Osmosis and Diffusion Lab using Potato Cores
Research Question:
Determine if there will be a difference of the movement of water through the potato cores in sucrose solutions of different concentration.
Introduction:
The process of water passing through the cell membrane is called osmosis. There are three types of osmosis. When the solution is hypotonic, that is, its concentration is lower than that inside the cell（a higher water potential）, water moves into the cell. When the solution is hypotonic to the cell, the concentration is higher than that of the cell, it has a lower water potential, and water tends to move out of the cell. When both sides of the cell membrane reach equilibrium, water particles move both ways—in and out at the same time—of the cell membrane. As sugar particles are too large to move in or out of the cell membrane, in this lab, water will move in or out instead. By recording the change of mass in the potato cores, we will be able to determine the extent to which osmosis is used and the concentration of solutes in the potato cells.
Hypothesis：
If the concentration of water in the sucrose solution is below that of the potato cores, then the final mass of the potato will appear lower that the initial mass. If the concentration of water in the sucrose solution is above that of the potato cores, then the final mass of the potato will appear higher than the initial mass.
Independent Variable:
Concentration of the sucrose solution
Dependent Variable:
Final masses of the potato cores
Controlled Variable:
Length of potato cores, length of time for osmosis to take place, volume of sucrose solution in each cup, number of potato cores in each solution, location where osmosis takes place.
Materials:
• Groups of 4 (2 buddy groups)
• Potato cores (4 per condition)
• Sucrose solutions (.2, .4, .6, .8, 1.0 )
• Distilled water
• Electronic balance
• Plastic weighing tray
• Plastic cups (6)
• Graduated cylinder (50 ml)
•...