Onion Skin Cell Lab

Purpose: To determine the effect of water and saltwater environment on an onion skin cell.

Materials: * Eye dropper * Microscope * Onion Skin Cell * Slide * Cover Slip * Iodine * Salt * Water

Procedure:

Part 1: 1) Attain an onion skin cell sample which has been soaking in tap water from your science teacher. 2) Prepare a wet-mount slide for the onion skin cell directed by your teacher. 3) Add iodine to the onion and place a cover slip on top of the onion. 4) Observe the slide under all magnifications and sketch Proper Biological Diagrams for each power. (4x, 10x, 40x)

Part 2:

1) Repeat the same lab procedure as you did with soaking onion skin cells in tap water last day, but now using the onion and soaking it into saltwater. 2) Prepare a wet-mount slide for the onion skin cell done by your teacher. 3) Add iodine to the onion and place a cover slip on top of the onion. 4) Examine the slide under all magnifications and sketch Proper Biological Diagrams for each power. (4x, 10x, 40x)

Hypothesis:

If tap water is added to the onion skin cells then the water will absorb and swell up because, osmosis is occurred and it becomes completely inflated.

If saltwater is added to the onion skin cells then the cells would wrinkle up and probably shrink because, once the onion is placed in salt solution, it will dehydrate since it’s hypertonic. The water would leave the cell by diffusion to get an osmosis balance.

Observations: Quantitative

Variables: * Amount of salt * Amount of water * What time you start the experiment * Where you place the onion * What temperature was the onion placed in before * How much iodine you drop on the onion skin * How long did you place the onion skin in either salt or tap