The experiment will be performed in controlled circumstances and I will try not to kill the fleas as there are many ethical issues using live organisms as harming creatures is un-ethical and immoral, the flea will be kept in water at all times so that it doesn’t coagulate in the air and die.
Apparatus
- Light microscope
- Pond water
- Caffeine concentration(s)
- Cavity slide
- Daphnia
- Timer/stopwatch
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. the caffeine used could be of the wrong concentration which could make the results inconclusive, the daphnia will be left until its heart rate returns to normal before the next concentration is tested to avoid caffeine being left in its system when I start the test, to count the heart rate I will tap out the amount of times it beats in a minute.
Results
Death of Gordon!!! TIME OF DEATH 9:42
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.