onion cells & other stuff

 A tale of two experiments...

First, the onion skins, which we looked at under microscopes in class; you peeled a fine layer of cells and mounted it on the slide.  You drew a picture of one or more of the cells with the purple cytoplasm and the cell wall, maybe a nucleus.  Then you added a drop of salt water and observed.  It should have looked like this, before and after:

In your lab notebooks, write up your experiment neatly. Title, description of  procedure, hypothesis (what do you think will happen?) drawings or photos, describe what happened, explain what happened.  In your explanation use the words from your worksheet: osmosis, greater/lesser concentration of water, hypotonic, hypertonic.  Label your drawings or photos with  cell wall, membrane, cytoplasm, nucleus.
(25 points)

Next, the Home Experiment:  Did it look like this?  I started with two glasses, one was 3/4s full and one was empty.  It took way longer that the directions implied; in fact, it took 24 hours to reach the point where the water levels were equal.  Now I am going to put one of the glasses on top of a book and see how that changes things.

Write this up in your lab books, if you have not already done so: Title, description of  procedure, hypothesis (what do you think will happen?), drawings or photos, describe what happened, explain what happened.