Biology lab. Observing plant and animal cells using the light microscope

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      Observing plant and animal cells using the light microscope


A red onion, potato, distilled water, iodine solution, methylene blue,  dropping pipette, fine forcps, scalpel, microscope, slides, cover slips, tooth picks.


A-Red onion epidermal cell:

1.Cut the onion in four, using a scalpel, from the top to the base. Take one of the fleshy scales using the scalpel cut a square (5mm by 5mm) on the outer, convex surface, which is dark red.

2. Using fine forceps peel of the surface of one of the colored epidermal squares. Place the fragment, with the torn surface facing down, onto a slide. Add a drop of distilled water and a cover slip.

3. Under high power, carefully adjusting the diaphragm, draw a colored cell from each preparation. Add a title and label.

In the microscope we can see that the onion cells have a rounded oblong shape. They zone tightly to each other. Each cell has a dense transparent cover (cell wall, which supports the form of the cell) with the more subtle areas - pores, which can be discerned only under high magnification, using them cell gets  the nutrients and take out  unwanted substances. The composition of membranes of plant cells is of special substances - cellulose, which gives them durability. Inside is a colorless viscous substance - cytoplasm.

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In the cytoplasm there is a  small, dense nucleus (containing the genetic information), where we can see the nucleoli.

Some cells do not have any nucleus, it means that they are already dead.

B-Cell of banana pulp:

1.Using a scalpel cut a slice of banana. Observe the skin with its prominent ridges and the central part which surrounds the pulp.

2. Take a very small sample of pulp (the size of a pin head) and place on the slide in a drop of iodine solution.  Then place a cover slip over it and crush it lightly.

3. Observe the ...

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