The movement of water molecules across a semi-permeable membrane is the process of osmosis. If there is a solute and a solvent, each containing different concentration levels, then the water would move along its concentration gradient until each side of the membrane are equal. The water moves because the membrane is impermeable to the solute and the solute concentrations may differ on either side of the membrane. Water molecules may move in and out of the cell, but there is no net diffusion of water. Water will move in one direction or the other, and this is determined by the solute or solvents concentration levels. If the two solutions are of equal concentrations, they will be isotonic. If the concentrations are unequal, the solution with the higher concentration is hypertonic, and the solution with the lower concentration is hypotonic.
What is the solute concentration of potatoes? We can determine this by conducting an experiment in which involves the process of osmosis. Potatoes are full of sucrose used for energy storage in plants. Sucrose is a carbohydrate found in food. It is a disaccharide, with a combination of fructose and glucose. Consumers break sucrose down into two monosaccharides so they can be absorbed more easily into the blood. Sucrose is too large of a molecule to diffuse through a semi-permeable membrane, and therefore needing to be broken down so they can move in and out of cells effectively. If potatoes are placed in a solute containing sucrose, then a concentration gradient would be present and the process of osmosis would naturally occur by moving water through the semi-permeable membranes. If the concentration of sucrose in the solution is less than the concentration of sucrose found in the potato, then the potato would decrease in mass. The opposite would occur as well, if the concentration of sucrose in the solution is more than that of the potato, then the potato would expand and gain in mass. In conducting this as an
Bibliography: Emerson, I.. "Osmosis and Diffusion - A Tutorial." Memorial University. N.p., n.d. Web. 2 Apr. 2013. http://www.mun.ca/biology/Osmosis_Diffus Smith. "Investigating the effect of concentration of blackcurrant squash on osmosis in chipped potatoes | Nuffield Foundation." Nuffield Foundation |. N.p., 24 Nov. 2011. Web. 2 Apr. 2013. (Figure 1.0) http://www.nuffieldfoundation.org/practical-biology/investigating-effect-concentration-blackcurrant-squash-osmosis-chipped-potatoes Steinberg, June. "osmosis." ESR 514 Homepage. N.p., n.d. Web. 2 Apr. 2013. http://www2.nl.edu/jste/osmosis.htm