The Effects of Potassium Chloride (KCl) on the Swimming Speed of Paramecium

 

Introduction:

Paramecium tetraurelia, a unicellular ciliate, is an easy to observe organism and perfect for experimentation considering the little upkeep necessary to maintain them. Paramecium being a ciliate means surrounding the organism is thousands of hair-like structures known as cilia. Cilia in paramecium act similarly like the flagella in eukaryotes, with the purpose of helping with movement. Movement is vital to the sustenance of paramecium as they need to be able to find nutriment and flee from their predators. Paramecium’s semi-permeable membranes are significant in this movement as what enters the cell can cause a change in the speed and mobility of it.

The paramecium lab initially started with my class investigating the effects on the swimming speed of the paramecium when exposed to certain environmental factors. With the class being split into six groups, we each chose different solutions to experiment with. The goal being to observe and record the altered speeds of the paramecium when exposed to these environmental factors, whether it be an increase, decrease or stability in speed. After collecting the data from all six groups, the group using the KCl became most intriguing as they had the greatest change in speed compared to the other groups. Since environmental factors can be influenced by human activity, conducting this experiment was important in finding out what are the actual impacts that humans cause to organisms. The class’s alternative hypothesis then became that there will be an increase in the swimming speed of the paramecium when potassium chloride is added to the environment. The null hypothesis for this experiment would be that there will be no change in the swimming speed of paramecium when potassium chloride is added to the environment.

 

Experimental Design:

 

Independent Variable	The addition of KCl
Dependent Variable	The swimming speed of the Paramecium (mm/s)
Standardized Variables	Paramecium tetraurelia: 10 mL Dryl’s solution: 200 mL
Levels of Treatment	2
Replication	6
Sample Size	8 per treatment level per group

Table 1: Experimental design

 

           The experimental design of this experiment included various variables which were necessary for coming up with appropriate results. (Table 1) The independent variable was the addition of potassium chloride to the paramecium. The dependent variable was the swimming speed of the paramecium, expressed in millimeters per second. The standardized variables were the Paramecium tetraurelia, specifically 10mL and the 200mL of the Dryl’s solution. In this experiment, we had two levels of treatment, one controlled group where no potassium chloride was added and the experimental group where 150mL of potassium chloride was added. There were six replications, as we had six different groups participating. The sample size included eight paramecia per treatment level for each individual group. The experimental prediction became, if potassium chloride (KCl) is added to an environment with paramecium, then the swimming speed of the paramecium will increase.

           To perform this experiment, we first placed a millimeter grid in the center of an electrophoresis chamber and filled it with 200mL of Dryl’s solution. After placing it under a dissecting microscope, we added the 10mL of paramecium to the center of the electrophoresis chamber over where the grid was placed. We waited for the paramecium to get accustomed to its environment and then observed and recorded the speed of eight paramecia. We used a stopwatch to track how many squares the paramecium moved over the span of seconds. This, in turn, gave us our swimming speed for the controlled group. Next, we added 150mL of potassium chloride to the electrophoresis chamber and again gave the paramecium time to adjust to the new environment. After that, we observed and recorded the new swimming speeds and behaviors of another eight paramecia. To analyze the data we collected, we used Excel to find the mean and standard deviation of both levels of treatments from the data collected from all groups. The t-value was calculated by hand using the formula provided in the course supplement.

 

Results and Data Analysis:

 

	Treatment Level A No KCl	Treatment Level B 150mL KCl
Mean (mm/s)	0.703	0.388
Standard Deviation	0.338	0.291

Table 2: Summary of data collected from all groups.

 

Figure 1: Average swimming speed of paramecium in both treatment levels with their standard deviation represented by the error bar.

 

t-calculated	4.893
t-critical for 95% confidence level	1.66
Degrees of Freedom	94
Confidence Level	<95.5%

Table 3: Results from t-test analysis

Table 2 shows the mean and standard deviation from the two treatment levels from all the data collected between the six groups. The two means exhibits that the average speed of the paramecium slows down after the potassium chloride is added in its surroundings. This data is needed to perform the t-test analysis to determine whether or not these numbers are statistically significant. Figure 1 shows this data in a bar graph and the standard deviation is represented by the error bars. The class mean for both treatment levels were similar in relation to the data my group obtained.  Table 3 was calculated manually using the average and standard deviations found and inputting the numbers into the t-value formula. The output was used to find the percent of confidence within the data.

Discussion and Conclusion:

In conducting this experiment, we were able to track the effects of potassium chloride on the swimming speed of Paramecium tetraurelia. Through the data obtained our t-value had a 95.5% confidence level, making our data statistically significant. The evidence shows there was a notable decrease in the swimming speed of the paramecium when potassium chloride was added to the environment. Therefore must reject the class’s alternative hypothesis that there will be an increase in the swimming speed of the paramecium when KCl is added to the environment. The null hypothesis that there will be no change in the swimming speed of paramecium when KCl is added to the environment is also rejected. Whilst there was a change in swimming speed of the paramecium since our data was not statistically significant, we cannot support these hypotheses. This can lead to the assumption that Paramecium tetraurelia reacts negatively to potassium chloride because of its effects on the speed. Since speed is so important to the livelihood of the paramecium, the slowing down of it by the potassium chloride is dangerous. Subsequently, this lets us become aware that human impact on paramecium and presumably other similar organisms are threatening.

           The next step of the research should include creating a larger treatment level. In our experiment, we stuck to two treatment levels, one without any potassium chloride and one with 150mL of potassium chloride. Incorporating more treatment levels at different concentrations would allow us to not only have a more significant set of data but also observe how the organism reacts to them. Having other various increases in the amount of potassium chloride used will allow us to see if the substance can actually alter the speed positively. Possibly, it was we used too much or not enough potassium chloride for there to be an increase in speed on the Paramecium tetraurelia.

 

Literature Cited:

Department of Biology City College of New York. Spring 2019. Paramecium Lab. Course Supplement for Biological Foundations I: 7-18, 23-35, 38-41.