Daphnia Magna Experiment
Lab Section: P0501
1. Materials and Methods:
Clean 3-well specimen chambers were kept in ice and a cooling chamber was then prepared to be put under the microscope, by filling it with ice and a small volume of water. This was done to ensure the temperature would remain around 15 degrees Celcius, which could keep Daphnia magna efficiently cool. Furthermore, the different concentrations were prepared in separately labeled eppendorf tubes, by adding distilled water to the 50 mM of caffeine to dilute them to the appropriate concentrations chosen. The slides were then put on the cooling chamber, after small fibers of cotton wool were placed on each well. Wide-mouthed …show more content…
Cotton wool was used to make counting the heart beats simpler by restricting the movement of Daphnia magna. The heart rate was measured after five minutes of letting Daphnia magna sit on the chambers to acclimate to the new environment as a comparison value for the treatments. The concentrations that were treated on the experimental group were 10 mM, 30 mM and 50 mM of caffeine solutions. Each treatment would be dispensed on one of three different Daphnia magna, and then left for five minutes on the cooling chamber, to acclimate to the treatment and the heart rate would be measured. The Daphnia magna would then be transferred into the recovery tank, so that new Daphnia magna could be used. This was repeated three times using different Daphnia magna for every trial with treatment. The same with would happen to the control group, except there would be no treatment added. The total sample size would be …show more content…
a) If caffeine can increase the heart rate of Daphnia magna, then an increase in concentration of caffeine will have a greater increase in the heart rate of Daphnia magna.
b) Foster R. 1997. A stroboscopic method to investigate the effect of caffeine on Daphnia heart rate. Journal of Biological Education [Internet]. [cited 2010 Dec 13]; 31(4): 253-255. Available from: http://www.tandfonline.com/doi/pdf/10.1080/00219266.1997.9655573 doi: 10.1080/00219266.1997.9655573
3. This manuscript supports my hypothesis because it is in regards to the outcome of Daphnia magna when treated with caffeine. The author wrote about how caffeine indeed did have an effect on the heart rate of Daphnia, by increasing its’ heart rate after absorption of the solution. In the data reported in this manuscript, all doses about 10-4 per cent w/v showed an increase in heart rate, more so with increased concentrations, which supports my