Ross Rybakowicz
BIO 115, Section AJ
November 15th 2014
Gametophyte Production in the C-Fern
Hypothesis
B strain does not send signal to call for production of light bulbs.
Methods
To test the hypothesis that the B strain did not send a signal for the production of light
bulbs filtrates and gametophytes were swapped to see which produced the light bulb shaped
gametophyte. The filtrates were the run off of nutrients from the certain strain that was being
grown. The B strain was the perti dish with just mitten gametophytes. The A strain was the petri
dish with mittens and light bulb shaped gametophytes. The negative control for this experiment
was the B filtrate on the B strain. This happened to be the negative control because no light bulbs
were produced. The positive control was the A filtrate on the A strain. The experimental control
was distilled water on the A strain. This was used to show the production of C-Fern without a
change in variables. The experimental treatment was the B filtrate on the A strain. This would
show whether or not the B strain sent a signal to call for the production of light bulb shaped
gametophytes. The plates were placed under a UV light and allowed to grow for a period of one
week. After the growth period, the total number of gametophytes was tallied, and the percent of
light bulbs in each plate were calculated.
Results
The experiment treatment resulted in 61.8% of light bulbs. The experiment control
yielded 33.3% of light bulbs. The positive control yielded 35.3% light bulbs and the negative
control resulted in 0% light bulbs (Table 1).
Discussion
The results from this trial rejected the hypothesis that the B strain does not send a signal
to call for the production of light bulbs because the percentage of light bulbs in the experimental
treatment, B filtrate on to A strain, was higher than the experimental control, A strain with
distilled water (Table 1). The second hypothesis that was tested was that the B strain does not
respond to the signal for production of light bulbs. The hypothesis used the same positive,
negative, and experimental control however the A filtrate was placed upon the B strain; this
would test whether or not the hypothesis was rejected or supported if the percentage of light
bulbs in the experimental treatment was higher than the amount in the experimental control
(Table 2). Both of the hypotheses were rejected from the data because they were both higher than
the percent of light bulbs in the experimental control. It was also found that the density of the
number of gametophytes played a role in this experiment as well. It showed that the higher the
density there was, the more light bulbs were produced.
The type of density that was used when executing this experiment was very important in
the data collection and analysis because the wrong density could lead to inaccurate information.
Since there were more light bulbs in the higher density plates of strain A, a lower density could
skew the data collected, leading to incorrect results in the final conclusion. If a lower density
plate were used, there would not be as many light bulbs as expected thus changing the data and
not supporting the outcome of this experiment. The density observation that was made toward
the beginning of the lab was crucial because without the proper density plates the data would
inaccurate to support or reject this claim.
The reason that light bulbs are produced is for genetic variation. A group of ferns that
only produce mitten gametophytes can survive on their own because these gametophytes are
hermaphroditic, however they do not increase the genetic variation since they self-fertilize. If the
environment were to change, the possibility of extinction would be much higher since there is no
genetic variation in the population resulting in slow or virtually no evolution and adaptation to
the new environment. The reason that this does not occur is that when a stressful environment
occurs a pheromone, antheridiogen, calls for the development of the male gametophyte to
increase the genetic variation of the offspring. In a stressful environment, the light bulb
gametophytes, dwarf males, would then reproduce with the mitten gametophytes, increasing the
genetic variation of the population leading to quicker adaptation to the environment. This
environmental strategy allows the C-Fern to survive and adapt to the environment in
encompasses (Hickok).
For future studies of C-Fern, multiple environmental factors could be tested to see which
one calls for the greatest number of light bulbs produced in the A strain. In order to test this, the
environmental factors, amounts of nutrients, water, sunlight, could be varied in order to see
which environment would call for the greatest release of the pheromone antheridiogen. These
differing variables would be tested and the results would be collected, which would be the
greatest number of light bulb shaped gametophytes.
Tables and Figures
Role in
Experiment
Application
Subject (A Number of Total Number Percentage
(filtrate and or B Strain) Light bulbs
of
of light
concentration
Gametophytes
bulbs
or water)
Experimental
B
A
89
144
61.8%
Treatment
Experimental
Water
A
7
21
33.3%
Control
Positive
A
A
12
34
35.3%
Control
Negative
B
B
0
55
0%
Control
Table 1. Table showing the amount of light bulbs and gametophytes found, percentage of light
bulbs, and which role in the experiment it was used for the first hypothesis.
Role in Experiment
Light bulbs Present
(%) (Average)
0
Experimental
Treatment
Positive Control
28.1
Negative Control
0
Experimental
54
Control
Table 2. Table shows the results of each of the controls and treatment that was used for the
second hypothesis.
References
Hickok, L., Warne, T., Baxter, S., & Melear, C. (n.d.). Sex and the C-Fern: Not
JustAnother Life Cycle. BioScience, 1031-1031. Retrieved November 22, 2014.