Daphnia Experiment

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Caffeine & Alcohol Effect on the Water Flea Heart Rate Abstract In this study, water fleas (Daphnia magna), a semi-transparent freshwater crustacean, are used to study the effects of caffeine and alcohol on heart rate. There was a control group used along with the alcohol and caffeine to ensure the results were more accurate. The prediction was the introduction of alcohol and each increased concentration of alcohol, would decrease heart rate and the introduction and subsequent increased concentrations of caffeine would increase heart rate. The results of this experiment proved the prediction to be correct with the alcohol, but the results from the caffeine were hardly noticeable. Methods & Materials…show more content…
Stress from the noises of our classroom or being moved from one environment to another or the age of the water flea could have changed the normal heart rate. Another experiment controlling these variables could bring about slightly different results. We followed a structured set of directions for experimenting with each variable. First a control experiment was preformed with only the water flea and aquarium water to establish a ‘normal’ heart rate of a water flea. My partner announced when I should begin counting the heart rate and after 15 seconds told me to ‘stop’. We then multiplied the number of beats by 4, and that was our fleas’ heart rate. We repeated this process twice more, and took our average from…show more content…
When the average heart rate from the Control group, (151), is compared against the 3 average heart rates recorded from the three strengths of alcohol, (133, 109, 109), I interpreted that the heart rate is reduced at all alcohol strengths. My hypothesis for the Caffeine portion of the experiment was that at the introduction of caffeine to the water flea, as well as each stronger level of caffeine to its system, the water fleas heart rate would increase. When the average heart rate from the Control group, (176), is compared against the 3 average heart rates recorded from the three strengths of caffeine, (175, 173, 176), I interpreted that the heart rate is similar to both the control test, as well as with all alcohol strengths. I did not expect those results; I anticipated a higher heart rate. Were I to conduct this project again, I would find a more accurate way to measure the heartbeats, wait longer between applications of both alcohol and caffeine and wait longer after each application of alcohol or caffeine for it to take effect in the water fleas system. I would also have a wider range of caffeine levels and alcohol levels to

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