Determining the Rate of Osmosis Through a Semi-Permeable Membrane
Determining the Rate of Osmosis through a Semi-Permeable Membrane
Schneider, Justin* Sec 16 and Thomas Hudson
Introduction
Water is the principle solvent in cells. There are three conditions that a cell may be subjected to in the cells physical environment. The cells may be isotonic, hypotonic, and hypertonic. Isotonic is when the cell and is environment have equal concentrations of solutes. Therefore cells in an isotonic solution do not experience osmosis. When the cell is hypotonic it has a lower concentration of solutes so water will move out of the cell. When the cell is hypertonic, it will have a higher concentration of solutes and water will move into the cell to attempt to reach an isotonic state. The primary purpose of this exercise is to measure the rate and direction of osmosis under different concentrations. The greater the concentration of the solute (sucrose) the faster the solution (water) will pass through the membrane trying to achieve an isotonic state (Vodopich and Moore. 2011.)
Materials and Methods To start the experiment 8 pieces of string were gathered; approximately 2 inches in length, sewing thread were used for this experiment. Four water soaked pieces of dialysis tubing that were 15 cm long were also used. A small beaker for bag A was filled with a solution of 25% sucrose, was labeled to keep separate from the other beaker. A larger beaker was used for bags B, C, and D. It was filled with a 1% solution of sucrose, and was labeled for good practice. Each end of the tubes was sealed by folding and tying it tightly with one of the pieces of thread. The other end of the tube was soaked with water and opened gently rolling it between the index and thumb fingers. Once one end of each tube was sealed and the ends were opened each tube was filled with a solution. Before filling each tube with its selected solution a small piece of paper with a letter A, B, C, or D written in pencil were inserted so they could easily be
Schneider, Justin* Sec 16 and Thomas Hudson
Introduction
Water is the principle solvent in cells. There are three conditions that a cell may be subjected to in the cells physical environment. The cells may be isotonic, hypotonic, and hypertonic. Isotonic is when the cell and is environment have equal concentrations of solutes. Therefore cells in an isotonic solution do not experience osmosis. When the cell is hypotonic it has a lower concentration of solutes so water will move out of the cell. When the cell is hypertonic, it will have a higher concentration of solutes and water will move into the cell to attempt to reach an isotonic state. The primary purpose of this exercise is to measure the rate and direction of osmosis under different concentrations. The greater the concentration of the solute (sucrose) the faster the solution (water) will pass through the membrane trying to achieve an isotonic state (Vodopich and Moore. 2011.)
Materials and Methods To start the experiment 8 pieces of string were gathered; approximately 2 inches in length, sewing thread were used for this experiment. Four water soaked pieces of dialysis tubing that were 15 cm long were also used. A small beaker for bag A was filled with a solution of 25% sucrose, was labeled to keep separate from the other beaker. A larger beaker was used for bags B, C, and D. It was filled with a 1% solution of sucrose, and was labeled for good practice. Each end of the tubes was sealed by folding and tying it tightly with one of the pieces of thread. The other end of the tube was soaked with water and opened gently rolling it between the index and thumb fingers. Once one end of each tube was sealed and the ends were opened each tube was filled with a solution. Before filling each tube with its selected solution a small piece of paper with a letter A, B, C, or D written in pencil were inserted so they could easily be
References: Raven, Johnson et al. 2011. Biology.9th edition. McGraw Hill. New York, NY. Vodopich and Moore. 2011. Biology Laboratory Manual, 9th Edition. McGraw Hill. New York, NY. Acknowledgements The author would like to thank Miss Kendra Hill for the education, and instruction. He would also like to thank Roel Rabara for his guidance and thorough instruction in the Biology 151 lab that has helped him understand how the scientific methods work as well as helping him improve his scientific research writing. Last but not least his lab partner Thomas Hudson who has helped find the results of their experiments and tests.