AP BIOLOGY

Detailed explanation-1: -In an experiment designed to study osmosis, several pieces of dialysis tubing were filled with sucrose solutions of varying concentration and placed in beakers containing distilled water. The rate and direction of water movement was determined by weighing the bags before and after placing them in the distilled water.

Detailed explanation-2: -In this practical, dialysis tubing is used as a surrogate cell membrane for a visual demonstration of osmosis and diffusion. A solution containing large molecules (Starch) and small molecules (Glucose) is placed inside the tubing; which is then placed in a solution containing iodine.

Detailed explanation-3: -Sucrose is a disaccharide and therefore much larger than the glucose, a monosaccharide, that was used in the experiment. Sucrose would be too large to pass through the dialysis tubing, so the water in the beaker should not test positive for sugar in the end result.

Detailed explanation-4: -When sucrose dissolves in water, weak bonds form between water and sucrose molecules. These bonds make it more difficult for water to move out of the solution by osmosis. Water molecules pass through a cell membrane in both directions.