Diffusion and Osmosis Essay Example

Introduction Diffusion and osmosis are two types of passive transport. Diffusion is a random movement of molecules from an area of high concentration to an area of low concentration. Osmosis is a type of diffusion that diffuses water through a selectively permeable membrane. There were two parts to the experiment, the dialysis tubing lab and the potato lab. In the first experiment, the dialysis tubing acted as a semi-permeable membrane. A semi-permeable membrane is a membrane that allows certain substances to pass through. In this experiment, several variables, including glucose, starch, and iodine potassium iodide were tested for permeability through the dialysis tubing. In the second experiment, several potato tuber cylinders were tested in different sucrose solutions. The potato cylinders were tested to see what would happen to its mass if they were in different sucrose solutions. There are three major terms that are mandatory to know before experimenting: isotonic, hypertonic, and hypotonic. An isotonic solution is when the solute concentration inside a system is equivalent to the solute concentration outside of a system, thus resulting in no net change of diffusion. In a hypertonic solution, the solute concentration outside of a system is larger than the solute concentration within a system, so water diffuses out of the system to attempt to even out the ratio disparity; this results in the system shrinking in mass. In a hypotonic solution however, the solute concentration is greater within the system than outside of the system, so water diffuses into the system; this results in the system being "bloated".

Hypothesis
Activity 3.1 B: A selectively permeable membrane only allows certain substances to pass through, often small molecules. Since glucose and I2KI are smaller than starch, I hypothesize that they will diffuse through the dialysis tubing, but not starch.
Activity 3.3 A: Osmosis is the diffusion of water that occurs in