How do you conduct the onion peel skin experiment?

This is a great experiment to view plant cells and practice your specimen staining skills. Firstly, you need to get together your materials:

• forceps
• Onion
• microscope
• Slide
• Iodine solution
• coverslip

Start by taking a small section of onion and peel off a thin layer of skin using forceps. Lie the tissue flat on the slide and add a drop of iodine solution. Slowly place on the coverslip to avoid air bubbles. Place the slide underneath the microscope at the objective lens and slowly work up to a higher objective lens by focusing using the course and fine focus.

I would help her by peeling the skin of onion and disected part would be examined by the help of compound microscope

When using onion skin to look at the cells under a microscope, the first thing you need to cut a small sample of onion using a scalpel. After this separate, the sections of onion and with tweezers remove a thin layer of onion skin. Place the onion skin onto a microscope slide and place 2 drops of iodine solutions (stain) on the onion skin (this allows you to see the cells). Carefully lower a cover slip on the sample. Place the slide on the base of the microscope and start on the lowest magnification (widest view). Focus until cells are found and then move up to the next objective lens.

In order to conduct the onion peel experiment, you need to be in a lab with the correct equipment such as a light microscope to view the onion cells. Firstly take a sample of an onion cell. This is simply done by peeling a thin layer of onion skin using forceps. Gently place the sample on a glass slide. Add a solution to stain the sample ( this could be iodine solution or methylene blue). This step is done to ensure that the cell can be viewed in detail under the microscope. Carefully place a slip over the sample and gently press the top. Ensure that you do not squish it too much as cells can be destroyed. Place the sample under a light microscope and jot down your observations. As this is a light microscope, the resolution will be lower than that of an electron microscope however, you will be able to view the cell in colour for this specific microscope.

Here's how to conduct the onion peel skin experiment in a few steps:

1. First, add a few drops of water or solution to the microscope slide to avoid dryness and wilting
2. Take a small piece of onion and using tweezers, peel off the membrane from the underside (the rough side).
3. Place the membrane flat on the surface of the slide.
4. Add a drop of Iodine solution to the onion skin
5. Using a pin, lower the thin glass coverslip or cover glass onto the slide. Make sure there are no air bubbles
6. Make sure the lowest power objective lens is in line with the optical tube, and the microscope light is turned on. Then place the prepared slide onto the stage of the microscope.
7. Looking from the side lower the tube using the coarse focus knob until the end of the objective lens is just above the cover glass. Do this carefully so as not to crack the cover glass (and possibly damage the objective lens).
8. Now look through the eyepiece and turn ONLY the smaller, fine focusing knob to move the optical tube upwards until an image comes into focus. The cells should look something like lizard skin.
9. Swap the objective lens for a higher powered one so that you can see the cells at greater magnification. You should be able to make out a nucleus in each cell.
10. Be very careful; these dyes can stain your skin and clothes. Could be dangerous if it is on you.

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.

• Use tweezers to peel off a thin layer of the onion skin.
• Careful place the skin on a glass slide and lay it out flat (be careful to avoid folds).
• Add a drop of iodine solution to stain the cells (this will make it easier to see).
• Place a cover slip (thin glass square) over the skin slowly by standing it up on one side and lowering it carefully until it is flat (this is to avoid air bubbles forming).
• Place the prepared slide on the stage of your microscope and secure in place with the clips.
• Make sure the main lens (objective lens) is on the smallest number (lowest magnification).
• Look through the eye piece and turn the rough focusing wheel/dial until you can clearly see the sample (cells may appear very small at this stage).

From now you can use the fine focusing wheel to focus more precisely and increase the magnification by changing the objective lens to a higher number as required. You may need to re-focus with the fine focusing wheel when you do this.

Materials: forceps, onion, microscope, slide, cover slip, iodine solution.

1. Pull a thin layer from the inner side of onion scale leaves. (5mm x 5mm will be good enough)
2. Add a drop of water in center of the microscopic slide.
3. Make the onion tissue lie flat on the slide without tissue folding or overlapping by using your forceps.
4. Add a drop of iodine solution on the tissue for staining.
5. Lower the cover slip gently to avoid formation of air bubbles.
6. Use blotting paper to remove excess solution if necessary.
7. Clip the slide onto the stage of microscope. Make sure the specimen is directly over the hole of the stage.
8. Observe in low power magnification first. If possible, turn to high power for detailed observation.

This is a great experiment to practice preparing and staining specimens and for light microscopy skills. The steps are quite simple. Just follow below!

Onion peel under the microscope method

Step 1: Take a small section of onion and peel off a single layer using a pair of forceps. This can be tricky so try find a corner of the onion section and peel back gently.

Step 2: Place the layer of onion on a glass slide and lay it flat and wrinkle free.

Step 3: Add a drop of Iodine soultion to the sample. This stain will turn blue-black for starch and will pick out the cells easily. Staining is necessary so that you can see the cells which are normally colourless at magnification.

Step 4: Gently place a coverslip over the stained onion being careful not to get air bubbles trapped.

Step 5: Place the slide on a light microscope and select the lowest objective lens. This will make it easy to focus on your sample.

Step 6: Use the coarse focus dial, move the stage until you can see the specimen through the eyepeice. Then use the fine focus dial to sharpen the image.

Step 7: Once sharp, move up to the next objective lens and repeat step 6.

Step 8: If you need to, repeat step 6 with the next objective. Once you can clearly see the cells you are ready to sketch and measure the onion cells. You should be able to see reagular onlong shaped cells in a brick-like pattern.

Key points to remember with this experiment;

Start with the lowest objective - this will make it easier to find your specimen.

Iodine stain is needed to add contrast to the cells so you can see them.

Remember; Magnification = Image Size/Actual Size!

Finally, don't forget the total magnfication = objective lens magnification x eyepeice magnification.