The Effects of KCl on the Swimming Behavior of the Paramecium Tetraurelia

By John Vlahos, Teddy Ofossu, Daria Williams, Rachelle Hill


The study of the swimming behavior of Paramecium tetraurelia has procured insightful information about the swimming behaviors of similar unicellular organisms . Furthermore, general knowledge for the interaction of chemical substances in the behavior of unicellular organisms can be obtained by c onducting relevant experiments o n the Paramecium tetraurelia .
P. tetraurelia is a very interesting organism and a closer examination of its qualities would be helpful for better understanding the reasons that it was selected for the purposes of the experiment. Paramecium Biology summarizes the essential qualities of P. tetraurelia as a model organism: "Paramecium tetraurelia … is a free living [ eukaryotic ] unicellular organism that feeds on bacteria and can be easily cultured in the lab. …[It] offers an interesting perspective on the basic cellular and m olecular processes of eukaryotic life. Its large size and exquisitely complex cellular organization facilitate… electrophysical studies of swimming behavior." ( " Paramecium Biology" at <>. ).
Previous experiments, conducted in the laboratory, showed that the various chemical compou nds used were affecting the swimming behavior of P. tetraurelia in two major ways. The swimming speed of the P. t etraurelia was either increasing or decreasing when compared to the speed of P. tetraurelia under normal lab conditions . For example, the addition of CaCl was increasing the swimming speed of the organism, whereas the addition of KCl was decreasing the speed of the or ganism . KCl was affecting the swimming speed of P. tetraurelia much more than the other chemical compounds used. This observation was very interesting, prompting in the further study of the effects of KCl on P. tetraurelia .
As described by David Nardozzi KCl is a metalhalide salt composed from potassium and chloride. It is soluble in water and it occurs naturally as a mineral of sylvite or sylvinite. KCl is primarily used in medicine, food processing and has industrial uses as a fertilizer and as a de-icing product ( "Potassium Chloride, KCl." Chemical and Filtration Products Texas - Chemical and Filtration Products Distributor - Solvents, Acids . ) . Extensive quantities of KCl can harm the human body and can caus e internal organ damage. ( "KCl-20 medical facts from" ., 15 Mar. 2017 ) . Studying the effects of KCl on a specific cell can be adventitious in understanding the effects of KCl in the human body overall. P. tetraurelia can be used in this study, since it is an accurate example of a complex eukaryotic cell.
Previous observations indicated that w hen superfluous KCl is introduced to the environment of the paramecium, the swimming behavior of the organism will be affected. Furthermo re, KCl is ionized in aqueous solutions producing K + and Cl - . The alter native hypothesis states that, if K + and Cl - are added to the environment of the para mecium, then the excess ions will offset the internal balance of the cell and they will gradually decrease the movement of the paramecium. The alternative hypothesis was formed around the fact that the interior and exterior differenc e of K + concentrations will affect the electrical potential difference and interact with the cells movement. ( Course Supplement for Biological Foundations I Bio 10100 . N.p .: Department of Biology City College of New York , page 8 ). The null hypothesis states that if excess K + and Cl - are added to the environment of P. tetraurelia , then the swimming speed of the organism will not be affected.

Experimental design

For this experimen t , the ind ependent variable was the presence of KCl solution to the environment of the paramecium. The treatment level in the experimental group was two drops of KCl with the standard laboratory pipet , in the control group no KCl was added . The dependent variable was the speed of the paramecium in its environment, that speed was calculated in mm/s. The s ample sizes were twenty-five and twenty-five per trea tme nt level, and a total of twenty- five replications. The species used in