The Effects of Caffeine on the Heart Rate of Daphnia magna. Laura Haggerty . Question. How does the introduction of caffeine affect the heart rate of Daphnia magna?. Background Information. Daphnia magna are minute water crustaceans commonly known as water fleas.
How does the introduction of caffeine affect the heart rate of Daphnia magna?
It was hypothesized that as Daphnia magna were introduced to increasing concentrations of caffeine, their heart rate would also increase
Independent variable- concentration of caffeine
Dependent variable- heart rate of Daphnia magna
Constants- spring water
Control- spring water with no added caffeine
100 mL graduated cylinders (2)
5 petri dishes
250 mL beakers (5)
Caffeine pill (200 mg)
Serial dilutions were made in five 250 mL beakers
This resulted in a control and four varying concentrations of 1 mg/ml, 0.1 mg/ml, 0.01 mg/ml, and .001 mg/ml
The Daphnia magna were placed in each solution in small petri dishes before being transferred to depression slides.
The depression slides were placed on a compound microscope and observed.
The heart rate of the Daphnia magna was then counted for ten seconds and multiplied by six to calculate the results for heart rate per minute.
Five trials were performed for each of the four concentrations and the control.