EDEXCEL IGCSE BIOLOGY
PRACTICLES
Investigate food samples for the presence of glucose - correct answer - add
benedict's solution and sample of food to a test tube
- heat in 60-70 degree water for 5 minutes
- observe colour
GLUCOSE = orange / brick red
NO GLUCOSE = blue
Investigate food samples for the presence of starch - correct answer - add a
few drops of iodine solution to the sample
STARCH = blue/black
NO STARCH = brown
Investigate food samples for the presence of protein - correct answer - add a
few drops of biuret solution to the sample
PROTEIN = violet/purple
NO PROTEIN = blue
Investigate food samples for the presence of fat (lipids) - correct answer -
Food sample is mixed with 2cm3 of ethanol and shaken
- ethanol is added to an equal volume of cold water
LIPIDS = cloudy emulsion forming
investigate how enzyme activity can be affected by changes in temperature - correct answer
- Starch solution is heated to a set temperature
- Iodine is added to wells of a spotting tile
- Amylase is added to the starch solution and mixed well
