Question

how will you test that leaves contain carbohydrates in the form of starch

Answer 1

Answer:

The iodine test is used to check the presence of starch in a sample. The iodine intercalates between the helices of the starch and gives blue-black color.

Steps:

1. Take a green leaf and keep it in boiling water for approximately 1 minute. It kills the leaf and prevent further photosynthesis. In addition, it helps in increasing the permeability of iodine into the tissue.
2. Transfer the leaf to the test tube containing ethanol and put the test tube in water bath until the leave become yellow or decolorized.
3. Wash the leaf with water and place it in a petri-dish.
4. Put iodine drops on the leaf.
5. Observe the change in color.

Development of blue-black color confirms the presence of starch in the leaf.