Rameia's Fast Plant Mini-Lab Report

Rameia Ramsey

Analysis

In this Fast Plant lab we planted and grew Wisconsin Fast Plants. By growing these  plants we were able to see what kind of data we would be working with and then manipulate the experiment to produce results that we wanted and would expect. In order to successfully do this we first planted a parent generation which would serve as the foundation for out other generations.  We continued to grow,water, and monitor the plants over a 35 day period in a classroom with the plants sitting on a watering system under fluorescent lighting.  After the growth of our first set of plants, there were a variety of leaf lengths. On day 9 we counted the amount of leaves grown and recorded the leaf lengths of the plants. Our sample size was 57 plants and the leaf lengths of the parent generation ranged from 2mm to 25mm with the average leaf length being about 9mm.  Through the process of artificial selection we decided to  keep plants with a leaf length of 12mm and over.  All of the other plants that did not meet this requirement were cut out and removed. After removing the plants that did not meet the requirements our sample size decreased to just 8 plants.  This meant we had killed off about 85% of the original parent generation.  With the surviving plants we did various calculations to determine the mean, standard deviation, standard error mean, and 95% confidence intervals of the plants.  From there we used bees to pollinate the surviving plants in order to create seed pods to use for the F1 generation. After we planted the newly formed seed pods we then planted them to create the F1 generation.  After this generation grew, we had observed the plants and decided on a question to test.

After the growth of the parent generation, we reached a sample size of 57 plants.  The plants varied in length but there was definitely a higher number of plants who had an average leaf length of about 9mm which is relates to the the mean of the all 57 plants being 8.83mm.  The median of the leaf lengths was 8.5mm so we can assume that our calculations are accurate.  We tested the standard error of the mean which tests the limits of the mean, meaning it accounts for other factors that could influence the mean of the plants.  The SEM of this generation was 0.45mm.  We also calculated the 95% confidence interval which helps to be 95% confident that the mean of our data only varies from other data by chance.  The upper 95% interval  was 9.74mm and the lower limit was 7.94mm.  In the graph shown you can see that there is a bell curve to the data collected.  Based on the data for this generation we used it as a foundation to figure out what we going to manipulate.  We found that there were very little amount of plants with leaf lengths of 12mm and above so we decided to keep those plants and pollinate them for future generations to be made.

After we had killed of 85% of the parent generation so that we only had plants with leave lengths of 12mm or more remaining, there were only 8 plants that remained.  Out of this group of plants there was not much of a variety of the leaf length.  The average leaf length for this group was 13.88mm, with the median being 13. 75mm again showing the accuracy of the data.  The SEM of this group of plants was exactly .45mm.  The 95% confidence interval for the upper limit was 14.78mm and the lower limit was 12.98mm.  There is definitely a significant difference between the survivors and the original parent generation.  Considering we have selected for taller plants we expect that the generation we breed for will be similar to this group and not the original parent generation.  The graph here also shows how there isnt a bell curve to the data either.  This data we collected was then used as a comparison for the F1 generation plants.       After pollinating the survivors of the parent generation, we came to have and F1 generation sample size of 32 plants. In this generation, there was more variety of the leaf lengths similar to like there was in the parent generation with the  the average leaf length being  6.46mm, this number being significantly lower than both the parent generation and the survivor generation.  The 95% confidence interval upper was 7.09mm and the lower limit was 5.83mm, again lower than the parent and surviving generation.  Throughout the generations none of the confidence intervals overlap which shows how our null hypothesis is rejected because there is a significant difference between all of the means of average leaf length for each generation. Our null hypothesis of this experiment was that there is no significant difference between the average leaf lengths of the parent generation and the F1 generation.  As a result of the experiment we reject the null hypothesis.   

Discussion

Conclusion:

This experiment modeled the effects of artificial selection on the Wisconsin fast plants.  This experiment proved that what is expected to happen does not occur as we were expecting to see that parent generation and F1 generation were to be similar.  There means as seen in the first and last figure are significantly different.  Also the confidence intervals do not overlap which means that there is a significant difference between the two generations.  This proves that we reject our null hypothesis. The graphs for the parent generation and F1 generation are also different.  The F 1 generation has shifted to the left which is the opposite of the extreme that we had selected for. With all of this information to look back upon I can make an assumption that the length of the leaves may not be a trait that is passed down even when you only experiment with one extreme of the leaf lengths.  Some of the limitations of the experiment could have affected our data could be the amount of seeds that actually grew into plants.  There were most likely some seeds that did not grow or plants that did not develop enough in order for us to count them as part of the population.  If there were more plants they could have potentially been apart of the survivor generation and help to contribute and pollinate for the F1 generation.  

Experimental Evaluation:

With the results from our experiment for the most part I feel confident that our numbers are correct.  But there are some factors and situations that could have contributed to slight errors in our numbers that could give us potentially a less than accurate result.  I feel as though most of the error that could have occurred was human error not an error of any instruments used. There could have been errors in the parent generation when measuring the leaf lengths of the 57 plants.  There was not one person designated to measuring, we were all measuring and counting different plants.  There is a very good chance that there could have been a misreading of the measurements and not accurate counting of the amount of plants.  We most likely don’t all have the same reasoning when we try to figure out the measurement of an object or deciding on whether or not to count a specific plant as developed or not. This in turn would have affected how many plants we had in the survivor generation and thus affect our results in the F1 generation.  Also, when we left our plants to grow in the classroom under the flourescent lights and on top of the water system we were not always checking up on them as we were supposed to.  So this could have also affected the growth of the plants and further affect the results we received. The light received by each of the plants could have also affected our results.  We never kept up with measuring how far away each of the plants were from the light, so not all of the plants were receiving equal amounts of light based on their positions which could have affected the growth of the plants.