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Effect of caffeine on heart rate on Daphina

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Introduction

Effects of caffeine on the heart rate of daphnia Aim: to observe the effects of different concentrations of caffeine on the heart rate of daphnia. Null hypothesis: caffeine has no effect on the heart rate of daphnia. Alternative hypothesis: as the concentration of caffeine increases so does the heart rate of daphnia. Scientific background: Caffeine is a nerves cell stimulant that increases heart rate by the stimulation of cardiac cells. Caffeine does this by blocking adenosine, a neurotransmitter that allows the body to relax. This blockage results in the adrenal gland to release adrenaline hormone, this causes the heart rate to increase, pupils to dilate, your muscles to tighten up, and glucose is released into the blood stream for extra energy. Caffeine also increases dopamine; this activates pleasure parts of the brain which activates the caffeine addiction. Over excess drinking of caffeine could result in restlessness, headaches, and increases blood pressure. Over a long term as the body gets used to the amount of caffeine, it needs higher concentrations for more energy, releasing more and more hormones. ...read more.

Middle

4. Place it under the microscope and count how many times its heart beats in 30 seconds on the stop clock. 5. When 30 seconds has past, stop the clock and record the heart beats in a table. 6. Repeat the sample 3 times with distilled water and record the results. 7. Repeat the method with 0.19% of caffeine concentration on another daphnia, and repeat the sample 3 times then record the results. 8. Do the same with 1.59% caffeine concentration and record the heart beats per 30 seconds on the table. The dependent variable in this experiment is the number of daphnia?s used to determine the increase in heart rate. And the independent variable is the concentration of caffeine used and the different sizes of daphnia used for each sample of caffeine. Repeat: for most of the results, three samples were made for each concentration of caffeine, to ensure that the results are as accurate as possible. ...read more.

Conclusion

This proves that the heart beat was gradually increasing as the concentration of caffeine was. The only anomaly shown is the second 0.19% caffeine solution result (60seconds). Evaluation: The method used did have some limitations like the different sizes of daphnia used for different concentrations of caffeine, some where smaller than others making it harder to read their pulse rate. And some further more active than others making it harder for the experimenter to count the number of heart beats per second. The method overall was accurate enough to use, however more repeats could have been done to ensure reliability of data, on the other hand the equipment used wasn?t as reliable to give accurate results, a device for counting all the heart beats were used their would be less errors in results due to the fact that the experimenter could have made a mistake. The results of the experiment raise questions like could the same effects seen on the daphnia apply to a human heart, and if so then what concentration would show a risk to the health of an individual. ...read more.

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