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Examination of Onion Epidermal Cells

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Examination of Onion Epidermal Cells

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Examination of Onion Epidermal Cells

Requirements:

Iodine solution – HARMFUL
Onion
Distilled Water

Apparatus:

Microscope
Microscope slides & cover slips
Tile
Knife
Tweezers
Pasteur Pipettes

Assignment:

I was given the onion once it had been chopped up on the tile, ready for me to peel back the skin I required using the tweezers.

I then placed piece of onionskin onto the microscope slide, making sure there were no folds or creases, and put a drop of iodine onto the slide as well, to view through the microscope.

On my first try the onion folded so I had to repeat the previous steps.

I then placed a cover slip, starting diagonally, to avoid any air bubbles in between the two layers. I then studied the layer of skin under the medium and strongest lenses of the microscope.

The iodine enabled me to see the cell wall, which showed as dark brown, the nucleus that was dark yellow and the cytoplasm that appeared a grey colour.

I then drew a detailed diagram of what I had seen through the lens (see attached) before cleaning up my work.

Evaluation:

Now I have viewed both my own cheek cell and the onion cell it has gained me a better understanding of the make up of different cells. The iodine used in this experiment helped me to identify the different parts of the cell, although had I more time I could of used a more permanent stain which could of showed a lot more through the microscope.

Also perhaps if I had had the time to experiment with different stains I may have found some different results. The iodine would of dried up the onion skin within a short space of time so had I been looking at it for longer this would not of been a good solution to use.

However, I managed to identify most of the cell, although the first piece of skin folded onto the microscope slide, the second caused me no problems.

On the whole it was a successful experiment.

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