Results:In this experiment the effect of different hormones on heart rate of Daphnia was examined. It was investigated which substances act as stimulants and which substances act as depressant. Initially, Daphnia was placed on depression slide under the microscope and the average heart rate was determined. Subsequently, Daphnia was treated with different type of hormone and the effect on Daphnia heart rate was observed. It was investigated which substances act as stimulants and which substances act as depressant. Daphnia was treated with aged water, caffeine, ethyl alcohol, nicotine, and epinephrine, and their effect on heart rate of Daphnia was observed. The results are posted on table 1:Table 1: Average heart rate for Daphnia at pre-stimulus and post stimulus for different hormones:# of TryAged WaterCaffeineEthyl AlcoholNicotineEpinephrineControlTreatedControlTreatedControlTreatedControlTreatedControlTreated1277.2278285.2343.2297.2266.8318.5274298344.82204.68200.67189.3272228171.3270.67238.67298.67324.673273.3289.3232.7262.7234222244126252295.34264.67194269.33324.67258167.33262.67272.67258.671845360.3283.4283.7310.4279.1235274.1339.6283.6252.262042602723283282282441602763407285324.7285335.3283.3299.3282.7270276.7299.38264259279300295296299294N/AN/AAverage266.643261.134262.029309.538275.325235.716274.455246.868277.663291.467StandardDeviation49.33744.37334.06829.42633.73450.31025.68770.69017.85756.964P valueP>0.05P0.05P>0.05P>0.05During initial observation, Daphnia was placed in microscopic slide and the average heart rate was calculated. Then, aged water was added to Daphnia and its effect on heart rate of Daphnia was observed.
The result is posted on table 1:Figure 1: Age water added to Daphnia.
From figure 1 it can be observed that, originally Daphnia had an average heart rate of 266.644+/-49 beats per minute. When the daphnia was stimulated with aged water, the heart rate decreased to an average of 261.134+/-44 beats per minute. After performing Mann-Whitney U statistical test no significant difference was observed in the average heart of Daphnia before and after the addition of aged water.
Daphnia was then treated with caffeine and the change in heart rate was observed. The result is posted on figure 2.
Figure 2: Daphnia treated with caffeineFrom figure 2 it can be seen that before the treatment, Daphnia had an average heart rate of 262.029+/-34 beats per minute. When solution containing caffeine was added to Daphnia, there was a significant change in heart rate...