In testing for starch in a leaf, the leaf is first boiled in water for about a minute so that the
Answer Details
In testing for starch in a leaf, the leaf is first boiled in water for about a minute so that the cells are killed. When a leaf is boiled in water, the high temperature causes the cells in the leaf to burst and break open. This releases the contents of the cells, including any starch that may be present. Boiling also deactivates the enzymes that break down starch, preventing them from interfering with the starch test. Once the cells are killed, iodine solution can be applied to the leaf to test for the presence of starch. The iodine will penetrate the cells and react with any starch that is present, causing it to turn blue-black in color.