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Why a green leaf is bleached before carrying out a starch test?
Extra information:
The iodine test can determine whether or not leaves contain starch (carbohydrate).
Here are the procedures for determining whether or not leaves contain starch:
Step 1: Collect a green leaf from a plant that has been in direct sunlight for at least a few hours.
Step 2: Half-fill a beaker with water and bring it to a boil.
Step 3: Place the leaf in a pot of boiling water and let it sit there for a few minutes to soften the cell wall.
Step 4: Boil the leaf in alcohol to extract the chlorophyll.
Step 5: Immerse the leaf in hot water to loosen its cells.
Step 6: Next, test the leaf for starch by dropping a few drops of iodine solution onto it.
A blue-black hue develops on the leaf once iodine is added, indicating the presence of starch in the sample.
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