What is the purpose of the dialysis tubing lab?
What is the purpose of the dialysis tubing lab?
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.
How does dialysis tubing demonstrate osmosis?
The dialysis tubing is a semipermeable membrane. Water molecules can pass through the membrane. The salt ions can not pass through the membrane. The net flow of solvent molecules through a semipermeable membrane from a pure solvent (in this cause deionized water) to a more concentrated solution is called osmosis.
What is the purpose of an osmosis experiment?
Purpose: To determine the biological changes that occurs over a period of time in different solutions and to relate these changes to osmosis and diffusion.
What is your hypothesis for this experiment osmosis?
Hypothesis: The greater the difference between the concentration of water inside a cell and the concentration outside a cell, the faster the rate of osmosis. This hypothesis could be wrong. Maybe the greater concentration difference will NOT lead to a faster rate of osmosis.
What properties does this experiment demonstrate about the dialysis tube as a model for a cell membrane?
This experiment showed that dialysis tubing is selective in its permeability to molecules. It was permeable to glucose and iodine but not starch.
What can you conclude about diffusion?
In diffusion, molecules move from high concentration to low concentration. A solution is a mixture of two substances with one dissolved in the other.
What is the independent variable in osmosis experiment?
Osmosis required practical variables: Independent variable: Concentration of sugar or salt solution.
What is the dependent variable in the osmosis practical?
Dependent Variable – The mass of plant tissue at the end. Control Variables – Volume of plant tissue. Surface area of plant tissue.
What was the result of the experiment using dialysis tubing iodine and a starch solution?
From the results of this experiment, it is obvious that glucose and iodine (potassium iodide) has smaller molecular size than starch. Because starch had larger molecular size, the dialysis tubing was not permeable to it (it didn’t allow it to readily pass through the pores of its membrane).
What do you conclude about the effects of molecular size on the diffusion of molecules across a semipermeable membrane?
1. What is the effect of molecule size on a molecule’s ability to diffuse across a semipermeable membrane? 2. If molecules are small enough, then they will diffuse across a semipermeable membrane because they can pass through its tiny openings.