Nova Southeastern University
This experiment gave a visual understanding of osmosis and diffusion. The first experiment proved that solutes would move down a concentration gradient if permeable to the selective membrane. The second experiment proved different solute concentrations affect the movement of water, depending on the solute concentration inside the cell. The purpose of this lab was to look for different solutes that can cross an artificial membrane and to observe the effect of different concentrations of sucrose on the mass of a potato cell. Results for Part One suggested that the molecular weight of albumin and starch was too large to pass through the dialysis tube, but glucose and sodium sulfate molecules were small enough to pass through the dialysis tube. Also, a decrease in water weight occurred due the dialysis tube being placed in a hypertonic solution. Results for Par Two showed the potato cell having a molar concentration of 0.2734, which caused sucrose concentrations above 0.2 M to have a decrease in mass. Inversely, sucrose concentrations below 0.2 M caused an increase in mass.
Diffusion is the random movement of molecules spreading evenly into available space (Cain, Jackson, Minorsky, Reece, & Urry, 2011). Movement of water also follows a similar concept, however, water can act as a shield for solutes and become unavailable to diffuse while in other cases water is free and will move to an area of low solute concentration to an area of high solute concentration: this processes is better known as osmosis (Keith, Messing, Schmitt, & Feingold, 2010). Osmosis and diffusion can occur along a permeable membrane or selective membrane. A cell with a selective membrane allows small molecules and ions to pass through but excludes others; also, substances that are able to pass through the membrane do so at different rates. On the other hand, permeable
References: Cain, M. L., Jackson, R. B., Minorsky, P. V., Reece, J. B., & Urry, L. A. (2011). Biology (9th Edition ed.). San Francisco: Pearson Education, Inc. Keith, E., Messing, C,. Schmitt, E., Feingold, J. (2010). Laboratory Exercises in Biology (3rd ed.). Dubuque, IA: Kendall Hunt Publishing Company.