Question

Explain the process of testing the presence of starch in leaves.

Answer 1

Starch:

1. Starch is actually the soft, white in color and the tasteless powder that is just insoluble in the cold water or the alcohol.
2. It is a powdery carbohydrate complex in the plants and is used as adhesives and sizes.
3. Iodine solution can be used to test the presence of starch in leaves.
4. Heat a leaf in boiling water for a few seconds. This helps stop the chemical reactions in the leaves.
5. Add this leaf to boiling ethanol for a few minutes. Boiling ethanol helps dissolve the chlorophyll and thus turns the leaf white.
6. Rehydrate the leaf by washing it with water and spread the leaf on a white base.
7. Add iodine solution onto the leaf with the help of a pipette.
8. The parts of the leaf that contain starch turn blue-black in color due to a reaction with iodine.