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Does caffeine affect the heart rate?

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Does caffeine affect the heart rate? Introduction The object of this experiment is to see the affects of caffeine on organisms and how potentially lethal it can be under certain circumstances. For this experiment I will be using daphnia (the water flea) as it has a very thin membrane meaning the caffeine will affect it almost instantaneously and its heart is visible through a microscope as it has a translucent membrane coating it. I believe that the caffeine will significantly affect the heart rate and behaviour of the daphnia as caffeine is a stimulant so speeds up the processes of the brain including respiratory and cardiac cycles. ...read more.


0 0 100 0.01 2 98 0.05 10 90 0.1 20 80 0.5 100 0 Variables other variables to consider when doing this experiment are temperature as it can affect the heart rate of the daphnia and cause outliers in my results, the size of the daphnia as this may affect their behaviour/activity meaning the results would be inconclusive, time exposed to each concentration so that each daphnia has absorbed as much caffeine so its bpm is similar in each result. Method For the experiment I will place a daphnia on the slide and will leave it exposed to the caffeine concentration for 5 minuets then count its heart rate for 1 minute, I will perform each concentration twice to try to reduce random and systematic errors that could be caused in the experiment e.g. ...read more.


TIME OF DEATH 9:42 0.3 129 177 177 186 0.2 177 192 201 210 Our results may be inaccurate as different fleas were used for concentrations 0.2 and 0.3 which could make our results inconclusive. Conclusion I think that the experiment supported my hypothesis of caffeine increasing the heart rate of the daphnia as the higher the concentration the higher the heart rate in our 1st flea, after that the results were less conclusive, if I had the chance to re do the experiment I would do more concentrations and find a more accurate was of counting the bpm as well as making sure that we use the same flea for every experiment as to get more reliable results. ...read more.

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    * Microscopes to view the heart-beats of the Daphnia as Daphnia are very tiny but transparent creatures. * Petri Dish will be used to place the cotton wool in so that the Daphnia will be more stable, and so it can be placed under the microscope so that the heartbeat of the Daphnia can be recorded.

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