Observing osmosis, plasmoylsis and turgor in plant cells
* Get a single layer of plant cells. If you are using red onion, cut a 1 cm square from a fleshy piece of onion and then peel off a single layer of the red cells. If you are using rhubarb, peel a piece from the epidermis. If you are using toadflax peel a piece of the lower epidermis of a leaf. * Place the strip on a slide and cover it with a drop or two of distilled water. Add a cover slip. * Look at the cells through a microscope. Start with the low power lens. Draw and label 3 plant cells. * Take another strip of cells from your plant material. This time mount the cells on a slide with 5% sodium chloride solution. * Examine the cells through the microscope. Draw and label 3 plant cells. * After a few minutes draw out the sodium chloride solution with a piece of filter paper placed at the edge of the coverslip. Replace it with distilled water added at the other side of the coverslip.
1 Describe the cells in distilled water. How are the cells in 5% sodium chloride different from this? Describe what happens when you take away the sodium chloride solution and add water.
2 Explain what happened to the cells in sodium chloride solution using biological terms. Try to include these words.
3 Explain what happened to the cells when you replaced the surrounding sodium chloride solution with water. Try to include the words from the list again.
4 What prevents the plant cells from bursting when they take in lots of water?
5 You’ve seen what happens to cells in epidermal tissue when they lose water. How does a whole plant look when it is short of water? How does it change when you give it water? Try to explain these observations using the ideas above.
6 Animal cells do not have the same...
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