A leaf of any plant, spirit, a beaker, test tube, burner, tripod stand, water, Petri plate, iodine solution, dropper, forceps.
Real Lab Procedure:
- Insert a leaf into a test tube gently with the help of forceps.
- Pour spirit into the test tube so the leaf thoroughly dips.
- Keep the test tube in a beaker half-filled with water.
- Place the beaker on a tripod stand.
- Boil the water until the spirit becomes green and the leaf becomes colourless.
- Take the leaf from the test tube carefully and wash it with water.
- Place it in a Petri plate and add a few drops of iodine solution.
- Drag the forceps to the top of the leaf.
- Drag the forceps with the leaf to the test tube and place them in the test tube holder.
- Drop the forceps with leaf inside the test tube.
- Click on the cap of the spirit bottle to open.
- Drag the spirit bottle to the test tube and drop it to pour.
- Drag the beaker containing water and drop it onto the tripod stand.
- Drag and drop the test tube containing the leaf to the clamp of the test tube stand to immerse it inside the beaker.
- Click on the burner knob to turn on the flame.
- Click again on the burner knob to turn off the flame.
- Drag the forceps to the test tube and drop to collect the leaf from the test tube.
- Drag test forceps with the leaf and drop it into another beaker containing water to wash the leaf.
- Drag the forceps and drop them into the beaker to collect the leaf again.
- Drag the forceps with a leaf and drop it onto the Petri plate.
- Drag the dropper containing Iodine solution onto a Petri plate.
- Drop the dropper to drop some iodine solution into the leaf inside the Petri plate.
What do we observe?
- As we add iodine solution to the colourless leaf, it turns blue-black.
What do we conclude?
- When we boil the leaves in spirit, they become colourless because chlorophyll pigments leach out.
- Leaves contain starch which gives a blue-black colour with iodine solution.
- Starch is synthesised in the green leaves in the presence of sunlight through photosynthesis.
- Starch is stored in leaves or transported to other parts of the plant.
- Since the activity involves the use of spirit and heating, it may be demonstrated by the teacher or done by the students under the teacher's supervision.