Name _____________________ Date ________

IB Biology Assessed Experiment - The Effect of Lipase on Lipids in Milk

Apparatus

Each student needs:

• 25ml Lipase solution (5%) (with added bicarbonate)
• 250ml milk
• 2 dropping pipettes
• 1 10ml graduated pipette & filler
• 1 stopwatch
• 1 thermometer
• 20 test tubes & labels.

Access to:

• Phenolpthalein indicator solution
• Water baths at 20°C and 30°C

Method

1. Measure accurately 10 cm3 of milk into 3 test tubes.
2. Add 10 drops of Phenolpthalein to each tube. (check it is pink)
3. Measure 1 cm3 of lipase enzyme into 3 clean test tubes.
4. Incubate all 6 test tubes in the water bath, until they reach the required temperature.
5. Start the stopwatch & carefully pour the milk into all 3 tubes of lipase.
   Record the exact starting times of each tube on a piece of paper as you do this.
6. Record the exact times when the test tube loses its pink colour completely
   (compare it to a pure milk standard solution)
7. Repeat the experiment at the next temperature until you have covered 20, 30, 40,50,60,70 °C
8. Remember to note any qualitative data as you work, and the precision of your equipment & method.

Results

This is being assessed.

YOU MUST ONLY RECORD YOUR OWN RESULTS IN THE TABLE

You MUST design the table of results yourself and include the original notes and numbers in the final report..