Daphnia Experiment
Effect of Caffeine on Daphnia Heart Rate:
Aim:
To investigate the effect of caffeine on the heart rate in Daphnia.
Hypothesis:
My hypothesis is that as the caffeine content increases, the heart rate if the Daphnia increases.
Equipment: * Culture of water flea – Daphnia * Caffeine of 5 different concentrations * Microscope * Counter * Cavity Slide * Pipettes * Stop clock * Distilled water * Test tubes * Petri dish
Method: 1. Remove one Daphnia and place it in the cavity slide 2. Remove the pond water and replace it with distilled water 3. Leave it for 5 minutes to acclimatize, then observe the heart rate under the microscope for 30 seconds, multiply the number by 2 to calculate the beats/min 4. Repeat with 2 more Daphnia 5. Repeat again, this time with a small concentration of caffeine solution in place of distilled water 6. Carry out for 5 more concentrations of caffeine
Variables:
Independent Variables: - Caffeine concentration Dependent Variables: - Heart rate of Daphnia
Other Variables to be controlled: - Temperature - Volume of solutions - Stress of Daphnia - Size of Daphnia - Time of acclimatisation
Results: Daphnia | Caffeine concentration/arbitrary units | Number of heart beats/min | Mean heart rate (bpm) | A | 0 (control) | 45 | 48.75 | | 5 | 50 | | | 10 | 53 | | | 15 | 47 | | B | 0 (control) | 68 | 73.25 | | 5 | 73 | | | 10 | 76 | | | 15 | 76 | | C | 0 (control) | 96 | 99 | | 5 | 101 | | | 10 | 99 | | | 15 | 100 | |
Analysis:
The number of heart beats increase, as the caffeine concentration increases, as shown in the results.
Conclusion:
The hypothesis was correct as the heart beat did increase as the caffeine concentration increased. However, this experiment could have been more fair due to the following: * All the daphnia used
Aim:
To investigate the effect of caffeine on the heart rate in Daphnia.
Hypothesis:
My hypothesis is that as the caffeine content increases, the heart rate if the Daphnia increases.
Equipment: * Culture of water flea – Daphnia * Caffeine of 5 different concentrations * Microscope * Counter * Cavity Slide * Pipettes * Stop clock * Distilled water * Test tubes * Petri dish
Method: 1. Remove one Daphnia and place it in the cavity slide 2. Remove the pond water and replace it with distilled water 3. Leave it for 5 minutes to acclimatize, then observe the heart rate under the microscope for 30 seconds, multiply the number by 2 to calculate the beats/min 4. Repeat with 2 more Daphnia 5. Repeat again, this time with a small concentration of caffeine solution in place of distilled water 6. Carry out for 5 more concentrations of caffeine
Variables:
Independent Variables: - Caffeine concentration Dependent Variables: - Heart rate of Daphnia
Other Variables to be controlled: - Temperature - Volume of solutions - Stress of Daphnia - Size of Daphnia - Time of acclimatisation
Results: Daphnia | Caffeine concentration/arbitrary units | Number of heart beats/min | Mean heart rate (bpm) | A | 0 (control) | 45 | 48.75 | | 5 | 50 | | | 10 | 53 | | | 15 | 47 | | B | 0 (control) | 68 | 73.25 | | 5 | 73 | | | 10 | 76 | | | 15 | 76 | | C | 0 (control) | 96 | 99 | | 5 | 101 | | | 10 | 99 | | | 15 | 100 | |
Analysis:
The number of heart beats increase, as the caffeine concentration increases, as shown in the results.
Conclusion:
The hypothesis was correct as the heart beat did increase as the caffeine concentration increased. However, this experiment could have been more fair due to the following: * All the daphnia used