The purpose of this investigation was to test the null hypothesis that there is no relationship between different chemical stimuli and their effect on the heart rate. To be able to see the effects of the different stimuli a Daphnia was used, or as some people call them a water flea.
The results for each particular stimulus in this experiment will probably be different, some will increase the Daphnia's heart rate, and some will slow its heart rate. This will be due to the different reactions of the chemicals to the body. As most everyone probably already knows different chemicals such as caffeine will speed up your heart rate and others, as alcohol will slow your heart rate.
The experiment on the Daphnia was performed as follows. The experimenters, or group members, first obtained and set up a microscope on their lab bench. Then they, used a Pasteur pipette, to obtain a Daphnia from the stock supply on the middle lab
I think that the null hypothesis that I stated in the beginning of this report can be rejected due to the outcome of the results. I think that there is a definite relationship between different chemical stimulus and heart rate.
I feel that in this lab procedure as in any lab procedure that there are areas of weakness. I think that the main area of weakness would just be human error in the testing of the Daphnia, whether it be a miscount in the number of heart beats or forgetting to turn off the light when not observing them. I also think that there was room for other errors. Another error could have been in the Daphnia itself. Daphnia have a short life span and if you were to grab one that was nearing that life span from the stock of them while conducting the experiment, you could have started out with a slower heart rate to begin with.
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