Names: Hui Ling, Luisa, Anyelina Juliet The Effect of pH Levels on The Speed of Paramecium Abstract: This experiment was a combination of in class observation and M. Saeed Heydarnejad \' s experiment. The purpose of this experiment was to compare the swimming speed of paramecium at acidic level of pH 5 to a control group of pH 6.8. The speed of 30 paramecium was collected under two environments: basic and acidic. The alternative hypothesize was accepted; paramecium swimming speed will be simnifically faster in acidic environments than in basic environments. Results showed significant difference in swimming speeds of paramecium in the acidic level. Introduction: Paramecium is a single-cell eukaryotic organism. They live in warm fresh water environments such as rivers and lakes. Paramecium have tiny hair all around the outside of their cell. These tiny hair like structures are called cilia. Cilia play an important roll in the movement of the paramecium. By moving the cilia back and forth, the Paramecium can move through the water and look for food. They feed on bacteria, yeast, algae, and other small protozoa. Because bacterias live in slightly acidic environments, p aramecia are attracted to acidity in the water (1-2). Previously in-class, an experiment was conducted in order to observe the behavior of the Paramecium. First the paramecium was placed in a depression slide, and observed under a dissecting microscope . It was observed that some of the paramecium moved back and forth in one line, while the others moved in angular motions. Then, their speed was measured using a 1mm boxed grid. The average swimming speed of the paramecium was recorded to be 0.167mm/s. Furthermore, the paramecium was observed in an electrophoresis chamber . A millimeter grid was placed on top of an electrophoresis chamber raised platform. 200mL of drill \' s solution was added on top of the chamber, and the paramecium was placed on top of the grid as well. Then, he lids of the electrophoresis chamber were turned on and the speed of the paramecium was counted using the millimeter grid again. The average speed of the paramecium was 0.53mm/s. However, this time the paramecium were moving in a zigzag motion from left to right all together. In addition , a previous experiment was done by M. Saeed Heydarnejad . In his experiment he observed the effect of pH levels on the Survival of Paramecium and its tolerance under normoxic and hypoxic conditions. I n his study normoxic condition was defined as air-aerated and a hypoxic condition as a low air-aerated for the media . The purpose of the experiment was to determine in which pH levels and in which conditions can paramecium survive. There were nine treatments of different pH solutions . pH levels of 4, 4.7, 5.7, 6.7, 7.7, 8.7, 9.7, 10.7 and 11.7 were made by adding acetic acid or sodium carbonate the solution with the paramecium. M ethylcellulose was added to the culture in order to slow their movement, this way it was easier for the instructors to count the paramecium. The experiment lasted three weeks. A paired t-test was used to compare the survival effect of varying pH under normoxic and hypoxic conditions. Significant differences were accepted at p<0.05. The experiment showed significant reduction in number of live s of paramecium under normoxic rather than hypoxic condition . The experiment showed that paramecium is more likely to survive at more acidic and hypoxic environment. At pH values of less than 4.7 or greater than 9.7, whether in normoxic or hypoxic conditions paramecium immediately died, whereas at pH 4.7-9.7 were able to survive. (3) Finally, t he following question arose from above observations: Does acidic environments have an effect on the swimming speed of the paramecium? It was hypothesized that paramecium swimming speed will be simnifically faster in acidic environments than in basic environments. The null hypothesis was Paramecium swimming speed will be simnifically slower in acidic environments than in basic environments. The experimental prediction was decided to be: If paramecium culture is placed on top of a millimeter grid on top of a raised platform in the electrophoresis chamber , and exposed to hydrochloric acid, and its swimming speed will be counted using the millimeter grid, then