Bio Term Essay

926 Words May 6th, 2013 4 Pages
Lard WEeduck
Dr. Lerdkig
Lab Report #2
November 9, 2011
Lab Report: Environmental Control of Sex Determination
Introduction
Ceratopteris richardii, known as a C-fern has a lifecycle referred to as alteration of generations, which consist of neither haploid nor diploid dominant. C-ferns are homospours plants which are important in that they can produce hermaphrioditic gametophytes in order to be able to self fertilize. However, some of the homospourous C-ferns only produce male gametophytes .The life cycle of Ceratopteris richardii starts as a diploid sporophyte which then, by meiosis, produces haploid spores. These spores then undergo mitosis to produce a haploid gametophyte, which can be either hermaphrodite( producing eggs and
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Results
The graph of our results showed the percentage of male gametophytes increasing and then leveling off (Figure 1). This was our trend because most of the points followed this pattern, however; there was a potential outlier at point (68, 32.3). The distribution of gametophytes on the culture plates varied. Plates A and F had even distribution but were very crowed with gametophytes, while plates D and C were evenly distributed but had less gametophytes. Plate E had clumping of gametophytes in the top left corner and plate B had clumping the the bottom right corner.

Figure 1. The relationship between the population density and the percentage of male gametophytes.
Discussion
The prediction that the percentage of male gametophytes would increase as the population density of the gametophytes increased, and the prediction that the percentage of male gametophytes would decrease as the population density of the gametophytes increased were not supported by our results. When the population density was low, the percentage of male gametophytes was relatively low because there would not be enough eggs to fertilize the sperm produced from both the hermaphrodite,and the sperm produced by the male gametophyte. When the population density was high, the percentage of male gametophytes was higher but still less than fifty percent because of the same reasons.The data from our results did support our…

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