

Caught in the Act

By Dr. Rose Davidson, STEM Coordinator
Freshman students in Biology investigated osmosis, the passage of a solvent through a membrane, using an egg to represent a cell. First, vinegar was used to dissolve the egg shell. Eggs were then placed in different concentrations of sucrose syrup solution. Once the hard shell was dissolved by the vinegar, the egg had a semi-permeable membrane, which allowed water to travel in or out of the egg, depending on the concentration of syrup in water. The students measured the change in mass of the egg to determine how sucrose concentration affected the osmosis process. They found that water moved into the eggs that were placed in dilute sucrose solutions until equilibrium was reached and they increased in size. Water moved out of the eggs that were placed in more concentrated sucrose solutions and the eggs shriveled up.

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