Click Here To Start Experiment #3 3) OSMOSIS AND DIALYSIS Sucrose Click Here To Start Experiment #3 Click Mouse Here to View Next Text on the Blackboard

Click Mouse Here to View Next Text on the Blackboard There are two parts to this experiment # 3. PART 1 will consider OSMOSIS and PART 2 will consider DIALYSIS. You will need to supply the following in your lab report for experiment # 3 Part 1 (Osmosis) Table of Osmotic Potential and Time Graph of Osmotic Potential vs Time Graph of Osmotic Change vs Time (Osmotic Rate) Answers to Questions (1 - 7) Part 2 (Dialysis) Table of Dialysis Tests Answers to Questions (1 - 6) To magnify the blackboard click on it to view a discussion on membrane transport Click Mouse Here to View Next Text on the Blackboard

Click Mouse Here to View Next Text on the Blackboard OSMOSIS is the diffusion of water through a selectively permeable membrane. Water will generally move quite freely through the cell membrane by diffusion. Osmotic movement of water occurs when the solute (non-penetrating) concentrations differ between the opposing sides of the cell membrane. A difference in solute (non-penetrating) concentrations means there is a difference in water concentrations and water will move from the region of higher concentration to a region of lower concentration. Click Mouse Here to View Next Text on the Blackboard

Click Mouse Here to View Next Text on the Blackboard For example, water osmotically moves into a cell when the fluid outside the cell has more water (less solutes) than the fluid inside the cell. In this case, as water moves into the cell, it swells as the water pressure inside the cell increases. Red Blood Cell Distilled Water Click Mouse Here to View Next Text on the Blackboard

Click Mouse Here to View Next Text on the Blackboard DIALYSIS is the separation of solutes according to their size by diffusion through a permeable membrane. Depending upon the molecular pore size of the membrane, solutes will either diffuse across the membrane or be restricted by their size. The device you will be using to collect data for the experiments is an osmometer. This is a device used to measure osmotic force. Click Mouse Here to View Next Text on the Blackboard

Click Mouse Here to View Next Text on the Blackboard PART 1 (OSMOSIS) MATERIALS Thistle tube (with mm markings) Thistle tube stand Dialysis tubing (selectively permeable membrane) Rubber band Sugar solution (20 % sucrose) Beaker Click Mouse Here to View Next Text on the Blackboard

Click Mouse Here to View Next Text on the Blackboard When you are finished with PART 1 of experiment # 3, be sure that you include the following with your lab report. Table of Osomotic Potential and Time Graph of Osmotic Potential vs Time Graph of Osmotic Change vs Time (Osmotic Rate) Answers to Questions (1 - 7) Click Mouse Here to View Next Text on the Blackboard

Sucrose Sucrose H2O H2O You will need to record your data from this experiment on a data table. You can access the data table by clicking on the link to the right. Click Mouse Here to Access the Data Table Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard STAND Sucrose Sucrose H2O H2O Procedure Click on the thistle tube stand in order to bring it to the table You will know you are pointing to the stand when the cursor changes. Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Sucrose Sucrose H2O Thistle tube H2O Now click on the thistle tube funnel to attach it to the tube stand. Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Tubing Sucrose Sucrose H2O H2O Next we will put the dialysis tubing on the bulb end of the thistle tube. You will need only a small piece. Click on the dialysis tubing on the shelf. Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Sucrose Sucrose H2O H2O Rubber Band Put a rubber band on the tube and dialysis tubing to hold it in place. You can accomplish this by clicking on the rubber bands on the shelf. Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Sucrose Sucrose H2O H2O Put the bulb of the thistle tube into the beaker of water. The water is distilled which means that it has no solutes in it (100 % water). Click on the beaker labeled as H2O. Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Sucrose Sucrose Now we will pour the sucrose solution into the thistle tube from the top. The sucrose solution is a 20 % sugar solution (80 % water). Click on the beaker labeled as Sucrose. Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard 33 30 26 22 16 START Record the original millimeter measurement of the sucrose solution in the column of the thistle tube on your data sheet. Next, record the movement of the sucrose solution every 15 minutes for 90 minutes. Click on the start button of the clock to begin measuring. 10 00:00 70:00 75:00 90:00 65:00 85:00 80:00 55:00 25:00 20:00 15:00 10:00 60:00 30:00 50:00 45:00 40:00 35:00 05:00 3 Click Mouse Here to View Next Instructions on the Blackboard

You may want to print the two links above to produce your graphs. From the data you have collected you will need to produce two graphs. One of the graphs will plot Osmotic Potential vs Time. The other graph will plot Osmotic Change vs Time. Graph of Osmotic Potential vs Time Graph of Osmotic Change vs Time You may want to print the two links above to produce your graphs. Click Mouse Here to View Next Instructions on the Blackboard

When you have finished your graphs you can compare them with the two links below. Yours should be very similar to these. Completed Graph of Osmotic Potential vs Time Completed Graph of Osmotic Change vs Time Click Mouse Here to View Next Instructions on the Blackboard

Questions 1 - 7 on Osmosis and Dialysis Answer the following questions about the experiment you have performed. Be sure to include the answers in your lab report. Questions 1 - 7 on Osmosis and Dialysis Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Text on the Blackboard When you are finished with part 1 of experiment # 3, be sure that you include the following with your lab report. Table of Osomotic Potential and Time Graph of Osmotic Potential vs Time Graph of Osmotic Change vs Time (Osmotic Rate) Answers to Questions (1 - 7) Click Mouse Here to View Next Text on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard You are now ready to begin part two of experiment #3. In this part we will be concerned about a process related to osmosis called Dialysis. Lugol’s Lugol’s Glucose Glucose H2O Starch H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Dialysis is the diffusion of a solute (salt, glucose, etc.) across a selectively permeable membrane. In this case the solute molecules always move from the stronger concentration (hypertonic) to the weaker (hypotonic). To magnify the blackboard click on it to view a discussion about dialysis Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Dialysis involves the movement of some, but not all, of the dissolved substances in a solution. The substance that moves has small molecules, so these can pass through the pores in the membrane, but other substances, with larger molecules, cannot escape. The green molecules are small enough to fit through the pores of the semi permeable membrane while the red molecules are too large. Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard This process occurs normally in the kidney. Substances with small molecules, such as salts, glucose and urea, continuously pass out of the blood through a membrane under pressure, but useful substances are later reabsorbed. Waste substances are then excreted as urine. Kidney Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard In this exercise you will measure diffusion of small molecules through dialysis tubing, an example of a semi permeable membrane. The movement of a solute through a semi permeable membrane is called dialysis. The size of the minute pores in the dialysis tubing determines which substance can pass through the membrane. The light blue object here represents a section of dialysis tubing. The red spheres represent molecules which are able to move through the dialysis membrane, while the blue spheres represent molecules too large to move out of the dialysis membrane solution. Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard A solution of glucose and starch will be placed inside a bag of dialysis tubing. Distilled water will be placed in a beaker, outside the dialysis bag. The dialysis bag with the starch glucose solution will be inserted into the beaker of distilled water. After 30 minutes have passed, the solution inside the dialysis tubing and the solution in the beaker will be tested for glucose and starch. The presence of glucose will be tested with glucose test strips. The presence of starch will be tested with Lugol's solution (iodine potassium iodide). Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard PART 2 (DIALYSIS) MATERIALS 30 cm section of dialysis tubing String 15 % glucose solution 1 % starch solution Glucose test strips Lugol’s solution Distilled water 2 Test tubes Large beaker Click Mouse Here to View Next Instructions on the Blackboard

Click Here to Access a Table of Dialysis Tests When you are finished with Part 2 of experiment # 3, be sure that you include the following with your lab report. Table of Dialysis Tests Answers to Questions (1 - 6) Click Here to Access a Table of Dialysis Tests Click Mouse Here to View Next Text on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Procedure Obtain a 30 cm piece of dialysis tubing Click on the tubing to obtain the dialysis tubing Lugol’s Tubing Lugol’s Glucose Glucose H2O Starch H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard We will now tie one end of the dialysis tubing with the string. Click on the string to tie the tubing Lugol’s Lugol’s Glucose Glucose H2O Starch H2O String Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard We can now place the dialysis tubing in distilled water to moisten it so that it will be easier to open. Click on the beaker of distilled water to bring it to the table then click on the dialysis tubing to place the tubing in the water. Lugol’s Lugol’s Glucose Glucose H2O Starch H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard While we let the dialysis tubing soak, we can access the glucose and starch solutions. Bring the two solutions to the table by clicking on either of them. Lugol’s Lugol’s Glucose Glucose Starch H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard We will need to develop a method to test for glucose in a solution as well as test a solution for starch. Lugol’s Lugol’s Glucose H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Use a table like the one you see below to record your results. You can use the link supplied below to view a table which can be printed. Lugol’s Click Mouse Here to View Next Instructions on the Blackboard Lugol’s Glucose H2O Starch You should indicate a positive or negative test for each of the solutions and tests in the spaces provided Glucose Test Tape Lugol’s Solution Glucose Solution Starch Solution Dialysis Tube Solution After Soaking in Distilled Water Beaker of Distilled Water Before Insertion of Dialysis Tube Beaker of Distilled Water After Insertion of Dialysis Tube Glucose Starch Click Here to View a Printable Version of This Table

Click Mouse Here to View Next Instructions on the Blackboard We will be using glucose test strips to test a solution for the presence of glucose. When the strip is exposed to glucose it will change color from yellow to blue. Lugol’s Lugol’s Glucose H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard We will be using Lugol’s solution to test for the presence of starch. When Lugol’s solution is in the presence of starch the solution will change to a dark blue color. Lugol’s Lugol’s Glucose H2O Starch Water Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Click on the test strips to bring them to the table. Next we will test the Glucose solution and the distilled water where the dialysis tubing is now soaking for the presence of glucose. Lugol’s Lugol’s Glucose Test Strips H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Click on one of the glucose test strips. You will be testing the glucose solution for the presence of glucose. As you have predicted, you will get a positive test. Record your data. Lugol’s Lugol’s Glucose H2O Starch The color change on the strip shows a positive test for the presence of glucose Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Click on another test strip to test the distilled water for the presence of glucose. Remember a positive test will turn the yellow end of the strip to blue. Record your results in your data table. Lugol’s Lugol’s Glucose H2O Starch Record your data Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Next we will test for starch in the starch solution and the distilled water. You will be using Lugol’s solution to test for starch. If starch is present the solution will turn a dark blue color. Lugol’s Lugol’s Glucose H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Click on the blue bottle of Lugol’s solution on the shelf to bring it to the table. You will need a test tube to test a small portion of the starch solution. Next click on the test tube rack. Lugol’s Lugol’s Test tube Glucose H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Next click on the eyedropper in the bottle of Lugol’s solution to add a few drops to the starch solution in the test tube. Record your results on your data sheet. Click on one of the eyedroppers on the shelf to add starch to the test tube. Lugol’s Glucose H2O Eye Dropper Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Next we will test the distilled water for the presence of starch. Click on the test tube rack to get a clean test tube Lugol’s Glucose H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Click on a fresh eyedropper from the shelf to add distilled water to the test tube. Lugol’s Glucose H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Next click on the eyedropper in the Lugol’s solution to add a few drops to test for starch. Record your results. Lugol’s Glucose H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Next we will open the dialysis tubing and fill it with about ½ full of starch solution and about ½ full of glucose solution. Leave enough of the tubing so that you can tie the end shut. Lugol’s Glucose H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Click on the dialysis tubing in the distilled water beaker to remove it so that it can be opened. Next click on the starch or glucose solution to fill the dialysis tubing. Lugol’s Glucose H2O Starch Glucose Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Next click on the yellow string to tie the top of the dialysis bag. Lugol’s Glucose H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Now click on the dialysis bag to insert it into the distilled water. Leave the dialysis bag in the distilled water for 30 minutes. Click the start button on the timer. Lugol’s Glucose H2O Starch START 00:00 25:00 30:00 20:00 10:00 15:00 05:00 Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Remove the dialysis bag by clicking on it. Open one end of the dialysis tubing by clicking on the yellow string holding one end together Lugol’s Glucose H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Click on the test tube rack to obtain a test tube. We will add a small amount of solution from the dialysis tubing to the test tube to test for glucose and starch. Lugol’s Glucose H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Click on one of the blue eyedroppers on the shelf to add solution from the dialysis tubing. Next click on the one of the glucose test tapes to test for glucose. Record your results Lugol’s Glucose H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Now we can test for starch by using a few drops of Lugol’s solution. Click on the eyedropper in the Lugol’s solution to add to the dialysis tube solution. Record your results. Lugol’s Glucose H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard We will now perform the same tests for glucose and starch on the solution of distilled water in which the dialysis tubing soaked for 30 minutes. We will need a clean test tube. Click on the test tube rack. Lugol’s Glucose H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Click on one of the blue eyedroppers on the shelf to add solution from the distilled water. Next click on the one of the glucose test tapes to test for glucose. Record your results Lugol’s Glucose H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Mouse Here to View Next Instructions on the Blackboard Now we can test for starch by using a few drops of Lugol’s solution. Click on the eyedropper in the Lugol’s solution to add to the distilled water. Record your results. Lugol’s Glucose H2O Starch Click Mouse Here to View Next Instructions on the Blackboard

Click Here to Answer Questions 1 - 6 Click on the link below to answer questions on part 2 of experiment # 3. Click Here to Answer Questions 1 - 6 Click Mouse Here to View Next Instructions on the Blackboard

Click Here to Access a Table of Dialysis Tests When you are finished with part 2 of experiment # 3, be sure that you include the following with your lab report. Table of Dialysis Tests Answers to Questions (1 - 6) Click Here to Access a Table of Dialysis Tests Click Mouse Here to View Next Text on the Blackboard

Continue to Experiment #1 Continue to Experiment #2 At this point you have finished experiment # 3, Parts 1 and 2 for this lab. Would you like to end your session or continue to another experiment? End this Session Continue to Experiment #1 Continue to Experiment #2

Click Here to Return to Experiment #3 Questions Considering tonicity how would you describe the relative tonicities of the, a) dialysis bag solution, and b) beaker solution? By analyzing the differences between the tonicities of the solutions in the bag and the beaker, where should water diffuse to, a) into the bag, or b) into the beaker? Did starch diffuse from the bag? Why or why not? Did glucose diffuse from the bag? Why or why not? Did osmosis occur during this experiment? Why or why not? Did dialysis occur during this experiment? Why or why not? Click Here to Return to Experiment #3

Click Here to Return to Experiment #3 Questions Over the 90 minute period, what distance did the column of sugar move? Which term is used to describe the tonicity of the distilled water? (Hypotonic or Hypertonic) Explain why the sugar solution rises in the thistle tube over time. Explain why the diffusion rate of water changed over the 90 minute period of time. We began the experiment by pouring a 20% sucrose solution into the thistle tube. Describe what the makeup of the sucrose solution probably is after the 90 minute period. (more or less than 20%). Describe why this change in sucrose % has changed. From the knowledge you have gained could you explain why it is not a good idea to drink salt water when you are thirsty. CLICK HERE FOR A HINT Click Here to Return to Experiment #3

Click Here to Return to Questions Drinking Salt Water Drinking water normally quenches your thirst. But when you drink salt water it seems to make you more thirsty. The water in your mouth creates a situation in which the cells in your mouth are in a hypertonic solution. In order to reach an equilibrium, a net water movement out of the cells takes place. Now the cells have even less water than before, and you feel even more thirsty. Salt water not only dries out your mouth but the cells in your body too! As it enters your body, the cells near it release water to reach equilibrium with the surrounding fluid. The cells shrink and may become damaged. This is a condition called dehydration, or excessive water loss. In order to make ocean (salt) water drinkable, a system has been devised to remove the salt. It is called distillation. Click Here to Return to Questions

Graph of Osmotic Potential vs Time 40 36 32 Measure of mm 28 24 20 16 12 8 4 15 30 45 60 75 90 Minutes Click Here to Return to Experiment #3 Click Here To View a Printable Version of This Table

Graph of Osmotic Change vs Time 8 7 6 Movement in mm 5 4 3 2 1 15 30 45 60 75 90 Minutes Click Here to Return to Experiment #3 Click Here To View a Printable Version of This Table

Graph of Osmotic Potential vs Time 40 36 32 Measure of mm 28 24 20 16 12 8 4 15 30 45 60 75 90 Minutes Click Here to Return to Experiment #3

Graph of Osmotic Change vs Time Click Here to Return to Experiment #3 8 7 6 Movement in mm 5 4 3 2 1 15 30 45 60 75 90 Minutes Click Here to Return to Experiment #3

Table of Osomotic Potential and Time Osmometer reading *Movement in mm 3 - 15 10 7 30 45 60 75 90 *To calculate movement in mm you will need to subtract the preceding value from the succeeding value Click Here To View a Printable Version of This Table Click Here to Return to Experiment #3

TABLE OF DIALYSIS TESTS You should indicate a positive or negative test for each of the solutions and tests in the spaces provided Glucose Test Tape Lugol’s Solution Glucose Solution Starch Solution Dialysis Tube Solution After Soaking in Distilled Water Beaker of Distilled Water Before Insertion of Dialysis Tube Beaker of Distilled Water After Insertion of Dialysis Tube Click Here to Return to Experiment #3 Click Here to View a Printable Version of the Table