Potato Essay, Research Paper

Osmotic activity in murphy cylinders Skill Area P: Planning

Purpose: To look into the consequence of changing concentration of a certain sugar solution on the sum of osmotic activity between the solution and a murphy cylinders.

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Hypothesis: Osmosis is defined as the net motion of H2O or any other solutions molecules from a part in which they are extremely concentrated to a part in which they are less concentrated. This motion must take topographic point across a partly permeable membrane such as a cell wall, which lets smaller molecules such as H2O through but does non let bigger molecules to go through through. The molecules will go on to spread until the country in which the molecules are found reaches a province of equilibrium, intending that the molecules are indiscriminately distributed throughout an object, with no country holding a higher or lower concentration than any other. For this peculiar probe I think that the lower the concentration of the sugar solution in the trial tubing the larger the mass of the murphy will be. This is because the H2O molecules pass from a high concentration, i.e. in the H2O itself, to a low concentration, i.e. in the murphy bit. Therefore, the french friess in higher H2O concentrations will hold a larger mass than in higher sugar concentrations. Plant cells ever have a strong cell wall environing them. When they take up H2O by osmosis they start to swell, but the cell wall prevents them from spliting. Plant cells become & # 8220 ; turgid & # 8221 ; when they are put in dilute solutions. Turgid means swollen and difficult. The force per unit area inside the cell rises and finally the internal force per unit area of the cell is so high that no more H2O can come in the cell. This liquid or hydrostatic force per unit area works against osmosis. Turgidity is really of import to workss because this is what makes the green parts of the works & # 8220 ; stand up & # 8221 ; into the sunshine. When works cells are placed in concentrated sugar solutions they lose H2O by osmosis and they become & # 8220 ; flaccid. & # 8221 ; This is the exact antonym of & # 8220 ; turgid & # 8221 ; . The contents of the murphy cells psychiatrists and pulls off from the cell wall. These cells are said to be plasmolysed. When works cells are placed in a solution, which has precisely the same osmotic strength as the cells, they are in a province between turgidness and flabbiness. We call this inchoate plasmolysis. & # 8220 ; Incipient & # 8221 ; agencies, & # 8220 ; about to be & # 8221 ; .

Variables: Variables Non-Variables to be considered

1 ) Solution concentration Surface country

2 ) Solution volume

3 ) Duration of experiment

4 ) Temperature

5 ) Solution

6 ) Conditions which experiment is kept in To make a just trial certain facets of the experiment will hold to be kept the same whilst one key variable is changed. I have chosen to change the concentration of the sugar solution. This will hopefully give me a varied set of consequences from which I hope to do a nice decision. If any of the non-variables below are non kept changeless it would intend it would non be a just trial. For case if one of the murphy cylinders was 1cm longer the surface country of the bit would be larger and there would hence be more infinite for osmosis to happen. Making all the trials at one temperature will command the temperature, so it can non consequence the consequences, so one am traveling to transport out my experiment in a controlled environment. To maintain the H2O potency of the murphy ab initio will be kept the same by utilizing the same type of murphy, which have been treated in the same manner, e.g. have all been cut without being washed and peeled. The mass of the murphy is a dependent variable, and this means that it will be measured

throughout the experiment. I will mensurate the mass in gms. The murphy cylinder will be measured before it is put in the solution, and after. This will let us to see whether

osmosis has taken topographic point, and to what extent.

The volume of the solution that the murphy french friess are kept in must be just. The cylinders must be wholly submerged in the solution, I will do certain the sum of solution will be kept the same to do it a just trial.


Planned method: A scope of sucrose sugar solutions will be prepared with concentrations 0 grinder, 0.25 grinder, 0.5 grinder, 0.75 grinder and 1 grinder.

Sections of murphy will be cut utilizing a scalpel and will be measured utilizing a swayer. This portion of the readying must be done really accurately as a alteration in the surface country may let more or less osmosis to happen.

The mass of each bit will be measured every bit good so that more consequences can be obtained. Three french friess will be placed in each trial tube each clip so that I can take an norm for each tubing.

I will utilize 10 milliliter of each concentration of sugar solution and one time in the trial tubes they each will be labelled.

The murphy pieces will so be placed in the different trial tubings and so left for 24 hours.

Then the murphy pieces will be removed, the surface solution removed by gently blotting paper towels over surface at the same force per unit area to maintain it a just trial and so they will be re-weighed.

Skill Area O: Obtaining grounds


1. Using a cork bore bit I cut cylinders out of the murphy

2. Using a scalpel and swayer I cut the cylinders down to approximately the same size. I had to be really careful whilst cutting the murphy as the scalpel is exceptionally crisp. I so had 15 french friess. 3.Taking a trial tubing rack I placed 5 trial tubings and so labelled them 0 grinder, 0.25 grinder, 0.5 grinder, 0.75 grinder and 1 grinder.

4. Using a pipette I pu

t the same sum of each different concentration of solution and set each trial tubing in the right topographic point in the rack

5.I so weighed every murphy bit on a top pan balance and recorded the weights in a tabular array.

6. I put 3 murphy french friess into each trial tubing and placed the rack in a controlled environment. 3 french friess were used to make an mean which gave me a better set of consequences and more accurate graphs.

7. After 24 hours I drained out the solutions in the sink and placed all the french friess on the paper towel in the order I had put them in the trial tubing as to non confound myself as to which bit came from which solution.

8. I dried each bit with the paper towel and so placed each one, one by one, on the top pan balance to weigh them and their weights were recorded in a tabular array.


& gt ; Whilst cutting the murphy, utmost attention and preciseness had to be taken with the scalpel as it is really crisp and could easy do a serious lesion.

& gt ; The measurings for the solutions had to be perfect as to non alter the out semen of the experiment.

& gt ; I had to guarantee that every clip I handled the murphies my custodies were clean and dry. This was to halt any sort of taint and made sure that I did non go through on any excess H2O onto the murphy.


This graph shown above gives the line of best tantrum for the per centum alteration in mass of the murphy cylinders. The graph is a curve that slopes downwards and does non travel through the beginning. Because the line is non consecutive and does non go through through the beginning, it means that the per centum addition and loss in mass and concentration are non straight relative. However, there is a form on my graph, and this is, as the concentration of the solution additions, the per centum alteration in mass lessenings. The graph shows that the per centum addition and loss in inversely relative to the concentration. The gradient does alter in my graph. It gets less steep as X axis gets bigger. This is because the murphy bit is going every bit flaccid as it perchance can, and so the alteration in mass of each molar concentration is going closer and closer together. From the line of best tantrum that has been added in, it can be seen that all of my points were really close to making a absolutely smooth curve. This shows that my consequences are reasonably dependable. My graph tantrums in with my anticipation of the experiment graph. It shows that the murphy cells addition in mass in solutions with a high H2O concentration and lessening in mass in solutions with a low H2O concentration. When the concentration reaches above 0.75 M, there appears to be no farther H2O loss, proposing that the cell is to the full plasmolysed. From the graph an estimation to the concentration of the murphy cell can be made as 0.13 M, as this is the point where the murphy is non increasing or diminishing in mass, this is known as the isosmotic point. This is where no osmosis is taking topographic point, both the murphy and the solution have an indistinguishable grinder concentration. The following point, 0.25 M Looss about 4.0 % . This shows that the H2O potency of the salt solution in the beaker is weaker than that of the murphy bit. The following, 0.50 M, looses about 8.0 % in mass. This shows that the salt solution has an even weaker H2O potency than 0.25 M and that osmosis took topographic point. This is why the murphy lost even more mass, and it shows that the H2O potency in the beaker is less than that of the murphy bit. This form carries on through the graph, and even more mass is lost, as more H2O moves out of the murphy into the solution. My consequences besides match with my initial anticipations.

Skill Area E: Evaluation

This experiment was really successful in my sentiment. I obtained accurate consequences from which I was able to make enlightening graphs. I think I took adequate consequences for the concentrations that I was utilizing, and the clip that I used for the experiment to last was plenty to let sufficient osmosis to happen.

However if I was to reiterate the experiment I could perchance seek to happen out the impregnation point of the murphy. The scope of concentrations was equal but I would perchance make more concentrations if I repeated the experiment so that I would hold a larger sum of consequences to prove this thought farther.

The film editing of the murphies was the most hard portion of the experiment as although I was entering my consequences by mass, it could good hold affected the surface country and so the overall rate of osmosis. If I were to reiterate the experiment I would take more attention when cutting the murphy to guarantee that all murphies would be the same weight and dimensions. I will besides utilize the same balance to weigh my murphy french friess. This is because the measurings may somewhat change between the top pan balances. I would hold liked to reiterate this experiment once more to obtain a 2nd set of consequences. This will hopefully bring forth more accurate consequences from which I will be able to pull a more accurate decision. There were non any out of the ordinary consequences, but some were non every bit near to the line as others. This may hold been caused when the murphy french friess were removed from the trial tubing and dried I may good hold dried some murphies more exhaustively than others and so some would hold more extra H2O, which would add to the mass. If the experiment was repeated I could happen another manner to dry the murphies that would guarantee that all were dried in the same manner for the same clip. However with all this said I think that the experiment was genuinely successful and I was really pleased with the complete comparing of my consequences with my initial anticipation.



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