CBSE Class 9 Practicals Science Preparation of stained temporary mounts of (a) onion peel, (b) human cheek cells & to record observations and draw their labeled diagrams. Students get here clear concept at this page.
i) Preparation of stained temporary mounts of (a) Onion peel (b) Human cheek cells and record observations and draw their diagram.
(a) Onion peel: For the preparation of stained temporary mount of onion peel.
Requirements: Onion, brush, distilled water, saffranine, watch glass, forceps, dropper, glass slide, cover slip, glycerin and microscope.
Procedure:
1) Take a watch glass and pour small quantity of distilled water into it.
2) Take an onion and cut the fine piece of peel of onion with the help of forceps.
3) After cutting the fine piece of onion peel, separate transparent onion peel in order to observe it under the microscope.
4) Place the transparent onion peel into watch glass containing distilled water, to remove any dust from the epidermis.
5) Take a small quantity of safranine with the help of dropper and pour in into watch glass.
6) Transfer the epidermis of onion peel into the watch glass containing safranine.
7) Keep the peel in safranine for approximately 30 sec and allow it to react with safranine.
8) After 30 seconds, transfer the onion peel from safranine containing watch glass to distilled water containing watch glass with the help of brush.
9) Now take a clean, grease free slide and pour 2-3 drops of glycerin on the slide. Along with that take onion peel and place it on the slide containing glycerin.
10) On this glass slide place a dry cover slip on the area containing glycerin and onion peel.
11) Remove the excess glycerin with the help of bloating paper.
12) Observe the slide under the microscope.
Observations:
1) By observing under the microscope, the separate cells can be visualized.
2) The cells contain protective covering called cell wall also observed among the cells.
3) The separate nucleus was seen in the center of the cell and the cytoplasm is surrounded in entire cell.
Result: In the slide, cell wall, nucleus and cytoplasm visualized easily.
Conclusion: The onion peel was successfully isolated and observed various structures under the microscope.
(b) Human cheek cells
Requirements: Cheek cells, toothpick, glass slide, needle, watch glass, methylene blue, distilled water, glycerin and microscope.
Procedure:
1) To collect the cheek cells, scrapping of the cheek on inner side should be done, to collect appropriate amount of cheek cells.
2) After collection of cheek cells, place a cheek cells in watch glass containing distilled water.
3) Mix the cheek cells with water thoroughly.
4) Take a clean greece free dry slide and add 2-3 drops of methylene blue on a dry slide.
5) With the help of brush take some cheek cells and mix with methylene blue.
6) Remove the excess methylene blue with the help of bloating paper.
7) After removing excess dye, place few drops of glycerin on a slide and mix it with cells and methylene blue.
8) Put the cover slip on the glass slide, gently press the coverslip to fix and spread all the cells.
9) Again remove excess fluid by bloating paper and observe the slide under microscope.
Observation:
1) In the slides observed under microscope, cells can be visualized.
2) Cell wall is absent but cell membrane can be observed.
3) The presence of nucleus at the center of the cell is distinct.
Result: The cheek cells were observed and their nucleus and cell membrane visualized.
Conclusion: The cheek cells were successfully isolated and observed under microscope.
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