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Samms / Heriberto
June 16th, 2017
Lab Partners: Jennifer Rodriguez, Dior Dieng
The effect of Magnesium Chloride on the Speed of Paramecium
Introduction, Hypothesis & Justification:
A ciliate is a single-celled animal of a phylum distinguished by the possession of cilia. An example of a ciliate would be a Paramecium tetraurelia -- a free-living, unicellular ciliate from the kingdom Protista. They thrive in warm, fresh environments such as rivers and lakes. Paramecia are perfect candidates for laboratory experiments, considering they pose no threat to human health, and the population is maintainable as long as there are no food sources present. Paramecium are found to have around 5,000-6,000 cilia (hair-like projections) on their surface, which allow them to move. Their movement is also dependant on calcium ions (Ca^2+). The differences of an electrical potential difference = voltage across the membrane of the cell so that the solution inside the cell is usually more negatively charged compared to the solution outside the cell. During this experiment, paramecium's swimming behavior is studied ; taking into account the direction they move, and how fast they are moving. Specifically, a millimeter grid is used to measure the distance travelled, over the amount of time that it took to travel that distance.
According to this background information, the class hypthesized that Magnesium Chloride will significantly slow down the paramecium (paramecium will take more time to cross 5 millimeters).
This experiment included 3 students (experimenters), who studied the effect of Magnesium Chloride on the speed of 50 paramecium ( sample size ). Students used two treatment levels (the control group, and the experimental group). The control group involved the paramecium being submerged in only dryl's solution (2 mM sodium citrate, 1 mM NaH2PO4, 1 nM Na2HPO4, 1.5 mM CaCl2, pH 6.8) inside of an electrophoresis chamber, while the experimental group involved the paramecium being submerged in dryl's solution mixed with Magnesium Chloride (50 mM ) inside of an electrophoresis chamber. First, the paramecium's speed was recorded 3 separate times, only submerged in dryl's solution. In order to record the speed, a millimeter grid was placed on the stage of the dissecting microscope. So, while the paramecium are swimming in the electrophoresis chamber, a millimeter grid is now present for the purpose of measuring distance traveled by paramecium in the unit of milimeters . A stopwatch was used to time how fast the paramecium traveled 5 millimeters. At this point, the data recorded would be distance in millimeters, and time in seconds. So, we would have the speed of the paramecium in millimeters per seconds. The experiment underwent its second treatment level, this time its experimental group. The paramecium's speed was recorded 3 separate times, except this time with 50 mM of magnesium Chloride ( independent variable )added to the dryl's solution. The dependent variable is the speed in millimeters per second of the paramecium. The replication of this experiment was only one . Students predicted that if the magnesium chloride is added to the paramecium culture, it will take more time for the paramecium to travel 5 milimeters , therefore making the paramecium speed up.
*Summary of above experimental design*
If magnesium chloride is added to the paramecium culture, it will take more time for the paramecium to travel 5 milimeters .
Speed of paramecium in millimeters per second
50 mL of Magnesium Chloride
30 volts of current, 225 mL of Dryl's solution, millimeter grid, dissecting microscope, stopwatch, electrophoresis chamber
Levels of treatment
Paramecium only submerged in Dryl's solution
Paramecium submerged in Dryl's solution and magnesium chloride
Results and Data Analysis:
Figure 1: Bar graph representing average swimming speed of Paramecium without 50 mL of MgCl2 (control), and with 50 mL of MgCl2 (experimental)
Mean speed (mm/s)
Figure 2: Mean swimming speed of control group and experimental group. Standard deviation of control group and experimental group
| t -calculated|
T-critical for 95% confidence level
Figure 2: t-test chart displaying t-calculated, t-critical, degree of freedom, and confidence level
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