Potato Osmolarity Lab Report

Ikenna Kuba

Mrs. Lucas

IB Biology HL

6 February, 2017

Deciphering The Osmolarity(concentration of a solution) of a Potato Cell including the concept of Water Balance.

Investigation Question

Determine the osmolarity of a potato?

Background

In the two day lab performed in class, we worked with a potato commonly known as White Potato but its scientific name is “Solanum tuberosum”(New World Encyclopedia, 2017). We can tell it is White potato and not Sweet potato due to the color of the potato, Sweet potato is usually orangish red(Difference Between.net, 2011) in color while white potatoes are white on the inside hence the name. In this lab we use portions of the tuber also known as the roots of the potatoes. This is because in order to find the

For instance in the case of Sucrose with 0.4M, the initial mass as well as the final mass is the same this means that it is isotonic because the amount of water going in and coming out is the same therefore it reaches an equilibrium, this explains why the percent change in mass is 0. Another example is seen in Sucrose with 0.6M and 0.8M, where in this case their final mass is less than their initial mass so it is a hypertonic solution and it has a higher osmolarity than a tissue. This is because the amount of water going into the cell is less than the amount going out of the cell, therefore the concentration of the solute is greater outside than inside of cell. Finally distilled water and Sucrose with 0.2M is a hypotonic solution and has a lower osmolarity than a tissue. This is as a result of the amount of water going in the cell is greater than that going outside the cell, therefore the concentration of the solute is greater inside than outside of the cell. According to the data an assumption can be made that the cause of weight change in the potato cylinders is the rate at which water moves in and out the cell. Another assumption can be made that the osmolarity anywhere from sucrose with 0.4M to 0.6M because the percent change in mass went

We had to first dry out the potato cylinders on a paper towel. In the process of drying off the water an error can occur if the potato cylinders were left in the towel for too long.

If too much of the water was dried off the potato cylinder, the data would be tampered with causing the relationship between the molecules of the solution and the concentration of the solute will be adjusted to having less water. This would make the data inaccurate. In future assessments we would have to thoroughly wipe off only excess water and to ensure that data is not dried up or erased.

The lab was expected to last for two days but due to the fact that there was no school we were unable to finish the lab forcing the lab to be extended to an extra day. During the span of 24 hours the data can change exponentially making the results have inconsistencies.

Since the lab was planned to be a two day lab but was done in the span of three days, the process might have taking too long and therefore led to change of data. In future labs we have to plan for the right date and time in order to prevent the data from changing.

Size of potato