Core Practical 1 Flashcards
Describe the aim of this practical
To investigate the effect of caffeine on the heart rate of Daphnia
Explain why caffeine is used in this practical
Caffeine acts as a stimulant drug and increases heart rate - Increases blood pressure - Damages endothelium - Inflammatory response - Causes atheroma - Blood clots - Increase risk of CVD
Explain why Daphnia are used in this practical
- Daphnia are transparent which allows us to see internal organs under a microscope
- Daphnia also have a simple nervous system so less of an ethical issue
List the limitations of using Daphnia in this practical
- Ethical concerns of Daphnia being unable to give consent
- Obtained results may not give accurate explanations for the effects of caffeine on humans
List risk factors for this practical
- Daphnia might die due to high concentrations of caffeine
- Daphnia might die due to exposure to heat
- Wash hands after handling Daphnia to avoid pathogens
Name the IV, DV and CV
IV: Concentration of caffeine solution
DV: Heart rate
CV: Time intervals of recording, Volume of solution, Time of acclimatisation and Age of Daphnia
Describe the procedure of this practical
- Place cotton wool to restrict movement of Daphnia on cavity slides
- Use a pipette to transfer one Daphnia to a cavity slide. Add a few drops of caffeine solution.
- View the Daphnia under the microscope using the lowest objective lens and focus on heart
- Use a stopwatch to record the number of heartbeats per minute
- Repeat procedure 3 times to get an average bpm. This increases accuracy of results.
- Repeat whole experiment with 0.10, 0.25 and 0.5 mol dm^-3 caffeine solutions.
Explain what conclusions can be made from this practical
The higher the concentration of caffeine, the faster the heart rate. This means higher increase in heart rate so higher increase in blood pressure and higher risk of CVDs.
