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The aim of this experiment is to determine which are sweeter potatoes or apples. We will determine this through the principles of osmosis.

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Introduction

Aim The aim of this experiment is to determine which are sweeter potatoes or apples. We will determine this through the principles of osmosis. Sucrose Solutions A set of six solutions will be used in this experiment. The solutions will be ready formulated by the technicians. Measuring Cylinder To accurately measure liquids, a measuring cylinder (ml graduations) will be used. Digital measuring scale with grams Before and after the experiment potato and apple pieces will be weighed to measure any change in mass. Stick rule with millimetres A stick rule will be used to measure any change in length of the potato or apple pieces from before the experiment. Beaker This will be used to pour excess or used sucrose into during the experiment. Test tubes Twelve test tubes, each will be used to containing potato or apple pieces in sucrose solution. Tweezers To handle the potato or apple pieces and prevent contamination. We would need to use tweezers preferably one for each. Filter paper In order to absorb the excess fluid filter paper will be used. This would prevent including water mass in weighing potato and apple pieces. Cutting board A cutting board will be used to protect tables and to provide a safe and stable cutting surface. Blade To cut off excess pieces of apple or potato. Test tube holder We will use a test tube holder to store test tubes before and during the experiment. Corer To cut out large uniform pieces of apple or potatoes a corer will be used. Marker pen In order to correctly identify test tubes and their contents, they will be labelled correctly with marker pens or glass crayons. Apparatus Hypothesis My hypothesis is that the greatest increase in mass and length will be seen at the lowest concentration (0 M). This is because it is water and so water will move into the cells. ...read more.

Middle

M 20 20 20 20 20 20 17 18 0.8 M 20 20 24 20 20 20 18 19 1.0 M 20 20 19 18 20 20 20 17 Mass of Apple Pieces (g) Mass of Potato Pieces (g) Concentration of Sucrose Solution (Molar) Before Treatment After Treatment Before Treatment After Treatment Bottom piece Top piece Bottom piece Top piece Bottom piece Top piece Bottom piece Top piece 0.0 M 1.3 1.3 1.4 1.2 1.6 1.7 1.9 1.9 0.2 M 1.5 1.2 1.6 1.4 1.6 1.8 1.6 1.8 0.4 M 1.4 1.5 1.5 1.6 1.7 1.8 1.2 1.3 0.6 M 1.5 1.3 1.4 1.3 1.6 1.6 0.9 1.0 0.8 M 1.5 1.3 1.4 1.3 1.6 1.9 0.7 0.9 1.0 M 1.5 1.4 1.3 1.4 1.9 1.7 0.8 0.8 Length of Apple Pieces (mm) Length of Potato Pieces (mm) Concentration of Sucrose Solution (Molar) Before Treatment After Treatment Difference (�mm) Before Treatment After Treatment Difference (�mm) Bottom piece Top piece Bottom piece Top piece Bottom piece Top piece Bottom piece Top piece Bottom piece Top piece Bottom piece Top piece 0.0 M 20 20 21 20 +1 0 20 20 21 21 +1 +1 0.2 M 20 20 20 20 0 0 20 20 20 21 +1 +1 0.4 M 20 20 20 20 0 0 20 20 19 20 0 0 0.6 M 20 20 20 20 0 0 20 20 17 18 -3 -2 0.8 M 20 20 24 20 +4 0 20 20 18 19 -2 -1 1.0 M 20 20 19 18 -1 -2 20 20 20 17 0 -3 Table 3: Change in length Table 4: Average change in length Length of Apple Pieces (mm) Length of Potato Pieces (mm) Concentration of Sucrose Solution (Molar) Bottom piece Top piece Average change Bottom piece Top piece Average change 0.0 M +1 0 +0.5 +1 +1 +1 0.2 M 0 0 0 +1 +1 +1 0.4 M 0 0 0 0 0 0 0.6 M 0 0 0 -3 -2 -2.5 0.8 ...read more.

Conclusion

Whereas for the apples this point was around 0.4 M --> 0.6 M. since we did not use a concentration for 0.5 M we cannot tell whether that was the point at which there was little or no osmosis. As mentioned in the scientific knowledge when in hypotonic solution water moves in by osmosis from the solution and when in a hypertonic solution the water moves out into the solution. Between these two types of concentrated solution can be a solution that has a similar concentration to the cell and so water movement in or out will not happen this solution is called an isotonic solution (around 0.2 M for Potato and 0.4 M --> 0.6 M for apples). Evaluation The majority of this experiment went to plan, but it was only after analysing the results that I found that the measurement of length change was inaccurate. At the time of measurement I do not recall any reason to question that anomaly. In the future I would understand the problem that aim is investigating properly beforehand so I can be fully prepared for anomalous results and understand why they have happened and if I need to redo them. I am pleased with the mass change results since they followed what would be expected and didn't show too anomalous results. This allowed me to still get good and interesting graphs and conclusions and also helped me to better understand Osmosis as a process in biology. To make the experiment more scientifically valid I would put each potato/apple pieces in its own test tube so that we could rule out interference and get more reliable results. I would also use a wider range of sucrose concentrations do that we could obtain more conclusive results. To further understand osmosis it would be interesting to investigate which factors affect it. This could be done using temperature controlled water baths and refrigerators for temperature investigation. We could alter the size of the pieces we place in the solution the bigger the pieces immersed the greater the surface area. ...read more.

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