CPAC 1: Daphnia

• Transport body

  Heart is visible

  • Monitoring heart rate is not invasive
  • Caffeine can diffuse from solution into frog through skin
• • Daphnia immobilised on cavity slide
  • Acclimatisation time in caffeine solution
  • Use Daphnia of same species, age, sex and size
  • Repeats and calculation of mean
  • Use of concentrations from graph
• Plain water to compare with caffeine solutions

  • To show resting heart rate
• Temperature of caffeine solutions: may increase or decrease heart rate

  Same sex/size/age of ghost shrimp: To produce more valid results
• Aquatic organism: take in caffeine from solution
• Invertebrate: less likely to feel pain
• Daphnia

  Independent: Caffeine concentration

  Dependent: Heart rate

  Control variables: Temperature, volume of solutions, size of Daphnia, time to acclimatise
• Minimise suffering of Daphnia

  • Return to natural habits
  • Replicate conditions to natural environment
  • Turn off microscope lamp (cold-blooded)
  • Not using an excessive amount of caffeine
• Daphnia

  • Must be placed in cotton wool to limit movement to count heart rate