Answer the following:

Explain the method of testing a leaf for starch.

Aim: To test the presence of starch in a leaf.

Material required:

Electric water bath or hot plate, 3 beakers of 250 ml, boiling tube, forceps, test tube holder, leaf to be tested ( leaf of China rose will be good), 90 % ethanol and iodine solution.

Procedure:

● Remove a green leaf from a plant that has been exposed to sunlight for a few hours.

● Fill three 250ml beakers half with water. Heat the water until it boils. Keep the water at boiling point. Put the leaf in the boiling water using forceps.

● Boil for 2 minutes.

● Put the boiled leaf in a boiling tube containing 90% ethanol.

● Put the boiling tube in hot water and boil for 10 minutes to decolorize leaf.

● Remove the leaf and wash cold water.

● Add a few drops of iodine solution to the leaf and observe.

After iodine solution was added...