Introduction
Diffusion is the net movement of particles from an area of higher concentration to an area of a lower concentration, and osmosis is the net movement of water across a selective permeable membrane (Biology Department, 2008).
The molecules can enter and leave the cell through a selective permeable membrane which allows molecules to enter the cells cytoplasm depending on their size, hydrophobicity and charge. There three types of water movement in osmosis. First is the isotonic solution which has no net water movement which means the concentrations inside and outside the cell is equal and the cell reached equilibrium. hypertonic solution is when the water moves outside the cell, while hypotonic solution is the movement of water towards the inside of the cell (Biology Department, 2008).
Osmosis has different effects on plant and animal cells. If an animal cell is placed in a hypotonic solution, it will swell and burst. While in plant cell it will only become turgid because of the cell wall that prevents plant cells from bursting. If placed in hypertonic solution, the animal cell will become crenate while the plant cell will only shrink its vacuole but will not lose its shape because the cell wall keeps the cells shape (Biology Department, 2008).
The Essay on Dconcentrations Of Solutions Determine The Mass Of A Potato
... conditions can be crucial to a plants health. In an isotonic solution, a plant cell has no net movement of water. A word for what occurs is ... flaccid. When solution is isotonic the vacuole is ...
The surface area to value ratio plays a big role in effecting the plant and animal cells from the point of osmosis and diffusion as this experiment demonstrates.
The goal of this experiment is to determine the osmolarity, calculate the percent weight change of plant cells in a solution of sucrose with different concentrations, determine whether the surface area to volume ratio has effect on osmosis, and finally to figure out whether mystery solution A and B are hypertonic or hypotonic solutions.
Materials and methods
The first part of the experiment was to determine the osmolarity of Solanum tuberosum tissues (potato tissues) in different concentrations of sucrose solutions. The concentrations varied from 0 to 0.6 M. From a potato, 4 pieces were cut into small cubes with a size of 1cm x 1cm x 1cm. The potato pieces were always placed on a wax paper or a plastic wrap and not on a paper towel because it will draw water from the tissues. For each potato piece, it was weighed individually with a Denver Instrument MXX-212 balance. The weight of each piece was recorded in a table and each piece was placed in a different test tube. 10ml of each solution of different concentrations was poured in each test tube with the same concentration labeled on the tube. The potato pieces were left for incubation for an hour at room temperature. After the incubation, each potato piece was weighed again using the same balance mentioned earlier. The new measurements were recorded in the table and the percentage of weight change was calculated and recorded in the same table. The formula to calculate the percentage of weight change is:
[ (weight after-weight before) / weight before ] x 100 = % weight change.
The second part of the experiment was to see how the surface area and volume effects the diffusion of water in and out of the cells. Two pieces of potato were cut with a size 1cm x 1cm x 1cm and 2cm x 2cm x 2cm. The two pieces were weighed using a Denver Instrument MXX-212 balance. The weight of each piece is recorded in a new table. Both of the potato pieces were placed in a beaker and covered with distilled water and were left for an hour for incubation at room temperature. After the incubation period was over, each potato piece was weighed again using the mentioned balance and the values were recorded in the table. The percentage of weight change was calculated as well as the surface area, volume, and the ratio of surface area to volume. The surface area of a cube is six multiplied by the square of the length of the side (6a2).
The Essay on Bio Potato Core Osmosis
Table 1: Weights of potato pieces Solutions for the potato pieces to be dipped in(M) | Mass of potato pieces in Grams (+/-0.01)(initial mass)| Time when the potato pieces were dipped in the solution in seconds (+/- 0.01)| Time when the potato pieces were taken out of the solution in seconds(+/- 0.01)| Mass of potato after a hour in Grams (+/- 0.01) (final mass)| Water | 2.62| 0| 0| 3.19| 0.1| 2.54 ...
The volume of the cube is the length of the side to the power of three (a3).
The final part of the experiment is to examine the effects of osmosis in plant cells, specifically, red onion cells (Allium haematochiton).
A very thin red leaf epidermal peel was obtained from a red onion and was placed on a microscope slide and submerged in two drops of isotonic saline (0.9% w/v NaCl).
Two other red onion peels were prepared and submerged in mystery solution A and B, both solutions on each peel. After the onion peels were left for five minutes to equilibrate in the solutions, coverslips were placed on the slides and were examined under the microscope (Leica DME) using a 10x objective. A labeled drawing was prepared for each onion peel.
Results
Table 1. Weight of potato sections before and after incubation in different concentrations of sucrose.
Sucrose Concentration (M) Weight before (g) Weight after (g) Percent weight change
0 1.55 1.70 9.68%
0.2 1.62 1.72 6.17%
0.4 1.66 1.62 – 2.44%
0.6 1.56 1.45 – 7.05%
According to Table 1, the potato pieces of the first part of the experiment had different results of percent weight change. The first and second potato pieces (0 M, 0.2M) had an increase in weight after incubation, which indicates that there was a net movement of water coming inside the potato cells and it gave a positive percent of weight change. The third and fourth potato pieces (0.4 M, 0.6M) had decreased in weight, which means there was a net movement of water going outside the potato cells; therefore it gave a negative percent weight change.
Figure 4. Percent weight change with sucrose concentration in the potato sections.
Figure 4 showed the relation between the percent weight change with the sucrose concentration. From Figure 4, it is shown that there is no net movement of water at the sucrose concentration of 0.345 M.
The Essay on Test Tube Solution Potato Change
... no difference between the change in mass of a potato piece weather placed in concentrated sugar solution or a pure water solution. This disagrees with ... 4. Using the scaled weigh the potato to 2. d. p. and record the weight. 5. The test tube rack and ... water, of higher concentration inside the potato cells, flows down a concentration gradient into the solution, which has a lower concentration of ...
Table 2. Percent weight change, surface area, volume, and ratio of surface are to volume of potato piece of different sizes.
Piece dimensions
(cm x cm x cm) Weight before (g) Weight after (g) Percent weight change Surface area (cm2) Volume (cm3) Surface area : Volume
1 x 1 x 1 1.35 1.59 17.80% 6 1 6:1
2 x 2 x 2 14.79 15.82 6.96% 24 8 3:1
In the second part of the experiment both of the potato pieces increased in weight and had a positive percent weight change according to Table 2. The ratio of surface area to volume was a factor in the diffusion of objects in and out of the potato cells. The smaller potato piece increased in weight more than the larger piece (Table 2).
With higher ratio there is a higher percent weight change.
In the last part of the experiment the onion cells (A. haematochiton) had different appearances in each solution. In the isotonic saline solution, the cell had a regular appearance compared to the hypertonic and hypotonic solution with no increase or decrease in size, which indicated that there was no net movement in that cell (Figure 3).
The vacuoles of the cells of mystery solution A had shrunk (Figure 2), therefore mystery solution A was a hypertonic solution with a net movement of materials going outside the cells. However, the cells in mystery solution B had a turgid appearance which is a “good” shape for the plant cells and it indicates that this solution was a hypotonic solution with a net movement of materials coming inside the cells.
Discussion
From Table 1 we can see that there was a significant change of weight in each potato piece in different concentrations. The pieces with positive percent weight change indicate that there was a diffusion of water into the potato tissues because there was less concentration of water in those tissues, which means those cells were in a hypotonic solution, and for that reason the water started diffusing into the tissues which increased the weight of the potato piece. On the other hand, the potato pieces with a negative weight change had a diffusion of water going out of the potato tissues (Table 1).
This is because the solution which the potato piece was placed had a low concentration of water, so the water started moving out the cells to balance the concentration of the solute. For that reason the potato piece recorded a decrease in weight. As the concentration of sucrose solutions started to increase, the percent weight change decreased, therefore the concentration of sucrose is inversely proportional to percent weight change in this experiment. Whenever there is a positive percent weight change it means there is a gain in weight, while a negative number means there is a loss in weight (Biology Department, 2008).
The Essay on Beetroot Cell Membranes
Beetroot samples: The same size beetroots will be used throughout the experiment this is to ensure that the impact of the temperature on every sample will stay the same, i.e. if having a bigger beetroot sample less pigments will be released into the test tube at lower temperature, or having a smaller beetroot sample more pigment will be released into the test tube. This error will change the ...
The potato cells in the isotonic solution had a regular shape compared to the cells in the hypertonic and the hypotonic solutions. The cells were neither turgid nor crenate.
In the second part of the experiment the two potato pieces had a positive percent weight change which means they gained weight from the diffusion of water into the tissues. The two potato pieces had different sizes with different ratios of surface area to volume which actually made a difference in the percent of weight change as it was comprehended from the experiment for the following reasons (Table 2).
In the smaller piece there was a bigger ratio of surface area to volume which makes it easier for water molecules to travel along and enter and leave the cells. While in the bigger piece it had a smaller ratio of surface area to volume which prevented the water molecules from reach all the cells due to the larger volume and surface area (Campbell & Reece, 2008).
In other words, the percent weight change is directly proportional to the ratio of surface area to volume.
Comparing the effects of surface area to volume ratio between prokaryotic and eukaryotic cells, it is noticed that there is a higher ratio in prokaryotic cells than eukaryotic (Campbell & Reece, 2008).
Because in general, prokaryotic cells are much smaller than eukaryotic cells which gives them a smaller surface area to volume ratio. Also, prokaryotic cells have cells walls which prevent them from bursting or shrinking from the diffusion of water in those cells. From this information, I can comprehend that prokaryotic cells have larger surface area to volume ratio.
The last part of this experiment was to determine whether the mystery solutions are hypotonic or hypertonic. The cells in mystery solution A had lost their natural appearance and shrunk. The vacuole of the cell has decreased in size which gives an indication that the mystery solution A is a hypertonic solution because it decreased the size of the vacuole (Figure 2).
The Essay on Surface Area To Volume Ratio And The Relation To The Rate Of Diffusion
Aim and Background This is an experiment to examine how the Surface Area / Volume Ratio affects the rate of diffusion and how this relates to the size and shape of living organisms. The surface area to volume ratio in living organisms is very important. Nutrients and oxygen need to diffuse through the cell membrane and into the cells. Most cells are no longer than 1mm in diameter because small ...
The cells of the mystery B had increased in size and became turgid due to the diffusion of water into the cell. From the appearance of the cell, it was clear that the vacuole of the cell has increased in size and its membrane became very close to the cell wall to the point we cannot see it, therefore the mystery solution is a hypotonic because it increased the size of the vacuole (Figure 1).
The only part of the cell that changed in both solutions was the center of the cell. In the hypertonic solution the center of the cell was crenate and had a lumpy appearance, while in the hypotonic solution the center increased in size and became turgid. That center of the cell is the vacuole, because in the vacuole is where all the diffusion of water and material goes in the cell.
Conclusion
This experiment helped to determine that the surface area to volume ratio has an effect on osmolarity, in other words it effected the diffusion and osmosis of material in and out of the cells. Also, it was determined that mystery solution A is a hypertonic solution, while solution B is a hypotonic solution. The osmolarity of the potato cells was calculated by means of measuring the percent weight change of the potato pieces in different sucrose concentrations.
