Experiments

• Qualitative Test

  A qualitative test records the presence or absence of starch. It is a yes or no question.
• To test for starch:

  1. Label boiling tube A+B (starch solution + water)
  2. Add 2cm3 starch solution to A
  3. Add 2cm3 water to B (control)
  4. Add 2-3 drops iodine solution to A+B
  5. Positive: yellow to blue/black
• Control

  A control is something used to compare the results of an experiment. This element remains unchanged following the experiment.
• To test for lipids

  1. Label 2 pieces of brown paper A+B
  2. Rub butter on A
  3. Drop water on B
  4. Leave to dry
  5. Hold up to light
  6. Positive: translucent spot
• To test for reducing sugar:

  1. Label boiling tubes A+B (glucose solution+water)
  2. Add 2cm3 glucose solution to A
  3. Add 2cm3 water to B (control)
  4. Add 2-3 drops benedict's solution to A+B
  5. Put tubes in 60° water bath for 5mins
  6. Positive: blue to brick red
• To test for protein

  1. Label boiling tubes A+B (protein solution + water)
  2. Add 2cm3 protein solution to A
  3. Add 2cm3 water to B
  4. Add 2-3 drops biuret solution to A+B
  5. Positive: Blue to lilac