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Osmosis. Aim: To study the effect of distilled water and different concentrations of sucrose solutions on the length of potato strips and thereby investigate the water potential of the potato cells in the aforementioned liquids.

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Introduction

Osmosis Aim: To study the effect of distilled water and different concentrations of sucrose solutions on the length of potato strips and thereby investigate the water potential of the potato cells in the aforementioned liquids. Introduction: Osmosis is the diffusion of water through a semi-permeable membrane from an area of high water potential (low solute concentration) to an area of low water potential (high solute concentration). It is a passive process in which energy is not required. Materials: - 6 large test tubes - Cork bore (5 mm) - Scalpel - Potatoes - Distilled water - Sucrose solutions (0.2, 0.4, 0.6, 0.8 and 1.0 mol/dm-3) Method: 1. With the help of a knife slices of about 0.5 cm think were cut from a potato (as uniform as possible). Using a ruler and a scalpel, 18 strips of potato were cut from these slices. These strips were about 0.5 cm wide and exactly 4 cm long. 2. Three strips were placed in each of the six test tubes. ...read more.

Middle

The data marked in bold is the data collected in our group Calculating the mean and standard deviation using; where, is the length of potato strip; is the mean length of the potato strips and is the number of observations. Table 2: The mean length of the potato strips in various solutions and the standard deviation from the mean. Sucrose solution (M) Mean length of potato strips (mm) � standard deviation 0.0 (Distilled water) 42 � 0.91 0.2 41 �0.76 0.4 39 �0.64 0.6 38 � 0.9 0.8 37 � 1.3 1.0 37 � 0.8 Fig 1: Figure depicting change in mean length of potato strips after their suspension in distilled water and various concentrations of sucrose solutions for 30 minutes; 0 corresponds to the normal length of the potato strips before their suspension i.e. 40 mm (no change); 2 corresponds to the increase in mean length of strips after suspension in distilled water i.e. 42 mm; 1 corresponds to the increase in mean length of strips after suspension in 0.2M sucrose solution i.e. ...read more.

Conclusion

As the concentration of the sucrose solution was increased, the mean length of the potato strips went on decreasing. Since as the solution outside the strips became more hypertonic, the water potential inside the cells became higher than outside and therefore, water moved out of the potato cells to the sucrose solution and hence a decrease in the mean length of the potato strips was noted. One of the limitations in this experiment was that the only factor taken into account was the change in length of the potato strips; the weight of the strips could as well be measured in order to investigate the water potential of the cells in potato tissue immersed in distilled water and various concentrations of sucrose solution. In addition, the experiment was carried out only once; hence in order to reach a better conclusion and obtain more reliable results, the experiment should be repeated and that the weight of the strips could also be taken into account. ?? ?? ?? ?? 4 ...read more.

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