Science: Presence of Starch in the leaf
Presence of Starch from the leaves can be demonstrated below:.
We picked the leaf which has green, pink and yellow. Look at the leaves below. Our experiment is to determine the presence of starch in the leaves. The experiment was conducted with 4 students where we allow the students to explore the presence of starch in the plants
Step 2: Once that is done, we place the leaf into a new test-tube with ethanol. Stand the test-tube in a beaker of hot water for around 10 minutes. To remove the chlorophyll
Step 3: Wash the leaf in cold water. You can use hot water too. Washing will soften the leaves and remove the alcohol
Step 4: Spread the leaf flat on the Petri dish and cover it with iodine solution. If the leaf turns blue-black, it means starch is present. Iodine turn from brown to dark blue within a second.
After conducting the required steps, we obtained the following results:
As you can see, the places which were green turned blue-black, indicating starch was present where chlorophyll was. The pale coloured parts of the leaf stayed the colour they were, indicating starch was absent. So we can conlude that chlorophyll is involved in photosynthesis producing starch. The reason why a substance like starch is used for storage in plants is because it is insoluble, and does not cause problems like osmosis, unlike glucose.
