All cells contain membranes that are selectively permeable, allowing certain things to pass into and leave out of the cell. The process in which molecules of a substance move from an area of high concentration to areas of low concentration is called Diffusion. Whereas Osmosis is the process in which water crosses membranes from regions of high water concentration to areas with low water concentration. While molecules in diffusion move down a concentration gradient, molecules during osmosis both move down a concentration gradient as well as across it. Both diffusion, and osmosis are types of passive transport, which do not require help.
When the concentration of the environment outside of the cell is lower than the inside…show more content…
The potato cores started to decrease in weight as the molarity went up. The potatoes that gained weight were the potatoes placed in deionized water, and the sucrose solution molarity of 0.1.
However, the potatoes started losing weight in the sucrose solution of 0.2 and up.
Sucrose Molarity 0 M 0.1 M 0.2 M 0.3 M 0.4 M 0.5 M 0.6 M
Final Weight (g) 5.1g 5g 4.7g 4.5g 4.2g 4.1g 4.2g
Initial Weight (g) 4.4g 4.5g 4.4g 4.3g 4.4g 4.5g 4.4g
Weight Change (g) 0.7g 0.5g -0.3g -0.2g -0.2g -0.4g -0.2g
% Change in Weight 15.9g 11.1g -6.82g -4.65g -4.55g -8.89g -4.55g
When the potato gains weight it was in a hypertonic solution, and when the potato loss weight it was in a hypotonic solution. If the potato would not have changed weight it would have been an isotonic solution, but that was not the case in this experiment. The potato either gained, or lost weight. This data therefore supports the hypothesis that the potato that would be more hypertonic to the sucrose solution and would gain weight, whereas the potato would be hypotonic to the solution and would lose weight. Based on the data from the graph, the osmolarity of the potato was 0.4 M. Osmolarity is the molar concentration of when there is no change in the weight of the potato. In
- Length: 710 words (2 double-spaced pages)
- Rating: Excellent
Will starch, water, glucose, iodine or a combination of the above diffuse across the membrane of the dialysis bag causing the bag to either expand or shrivel?
Hypothesis & Strategy
I believe that the smaller molecules, such as glucose and water will diffuse through the dialysis bag’s membrane causing it to expand, due to the concentration gradient. I would test this hypothesis by filling the bag with a solution consisting of water, glucose and starch, tie it off and weigh it. I would then place the bag in a beaker of water and let it sit for a day. Then I would reweigh the bag.
· Dialysis Tubing
· Glucose Starch Solution, 15mL
· IKI Solution, 5mL
· 4 Glucose Indicator Strips
· 1 Graduated Cylinder
· 1 Plastic Cup, 250mL
1. Pour 15mL prepared glucose/starch solution into the graduated cylinder.
2. Get a piece of tubing and use a sting to tie a knot on one end of the tubing.
3. Open the tubing and pour 15mL of the glucose/starch solution into the tubing.
4. Determine the initial glucose content in the tubing by using the glucose indicator strip. Record the data in Table 1.
5. Tie another not at the other end, leaving room for expansion
6. Record the color of the solution in the bag in Table 1.
7. Fill a 250mL beaker approximately 2/3 full with distilled water. Add 5mL of iodine to the beaker.
8. Record the color of the solution in Table 1.
9. Determine the beaker glucose content using the glucose indicator strip and record the data in Table 1.
10. Completely immerse the dialysis bag in the solution in the beaker.
11. Wait at least 30 minutes or until there is a noticeable change in the color of the solution in either the beaker or the dialysis bag.
12. Remove the dialysis bag from the beaker reweigh it and record the final color and glucose content of the dialysis bag and the beaker. Record this data in Table 1.
13. Wash your hands and clean up lab area.
Color Glucose Content Bag
Time Dialysis Bag Beaker Dialysis Bag Beaker Weight
Start Cloudy white Gold 500 mg/dl Negative 49.5g
After 30 minutes Cloudy Purple Clear 100 mg/dl 100 mg/dl 50.9g
1. What do your observations tell you about the presence of glucose, starch, and IKI in the dialysis bag and the beaker before and after the experiment?
Before the experiment the dialysis bag had water with glucose and starch dissolved in it, while the solution in the beaker consisted of water and iodine. After the experiment the iodine had diffused into the bag while the glucose had diffused out of the bag. This is evident because at the conclusion of the experiment the bag was purple due to the reaction of iodine and starch.
How to Cite this Page
|Diffusion Lab Essay - Diffusion Lab Problem Will starch, water, glucose, iodine or a combination of the above diffuse across the membrane of the dialysis bag causing the bag to either expand or shrivel. Hypothesis & Strategy I believe that the smaller molecules, such as glucose and water will diffuse through the dialysis bag’s membrane causing it to expand, due to the concentration gradient. I would test this hypothesis by filling the bag with a solution consisting of water, glucose and starch, tie it off and weigh it.... [tags: essays research papers]||710 words|
|Diffusion and Osmosis Essay - Diffusion and Osmosis Lab Report on Diffusion and Osmosis Our objective is to figure diffusion and osmosis. Diffusion is the process whereby particles of liquids, gases, or solids intermingle as the result of their spontaneous movement caused by thermal agitation and in dissolved substances move from a region of higher to one of lower concentration. Osmosis is a process of absorption or diffusion suggestive of the flow of osmotic action. In our experiment in lab class, we did a procedure to observe osmosis along a free energy gradient.... [tags: Papers]||715 words|
|A Basic Understanding of Diffusion and Osmosis Essays - A Basic Understanding of Diffusion and Osmosis The purpose of this lab was to have a basic understanding about concepts diffusion and osmosis. In this lab we had dialysis tube as a cell membrane of cell, which lets small particles pass through it and we had test tube as tightly joined surface, which doesn’t let any particles pass through it. As a result we saw that small particles like glucose and iodine diffused through dialysis tube, but large particle like starch couldn’t diffuse dialysis tube.... [tags: Papers]||938 words|
|Diffusion Essay - Lab Report #1: Diffusion Introduction: The human body undergoes a variety of processes throughout each and every day in order to sustain life. Tasks such as walking, breathing, and digesting what has been eaten are sometimes considered mundane, even taken for granted. One such process that is necessary to maintain life is diffusion. Diffusion is a key factor in moving ions, fuels, and other molecules into and out of the blood. It is one of the most important components in supplying oxygen to the alveoli and removing carbon dioxide.... [tags: essays research papers]||1787 words|
|Essay about Water Lab Report - Water is a charged or polar molecule (H+ - O- - H+) that is always moving across cell membranes. Scientists theorize that this is possible because it is such a small molecule or because there are special gap or pores that allow water movement through the cell membrane. The predominant direction of water flow is determined by the concentration of the solutes (non-water molecules) inside and outside of the cell. Water molecules will show a new movement from an area of higher water concentration (& lower in solutes) to an area of lower water concentration (& higher in solutes).... [tags: Lab Report]||550 words|
|Essay on beet lab - MATERIAL AND METHODS Stability of cell membrane using pH For the lab experiment for testing the stability of beet cell membranes using pH, many materials were used as follows. Obtaining a beet we punch out cores, using a cork borer. After washing the cores we put each one inside a separate test tube, and added a different pH solution in each one. After 3 minutes in these exposure solutions, we took the beet out with a dissecting needle. Then transferred each beet to a separate test tube containing deionized water.... [tags: essays research papers]||831 words|
|Proving that Osmosis and Diffusion Occur in Artificial Membranes by Using a Dialysis Tubing - Proving that Osmosis and Diffusion Occur in Artificial Membranes by Using a Dialysis Tubing Hypothesis- Osmosis and diffusion will continue until equilibrium is reached and net movement will no longer occur. Solute size and concentration gradient across the selectively permeable membrane will effect diffusion. Materials- please refer to transport across semi-permeable membranes: diffusion and osmosis laboratory exercise hand out. Procedure: please refer to transport across semi-permeable membranes: diffusion and osmosis laboratory exercise hand out.... [tags: Papers]||446 words|
|How the Rate of Diffusion Changes When Increasing the Difference in Concentration - How the Rate of Diffusion Changes When Increasing the Difference in Concentration Planning A: Research Question: How will the rate of diffusion be affected if I increase the difference in concentration. Hypothesis If we add more dye drops into the water beaker then it should take more time to spread/diffuse through the water because the molecules in the dye, when they are all together, are more organized then if they were spread apart. Since it is a energetic state, it will tend to do spread.... [tags: Papers]||417 words|
|Essay on Investigating the Water Potential of Celery Cells - Investigating the Water Potential of Celery Cells Aim === I will be investigating the water potential of celery and to find out which solution will be isotonic with the celery cells, in other words equilibrium between the two no water will leave the cell, or enter. I will do this by following this method. Method 1. Cut a 5 cm length of celery stem 2. Cut through the grooves to divide the stem into thin strips 3. Dry the cell sap from the strips using a paper towel 4.... [tags: Lab Report]||862 words|
|Osmosis Lab Essay - Abstract In the Biology Laboratory session, I worked with two partners on Osmosis. It means the diffusion of water across a selectively permeable membrane, which is the plasma membrane in a biological system. The purpose of this activity is to find the weight of potato cores in two separate beakers. One beaker contains distilled water and other one is 10% NaCl. Before performing the laboratory test, we made two hypotheses. The first one is the weight of potato cores in 10% NaCl will decrease in gram.... [tags: Science]||1094 words|
Diffusion Lab Starch Solution Glucose Strip Indicator Cylinder Record Knot
The glucose content of the beaker was higher at the end of the experiment than in the beginning, proving that the glucose had diffused into the beaker from the bag.
2. What can you conclude about the permeability of the dialysis bag membrane? Which compounds were able to diffuse through the membrane? Which were not? Why were only some able to pass through?
The dialysis bag’s membrane was a selectively permeable membrane. Iodine, glucose and water were able to diffuse through the membrane while starch was not able. This occurred because while iodine, water and glucose molecules are small enough to diffuse through the membrane, disaccharides like starch are too large to diffuse through the membrane.
3. Was there more or less water in the dialysis bag at the conclusion of the experiment? Why?
There was more water in the bag at the conclusion of the experiment because there was a higher concentration of water outside the bag than inside, creating a concentration gradient.
4. Why did you weigh the bag? Did the weight increase or decrease? What does this prove?
We weighed the bag so that we would know if there was any increase in weight or water in the bag at the conclusion of the experiment. The weight increased. This proves that the bag’s membrane was selectively permeable.
After doing the experiment I could clearly see that the iodine moved in to the dialysis bag, and some of the glucose move out of the bag to be at equilibrium. We found this out because of how the test strips came out positive for the solution inside the beaker.