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Purpose: To investigate the effect of caffeine on the heart rate of Daphnia (water fleas).

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Introduction

Does caffeine affect heart rate? Purpose: To investigate the effect of caffeine on the heart rate of Daphnia (water fleas). INTRODUCTION: Caffeine is a drug that is naturally produced in the leaves and seeds of many plants. It is also produced artificially and added to certain foods. These days, caffeine is also used as flavour enhancer in wide range of cola and other soft drinks. In addition, it has medicinal use in aspirin preparations and is found in weight-loss drugs and as a stimulant in Red Bull. In humans, caffeine acts a stimulant drug, causing increased amount of stimulatory neurotransmitters to be relaxed. At high levels of caffeine consumption can lead to restlessness, insomnia and anxiety, causing raised stress level and high blood pressure. This can lead to heart and circulatory problems. ...read more.

Middle

Using a pipette, transfer one water flea to the cavity slide. Remove the excess water from the slide using filter paper. Do not remove all the water as this may cause the daphnia flea to die. View the water flea under low power, as high intensity light may evaporate the water in the slide. You can see the heart of the flea through its translucent body. Using a stopwatch record the number of heart beats per minute, use a click counter. Record the heart rate of the daphnia with 5 different concentration of caffeine solution. Repeat the procedure again using other water fleas, and new apparatus, also use different concentrations of caffeine and record you results. Results: Our results: Caffeine solution heart rate/ BPM 2nd test Average Control, distilled water 190 186 188 0.1 190 194 192 0.2 234 216 225 0.3 238 204 221 0.4 174 230 202 0.5 136 210 173 ...read more.

Conclusion

There are various ethical issues to consider while carrying out the experiment. It was decided that doing test on daphnia was necessary for the sake of science as it may be useful for research in future. The daphnia can be easily found in lakes so there is no major risk to the eco system and natural habitat while doing these experiments. The most important ethical issue regarding the use of daphnia is that higher concentration of caffeine may kill the organism. In the class average pool we recorded the average results of all the students who did the experiment. This will give us a good idea whether the heart rate of daphnia increased, in this case it did. If the experiment was to be done again, I would record the temperature of the culture and the room thus reducing errors and making the results more accurate. Conclusion Overall the experiment was successful and we did see a rise in heart activity as caffeine was added to the daphnia. ...read more.

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Here's what a star student thought of this essay

4 star(s)

Response to the question

The purpose of the experiment and the introduction are well done. The effects of caffeine are defined and this leads to what the candidate would expect to happen in the experiment. The main body of text is well presented but ...

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Response to the question

The purpose of the experiment and the introduction are well done. The effects of caffeine are defined and this leads to what the candidate would expect to happen in the experiment. The main body of text is well presented but the conclusion is not well portrayed as it does not take into account external factors which may have affected the experiment.

Level of analysis

The hypothesis is clearly defined and well researched. The method is clearly explained with images that aid the candidates explanations. The flea may have had a fast heart beat being such as small animal so it is dubious as to whether the candidate could get accurate results from this experiment so should maybe have used a larger organism. The candidate did not identify enough errors and improvements with the experiment but considered possible ethical issues with using live organisms thoroughly.

Quality of writing

Punctuation, grammar and spelling are all to a high level and the layout of the experiment is done well and clearly.


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Reviewed by skatealexia 07/07/2012

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