conclusion for osmosis potato experiment

Understanding Osmosis Using Potato Osmometer

To study by demonstrating the osmosis process by potato osmometer.

What is Osmosis?

Osmosis is the phenomena in which solvent molecules pass through a semi-permeable membrane from an area of higher concentration to an area of lower concentration. The process continues until the quantity of fluid is balanced or equalized in both regions, the region of higher concentration and the region of lower concentration of the semipermeable membrane. In other words, osmosis is the diffusion or movement of water from a region of higher water potential to a region of lower water potential.

In osmosis, what are solvent and solute?

The fluid that permeates through the semipermeable membrane is called the solvent, whereas the solute is the dissolved particles in the fluid.

What is the solution?

The mixture of solute and solvent form the solution.

List the different types of solutions.

The following are the types of solutions:

• Hypertonic solution – It is a solution with a high solute level. If living cells are placed in a hypertonic solution, because of lower concentration water moves out of the cell causing it to shrink and becomes plasmolyzed.
• Hypotonic solution – It is a solution with low concentration levels of solute. If living cells are placed in this solution, water passes into the cells because of higher water concentration in comparison to the cell causing the cells to swell and turn turgid.
• Isotonic solution – A solution is said to be isotonic if both solutions have an equal concentration of solute. If living cells are placed in an isotonic solution, no change is shown as there is the equal concentration on both the regions hence the cell retains its original shape.

Material Required

• A fresh large-sized potato tuber
• 20% sucrose solution
• Scalpel/blade
• A Bell pin needle that is labelled with a waterproof ink

• Slice the potato tuber into two equal halves with the help of a scalpel or a blade. The outer skin is to be peeled off. Since the tuber shape is irregular, slice the halves into squares
• From the mid-region of the tuber, scoop from the soft parenchyma, so as to form a tiny cavity of a square or a circular shape. At the base, the cavity prepared should have a minimum thickness.
• Fill up half the cavity with the freshly prepared 20% sugar solution. Into the cavity, fix a pin in a way that the mark is in the same line with the layer of the sucrose solution.
• Set up the osmometer in a Petri dish/beaker that is filled with water in a way such that 75% of the potato osmometer is immersed in water
• The set up should remain uninterrupted for close to 1 hour.
• Notice the sugar solution in the osmometer towards the end of the experiment
• Carry out the experiment with the help of water in the cavity and the sucrose solution in the petri dish/beaker.

Observation

After a period of time, within the osmoscope, the sugar solution rises and is seen coloured.

• An increase in the level of sucrose solution is observed in the osmometer. It is because of the entrance of water due to endosmosis from the beaker.
• Also, a water potential gradient is built between the sucrose solution in the external water and the osmometer.
• Though both the liquids are divided by living cells of the potato tuber, they allow the entrance of water into the sugar solution.
• This demonstrates the entrance of water into the sugar solution through the tissues of potato serving as a selectively permeable membrane.

Viva Questions

Q.1. What is plasmolysis?

A.1. It is a process, wherein the protoplasm of the plant cell turns round as a result of contraction when placed in a hypertonic solution due to exosmosis resulting in the decline in the tension of the cell wall.

Q.2. What is the significance of osmosis?

A.2. Osmosis maintains cell turgidity. It causes the transportation of nutrients and discharge of metabolic waste products. It preserves the interior environment of a living entity to maintain an equilibrium between the intracellular fluid levels and water.

Q.3. What is diffusion?

A.3. The movement of molecules from a region of higher concentration to a region of lower concentration. Osmosis is a type of diffusion.

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Study of Osmosis by Potato Osmometer

A study of osmosis can be done using a potato osmometer. Osmosis is a phenomenon in which water moves from high solvent to low solvent concentration. The movement of water occurs between two compartments, separated by a semipermeable membrane .

The cell membrane of living organisms behaves as a semipermeable or selective membrane. The permeability of a selective membrane differs based on the size, charge and mass of different molecules.

Biological membranes are impermeable to large biomolecules and polar molecules like ions. But, non-polar molecules (lipids) and small molecules (oxygen, carbon dioxide etc.) can cross the selective barrier.

Water is the solvent that travels down or up the cell concentration gradient through osmosis. We can study water diffusion by creating two compartments and a semipermeable membrane in between.

The difference in the concentration of solutes or solvents between two compartments is the driving force responsible for water movement. Here, we need to note that only solvents can pass the selective barrier, not solutes.

Thus, the diffusion or distribution of water is related to osmosis . This post describes the meaning, requirements, procedure and results of the potato osmometer experiment.

Content: Study of Osmosis by Potato Osmometer

Potato osmometer, materials required, precautions.

It is a common experiment to demonstrate both endosmosis and exosmosis using a potato. Using a potato Osmoscope, we can study osmosis in a living system.

Here, a potato is used because the porous outer surface of the potato acts as a selective membrane .

• The contents within the cell form one compartment.
• The solution surrounding the cell forms another compartment.

Thus, a selective membrane separates two compartments and allows the process of osmosis .

• High solvent concentration in the cell surrounding.
• Low solvent concentration in the cavity of potato tuber.

Following the rule of osmosis, water in the cell surrounding enters the tuber cavity via the cell membrane.

• High solvent concentration in the cavity of potato tuber.
• Low solvent concentration in the cell surrounding.

Following the rule of osmosis, water in the potato cavity enters the surrounding solution via the cell membrane.

• Peeled off potato
• Concentrated sugar solution
• Petri plate

Video: Study of Osmosis

To perform the potato osmometer experiment, we need to follow the given procedure:

• First, peel off the large-sized potato using a peeler or knife.
• Then cut the upper and lower portions of the peeled potato using a knife. Through this step, we can easily place the potato on the Petri plate.
• Using a knife, make a cavity from the centre of the potato deep into the bottom, leaving some space. Here, the bottom of the potato will function as a selective membrane.
• Then, keep the potato on the Petri plate.
• To study endosmosis , pour water into half of the Petri plate. Next, pour the concentrated sugar solution into half of the cavity created in the potato.
• To study exosmosis , add concentrated sugar solution on the Petri plate and water into the cavity of the potato tuber.
• Then, fix a pin into the potato tuber-A and B to mark the level of sugar solution and water added into the cavity.
• Leave the plate undisturbed for some time until you notice any change.

Observation

• Observe the level of sugar solution in the cavity of potato tuber-A.
• Notice the level of water in the cavity of the potato tuber-B.

Potato Osmosis Experiment Results

• The level of sugar solution in the cavity of potato tuber-A increases . It occurs because the water in the Petri plate will move towards the cell with a high solute or low solvent concentration. This experiment shows endosmosis , as water goes into the cell or potato tuber.
• In contrast, the level of water in the cavity of potato tuber-B decreases . Here, water in the cavity moves toward the solution in the Petri plate due to the high solute concentration in the surrounding. This experiment shows exosmosis as water leaves the cell or potato tuber.
• The cavity should be deep enough by leaving a minimum thickness at the bottom.
• The sugar solution should have a high osmotic concentration.

The water movement from the Petri plate to the potato cavity or vice versa is due to the difference in the solvent or solute concentration between the two compartments.

Related Topics:

• Germination of Plant
• Difference Between Root and Stem
• Nerve Impulse
• Ozone Formation
• Examples of Adsorption in Daily Life

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Osmosis Lab Conclusion

Why did some potatoes lose mass?

Potatoes A, E (and sometimes C) lost mass because they were placed in hypertonic solutions . That means the potato possessed more water than their environment and left the potato due to osmosis .

Why did some potatoes gain mass?

Potatoes B, D (and sometimes C) gained mass because they were placed in hypotonic solutions . That means the potato possessed less water than their environment and entered the potato due to osmosis.

Why did some potatoes stay the same mass?

(Sometimes potato C) neither gained nor lost mass because it was placed in an isotonic solution . That means that the potato and the environment possessed the same concentration of water , so no water movement was observed.

How did you determine the concentrations of the solutions?

Osmosis means that water will diffuse from a high concentration of water to a low concentration of water . A higher concentration of water exists in a hypotonic solution and a low concentration of water exists in a hypertonic solution.

Potato A lost the most mass, meaning it was placed in the most hypertonic solution. Since the most hypertonic solution used in lab was 0.8 M, Potato A was placed in 0.8 M solution.

The next most mass loss was Potato E, so it was placed in the next most hypertonic solution: 0.6 M.

Potato D gained the most mass, meaning it was placed in the most hypotonic solution . Since the most hypotonic solution used in lab was 0.0 M, Potato D was placed in 0.0 M solution.

The next most mass gain was Potato B, so it was placed in the next most hypotonic solution: 0.2 M.

Why did you calculate percent change in mass?

Percent change in mass was calculated to control for any differences in initial mass recordings.

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Science Experiments on the Osmosis of a Potato

Osmosis Experiments With Potatoes for Kids

Osmosis, the process in which solvent molecules move from an area of lower solute concentration to an area of higher solute concentration, can easily be demonstrated with potato experiments. Potatoes are full of both water and starch, and will gain water when immersed in watery solutions. Conversely, they will lose water when in concentrated solutions, such as those containing a great deal of starch. You can use potatoes to set up osmosis experiments for students of all ages and levels.

Potatoes in Saltwater

Cut a potato in two, and immerse one of the halves in a very salty solution of water — one containing a quarter cup of salt in a cup of water. Immerse the other piece in tap water containing no added salt. Leave both in their respective solutions for half an hour, then remove the potato halves from their solutions and observe their differences. The one in the salty solution will have shrunk, indicating that water is diffusing from a less concentrated solution to a more concentrated solution. The one in the tap water solution, in contrast, will actually swell slightly, indicating that it is taking in water.

Salt, Sugar and Pure Water

This experiment helps students to differentiate between different degrees of concentration gradients. Make one salt water solution, one sugar water solution, and for the third solution, simply use tap water. Make three thin potato slices — 1/2 cm thick. Place each potato slice into each of the solutions, and leave the slices in the solutions for a half hour.

Observe that the slice placed in salt is very flexible, while the slice placed in sugar is flexible, but less so. Since potatoes already contain sugar, less water will diffuse out of the potato placed in sugar water. The slice placed in water will be rigid, since it will absorb water.

Potato Lengths in Saline Solutions

Give your students potato "cylinders" that are uniform in length and size: for instance, you could cut them to be 70 mm in length and 7 mm in diameter. Make solutions of saline in three different concentrations, 20 percent, 0.9 percent and 0.1 percent. Have the students measure the lengths and diameters of the potato cylinders before and after soaking them in the saline solutions for half an hour. Then, have them calculate the changes in the lengths and diameters of the cylinders, and plot the saline concentrations versus the changes.

Potato Cube Weights

Cut potatoes into four groups of small, uniform cubes measuring 1/2 cm by 1/2 cm. Make four different solutions of sucrose: 10 percent, 5 percent, 1 percent and 0.01 percent. Weigh each group, on a mass balance, before immersing it in the appropriate sucrose solution for half an hour. After immersion, weigh each group again and have your students calculate the changes in the potato masses. Ask them to comment on why a group gained mass, lost mass or retained the same mass.

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• The Teachers Corner: Science Experiment--Osmosis

About the Author

Tricia Lobo has been writing since 2006. Her biomedical engineering research, "Biocompatible and pH sensitive PLGA encapsulated MnO nanocrystals for molecular and cellular MRI," was accepted in 2010 for publication in the journal "Nanoletters." Lobo earned her Bachelor of Science in biomedical engineering, with distinction, from Yale in 2010.

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Effect of Salt Concentration on Osmosis in Potato Cells Lab Answers

• Effect of Salt Concentration on…

INTRODUCTION

The cell membrane surrounds the cell and is responsible for regulating substances within the cell. There are many processes in which substances can travel through the membrane, one being osmosis.

Osmosis is a form of passive transport (no energy required) and is a type of diffusion in liquid substances. It is the transport of water molecules through the semipermeable section of the membrane from areas of low to high solute concentration (Figure One). Osmosis helps provide support in a plant cell. Furthermore, osmosis ensures the balance of liquid levels so that the cell doesn’t burst or shrivel. Water is attracted to the salt in cells and travels to where there is more salt to balance the levels. Therefore, the three states of an environment (hypertonic, hypotonic, and isotonic) determine the movement of water across the membrane.

For instance, if the water inside the cell is hypotonic compared to the extracellular environment, then water will travel into the cell by osmosis. When the water inside the cell is hypertonic compared to the extracellular environment, water travels out through osmosis. If both areas are isotonic, then both solutions will continue to remain balanced.

Potato Osmosis Lab Report

 Why Does Potato Shrink in Salt Water?

To determine the effect of salt concentration has on the rate of osmosis.

If the salt solution concentration is increased, then the potato will experience a larger decrease in mass due to the occurrence of osmosis.

Independent Variable: The three NaCl solutions (5%, 10%, and 15%) and the distilled water (containing 0% salt).

Dependent Variable: The rate of osmosis measured by the average percentage change in mass.

• 4 x 250 ml beakers
• Measuring Cylinder
• Electronic scales
• Paper towel
• 50 ml distilled water
• 50 ml 5%, 10%, 15% NaCl Solution
• Peel the potato.
• Accurately cut 4 cubes of potato that measure 2 x 2 x 2cm.
• Weigh all potato cubes individually and record data.
• Place 50 ml distilled water in a beaker.
• Place the 2 potato cubes in the distilled water.
• Leave for 20 minutes.
• Use a spoon to carefully remove the 2 potato cubes from the beaker and place them on a piece of paper towel to remove excess water.
• Record any visual observations in your table.
• Weigh the cubes and record.
• Calculate the change in mass.
• Calculate the % loss or gain in mass and record it in the table.
• Place the potato cubes in the container for disposal.
• Repeat steps 3 to 12 for 5%, 10%, 15% salt solution with a five-minute delay in-between each solution.

SAFETY AUDIT

The predicted risk level of the practical ‘Effect of salt concentration on Osmosis in Potato Cells’ is low.

RECORDING OF CHANGE IN POTATO CUBES:

Observations: The texture of the potato became spongier after the occurrence of osmosis. Water became slightly cloudy and starchier.

The overall trend showed the salt solution with higher concentration to experience a greater rate of osmosis resulting in a larger decrease in mass apart from the end of the individual graph, which would suggest a random error to have taken place. Both sets of osmosis potato experiment salt solution results data showed solutions with higher concentration is hypertonic compared to the potato cells meaning the water would travel to the solution because it contained more salt.

Evidently, the rate of osmosis in solutions with less salt was of a lesser extent because the water from the potato cells was less attracted. The distilled water was hypotonic compared to the potato cells that contain approximately 2% salt. Hence why both the individual and class data indicated a gain in the potato mass. These results were represented in the negative linear trend in the graph (Figure Three). The osmosis practical posed no situation where the potato cell and solution were in an isotonic state; however, it could be predicted that no overall net movement would occur, and the potato mass would stay the same.

It is important to keep all controlled variables the same across all salt solutions to produce accurate data. If variables differ among the solutions then results would be influenced, producing inaccurate data. Various errors can be encountered in a practical way that can influence results, making them differ from the true answer.

The specific error encountered cannot be determined by the graph however the scatter and/or translation of data from the line of best fit can determine that there are errors involved. There were 10 sets of data undertaken that were all similar, comparing the individual data with the line of best fit from the class data (Figure Five) can show where random errors may have occurred.

If the entire set of data was to be moved but have a similar shape in the line of best fit, then it could be determined that a systematic error was of occurrence. The presence of random errors can be seen in the scatter graph (Figure Five), with the data from the 5% solution varying greatly and having an outlier.

A random error met was the slight difference in the size of potato cubes. A human cannot cut all potato cubes with precision, having the same weight and dimensions across all cubes. Although only a slight difference occurred with cubes ranging from 8.5 to 10.6 grams, smaller cubes would have a more efficient rate of osmosis due to their greater SA: Vol ratio and they would have a larger decrease in mass. This could be improved by using technology that can be relied on to cut all cubes with precision.

The accuracy of a human starting the stopwatch at the exact time the potatoes were submerged is unreliable because of their reaction time. The inaccuracy of time can result in some cubes being submerged in the solution for longer and allows time for more osmosis to occur, meaning the mass will be invalid.

For accurate timing, technology could be used to start and end exactly when the cubes are submerged and taken out. Another random error present was the excess water removed after the occurrence of osmosis. Drying the cubes with a paper towel could not be the same across all cubes and could remove different amounts of water from each cube.

This would change the mass because the cubes with less water soaked up, would have a heavier mass.

The systematic errors encountered in the practical included the calibration of equipment such as the stopwatch under the assumption that it was already working, causing invalid data.

Assumptions can also become a cause of a systematic error, an example being the assumption of the salt concentration in the solution as it was not tested prior to the practical and could result in consistently high/low results. Environmental effects such as the temperature of the lab, the potato cell concentration, and the potato age are systematic errors that can be present in the practical.

It was determined by testing potato cubes in salt solutions with different concentrations, that when the salt solution concentration was increased, the potato experienced a larger decrease in mass due to the occurrence of osmosis. This was evident from the results of the potato osmosis experiment lab report. The hypothesis for the potato in salt water experiment was supported by the individual data (Figure Two) and where errors occurred, the true value was supported by the class data.

Some limitations in the experiment were present such as the limited equipment such as technology that could have improved the precision, resulting in inaccurate data, and the inability to repeat the experiment, lowering the validity and reliability of the data gained. This conclusion aligns with typical potato osmosis experiment conclusions.

BIBLIOGRAPHY

Osmosis – an overview | ScienceDirect Topics (2020). Available at: https://www.sciencedirect.com/topics/neuroscience/osmosis (Accessed: 18 March 2020).

Diffusion and Osmosis – Difference and Comparison | Diffen (2020). Available at: https://www.diffen.com/difference/Diffusion_vs_Osmosis (Accessed: 23 March 2020).

Tonicity: hypertonic, isotonic & hypotonic solutions (article) | Khan Academy (2020). Available at: https://www.khanacademy.org/science/biology/membranes-and-transport/diffusion-and-osmosis/a/osmosis (Accessed: 23 March 2020).

(2020) Colby.edu. Available at: http://www.colby.edu/chemistry/CH142/lab/ErrorAnalysisExample.pdf (Accessed: 27 March 2020).

Figure 5, Class Data (Taken away group 3, inaccurate data)

[1] Tonicity: hypertonic, isotonic & hypotonic solutions (article) | Khan Academy (2020). Available at: https://www.khanacademy.org/science/biology/membranes-and-transport/diffusion-and-osmosis/a/osmosis (Accessed: 23 March 2020).

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This has helped me with my osmosis egg lab assignment, thank you so much

when was this published?

probably 23 march 2020 since that is when they made their bibliography (cited sources)

thank you so much for this, I had a lab report due today on this topic, and it really helped me out!

This was very neat and important information

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Conclusion of osmosis potato lab

Osmosis means that water will diffuse from a high concentration of water to a low concentration of water.

Explanation:

• The concept of osmosis is clearly demonstrated by this experiment.
• Water molecules are observed to have moved from the region where they are highly concentrated to the region where they have a low concentration through a semi permeable membrane in the cells of the potato.
• A higher concentration of water exists in a hypotonic solution and a low concentration of water exists in a hypertonic solution.
• In this lab we will test samples of potato tissue to see how much water they absorb or release in salt solutions of varying concentrations.

The concept of osmosis is clearly demonstrated by this experiment. Water molecules are observed to have moved from the region where they are highly concentrated to the region where they have a low concentration through a semi-permeable membrane in the cells of the potato.

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