Question

list out the materials required for observing nucleus in onion Peel Cells and cheek cells write your observations.please answer me please ​

Answer 1

Answer:

eal Lab Procedure

Pour some distilled water into a watch glass.

Peel off a leaf from half a piece of onion and using the forceps, pull out a piece of transparent onion peel (epidermis) from the leaf.

Put the epidermis in the watch glass containing distilled water.

Take a few drops of safranin solution in a dropper and transfer this into another watch glass.

Using a brush, transfer the peel into the watch glass containing the safranin solution.

Let this remain in the Safranin solution for 30 seconds, so that the peel is stained.

Take the peel from the Safranin solution using the brush and place it in the watch glass containing the distilled water.

Take a few drops of glycerine in a dropper and pour 2-3 drops at the center of a dry glass slide.

Using the brush, place the peel onto the slide containing glycerine.

Take a cover slip and place it gently on the peel with the aid of a needle.

Remove the extra glycerine using a piece of blotting paper.

Place this glass side on the stage of the compound microscope and view it.

Observations

There are a large number of regularly shaped cells lying side by side and each cell has a distinct cell wall.

A distinct nucleus is present on the periphery of each cell.

Lightly stained cytoplasm is observed in each cell.

A large vacuole is present at the centre of each cell, and is surrounded by the cytoplasm.

Conclusion

As cell walls and large vacuoles are clearly observed in all the cells, the cells placed for observation are plant cells.

Precautions

Use a brush to transfer the peel from one apparatus to another.

Staining of peel should neither be too dark, nor too light.

Extra glycerine stain should be removed using blotting paper.

To Prepare Stained Temporary Mount of Human Cheek Cells

Materials Required

Real Lab Procedure

Gently scrape the inner side of the cheek using a toothpick, which will collect some cheek cells.

Place the cells on a glass slide that has water on it.

Mix the water and the cheek cells using a needle and spread them.

Take a few drops of Methylene blue solution using a dropper and add this to the mixture on the slide.

After 2-3 minutes remove any excess water and stain from the slide using a blotting paper.

Take a few drops of glycerine using a dropper and add this to the test mixture.

Take a clean cover slip and lower it carefully on the mixture with the aid of a needle.

Using a brush and needle, press the cover slip gently to spread the epithelial cells.

Remove any extra liquid around the cover slip using a blotting paper.

Place this glass side on the stage of the compound microscope and view it.

Observations

A large number of flat and irregular-shaped cells are observed.

The cells do not have a cell wall. However, each cell has a thin cell membrane.

A deeply stained nucleus is observed at the centre of each cell.

No prominent vacuoles are observed in the cells.

Conclusion

As the cells observed do not have a cell wall, nor a prominent vacuole, the cells of the specimen on the slide are animal cells.

Simulator Procedure (as performed through the Online Labs)

The ‘Select view’ drop down list allows you to select either the Microscope or Binocular View (It is the 'Binocular view' through which you can see the cell structure as viewed through the microscope).

To select the sample, you can use the ‘Select sample’ drop down list.

To change the power of the lens, you can choose a lens from the ‘Select objective lens’ drop down list.

For coarse adjustments, you can either click on the up and down arrow of ‘Coarse adjustment’ knob, or 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.

You can redo the experiment by clicking on the ‘Reset’ button.

Precautions

Ensure toothpick used to scrape the cheek is clean, so it does not cause infection to the cheek.

Extra glycerine stain should be removed using blotting paper.

Answer 2

Answer:

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Explanation:

To prepare stained temporary mount of onion peel cells and to record observations and draw labelled diagrams.

MATERIALS REQUIRED

Onion, plain slides, coverslip, watch glass, needles, forceps, brush, blade, safranin, blotting paper, glycerine and compound microscope.

THEORY

Onion is a multicellular plant. Like other plant cells, the cell of onion peel consists of a cell wall, cell membrane, cytoplasm, a large vacuole and a nucleus. The nucleus lies at the periphery of cytoplasm and vacuole is located in the centre. Presence of large vacuoles and cell wall confirms that cells of onion peel are plant cells.

PROCEDURE

Take a piece of onion and bend it to remove the transparent membranous structure called onion epidermal peel. With help of forcep remove the peel from its inner side.

Place the peel in water in a watch glass.

Add a few drops of stain safranin, to the watch glass containing the peel for staining.

Now, wash the leaf peel with water and transfer it on to a clean slide with the help of brush.

Remove extra water from the slide surrounding the peel with the help of blotting paper.

To this slide, add a drop of glycerine over the peel and place the coverslip in a manner to avoid entry of air bubbles.

Soak away the extra glycerine with blotting paper.

Examine slide under the microscope.

cbse-class-9-science-practical-skills-slide-of-onion-peel-and-cheek-cells-1

cbse-class-9-science-practical-skills-slide-of-onion-peel-and-cheek-cells-2

OBSERVATIONS

A large number of rectangular cells with distinct cell wall can be observed.

Cytoplasm is seen as thin layer of deep coloured substance on inner surface of cell wall.

A big central vacuole is present in the cell.

A deeply stained round body called nucleus is seen in each cell.

cbse-class-9-science-practical-skills-slide-of-onion-peel-and-cheek-cells-3

RESULT

The epidermal peel of onion comprises of rectangular shaped cells. Each cell comprises of a nucleus, a central vacuole, thin layer of cytoplasm and cell wall.

As cell walls and large prominent vacuole are present in each cell, the cells placed under observation are plant cells.

PRECAUTIONS

Always take a clean slide and hold it by its edges to avoid making the slide dirty.

Peel should be properly stain. Avoid under-staining or excessive staining of the peel.

Always transfer the peel with the help of brush.

Mounting of the peel should be done in centre of slide.

Avoid folding of the leaf peel.

Remove extra glycerine with the help of blotting paper.

Avoid entry of air bubbles while placing the cover slip.