Experiment 3: Leaves prepare starch during photosynthesis


Study that leaves prepare starch by the process of photosynthesis


Materials required:

  • Spirit (Absolute alcohol)
  • Dropper
  • Test tubes
  • Burner
  • Iodine solution


  • Insert a leaf into a test tube gently
  • Pour spirit into the test tube so that the leaf completely dips in it
  • Mildly heat the test tube using test tube holder till the spirit becomes green in colour and the leaf becomes colourless
  • Take out the leaf carefully from the test tube and wash it with water
  • Place it in another test tube and add a few drops of iodine solution. note the change in color of iodine solution


  • As we add iodine solution on the colourless leaf, it turns blue-black.


  • When we boil the leaves in spirit they become colourless because chlorophyll pigments leach out.
  • Leaves contain starch which gives blue-black colour with iodine solution.
  • Starch is synthesised in the green leaves in the presence of sunlight by the process of photosynthesis.
  • Starch gets stored in leaves or gets transported to other parts of the plant