with
statistical values
• a conclusion that addresses the general importance of the
experiment, with respect to
the theme
Introduction
The rationale of the introduction is to logically discuss the
importance and the purpose
and importance of the study. It is typically organized in an
inverted triangle format, such that the
first paragraph provides a broad background of the study. The
introduction then gradually
narrows to the last paragraph that provides the specific
hypotheses of the study. Below is a
general outline, but please follow the specific requirements
detailed in the lab handouts.

• The introduction should start with a broad background to
orient the reader to the general
theme (natural selection, fitness, demography, biodiversity,
etc.), and why it is important
to study.
• The second part of the introduction should provide the premise
of the study. What is
currently known about the theme? What similar studies have
been conducted to address
the theme and what are their results? This is where most of the
previous studies are used
to make a case for the purpose of the study. This part may
consist of multiple paragraphs
that each discuss a single topic.
• The third part of the introduction should discuss what is still
unknown about the subject.
What is the study trying to answer? How will the study attempt
to contribute to the body
of knowledge about the theme?
• Finally, the introduction should provide a testable hypothesis
with predictions. “Testable”
means that there is a way to gather data and the data can be
analyzed to find an answer.
Methods
• The methods should contain enough detail so that the
experiment can be repeated. This
should include the statistical analyses.
• The methods should be written in paragraph format.
• The methods should be written in past tense because it

outlines what procedures were
done.
• Do you best to use passive voice.
• The methods should identify the control (if any) and
treatments.
• Similarly, the methods should identify the independent
variables and dependent (if any)
variables.
• The methods should explain why specific procedures were
taken.
o For example, “The salinity of each tide pool observed was
measured using a
Vernier LabQuest 2 with a salinity probe. The salinity was
measured in parts per
thousand (ppt) and it was collected to determine whether there
was a relationship
with the size of Lottia gigantea, such that smaller individuals
were associated
with more saline conditions.”
• Statistical analyses should be explicitly stated, especially how
the test could support the
hypothesis.
o For example, “A chi-squared test was performed to examine
whether the

population of D. melanogaster deviated from Hardy-Weinberg
equilibrium during
the course of the experiment. A significant difference in allele
frequency between
the beginning and the end of the experiment will show that at
least one criterion
of Hardy-Weinberg equilibrium has been violated.”
• If data were collected in the field, the study site should be
provided.
Results
There are two components that need to be in the results. The
first component is a written
summary of the data trends and statistics. The second
component is figures and/or tables that
graphically display the trends and statistics. The written
summary has to come before the figures
and tables; the former provides the context for the latter.
Additionally, the results should contain
as few figures and tables as possible. If a table is showing the
same information as a figure, get
rid of the table.
• The written summary should objectively state the overall
outcomes and general trends of
the experiment in paragraph format. Describing each datum is
not useful or informative.
• The results should not include any raw data; manipulated data
are okay.
• The results should not include interpretations of the results;
interpretations belong in the
discussion section.
• The results should include the statistical

significance/insignificance (p-values) as often as
they are mentioned.
• The figures and tables should be referenced in the written
summary and are numbered
independently.
o “Figure 1 shows…”
o “…population increased (Table 1).”
• The figures and tables should be arranged in order of
reference (sequentially). Do not talk
about Figure 2 first if Figure 1 appears first. If you must,
change the order of the figures
and tables.
• The results should include the fewest number of figures and
tables as possible.
• If figures are included, descriptive captions should be placed
below the figure. The
importance of descriptive captions is that the figure (or table)
should be clear enough to
stand on their own.
o For example, “Figure 1: During the four weeks of sampling,
the number of A
alleles (black lines) increased while the number of a alleles
(gray lines) decreased
in D. melanogaster. Weekly data are averaged and error bars are
provided to
show the variation in the data. Population allelic frequencies for
Week 3 through
Week 5 were statistically significant (p<0.05) when compared
to the initial
population.”

• Figures should have axes clearly labeled with the appropriate
units. If you have
dependent variables, it should be placed on the y-axis.
• Do not include gridlines as they obscure the data.
• Titles are not necessary, as the caption should provide this
information.
• The data should fill the figure and the figure should be large
enough to show detail.
• If tables are included, they should convey a different set of
information from the figures.
If not, keep the figure and get rid of the table.
• Descriptive captions should be placed above the table.
o For example, “Table 1: Pairwise genetic distances of 16S
rRNA among
specimens of Amusium pleuronectes, Ylistrum balloti, and
Ylistrum japonicum.
Asterisks (*) indicate the Ylistrum specimens. Values below the
diagonal indicate
percent sequence similarity; pairwise comparisons above the
diagonal are
presented as a heat map, with dark shades representing higher
similarities between
sequences. Labels for Amusium and Ylistrum specimens are as
follows: source

(SL, Serb Lab; GB, Genbank), unique numerical identifier, and
country (AU,
Australia; CN, China; JP, Japan; NC, New Caledonia; PH,
Philippines; QL,
Queensland, Australia; TH, Thailand; WA, Western Australia,
Australia).”
• Tables should have clearly labeled column and row headings
with units (as necessary). If
you have dependent variables, they should be the column
headings.
Discussion
The purposes of the discussion are to explain how the
experiment supports or do not
support the hypotheses, and to explain how the experiment
relate to the general theme discussed
in the introduction. As opposed to the introduction, the
discussion follows a normal triangle (not
inverted) format, such that the first paragraph discusses the
specific outcomes of the study. The
discussion then gradually broadens to the last paragraph
explaining the overall importance of the
study.
• The first part of the discussion should restate the hypotheses,
the major outcomes, and the
general trends. It should also state whether the outcomes and
trends do or do not support
the hypotheses.
• The second part of the discussion should explain how the
experiment helped in
understanding of the general theme. This should discuss
similarities and/or differences in

results comparing similar studies. Be careful with making
overly broad generalizations.
What do the results mean and what do they not mean?
• The third part of the discussion should explain how the
experiment did not help in
understanding of the general theme. You may discuss the
limitations and unexpected
outcomes of the study and how the experiment could be refined
to further help in
understanding the general theme. However, do not state any
errors. Errors should have
been avoided or corrected.
• The discussion should then conclude with a summary of the
overall importance, to
science and to society, of examining the general theme.
Literature Cited
The format of references vary. For this course, use the
following guidelines:
• The references must be listed alphabetically, by the first
author’s last name.
• The references must have the “hanging” paragraph format, as
shown in the examples
below.
• There must be at least three (3) primary and peer-reviewed
references.
o Primary means that the authors who wrote the reference
conducted the study.
Books are considered secondary literature.

o Peer-reviewed means other scientists read the study and
agreed it was acceptable
for publication.
• All three (3) references must be cited in the text.
• The in-text citations must be formatted according to the
following conventions:
o One author
§ “Chan (2000) found that…”
§ “According to Chan (2000), the…”
§ “was not a major factor (Chan, 2000).”
o Two authors
§ “García and Smith (2000) found that…”
§ “According to García and Smith (2000), the…”
§ “was not a major factor (García and Smith, 2000).”
o Three or more authors (“et al.” is Latin for “and others.”
Alternatively, one can
write “and colleagues” or “and coauthors.”)
§ “Smith et al. (2000) found that…”
§ “Smith and colleagues (2000) found that…”
§ “Smith and coauthors (2000) found that…”
§ “According to Smith et al. (2000), the…”
§ “According to Smith and colleagues (2000), the…”
§ “According to Smith and coauthors (2000), the…”
§ “was not a major factor (Smith et al., 2000).”

• The references should either be in APA or Harvard format.
o For example, Journal article in APA format:
Spoelstra, K., Wikelski, M., Daan, S., Loudon, A. S., & Hau, M.
(2016). Natural selection
against a circadian clock gene mutation in mice. Proceedings of
the National Academy of
Sciences, 113(3), 686-691.
o For example, Journal article in Harvard format:
Spoelstra, K., Wikelski, M., Daan, S., Loudon, A. S. and Hau,
M., 2016. Natural selection
against a circadian clock gene mutation in mice. Proceedings of
the National Academy of
Sciences, 113(3), pp.686-691.
o For example, Book in Harvard format:
Fisher, R.A., 1930. The genetical theory of natural selection: a
complete variorum edition.
Oxford University Press.
Formatting
There is a general format that most research papers follow, but
many vary. The most
important format to follow is the one provided by the publisher
or instructor. For this course, use
the following guidelines:
• You must submit the report as a Word document so that the
following items can be
assessed. If another document type is submitted, points will be
deducted because the
correct formatting cannot be evaluated.

• A cover page is not necessary.
• There is no page limit.
o The reason for this is that the focus needs to be on
communicating what the
research is about, not on how many pages it takes. Additionally,
people’s
communication skills vary. However, there are some general
patterns. For
example, a four-page report tends to lack sufficient information
and detail. In
contrast, a 30-page report tends to be verbose and tangential. As
with any writing
assignment, the best way to start is by creating an outline. An
outline ensures that
only the necessary and relevant information are in the report
and it will help in
being organized and staying on task.
• Use 1.5 spacing paragraph format.
• Use either Arial or Times (New Roman) fonts.
• Use the standard 12-point font size.
• Use the standard one-inch margins on all sides of the paper.
• Use page numbers. It does not matter where on the page they
are, just be consistent.
• Use the appropriate measurement units where necessary.
Science uses the metric system,

so make sure units are in meters, liters, or grams.
• Use the correct species scientific names. Below is the
scientific name of the common
fruit fly written in two acceptable forms. The genus name is
always capitalized but the
species name is never capitalized. The entire species name is
either italicized or
underlined, but not both.
o Drosophila melanogaster
o Drosophila melanogaster
o When the species is first introduced, the full species scientific
name should be
used (as above). Subsequent mention of the species can be
shortened as D.
melanogaster (or D. melanogaster).
• The report must be organized as this guideline is presented:
Title, Abstract, Introduction,
Methods, Results, Discussion, and Literature Cited.
• Each section of the report should have a natural flow from one
idea to another. It should
not jump back and forth between ideas.
• Similarly, each paragraph should have a natural flow with a
topic sentence about a single
concept, a body that supports the idea, and a conclusion or
transition sentence.
• Be sure the report is easy to read (clear and effective
communication); keep spelling and
grammar errors to a minimum.

Table 2: Below is a detailed rubric used for evaluating formal
laboratory results. A P will
indicate the specific criterion is met and will receive a score of
10. An O will indicate the specific
criterion is not met and will receive a score of 5. “Most” and
“some” will indicate two different
levels of meeting the criterion, such that “most” will receive a
score of 8 while “some” will
receive a score of 7.5. A “0” will indicate no attempt was made
to address the criterion and will
receive a score of 0. A “-” will indicate that the criterion is does
not apply and will not be scored.
Title: Criteria Evaluation Percentage (5)
Is it descriptive and informative?
Does it contain the major result with respect to the variables?
Is the focus species identified (if applicable)?
Is the author’s name included and formatted correctly?
Is the author’s institution included and formatted correctly?
Is the institution’s address included and formatted correctly?
Abstract: Criteria Evaluation Percentage (15)
Is the general purpose of the study stated?
Is the specific objective stated?
Are the hypotheses stated?
Is the most important method described?
Is the result that addresses the hypotheses stated?
Are statistical values provided?

Is a conclusion provided?
Does the conclusion address the general importance of the
experiment?
There should not be any references.
Introduction: Criteria Evaluation Percentage (15)
Does it follow an inverted triangle format?
Is the general theme explained?
Is the importance of the general theme explained?
Does the introduction explain what is known about the subject?
Does the introduction discuss similar studies and their results?
Does the introduction discuss what is unknown about the
subject?
Does the introduction provide the purpose of the experiment?
Does the introduction discuss how the experiment will
contribute to the body of knowledge about the theme?
Does the last paragraph contain a testable hypothesis?
Methods: Criteria Evaluation Percentage (15)
Can the experiment be repeated with the information provided?
Is the methods written in paragraph format?
Is the methods written in past tense?
Is passive voice used?
Are the controls (if any) and treatments identified?
Are the dependent (if any) and independent variables identified?
Do the methods explain why specific procedures were taken?
Were the statistical tests explicitly stated?

Were the statistical tests appropriate to answer the hypotheses?
Is the study site provided (if applicable)?
Results: Criteria Evaluation Percentage (15)
Does the section contain text that describes the trends?
Is the text written in paragraph format?
The text should not include each datum.
The text should not include raw data.
The text should not include interpretations.
Does the text include statistical significance/insignificance (p-
values)?
Does the text appear before any figures and tables?
Are figures included?
Are figures referenced in the text?
Are the figures numbered independently?
Are the figures ordered sequentially?
Do the figures contain descriptive captions?
Are the captions placed below the figure?
Do the figure captions include p-values (if applicable)?
Are the figure axes clearly labeled?
Are the units included in the axes’ labels (if applicable)?
Are the dependent variables on the y-axis (if applicable)?
The figures should not have any gridlines.
The figures should not have any titles.
Does the data fill the figure?
Is the figure easy to read?
Are tables included?
Are tables referenced in the text?
Do the tables show different information from the figures?
Are the tables numbered independently?
Are the tables ordered sequentially?
Do the tables include descriptive captions?

Are the table captions placed above the table?
Do the table captions include p-values (if applicable)?
Are the rows and columns clearly labeled?
Are the units included in the row and column labels (if
applicable)?
Are the dependent variables on the column headings (if
applicable)?
Is the table easy to read?
Does the section contain the fewest number of figures and
tables?
Discussion: Criteria Evaluation Percentage (15)
Does the section follow a non-inverted triangle format?
Are the hypotheses restated?
Are the major outcomes and general trends restated?
Is the support (or lack thereof) of the hypotheses explained?
Is an explanation given on how the experiment helped in
understanding the general theme?
Is the experiment compared to similar studies?
There should not be any overly broad generalizations made.
Are the limitations discussed?

Are the unexpected outcomes discussed?
Are future directions discussed?
There should not be any errors discussed.
Is the overall importance to science discussed?
Is the overall importance to society discussed?
Literature Cited: Criteria Evaluation Percentage (10)
Are they listed alphabetically?
Are they in “hanging” paragraph format?
Are there at least three (3) primary and peer-reviewed
references?
Are they all cited in the text?
Are the in-text citations properly formatted?
Are they in APA format?
Formatting: Criteria Evaluation Percentage (10)
Is the report a Word document?
There should not be a cover page.
Does the report use the 1.5 spacing?
Is it written in either Arial or Times (New Roman) fonts?
Is it written using the 12-point font?
Does it have one-inch margins on all sides of the paper?
Does it have page numbers?
Are the appropriate measurement units used?
Are scientific names properly formatted?
Is the report organized (similar to the guideline)?
Does every section have a natural flow?
Does every paragraph consist of a single topic?
Is the report clear and easy to read?

General theme
· Population growth
· Carrying capacity
· Competition for resources
· Interest specific: fertilizers, nutrients, space in the cup,
· Limited resources?
· They grow on the surface they cant grow below water, surface
are of the water needs to be large enough to be able to support
water
· References what kind of references did u think about?
Something talking about why we are using them, using our
subject/plant for experiment, something about population
growth,
· Look at population growth specifically exponential and
logistic curves you
· Use insects
· Flowers
· beatles
· anything to make a case for whatever hypothesis you may
have!
· How to estimate K: take the last count of whatever population
you are looking at,
· JR: Your cuurents counts are 19 22 22 21 19 21
· Things may level off things may change in a week
· Use that table
· Break up that formula into various parts based on the counts
that you will get next week
· You want to estimate what jr
· You will do that for every cup you have and put that in the
files that I send to you

· Three figures
· 1.Class average growth curves
· 2. A and o curves
· 3. k& R
· How are you going to graph this: BAR graph to show the
differences to see if it actually is significant or not include the
air bars to see if its significant
· Is there Another test that is appropriate: Yes
· T is test for two groups
· Bio nova is for 2 or more /more rigorous test anyway
Sheet1Treatment 1: distilled water onlyTreatment 2: fertilized
distilled
waterGroupDayABCDEFJasmine0151515151515Rachel3.51815
16181618Abdull720151818172010.52017202017201422202322
202117.51820232320212119222221192124.5191922222021281
72121211921K182021.521.519.521r0.380.650.760.7610.32dayN
dNdN/(Nt-1*dt)K/(K-Nt-
1)r01511830.261.222020.11111110032000-9042220.025-4.5-
0.225518-4-0.036363600.1636363661910.000925926-18071900-
180817-2-0.01315791.8947368 r(averge)0.38dayNdNdN/(Nt-
1*dt)K/(K-Nt-
1)r0151150040215004031720.136.670.5342030.1801.18520000
062220.1-100719-3-0.14201.3682120.112.11
r(averge)0.38dayNdNdN/(Nt-1*dt)K/(K-Nt-
1)r01511610.073.310.2221820.133.910.4932020.116.140.68423
30.1514.332.1552300-14.330622-1-0.04-43.330.6272200-
430821-1-0.05-431.95 r(averge)0.76dayNdNdN/(Nt-1*dt)K/(K-
Nt-
1)r01511830.23.310.66218006.14032020.116.140.6842220.114.
331.4352310.05-43-1.95621-2-0.09-

14.331.2572210.05432.05821-1-0.05-431.95
r(averge)0.76dayNdNdN/(Nt-1*dt)K/(K-Nt-
1)r01511610.074.330.2921710.065.570.35317007.8042030.187.
81.3852000-390619-1-0.05-391.9572010.05392.05819-1-0.05-
391.95 r(averge)1dayNdNdN/(Nt-1*dt)K/(K-Nt-
1)r01511830.23.50.722020.1170.783200021042110.05211.0552
10000621000072100008210000 r(averge)0.32

Duckweed LabAn Experimental Study of Population Growth Introd.docx

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