AIM
To prepare a temporary mount of a leaf peel to show stomata.
MATERIALS REQUIRED
Leaf of tradescantia or periwinkle or balsam, slides, coverslips, forceps, needles, cotton cloth, brush, blotting paper, watch glass, blade, dropper, glycerine, safranin
THEORY
1. Stomata (singular: stoma) are tiny pores found in the epidermis of leaves of the green plant through which exchange takes place.
2. Each stoma is bounded by two guard cells which unlike the other epidermal cells, possess chloroplast.
3. The walls of guard cells are thicker and more elastic, i.e., they are thickened on the inner side and thinner and more elastic on the outer side.
4. The guard cells control the opening and closing of stomata.
5. When water flows into the guard cell, they swell expand and cause the stomatal pore to open. On the contrary, when they lose water, they shrink and close the stomatal pore.
PROCEDURE
1. Take a leaf of the green plant and remove the peel from its lower surface by tearing the leaf.
2. Place the leaf peel in the watch glass containing water, so that the peel does not dry during the experiment.
3. Add 1-2 drops of safranin to the watch glass containing the peel of leaf to stain.
4. Select a thin leaf peel and place it in the centre of a clean slide with the help of the brush
5. Put few drops of glycerine on the slide over the peel with help of a dropper.
6. Now, using a needle gently place a coverslip over the strained peel slide.
7. Remove the excess stain and glycerine with a blotting paper.
8. first, observe the slide under the lower magnification (i.e., 10 X) of a compound microscope and then, under the higher magnification (i.e., 45 X).
OBSERVATIONS
1. Epidermis or leaf peel consists of many cells which are irregular in outline and are arranged in a single layer with no intercellular spaces.
2. These tiny pores are called as stomata and are seen in the epidermal cells.
3. Each stoma consists of two kidney-shaped guard cells.
4. Each guard cell has a nucleus and chloroplasts.
5. The diagram of the leaf peel shown below:
RESULT
Minute apertures called stomata are well observed in the temporary mount of leaf peel.
PRECAUTIONS
1. The peel should be freshly plucked from the leaf.
2. The peel should not be allowed to dry.
3. Leaf peel should not be over stained.
4. The slide to be used must be clean.
5. The peel should be placed in the centre of the slide for best view.