Lab write up was designed by students with the assistance of Mr. Ison.
Observation:
How can you model permeability of a cell?
Inferences:
1. Water can cross the cell membrane (osmosis)
2. Small particles can cross the cell membrane (diffusion)
3. Things have a tendency to move from high concentration to low concentration until it reaches equilibrium.
Hypothesis:
If small particles are put in high concentration on one side of a membrane, then they will move to the side with lower concentration until it reaches equilibrium.
Experiment:
Materials - sandwich bag, cup, iodine, starch, and water
Procedures:
1. Fill the cup with water about half full.
2. Add about 1 mL of iodine to the cup.
3. Put 3 scoops of starch into the sandwich bag.
4. Put a small amount of water into the sandwich bag until it is of milky texture.
5. Tie off the top of the bag.
6. Rinse the bag and your hands to remove any starch.
7. Place the bag inside the cup.
8. Observe after about 10-15 minutes.
Data:
The inner contents of the bag was white initially. After allowing the experiment to run the inner contents of the bag was purple. The contents of the cup was a golden brown color. After allowing the experiment to run the contents of the cup was of a golden brown color, but had slightly lightened.
Conclusion:
*Students were to write their own conclusions and answer the 3 questions on page 187.
