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Vitamin C Practical

Investigation to find out how much vitamin C is present in a food sample

DCPIP turns colourless in the presence of vitamin C.

  • Make up several vitamin C solution of different, known concentrations. Ideally, six different
  • Measure out a set volume of DCPIP, into a test tube
  • Add one of the Vitamin C solutions to the DCPIP, drop by drop, using a pipette
  • Gently shake the test tube for a set length of time after each drop of vitamin C solution is added
  • When the solution turns colourless, record to volume of vitamin C solution that has been added
  • Repeat the experiment twice more, with the same solution, and take an average
  • Make sure you keep all other variables constant during the experiment
  • Repeat procedure with each solution
  • Use result to make a line graph, showing volume of vitamin C solution against its concentration- this is a calibration curve
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Investigation Using Daphnia

Investigation into the effect of caffeine on heart rate

  • Make up a range of caffeine solutions of different concentrations and a control solution that has no caffeine in it at all
  • Transfer on Daphnia into a dimple on a cavity slide
  • Place a slide onto the stage of a light microscope and focus it on the beating heart of the Daphnia
  • Place a small drop of caffeine solution onto the Daphnia
  • Count the number of heartbeats in 10 seconds and times by six to calculate beats per minute
  • Repeat this 10 times using the same concentration of caffeine but different Daphnia individual each time
  • Keep all other factors constant
  • Repeat the experiment using the other concentrations of caffeine solutions
  • Compare the results to see how caffeine concentration affects heart rate

It is a vertebrate and so feels pain, will die, cannot give consent

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