Question

ouestion no. 26 plz tell me

Answer 1

AIM :- To prepare stained temporary mount of Onion peel and to record observations and draw labelled diagrams .

MATERIAL REQUIRED :- Onion , Plane slides , Coverslip , Watch glass , Forceps , Needles , Brush , Blade , Safranin , Filter paper , Glycerine and microscope .

PROCEDURE

1) Take a piece of Onion and with the help of a Forcep gently pull a thin , transparent peel from its ventral or inner side .
2) Keep this peel in water in a Petri dish or watch glass .
3) Add a few drops of Safranin stain in the watch glass to stain the peel . Both over staining and under-staining should be avoided .
4) Now transfer the peel on a clean slide with the help of a brush and needle .
5) Cut the portion of the peel to a proper rectangular or square shape of about 2 to 3 mm in size with the help of a blade and a needle .
6) Remove the excess of water or stain , if any , from the slide surrounding the peel with the help of a blotting paper .
7) Add a drop of glycerine on the slide over the peel and put the Coverslip gently . Care must be taken to avoid the entry of air bubbles and the mounting should be done in the centre of the slide .
8) After putting the Coverslip , press it a bit with needle to spread the glycerine over peel properly .
9) Examine the slide under the microscope .

OBSERVATIONS

1) There are a large number of cells lying side by side with distinct cell walls .
2) A distinct nuclues is present on one side of the cell .
3) A big Vacuole is present in the centre of the cell .

PRECAUTIONS

1) Always hold the slide by its edge to avoid making the slide dirty .
2) A thin and properly stained peel should be selected for final mounting .
3) Always use a brush to transfer the peel from watch glass to the slide . Do not use needle .
4) The folding of the peel should be avoided .
5) The slide and coverslip must be cleaned before use .
6) The mounting of the peel should be done in the centre of the slide .
7) Always put the Coverslip gently to avoid the entry of air bubbles .
8) Oozing of glycerine should not be there .