Summary Of Daphnia's Heart Rate

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The purpose of this experiment was to test whether or not the heart rate of a daphnia was effected by three different solutions being added: alcohol, lactic acid and, caffeine. We determined that when alcohol was added the heart rate would decrease. When lactic acid was added the heart rate would decrease, as well. When caffeine was added the heart rate would increase. We determined that alcohol would slow the heart rate because it is a depressant. Since humans that drink alcohol suffer from a depressed cardiovascular system and slower brain function, this, in turn, leads to a slower heart rate, because of this we thought that it would also depress the daphnia (Niedziocha 2015). We determined that lactic acid would lower the heart
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Examining the changes in heart rate of daphnia may not translate to the same changes that all vertebrates would experience, but it does provide us with an opportunity to examine how different chemicals effect metabolic processes.
By recording the heart rate of daphnia after different chemicals are given, we should have a better understanding of how daphnia’s are effected by both stimulants and depressants. If the daphnia’s heart rate is less bpm when alcohol and lactic acid are added, then the heart rate was lowered. If the daphnia’s heart rate is a higher bpm when caffeine is added, then the heart rate will increase.
Materials and
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Our results did support our hypothesis. As you can see in Table 1 when alcohol was administered to the daphnia their heart rates did slow down. The average heart rate when alcohol was administered was 92 BPM versus the baseline heart rate average of 191 BPM. When lactic acid was administered their heart rates also went down to 157 BPM. When caffeine was added their heart rates went up to an average of 193 BPM, so this was just a tad higher than the baseline rate of 191 BPM.
Our results did follow along with our predictions. In the case of the alcohol and lactic acid being added the heart rate went down pretty significantly. In the alcohol’s case more drastically than the lactic acid. As you can see from Table 1, we even had one of our daphnia specimens die from the heart rate slowing down too much, most likely.
It was expected that caffeine would raise the heart rate even more than it did. Our results indicate that the heart rate only went up a very small margin of 2%. This reason was not significantly higher than its base rate could be that the daphnia was stressed from already having other chemicals given to it. It also could have been stressed from the beginning due to being squished by the petri dish cover and this would have given us a higher baseline heart rate to begin

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