Summary- explain what happened in your data and record your group's suggested order of the solutions least to most concentrated. Was your group's estimate correct?
Exercise 1B Purpose Osmosis is the movement of water from a high concentration to a low concentration within a solution.
In this second part of the experiment, we have several dialysis bags filled with different molarities of sucrose. We will place these bags in separate tanks of distilled water, and see after 30 minutes where the water moved. If our bags increase in mass, we know the bag was in a hypotonic solution, which allows water to rush inside our mock cell.
Other wise, should the bag lose mass, then the solution was hypertonic, and water diffused out of the cell where a majority of the sucrose could be found. Thus we get three states, called hypertonic, isotonic, and hypotonic.
A membrane placed in a hypertonic solution will loose water because there is a higher concentration of solute outside the membrane. In an isotonic solution, the concentrations inside and outside of the membrane are the same, so there is no net water movement.
Methods Each dialysis bag was assigned a different molarity of sucrose to determine how the tonicity of the solution affects increase or decrease of the dialysis bag's mass. The solutions were ordered by increasing molarity, as shown in the picture above. Each dialysis bag was carefully blotted and massed before and after being submerged in its assigned solution.
From this information, we were able to determine a percent change in mass for each dialysis bag. Data Mass of Dialysis Bags after Being Submerged in Sucrose Graphs As the molarity of the solutions in the beaker increases, the mass of the bag also increases.
Discussion This lab demonstrates the process of osmosis through the movement of water from the beaker into the bags containing the sucrose. As the amount of sucrose of each bag independent variable increased, the weight of the bag dependent variable itself also increased.
When we placed the different sucrose bags within the beaker filled with distilled water, the water began moving from the beaker, through the permeable membrane, and into the bag.
This movement of water from an area of high concentration to lower concentration is called osmosis. This is evident though the increase of weight within each of the bags.
Also, because each of the bags contained a different amount of sucrose concentration the amount of water that moved within each bag also differed.
As a result, the graph displaying the weights of the bag increased as the amount of sucrose concentration was increased. The only concern for this lab is that the bag of distilled water within the distilled water beaker also increased in weight which should not have because it should already be an isotonic solution.
This increase in mass might have been due to the excess water on the bag after we pulled it out the beaker and weighed it again. Otherwise our predictions about the bags all increasing in weight were correct. Conclusion In this lab, we were testing the relationship between a solute's concentration and the movement of water molecules through a selectively permeable membrane.
Water moves quickly through the dialysis bag, our selectively permeable membrane, in order to reach equilibrium between the two solutions.
References Exercise 1C Purpose This activity involves the use of potato cores, which function as non-living plant cells but will still abide by the rules of water potential and solution tonicity.
In a similar manner to the dialysis bags, we can determine a solution's water potential by finding the masses of each potato core before and after being submerged in the given solution. Water will always move from a higher to lower potential, so in the case where more of the solute is outside the cell, there is more water within the potato core and therefore more potential.
So water therefore leaves the cell and the mass steadily decreases until the solution is isotonic and secured at equilibrium. Introduction When we combine all of the concepts we have learned above and combine them, we get water potential.
Water potential is not a process, it is merely an explanation to better define how water diffuses. Water diffuses from an area of high water potential to area of low water potential.Lab 1: Diffusion & Osmosis.
Conclusions. water moves from high concentration of water (hypotonic=low solute) to low concentration of water (hypertonic=high solute). Using two different models, students will simulate the movement of water and nutrients across a cell membrane and observe osmosis in living tissue, enabling a clear understanding of the properties of osmosis and diffusion and their role in maintaining homeostasis in the cell.
The purpose of this lab was to test and observe the process of diffusion and osmosis in certain situations. In this experiment, we were tasked with calculating the percent change of dialysis bags and potato cores as the go through this process.
For the pre lab, phenolphthalein, agarose, and sodium hydroxide (reactants) were combined to make a pink, tough gel (product). Two pieces of the gel were cut out, one with an apple shaped cookie cutter and the other with a potato corer.
AP Biology 16 April Lab 1: Osmosis and Diffusion The purpose of this experiment is to decide which flasks correspond to the solute concentration of sucrose, which are 0. 8M, 0. 6M, 0. Kellogg/AP Biology Osmosis/Diffusion and Water Potential Lab PART 1: Diffusion Introduction: The movement of particles into and out of a cell through the plasma membrane is a highly regulated process involving many different proteins, movements, and cellular energy.