Practical no 1

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Temporary preparation of Stomata  (on the ruled page/ right hand side)

Aim: To prepare a temporary slide and observe stomata under a compound microscope.

Materials required: Watch glass, dropper, forceps, stain- safranin, glycerine, brush, needle, petri dish, glass slide, cover slip, compound microscope.

Procedure:
  1. Fold the leaf and carefully tear along the bruised area of the lower side of the leaf.
  2. We can see a colourless narrow border along the torn edge.
  3. Carefully pull out the thin membranous transparent layer from the lower epidermis using a forceps.
  4. Put the epidermis into a watch glass containing distilled water.
  5. Take few drops of Safranin solution using a dropper and transfer this into another watch glass.
  6. Using a brush transfer the epidermis into the watch glass containing the Safranin solution.
  7. Keep the epidermis for 30 sec in the Safranin solution to stain the peel.
  8. To remove excess stain sticking to the peel, place it again in the watch glass containing water.
  9. Place the peel onto a clean glass slide using the brush.
  10. Take a few drops of glycerine using a dropper and pour this on the peel.
  11. Using a needle, place a cover slip over the epidermis gently.
  12. Drain out the excess glycerine using a blotting paper.
  13. Take the glass slide and place it on the stage of the compound microscope.
  14. Examine the slide through the lens of the compound microscope.

Precautions
  1. The epidermal peel should be taken from a freshly-plucked leaf.
  2. Take the epidermal layer from the lower surface of a leaf, as it has more stomata.
  3. Always use a clean glass slide.
Inference/ result: Stomata are present in the epidermal cells of the lower surface of the leaf. through which they carry out gaseous exchange and transpiration.

(on the blank page/ left hand side)

Experimental setup:



Observations:
  1. The epidermis is made of layers of cells that have distinct cell walls, a nucleus and cytoplasm, and are closely packed.
  2. The epidermal layers are broken at places. These openings are the stomata.
  3. Each stoma is guarded by a pair of bean shaped cells that are guard cells.

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