The Big Finale

After a final measurement, the students each made a graph to show how their eggs were affected by the various solutions they used. Most of them showed an overall increase in size. Others showed fluctuation through the course of the lab.

The point of this lab was to give students a chance to see the effect of solutions with different densities on a membrane bound cell. The more stuff there is dissolved in the solution, the higher its density, and the more the egg will shrink. However, if there is more stuff dissolved inside the cell, which for the most part is what we observed in class, then the water outside the cell will move inside, causing the egg to swell.

If students were to try this at home, with permission of course, placing a de-shelled egg in an extremely dense fluid, like corn syrup or molasses, would cause the egg to shrink as water moved out of the cell, following its concentration gradient.

Overall, the students did very well on this lab. We only had a couple of mishaps involving broken eggs. None of them ruined any books, papers or articles of clothing.