Research question:
The potato chores are submerged in different sucrose-concentrated solutions. Will their size decrease/increase the higher the sucrose concentration gets?
Aim/Hypothesis
The size, as well as the mass of a potato, will decrease if submerged in a high sucrose concentrated solution as the water molecules inside of the potato chore will move out of the cell in order to create an equilibrium on both sides. However, if a potato is submerged into a distilled water beaker or a low sucrose concentrated solution, its size, as well as the mass, will increase.
This thought roots from the natural osmotic movement are solutions such as hypoosmotic, hyperosmotic and isosmotic. Considering it has been proven that water molecules move from a hyperosmotic solution (concentrated) to a hypoosmotic solution (diluted/less concentrated) in order to reach an isosmotic solution, where there is an equal amount of sucrose concentration on both sides of the semipermeable membrane creating an equilibrium.
Background information:
Both animal and plant cells have and use the principles of osmosis to transport water in and out of themselves and osmosis on its own is one of the fundamental bases of biology and its studies circulating areas such as Osmoregulation and how cells regulate osmotic pressure and maintain a homeostatic environment. The movement of water depends completely on the osmotic pressure, which are isotonic, hypotonic and hypertonic solutions, which manipulates the direction.
Plant cells: Osmosis is very important for the plants to be able to absorb water from the soil and thus survive. The roots are like numerous root hair cells, which increase the surface area by volume ration in order to be able to absorb more efficiently.
Animal Cells: Osmosis is important for animals in order to keep the ion concentration balanced between the internal and external environment of a cell as well as be able to transport water molecules by osmosis through capillaries to each cell in a body to keep the cells firm, healthy and functional. A process called osmoregulation which is provided by the kidney to regulate the concentration of water and salt in the blood (the process also controlled by the hypothalamus in the brain). The regulating change differs depending on where the animal lives. If it is an animal living in a dry land/salty water have a longer osmoregulation process in order to conserve water. An example would be the Kangaroo rate in a dry environment, which has adapted its body by having a long loop of henle in the inner medulla to maximize urine concentration and conserve water. However animals surrounding/ on freshwater must conversely get rid of water as fast as possible by osmosis.
Osmosis in Plant cells:
Plant cells are usually in hypotonic environments and tend to have more concentrated fluid inside their cells then its external environment. If water molecules would be allowed to move into the cells, it would raise the turgor pressure (rigidity of cells and tissues) making the plant turgid and unable to stand upright. If the plant cells would be in a hypertonic environment, then all the water would leave the cell making it plasmolysis. The Cytoplasm would pinch away from the cells walls and the cell would no longer function. And if the cell would be in a isotonic environment, then the cell would turn flaccid and wilt.
Osmosis in animal cells:
Animal cells in a hypotonic solution, start taking in water molecules and end up bursting. Conversely, plant cells have a rigid cell wall which prevents their cells to burst in a hypotonic solution and instead end up in a turgid state (hard and swollen). In a hypertonic solution, an animal cell starts diffusing water out of itself and shrivels, which gives the conclusion that an animal cell needs to be surrounded by a isotonic solution in order to function properly.
Introduction:
Osmosis is the confined improvement of water particles from a locale of high water center to a region of lower water obsession (lower solute obsession to higher solute center), over a not entirely permeable membrane. The plasma layer is explicitly vulnerable, and it controls the advancement of substances every through cell, yet water can move wholeheartedly all through the telephone, allowing absorption to occur. Potato cells have explicitly permeable movies and therefore can be used to show the system of absorption.
As plant cells for the most part have a higher solute community than their condition (lower water fixation), when submerged in H20, the potato strips will be incorporated by a district of high water place since water has a solute social occasion of 0.3 This would gather that the refined water is hypotonic whereby it has a higher centralization of water than the potato cells, making water stream from the locale of higher water community (water answer for) the zone of lower water focus (potato cell).
However, as the duration given for osmosis to occur increases, the volume of fluid in the cell will increase as water continually enters the cell, increasing its turgidity (when pressure inside the cell increases as the volume of its contents increases). Eventually, the cell wall will be stretched to the maximum, achieving full turgor, which will then force water back out of the cell due to the high pressure within the cell. Thus, it is likely that over a long period of time, the water solution will become isotonic: where the water concentration within the cell increases until it is the same as the surrounding solution and water particles move both in and out of the cell, causing the cell to remain the same size.
To begin with, we shall understand the term Osmosis, which is a process by which water molecules move from an area of low solute concentration to an area of high solute concentration through a semipermeable membrane in order to reach an equilibrium point between the inside and outside of the cell. Osmosis is one of the many forms of Passive transport, meaning it requires no energy (Adenosine triphosphate) to happen. In this lab experiment, we will use different sucrose concentration solutions (0.0, 0.2, 0.4, 0.6, 0.8, 1.0 mol/dm³) and compare it will distilled water solution as well to see how each solution affects the size of the potato and how high the diffusion of osmosis in each solute concentration will be in comparison to one another.
Variables:
Dependent Variable
30 potatoes chores were measured to be 4 cm long, 0.5 cm wide and 0.5 cm thick. It was an analogue measurement with a ruler, knife and scalpel, giving an uncertainty of (or.
Independent Variable
Concentration of different sucrose solutions:
1. 0.0mol/dm3 (distilled water)
2. 0.2mol/dm3
3. 0.4mol/dm3
4. 0.6mol/dm3
5. 0.8mol/dm3
6. 1.0mol/dm3
Controlled Variables
Why
How?
- Diameter of potato chores
- Length of potato chores
- Surface area to volume rate affects the rate of osmosis and its efficiency.
- Surface area to volume ratio affects the rate of osmosis and its efficiency.
- 5 cm width was measured with a ruler and then cut with a scalpel as precisely as possible.
- 4 cm length was measured using a ruler and then cut as precisely as possible with a scalpel
The duration time in which the potato chores were submerged in different solutions
In order to obtain a reliable result all the tests must be made under the same amount of time, considering if some would remain stay longer, more diffusion of the water would occur and the results would be thus false.
The potato chores were cut around the same time and put in the water around the same time as well. The whole process went on for about 24 all the potatoes were taken out at the same time.
Temperature
Temperature affects the rate of diffusion, considering the rate of diffusion depends on the kinetic energy available which is on its own dependent on the temperature. The higher the temperature the higher the temperature.
The potatoes were cut and put into the solution in the same room with very low temperature difference as well us kept in the same temperature overnight until they were taken out.
Volume in each beaker covering the potato chores
If the chores of 24 hours any of the potato chores would have turned with a tip outside of the water, the result would be falsified, considering osmosis would have then been cut from the complete surface of the potato chores.
The potato chores were put in the solutions in the beaker in the beaker and covered with a foil to avoid any of the potatoes sticking out.
Uncontrolled variables
Explained
PH
An increase in H+ in the solution reduces the level of free solutes in the solution, thus reducing the concentration gradient, increasing the speed of osmosis.
Pressure
The higher the pressure, the faster the molecules will move faster because they are being pushed across a low concentration.
Light and dark
The brighter the light, the faster the osmosis will take place and one cannot control day and night.
Fresh sucrose solution
Considering the different sucrose solutions have been used several times by many students and the lid to the jar has been opened many times over, maybe the amount of evaporated water has become significant by now.
Material and apparatus:
- Six beakers (no uncertainty considering they were not measuring beakers and not marked)
- Scalpel
- Knife
- Cutting board
- Potatoes
- Plastic ruler (±0.1mm)
- Pencil
- Tape
- Prepared sucrose solutions: 0.0 mol/dm³(Distilled water), 0.2 mol/dm³,0.4 mol/dm³, 0.6 mol/dm³, 0.8 mol/dm³, 1.0 mol/dm³
Procedure:
- The working area was cleared out and a cutting board was placed on the table.
- Approximately 4-5 potatoes with a medium size (not too small) were placed on the cutting board.
- With a ruler, sides of the chosen potatoes were measured and reached the length of 4 cm.
- With a knife, sides of the potatoes were cut and turned into rectangularly shaped potatoes.
- 0.5 cm width and thickness was marked with a scalpel first and then slowly and precisely cut throughout, making a smaller rectangle.
- Step 3-6 was repeated until 30 potato chores were made.
- 6 beakers were placed beside the potato chores on the table.
- A piece of tape was put on each beakers side and with a pen, each was labeled on the tape according to what concentrated sucrose solution they were going to contain.
- After each tag on the beakers, the written sucrose solution on the beakers was poured until they all were half full.
- 5 potato chores were then placed in each and altogether put in a box.
- After 24 hours the potato chores were brought out of the solutes and then the final lengths were measured.
Table 1: Shows in more detail the final lengths of all 30 potato chores placed in different concentrations of sucrose as well as the standard deviation on the side.
Sucrose concentration
Initial length
Final Average
Average change
Standard deviation
0.0
4.0
4.35
0.32
0.13
0.2
4.0
3.97
-0.06
0.11
0.4
4.0
3.62
-0.38
0.08
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0.6
4.0
3.56
-0.44
0.09
0.8
4.0
3.42
-0.58
0.08
1.0
4.0
3.38
-0.62
0.13
Table 2: Shows the percentage change in different sucrose solutions, giving the conclusion that higher the sucrose solution gets the more the potato chores shrink in size.
Sucrose Concentration mol/dm3
Percentage change (final change- initial/initial x 100)
0.0
8 %
0.2
-1.5 %
0.4
-9.5 %
0.6
-11 %
0.8
-14.5 %
1.0
15.5 %
Graph:
Graph 1. Show the final average lengths (cm) of each potato chore in different concentrated sucrose solutions (mol/dm3):
Initial observation:
The potatoes were generally:
Rigid
Pale/yellow colored
Kind of bendable
Similar in size and shape
Final observation:
The potato chores were out of being submerged in different sucrose solutions for 44 hours and were soggy and soft.
The higher the sucrose solution, the smaller the potato chores were leading to the conclusion that the solution had made the potatoes shrink.
The lower the sucrose solution was, especially with the distilled water, the larger the potato chores were leading to the conclusion that the solution had made the potatoes grow in size.
Conclusion/evaluation:
As the results show, the hypothesis given was correct and the potato chores did grow in low sucrose concentration/distilled water and did shrink in high sucrose concentration. This also gives another fact that if the potatoes were to be measured in weight, we would then see that the mass would decrease in a high sucrose concentration and decrease in a low sucrose concentration/distilled water.
The largest % average size change was between the sucrose solution 0.6 and 0.8 from -11% to 14.5%, which is a point of which we can see that the potato chore simply shrunk and got more affected from 0.8 mol/dm³ and down. In distilled water, the percentage average change from the initial size was 8%, which supports the hypothesis even more with the fact that the lower the sucrose concentration is, the more water will move inside the potato.
The average size change between sucrose concentration 0.2 and 0.4 mol/dm³ was not so much in comparison to all the others, giving the conclusion that the potato chores original sucrose concentration must have been between those two values. As told above in section “Introduction” we explained who osmosis is the net movement of water molecules moving from a low solute concentration to a high solute concentration, meaning that between those two sucrose solutions, we probably hit very close to a isotonic solution (not exactly but still).
A further consolidation of the hypothesis, results, and the background information is how the potato chores in distilled water and in the sucrose solution 0.2 mol/dm³ were indeed turgid and the potato chores in 0.8 mol/dm³ and higher were flaccid as well as felt a bit squishy.
A wide range of errors can be kept in consideration when it comes to the measurement of temperature, potato chores and the fact that we manually kept on touching the potatoes with our hands which could have defected the sugar distribution across the potatoes surface and altering the osmosis results. Another error factor would also be the fact that more than one potato was required in the experiment to get the 30 potato chores, thus us having several different sucrose sources and by the fact that each potato has different levels of nutrition, the results might have a deficiency inaccuracy in this area.
- Weakness
- Significance
- Improvements
- Measuring equipment
As seen in ‘Apparatus’ part of the lab report, no uncertainty was stated for the beakers considering none of the beakers were labeled and really measuring equipment, but just small plastic boxes. Thus the volume could not be measured and put in the data and the pressure could not be taken into account.
We also measured and cut the potatoes manually with a ruler, a given knife and scalpel.
Using a measuring beaker, labeled as well as having a precise uncertainty for less errors along the experiment.
Using a cutting device/ measuring device to avoid high uncertainities in potato sizes.
Use a borer to maintain a better efficient surface area between all the 30 potato chores.
Controlled Temperature
Even though the potatoes were cut in the same room as well as kept in the same environment (they were transported from the cutting room to another room overnight ), doors were opened and closed many times leading to the change of temperature and thus giving higher uncertainites in the results.
Measure/take the temperature from the beginning of the experiment, keepthe potatoes in the same environment without changing location for higher accuracy.
The time in which the experiment was done
If the experiment would have been done early in the morning, maybe the uncontrolled factor. ’Light and dark would have a lower significance
Doing the experiment early in the morning.
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