Experiments

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

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