The Life Cycle of the Fern
Introduction:
This essay will discuss the fern life cycle as taught in biology lab. The essay will
cover the basic process which we used to grow a fern. I will discuss the methods and
the
results of the lab exercise. Finally, I will discuss the evidence of the methods and
results
that were obtained .
Methods and Results:
To begin our experiment we obtained a petri dish from our lab instructor which
contained fern spores and the food they needed to survive. We then look at the spores
through the micro scope. It was to soon to see anything but little green dots. We then
put
our petri dishes under a light until next week.
When we came in next week we observed our fern spores through the dissecting
microscope. We looked to see if we could find anything germinating. We quickly noticed
something that appeared like an air bubble squirting out something green. This was our
fern spore which was germinating. Next, we removed a few of the germinating spores
from the petri dish and put them under a compound microscope scope. We found the
spore wall and observed how the developing gametophyte had broken through the wall, as
instructed by our lab manuals. One could also identify the chloroplasts with in the
cell.
We then put up our dishes for another week.
The third week of our fern lab we identified the difference between male and
female gametophytes. We did this by taking a culture from our petri dish and placing it
under a dissecting microscope. Due to the male and female being both located on the
same prothallus it was necessary to obtain the exact location of the antherium and the
archegonium from the lab book or the instructor. Once this was done it was fairly easy
to
tell the difference between the male gametophyte or (antheridium) and female
gametophyte (archegonium) on the prothallus. The antheridium was located around the
perimeter of the prothallus, near the rhizoids. The antheridium was located near the
growing notch on the under side of the prothallus. To me the growing notch seem to like
red dots set up like bowling pins. We also observed sperm swimming around the
archegonium. We then put our fern lab petri dishes back under the light until next week.
By the forth week of our fern lab experiment our gametophytes had grown quite a
bit. We briefly looked at them under a compound microscope, but there was no valuable
information learned from this. The gametophytes would be large enough in the next
couple of weeks to transplant them into three liter soda bottles to grow into full size
fern
plant. This would complete our fern life cycle experiment.
Discussion:
In this section I will talk a little about what I learned from the fern life cycle from
first germination to final result, a full grown fern plant. I will begin by saying that I
had to
learn a lot of specific terms to be able to follow the experiment. It is imperative to
understand the basics get a handle on the whole. Anyway, I will start from the beginning.
I
learned that their were several different stages in which a fern had to go through in
order
to grow into an adult plant. I will describe the fern life cycle as learned in biology
lab and
the lab manual. First the fern was given to us as a gametophyte. The gametophyte
contains
an antheridium, which is the male sex organ that produces the sperm, and the archegonim,
the female sex organ were fertilization takes place. This allows the fern gametphyte to
fertilize itself. Once this happens the gametophyte will give rise to a sporophyte. Then
the
sporophyte will produce more spores and the spores will produce more gametophytes,
thus completing the cycle of life once again.
I learned a lot by watching the experiments through a microscope. The hands on
experience really help to understand what was going on in the gametophyte. When one
could actually see the archegonium and the anteridium on the prothallus it seem to help
make sense of the lab experiment. One could even see the sperm going to the
aechegonium, which lead to fertilization. I can remember looking into the microscope and
seeing the green ooze squeezing out of the cell wall.
In conclusion, all of this combined lead me to believe the fern life cycle did indeed
happen as the lab book and instructor had taught. The experience of studying the fern
life
cycle did spark my curiosity in the development of life from cells. It really amazed to
see
an adult fern grow from something I had to look at through a microscope.
|