During the demonstration of stomata on the leaf peel two experimental sequences were compared. In the first case leaf peel was placed in water and then in safranin for 30 seconds and in the second case leaf peel was placed in water and then in safranin for 30 minutes. Which of the following can be considered to be a possible observation?
a. Both samples showing over-staining
b. Both samples showing under-staining
c. Second case showing proper staining
d. First case showing proper staining
Answers
Answer:
Demonstration of Stomata on a Leaf Peel
Theory
Materials Required
Real Lab Procedure
Pluck a fresh leaf from a balsam plant.
Fold the leaf and carefully tear along the bruised area of the lower side of the leaf.
We can see a colourless narrow border along the torn edge.
Carefully pull out the thin membranous transparent layer from the lower epidermis using a forceps.
Put the epidermis into a watch glass containing distilled water.
Take few drops of Safranin solution using a dropper and transfer this into another watch glass.
Using a brush transfer the epidermis into the watch glass containing the Safranin solution.
Keep the epidermis for 30 sec in the Safranin solution to stain the peel.
To remove excess stain sticking to the peel, place it again in the watch glass containing water.
Place the peel onto a clean glass slide using the brush.
Take a few drops of glycerine using a dropper and pour this on the peel.
Using a needle, place a cover slip over the epidermis gently.
Drain out the excess glycerine using a blotting paper.
Take the glass slide and place it on the stage of the compound microscope.
Examine the slide through the lens of the compound microscope.
Simulator Procedure (as performed through the Online Labs)
You can select the type of view from the ‘Select view’ drop down list (it is the 'Binocular view' through which you can view the cell structure).
Select the permanent slide of the leaf peel from the ‘Select sample’ drop down list.
You can change the power of the lens from the ‘Select objective lens’ drop down list.
For coarse adjustments, you can click on the left and right arrows of 'Course Adjustment' seen on the left controls panel.
For fine adjustments, you can click on the left and right arrows of ‘Fine adjustment’ seen on the left controls panel.
Using the scroll bar, scroll down the screen for the ‘Slide adjustment’, which lets you observe each part by clicking on the four way directional arrow.
You can select the ‘Identify parts’ check box to see the labelled parts of the stomata.
To redo the experiment, click on the ‘Reset’ button.
Observations
The epidermis is made of uniseriate layers of cells that have distinct cell walls, a nucleus and cytoplasm, and are closely packed.
The epidermal layers are broken at places. These openings are the stomata.
Each stoma is guarded by a pair of bean shaped cells that are guard cells.
Precautions
The epidermal peel should be taken from a freshly-plucked leaf.
Take the epidermal layer from the lower surface of a leaf, as it has more stomata.
Always use a clean glass slide.
Answer: