In this lab we were asked to examine the response of an organism to the presence of chemicals. In this case, the organism we were examining was a Daphnia. Two separate unknown chemicals and a control were used in the process, with the control being water. Our predictions were that one of the solutions would cause the heart rate to increase, while the other solution would cause the heart rate to decrease.
Methods.
In the beginning of the lab, we acquired a Daphnia from a tank of water with a syringe. Placing the Daphnia on the microscope, we then recorded it's heart rate four different times for fifteen-second intervals. After these trials were complete, we then repeated it. However, this time, we put the Daphnia in "unknown 1"." After engulfing the Daphnia in the solution, we again ran the trial, recording its heartbeat once more. After this portion of the trial was finished, we again started another set of trials. This time, we gave the Daphnia "unknown 2"". We again recorded its heart rate four different times at fifteen-second increments. At the end of the solution trials, we put the Daphnia in water, and let it recover". After about 5 minutes of recovery we then did one more set of trials, and recorded it's heart rate one last time. .
Results.
When doing trial 1, the Daphnia had not been given either unknown chemical yet, so the heart rate was it's natural heart rate. In trial 1, the Daphnia had a heart rate of 33, trial 2 a heart rate of 30, trial 3, a heart rate of 29, and trial four, a heart rate of 40. This "normal " heart rate averaged about 33 beats per fifteen-second interval. After this phase was over, we gave the Daphnia "unknown 1"". We again ran four trials for it, which resulted in the numbers 26, 26, 31, and 26. This averaged out to 27.25 and showed a decrease in the heart rate of the Daphnia. After phase two, we gave the Daphnia "unknown 2"." .
We ran the trial four times. The numbers for this trial showed an increase in heart rate, with 38, 38, 38, and 32.
