Experiment 3: Leaves prepare starch during photosynthesis

Objective

Study that leaves prepare starch by the process of photosynthesis

 

Materials required:

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

Procedure:

• 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

Findings:

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

Conclusions:

• 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