BIOLAB ACTIVITY 5
OSMOSIS AND THE CASE OF THE SALAD GREENS
Imagine opening up the refrigerator to take out carrots, lettuce, cucumber, tomatoes and other vegetables in order to prepare adelicious, crisp salad for the family’s dinner. You rinse off the vegetables, slice them up, place them in a big bowl, and lightly season them with salt, pepper, and salad dressing. Finally you place thebowl of salad in the refrigerator , finish off some homework , and listen to a few CDs until it is time to eat. At dinner, as you prepare to enjoy your crunchy creation, you suddenly realize that youronce delicious-looking isn’t so desirable anymore. The carrots feel like rubber coins, the cucumbers are dry and limp, and lettuce is wilted. What has happened to your salad?
Wilting houseplants,rubbery carrots, and limp lettuce all illustrate the same important biological phenomenon: osmosis, the diffusion of water. In this activity you will investigate how the process of osmosis affects plantcells, and learn some ways to prevent sad salad greens!
1. Bring 2 150ml. Glass flasks (small baby juice flasks are ideal) with their lid.
2. Fill them three-fourths full withdistilled water
3. Add 3 teaspoons (10g) of table salt to one beaker, stir thoroughly, and label it “salt water”
4. Cut one carrot in 2 lengthwise, try to obtain two similar carrot sticks. Tie threads orstring tightly around each carrot half. Be sure it is tight around each piece.
5. If necessary, cut carrot sticks so that they fit submerged in the beakers. Place one stick into each of the 2 flasks6. Allow beakers to stand undisturbed for 24 hours
7. Remove the carrot sticks. Observe the tightness of the threads. Squeeze and bend each carrot stick to determine its texture.
8. Complete thetable based on your results and observations from the experiment
|Condition of carrot |TYPE OF WATER |
|Stick: |Distilled/ salty |
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