ABSTRACT Cells are important because they carry out all activities necessary for life. Cell structure can be examined and observed under a light microscope. The cell membrane is a critical component of the cell because it controls which materials pass through the cell. Osmosis, the movement of free water across the cell membrane, is demonstrated by examining the movement of material across the cell membrane of potato tissues. Potato tissues were put into various concentrations of NaCl to examine the effect of concentration on the potato tissues. Our hypothesis is if there is a higher concentration of NaCl, then the potato tissues will decrease in weight. In addition, the effect of concentration gradient and temperature on the rate of osmosis in an artificial system were investigated by using dialysis tubing. In this lab, the investigated variables were the change in temperature between 15°C and 55°C and the change in concentration of the NaCl solution. Our hypothesis is if there is a greater concentration gradient, then it will have a greater effect on the increased rate of osmosis compared to temperature. Determined was that as temperature and concentration gradient increased in solutions, the rate …show more content…
Leaf tissues from Elodea, a waterweed, are an example of a eukaryotic plant cell. The structure of plant cells can be examined and compared to those of animal cells. Plant cells contain rigid cell walls and chloroplasts that make them different from animal cells. The chloroplast are mostly located near the cell wall to maximize the amount of sunlight they receive. Plant cells are affected by the concentrations of solutions that they encounter. Hypertonic solutions cause the cell membrane to shrink and detach from the cell wall (Urry et al., 2016). This is known as plasmolysis. Our hypothesis is if chloroplasts come in contact with a salt solution, then they will clump
As we know that osmosis means diffusion or dispersion of water through a selectively permeable membranes from high concentration to a lower concentration and there are many different factors that can affect the rate of Osmosis such as temperature particle size and the size of concentration ingredient. As we know that higher temperature can cause osmosis to occur at much faster rate because a molecule are more likely to pass through the selectively permeable membrane quicker than they would at a lower temperature. In this experiment the sucrose molecule was too large to pass through the dialysis bag, while water molecule able to move freely in and out due to their small size. Lastly the congregation gradient can greatly affect the rate of osmosis
The Osmosis and Diffusion lab was conducted to provide us with information on how built up mucus affects those conflicted by the recessive genetic disease, Cystic Fibrosis., due to a mutation to the membrane regulating chloride (Cl-). This mutation prevents the Cl- from leaving the cell causing the amount of sodium (Na+) in epithelial cells, which results in extreme mucus on the lungs and airways causing this disease to be fatal if not treated but treatment does not equate to a long lifetime. During the lab we took the data from three parts: Diffusion, Osmosis in an Elodea Cell, and finally the Role of Osmosis in Cystic Fibrosis. During Part 1 we looked at diffusion across a semipermeable membrane for starch and glucose, which resulted in both having a negative solution when placed in a semipermeable membrane. Then we looked at osmosis in the Elodea Cell to watch for the occurrence of Plasmolysis, when a cell’s plasma membrane pulls away from the cell, and how a plant cell is affected by both hypertonic and hypotonic solutions. Finally, we observed the role of Osmosis in Cystic Fibrosis using dialysis bags to represent a normal cell and a Cystic Fibrosis cell with the normal containing 1% NaCl while the Cystic Fibrosis bag contained 10% NaCl. After we ran the experiment, we looked at the Percent Change in Mass and compared them after 30 minutes. We found that Cystic Fibrosis cells didn’t change mass as much as the normal cell ending with a change in mass over -1%. The
I know that osmosis will occur in the vegetables, but I am not sure of
The lab for this paper was conducted for the topic of osmosis, the movement of water from high to low concentration. Five artificial cells were created, each being filled with different concentrated solutions of sucrose. These artificial cells were placed in hypertonic, hypotonic, or isotonic solutions for a period of 90 min. Over time, the rate of osmosis was measured by calculating the weight of each artificial cell on given intervals (every 10 minutes). The resulting weights were recorded and the data was graphed. We then could draw conclusions on the lab.
Van’t Hoff’s Law suggests that the osmotic potential of a cell is proportional to the concentration of solute particles in a solution. The purpose of this experiment was to determine if there are any differences between the osmolalities, the no-weight-changes of osmolalities, and the water potentials of potato cores in different solutions of different solutes. The percent weight change of the potato cores was calculated through a “change in weight” method. The potato core’s weight was measured before and after they were put into different concentrations of a solute for 1.5 hours. In our experiment, there were no significant differences from the osmotic potentials of our results and the osmotic potentials of other scientists work. Ending with chi square values of 2.17 and 2.71, and p values of 0.256 and 0.337, concluding that there is no difference in water potentials of potato cores in different solutions of different solutes at varying concentrations.
Osmosis is defined as the tendency of water to flow through a semipermeable membrane to the side with a lower solute concentration. Water potential can be explained by solutes in a solution. The more positive a number is more likely it will lose water. Therefore should water potential be negative the cell the less likely it will lose water. In using potatoes the effects of the molarity of sucrose on the turgidity of plant cells. According to Clemson University, the average molarity of a White potato is between .24 M and .31 M when submerged in a sorbitol solution. This experiment was conducted with the purpose of explaining the relationship found between the mass in plants when put into varying concentrations of sucrose solutions. Should the potatoes be placed in a solution that contains 0.2M or .4M of sucrose solution it will be hypotonic and gain mass or if placed in .6M< it will be hypertonic and lose mass instead. Controlled Variables in this lab were: Composition of plastic cups, Brand of Russet Potatoes, Brand of Sweet Potatoes and the Temperature of the room. For independent variable that caused the results recorded it was the different Sucrose concentrations (0.0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M). The dependent variable was the percentage change from the initial weighs to the final. The cup with .4 molarity was the closest to an isotonic solution and was used as the control group for the lab. Water potential is the free energy per mole of water. It is
The Graphs below show the percent changes in mass for both the class averages and our group's averages:
Osmosis is the movement of water molecules from high concentration to low concentration through semipermeable membranes, caused by the difference in concentrations on the two sides of a membrane (Rbowen, L.). It occurs in both animals and plants cells. In human bodies, the process of osmosis is primarily found in the kidneys, in the glomerulus. In plants, osmosis is carried out everywhere within the cells of the plant (World Book, 1997). This can be shown by an experiment with potato and glucose/salt solution. The experiment requires putting a piece (or more) of potatoes into glucose or salt solution to see the result of osmosis (a hypertonic type of solution is mostly used as it would give the most prominent visual prove of
will never be the same weight as we had to cut them ourselves and it
The purpose of methodology is to maintain the most accurate results by conserving the temperatures of each sample of potato. By wrapping the potatoes in tin foil, it not only maintains the heat of each, but it also allows them to have close to almost the same temperature with each other when they are trapped with the same heat. This makes sure that the hot potatoes do lose their heat and that the cold potatoes remain cold. Maintaining the same temperature for each potato prevents the results of the trials for the same potato from being different from one another. The control group consists of having the same type of potato, washing all the potatoes in the same water to get rid of grime, having about the same sized potato pieces, using 150 mL
The movement of water molecules across a semi-permeable membrane is the process of osmosis. If there is a solute and a solvent, each containing different concentration levels, then the water would move along its concentration gradient until each side of the membrane are equal. The water moves because the membrane is impermeable to the solute and the solute concentrations may differ on either side of the membrane. Water molecules may move in and out of the cell, but there is no net diffusion of water. Water will move in one direction or the other, and this is determined by the solute or solvents concentration levels. If the two solutions are of equal concentrations, they will be isotonic. If the concentrations are unequal, the
In this experiment, the osmotic concentration is found with potato slices placed in sucrose solutions. Osmosis in this model is the net movement of water between the potato cell and the sucrose solution. The movement of water is determined by the molarity of sucrose. As the molarity of sucrose increased then the concentration in the solution also increased. H2O will move through the cell membrane to areas of higher concentration in order to reach equilibrium. If cells are placed
Purpose: The purpose of this lab is to familiarize you with osmosis and, specifically, what happens to cells when they are exposed to solutions of differing tonicities.
The difference is that along with large molecules, living cells prevent molecules with positive charges and solubility. This is not representing in dialysis tubing, and is only found in living cells because the tubing is only based on molecular size (98). When referring the rate of diffusion, the concentration gradient influences the diffusion rate, based on the factors of temperature. The ability for molecules diffuse from high to low concentrations primarily depends on the concentration gradient between the two areas.(96-99). My hypothesis for the study is that in the hypotonic, hypertonic, and isotonic solutions, the direction and rate of osmosis will determine based on the concentration inside the dialysis tubing. My prediction is that if the solution is hypotonic the results will decrease, if the solution is hypertonic the results will increase and if the solution is isotonic the solution will vary and or remain constant.
The aim of the sixteenth of November experiments was to observe how three different solutions with various sucrose concentration influenced osmosis in relation to three onion cells and the impact on the cells structure.