# 19 Flies Osmosis Experiment

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In this trial, water was placed on one side of the double sided bottle while a base with a pH of 11 was placed on the other side. After brief disorientation of the fruit flies’ locations, they were given 5 minutes to travel and choose a side. Both the graph and table display 19 of the fruit flies moving away from the weak acid towards the water with the neutral pH of 7 while 6 fruit flies remained on the side of the weak acid. Using the chi-square method, we determined that our degrees of freedom were 1, thus we had to compare our chi-square values against the number 3.841. This number found using a table of X2 distribution. The chi-square values were found using the following equation: (o - e)2e in which o equals the number of flies on a side of the bottle and…show more content…
In our first experiment, the results ended up being that 15 flies actually chose the more acidic pH of 2 over the 11 that chose water. In our second experiment, 24 flies chose to go towards the more neutral pH of water while 2 chose to go towards the less neutral pH of 5. And in our final experiment, 19 flies chose to move towards the water while 7 chose to move towards the extremely basic pH of 11. We determined our experiment to be successful because in each experiment, the majority of flies chose the more neutral pH of water, except in the experiment with pH 2. This “majority” was determined using the chi-square values. In test one, the chi squared value, which was 18.62, was far greater than the table value, 3.841. This meant that test two supported the hypothesis: the flies were statistically deterred by pH 5. Similarly, in test 3, the chi square value, 6, was higher than the table value, 3.841. As before, this meant the flies were statistically deterred by pH 11, further supporting our hypothesis. This However, test two’s chi square value, 0.31,