The Effect of pH on Trap Closing Times in Venus Flytraps (Dionaea muscipula) {italicize}
David Yu and Haider Alhamawendi
Department of Biological Sciences
Saddleback College
Mission Viejo, CA, (delete comma after CA) 92692
The poorly understood trap closure mechanism of the Venus Flytraps still irk (irks)
scientists today. A highly complex plethora of mechanisms occur simultaneously to close
the terminal leaves of the Carolina native plant in order to trap prey. One of the fastest
movements recorded in the plant behavior measuring (sounds awk- maybe change to “is
measured to be”) about one-tenth of a second. In this experiment, the acid growth theory is
tested as Dionaea muscipula (n=15) are placed into three separate pH values (3, 5, 7). The
hypothesis tested whether or not (so are you hypothesizing that that the pH 3 group will or
won’t have that result, just clarify ) the pH 3 group would result in the fastest trap closing
times. Experimentation found that the pH 3 group’s average closing time was 1.48 ± .0689
(± S.E.M., n=5). The pH 5 group’s average closing time was 1.134 ± .065 (± S.E.M., n=5).
The pH 7 group’s average closing time was 1.44 ± .078 (± S.E.M., n=5). This study found
statistical significance (P<0.01, ANOVA) between the three groups. The pH 5 group
(Bonferroni Post-Hoc) was found to be significant between the pH 3 and pH 7 groups
which rejects the original hypothesis.
Introduction
The mechanism(s) by which Venus flytraps (Dionaea muscipula) enclose prey within its
uniquely shaped terminal leaves still remain a mystery (Fagerberg and Allain, 1991). The Venus
flytrap is an insectivorous plant found in the Carolina bogs and swamplands (Ueda et al., 2010).
In its natural habitat, the Venus flytrap lives in media, or soil, which lacks necessary nutrients to
synthesize proteins for growth. They compensate by consuming large terrestrial insects, such as
ants and spiders, as a source of nitrogen and phosphorus. The natural environment of Venus
flytraps are (is) also constant within a pH range of 4-5. Although the exact mechanism of trap
closure is poorly understood, the link between motor cells and chemical or electrical stimulation
has attracted the attention of many researchers (Forterre et al., 2005; Hodick and Sievers, 1989;
Volkov et al., 2007). Researchers, however, have found that action potentials induced by an
influx of Ca2+ ions have a large role in the trap closure (Hodick and Sievers, 1989). On the
outside, Venus flytraps have numerous small structures called stellate trichomnes— they
protrude from the surface of marginal hairs, stem, and outer leaf surface, which cause
subthreshold stimulation, and sensitize the trigger hairs (Dipalma et al., 1966). The trigger hairs
are found inside the terminal lobes of the Venus flytrap. Mechanical stimulation of two trigger
hairs within 30 seconds of each other will cause enough Ca2+ ions to be released and reach
threshold. From there, the Venus flytrap is able to depolarize until an inevitable action potential
occurs causing the trap to close (Hodick and Sievers, 1989). Although this information is only a
fraction of the entire process. , researchers will explore the proposed acid growth theory— a
theory that states hydrogen ions diffuse into cell walls therefore lowering pH and loosening
extracellular components which facilitates the closing of the trap (Williams and Bennett, 1982).
Materials and Methods
Fifteen Venus flytraps (Dionaea muscipula) {I italicized this} and a (delete) 5 oz. of
dried sphagnum moss was (were) received from Joel’s Carnivorous Plants. Investigators
purchased Dart brand Styrofoam cups, created two sets of holes on the lateral side, and created
one hole on the posterior side (Figure 1). The dried sphagnum moss was rehydrated in
Arrowhead brand distilled water. Venus flytraps were then transplanted with rehydrated
sphagnum moss in Styrofoam cups. Venus flytraps were kept inside an investigator’s room in
Irvine, CA near a window (they received approximately 5-8 hours of sunlight per day), and
submerged (inside a plastic tub and only enough to cover the first set of holes) in distilled water
when the experiment was not taking place. Every cup, each containing a Venus flytrap, was
evenly divided, and randomly labeled using a random number generator with values 3, 5, or 7
(corresponding to each individual pH group being tested). Investigators prepared 3 (three) pH
solutions using 3 separate gallons of Arrowhead distilled water, and General Hydroponics (GH)
brand pH down/up solutions. Investigators added small, but unmeasured amounts of each GH pH
solution into the gallons of distilled water; the gallons were then shaken to allow for full
dissociation. After 15 minutes, the gallons were measured with both EM Science brand pH
indicator strips (measures pH 0.0-6.0) and GH brand pH indicator solution (measures pH 4.08.5). Investigators repeated the process until the desired pH values were obtained.
Figure 1. (changed to bold) Lateral and Posterior view of Styrofoam cups. Holes were each
approximately 2.54 cm in length and 1 cm in width on the lateral side. They were cut 1 cm from
the base of the cup and 3 mm from the base of the cup. A 2 cm circle, under the cup, was also cut
to allow absorption of water
Investigators took each pH group, each consisting of five Venus flytraps, out of distilled
water and into two metal trays. The metal trays were filled, up to the first set of holes in the
Styrofoam cups, with their designated pH solution. The Venus flytraps were soaked in the pH
solutions for an hour. After an hour, the investigators triggered the Venus flytraps’ trigger hairs
with a small stick, and recorded the closing times with a Samsung S5 Galaxy smartphone. The
video footage was transferred to Windows Movie Player where the closing times could be
accurately counted and recorded. This process was repeated approximately twice a week for
three weeks between October 21st and November 11th. The data set was run through an (a) oneway analysis of variance (ANOVA) and a Bonferroni Post-Hoc correction. An ANOVA was
used due to the 3 (three) groups involved and a Bonferroni Post-Hoc correction was used to
ensure statistical significance in results (if it was statistical (statistically) significant in the first
place).
Results
Each group of Venus flytrap, consisting of pH 3, pH 5, and pH 7, had their mean closing
times calculated after six trials conducted twice a week (Figure 2). Highly significant difference
was found between the three data sets after running a single factor analysis of variance (single
factor ANOVA). The pH 3 group’s average closing time was 1.48 ± .0689 (± S.E.M., n=5). The
pH 5 group’s average closing time was 1.134 ± .065 (± S.E.M., n=5). The pH 7 group’s average
closing time was 1.44 ± .078 (± S.E.M., n=5).
WHAT IS THE P VALUE???
GET RID OF FIGURE BORDER
Mean Venus Flytrap Closing Times (sec)
1.8
@
*
1.6
1.4
* @
1.2
1
0.8
0.6
0.4
0.2
0
3
5
pH
7
Figure 2.(bolded) Mean Venus flytrap closing times.(delete this statement, repetitive) Mean
Venus flytraps closing times by pH values where the pH 5 group is significantly different than
both the pH 3 group and the pH 7 group. Error bars are ± SEM.
(Mention the Bonferroni correction in the results)
Discussion
The Venus flytraps (Dionaea muscipula) closing times reflect the favorability in the pH 5
environment. The Venus flytrap shows significant increases in trap closure time after being
subjected to non-optimal pH values. As the Bonferroni correction showed significance between
pH 5 and pH 3, and between pH 5 and pH 7. The results of the experiment do not support the
hypothesis stated, however, there is statistical significance that pH 5, an acidic pH, is preferred
over other pH values. In accepting the null hypothesis, the experimenters do not fully refute the
original hypothesis as the acid growth theory could not be proven to be incorrect. Instead the
experimenters made the assumption that pH positively correlates with faster Venus flytrap
closing times without limitations. Experimenters were unable to access similar research to either
confirm or deny their results.
Future experimentation on the subject should be advised to conduct during non-winter
months. As Venus flytraps are known for their fraction of a second closure times. The dormancy
of Dionaea muscipula brought on by end of the fall season can explain the general slowness of
trap closure rates. Although all traps seem to have been affected equally, more accurate times of
Venus flytraps may prove beneficial. Future experimentation should also be advised to transplant
for at least a month before conducting experimentation as it may assist in increasing accuracy.
Literature Cited
Dipalma, J.R., McMichael, R., and Dipalma, M. (1966). Touch Receptor of Venus Flytrap,
Dionaea muscipula. Science 152: 539-540.
Fagerberg, Wayne R., and Allain, Dawn. (1991). A Quantitative Study of Tissue Dynamics
During Closure in the Traps of Venus’s Flytrap (Dionaea muscipula Ellis). American
Journal of Botany 78: 647-657.
Forterre, Y., Skotheim, J.M., Dumais, J., and Mahadevan, L. (2005). How the Venus Flytrap
Snaps. Nature 433: 421-425.
Hodick, Dieter, and Sievers, Andreas. (1989). On the Mechanism of Trap Closure of Venus
Flytraps (Dionaea muscipula Ellis). Planta 179: 32-42.
Ueda, Minoru, Tokunaga, Takashi, Okada, Masahiro, Nakamura, Yoko, Takada, Noboru,
Suzuki, Rie, and Kondo, Katsuhiko. (2010). Trap-Closing Chemical Factors of the Venus
Flytrap (Dionaea muscipula Ellis). ChemBioChem 11: 2378-2383.
Volkov, A.G., Adesina, Tejumade, and Jovanov, Emil. (2007). Closing of Venus Flytrap by
Electrical Stimulation of Motor Cells. Plant Signaling & Behavior 2: 139-145.
Williams, Mary E., and Mozingo, Hugh N. (1971). The Fine Structure of the Trigger Hair in
Venus’s Flytrap. American Journal of Botany 58: 532-539
Williams, Stephen E., and Bennett, Alan B. (1982). Leaf Closure in the Venus Flytrap: An Acid
Growth Response. Science 218: 1120-1122.
(I’m pretty sure you’re supposed to have 10 sources in your literature cited??)
Review Form
Department of Biological Sciences
Saddleback College, Mission Viejo, CA 92692
Author (s): David Yu and Haider Alhamawendi
Title: The Effect of pH on Trap Closing Times in Venus Flytraps (Dionaea muscipula)
Summary
Summarize the paper succinctly and dispassionately. Do not criticize here, just show that you understood the paper.
This paper was about the closing speed of the traps of Venus Flytraps based on the different pH
groups: 3, 5, 7. The experimenters tested to determine if the pH 3 group would have the fastest trap
closing time compared to the pH 5 and pH 7 group. The investigators used fifteen Venus flytraps and
kept them in a Styrofoam cup apparatus with several holes and rehydrated moss when the experiment
was not taking place. They made the three different pH solutions using Arrowhead distilled water and
the GH pH down/up solutions, making sure that they got the desired pH values of 3, 5, and 7. Five Venus
flytraps were put into each pH group for about an hour. Afterwards, the investigators triggered the
“trigger hairs” of the Venus flytraps and recorded the time it took for the traps to close. Once collecting
the data, the investigators ran a single- factor ANOVA to compare their mean closing times. There was a
statistical difference between the three pH groups. A Bonferroni Post-Hoc test was run which
determined that the pH 5 group was significant amongst all the groups.
Yellow highlights = delete or change
Red highlights= changes/ corrections
General Comments
Generally explain the paper’s strengths and weaknesses and whether they are serious, or important to our current
state of knowledge.
I believe that overall this paper is pretty well written. The introduction gives adequate
background information for a reader with no previous experience on the topic to thoroughly understand
the logistics. The authors make the information simple to understand while still staying true to the core
of the topic. The materials and methods were clearly explained and I enjoyed the use of the visual aid in
figure 1. The results and discussion were good as well. I like the point brought up in the second
paragraph of the discussion portion, about how seasons could be a factor in the rate of trap closing
time.
Although the paper was quite strong, there needs to be minor changes made. These changes are
mostly in grammar/phrasing throughout the paper. I know the p value was mentioned in the abstract
but it’s not mentioned in the results, so make sure to add that. Once the paper is proofread it should be
good to go for publication.
Since I didn’t know any previous information about Venus Flytraps and their mechanism of trap
closure, I was very intrigued by this paper. I think that it’s a good study and it’s important in the sense
that the more we know about our surroundings the better educated we are as human beings. Testing
the various pH’s and seeing what their relationship to the closing rates of these Venus Flytraps were
could be fundamental information for the future.
I’m not extremely surprised by the fact that the pH 5 group had the fastest trap closing time due
to the fact that in the introduction the authors mentioned how the natural environment of these Venus
flytraps is around pH range of 4-5. Therefore, since 5 is the closest number in that range out of the three
possible pH groups used in the experiment it makes sense.
Technical Criticism
Review technical issues, organization and clarity. Provide a table of typographical errors, grammatical errors, and
minor textual problems. It's not the reviewer's job to copy Edit the paper, mark the manuscript.
This paper was a final version
This paper was a rough draft
Typographical errors:
I didn’t find any actual typos throughout the paper. Things weren’t
misspelled. Some things might sound a little awkward, so make sure to
read it aloud and clearly to make sure it makes sense and flows well.
Grammatical errors:
There were definitely a few things that need to be changed grammar
wise. All changes that need to be made are highlighted in the paper.
Some main ones were the misuse of singular/plural forms of words or
sentence structure.
A few things format wise need to be corrected: the figure titles for the
captions need to be bolded and the figure border for Figure 2 needs to
be removed. Check a couple of the commas that were used, specifically
in the header underneath the title where there is a misuse of one.
Textual problems:
Overall, once this paper applies the few revisions that I made, I believe that it is ready for publication.
Recommendation
 This paper should be published as is
 This paper should be published with revision
 This paper should not be published