Just as in the graph comparing the surface area to diffusion efficiency, the middle point cell 2 seems far away from the trend line, but is actually only a very small amount away because the range of the dependent variable is so minimal. By doing this with different sized cells, the rates of diffusion diffusion efficiency and time of diffusion can be compared and analyzed. These cells must be as efficient as possible, so they must have the optimal size to do so. The first test tube had 1 ml of the 500 KmnO4 added to it. The question therefore arises of whether volume or surface area affect the diffusion rate separately, or if the surface area to volume ratio is what makes the difference. Again I left the eggs in the beakers for another 24 hours to let the substances soak into the egg and create change.
Next, we had to find the water potential of the potato. Describe the results of the attempts to diffuse glucose and. Students will record their predictions and work in groups to design a data collection table for their expected data. Data Table Record the amout of liquid in the beaker in ml Observations Day 1 Day 3 Day 5 Day 7. Sarah, Liza, Karina, Susanna Investigating Osmosis and Diffusion Results and Observations Data Procedure 2: Modeling Diffusion and Osmosis Questions Methodology Procedure Results and Observations Procedure 3: Observing Osmosis in Living Cells Questions Methodology Procedure Materials Equations 1.
The confidence level of 0. When acid is present, the indicator becomes clear. Because of these alike volumes, their ratios were very close, and Cell 2, the smaller one, had a smaller ratio, the opposite of the trend we expected to see. Lesson organisation This activity could be carried out by students working as individuals or in pairs, depending on the number of microscopes available. This line is where the points from the unknown sucrose solutions will lie on since the change in mass and sucrose concentration should have a relatively linear relationship. In general, it shows that with a greater surface area, the diffusion efficiency is greater. Our results were in complete accord with our predictions because it is clear from our graph that all of the solutions with negative changes in mass did indeed have a sucrose concentration higher than that of which we determined for the sweet potato and vice versa for when there was a gain in mass.
All of the variable affecting the experiment was considered and prevented from changing the results. Conversely, we predict that the beaker containing water inside the cell and orange juice surrounding will have a decrease in mass as there is a higher free water concentration inside the cell, therefore causing the water to move out. When the egg was place in the water, in which direction did the water molecules move? Using dialysis tubing, we can create models of living cells and then fill them with different solutions to observe osmosis and ultimately determine the rate of diffusion. The thinking process behind my hypothesis was the thought that since the egg contains a lower concentration than the corn syrup, water particles from the egg will transmit out of the egg to give the corn syrup which has a higher concentration to lower its concertation. Purpose: To investigate the concepts of osmosis and diffusion using eggs submersed in a variety of substances. Background Hypothesis What affect does surface area and volume have on the diffusion rate of a cell? Day Two: On day two, observe what has happened to your eggs. After making an educated guess as to the molar concentration of each solution, solute potential can then be calculated and used to find the water potential, which in turn is used to compare the rate and direction of osmosis in each solution.
Concentration gradient is the comparison of the concentration of a substance on one side of a membrane, as opposed to the concentration on the other side. Then the second test tube had 1 ml from test tube one and 4 mL of water. The raisins were left to sit for two days and later were observed. They collect measurements of height, width, and mass before and after the soaking of the candy overnight. Results were that the smaller substance passed though the membrane easily and rather quickly, and the larger substance did not penetrate the membrane whatsoever. The dependent variable was the weight of the egg s. This time mount the cells with a couple of drops of 5% sodium chloride solution.
Time each of the cells separately until they are completely clear with no pink dye visible. I was correct because i also predicted that the egg in water would not change its appearance because no food colouring, sugar or other changing substance were added. We predict that the beaker containing orange juice in and water out will show an increase in mass because there is a higher free water concentration outside the cell membrane so the water moves inward. Osmosis is the process by which water molecules diffuse across a cell membrane from an area of higher concentration to an area of lower concentration. I have found this lab helps students to better remember and comprehend these terms and concepts. Since water tends to move to where there is a lower concentration of free water, we can determine how the concentrations compared before osmosis occurred based on if the weight increased or decreased inside the cell. The agar plate had two spots that had spread out from the tow original holes.
The procedure of the lab is structured and given to the students. Selectively permeable membranes allow some molecules to move through, while not allowing others. Orange juice contains fructose and glucose, both of which are large molecules and require active transport to pass through membranes. Discussion In my hypothesis I stated that if diffusion and osmosis across a selectively permeable membrane are related to the substance the membrane in submersed in, then an egg submersed in corn syrup will make it heavier as a result of water particles moving into the egg. Methodology Discussion We predicted the sucrose concentrations of the unknown solutions by using the information we knew. So again the hypothesis was supported the tap water caused the gummy bear to grow, while the salt caused them to shrink.
Also put the group number on each jar. Theory When a concentration gradient exists within a fluid consisting of two or more components, there is a tendency for each constituent to flow in such a direction as to reduce. Materials needed: Gummy bears at least 2 per group , method of measuring height and mass of bear, containers for water. The answers to this study are important because cells with specialized functions are able to do their job well based on their cell size and surface area balance. Data was collected by weighing potato pieces on a balance. The control was the one of the raisins in an empty container.
How do the contents of orange juice fructose and glucose affect the rate and direction of osmosis? Replace it with distilled water added at the other side of the coverslip. A transfer of water was the reason for these changes in both cases. As the salt concentration increased, the size of the cell membrane decreased. Seal one end of each tube by tying it into a knot. In cells, Diffusion occurs through… 1599 Words 7 Pages Osmosis and diffusion are two important processes in the human body that help in the functioning of cells and homeostasis, or maintaining balance within the body. A faster increase or decrease in weight indicates a faster rate of diffusion. The movement of water across cell membranes and the balance of water between the cell and its environment are crucial… 2166 Words 9 Pages Diffusion and Osmosis of Solutes and Water Across a Membrane Brittany Bacallao Nova Southeastern University Abstract: This experiment gave a visual understanding of osmosis and diffusion.