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Determination of Water PotentialOf Potato Tissue

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Introduction

EHSEN KHOKHER Determination of Water Potential Of Potato Tissue Introduction: Osmosis: is the movement of water through a semi permeable membrane from a high water concentration to low concentration. Osmosis is movement of water, which takes place through the cell membrane that separates the cell contents from the surroundings. Cell membranes allow some substances to pass through and stop other substances from passing: they are partially permeable. In general, substances pass through a membrane if their particles are smaller than the pores in the membrane. When a partially permeable membrane separates two solutions, water passes through the membrane in both directions. The net flow of water is from the more dilute solution to the more concentrated solution. The flow continues until the two concentrations are equal. The flow of water from a more dilute solution to a more concentrated solution is called osmosis (see diagram). Partially permeable membrane Concentrated Sugar Solution Dilute Sugar Solution Sugar Molecule Water Molecule Water potential is how likely the water is to leave the solution. High water potential is when the water is highly likely to leave. ...read more.

Middle

Mean length of potato at end CHIP 2 (cm) Mean length of potato at end CHIP 3 (cm) Mean change in length of potato (cm) Mean Chan-ge (cm) % Mean chan-ge in leng-th 1.0 6.0 5.5 5.3 5.5 5.43 -0.57 -9.5 0.75 6.0 5.5 5.4 5.4 5.43 -0.57 -9.5 0.5 6.0 5.9 6.0 5.9 5.93 -0.07 -1.17 0.3 6.0 6.0 6.0 5.9 5.96 -0.04 -0.5 0.2 6.0 6.0 6.2 6.0 6.07 +0.07 +1.17 0.1 6.0 6.0 6.4 6.0 6.13 +0.13 +2.17 Table 2 Showing Water Potential Conc. Of Sucrose (M) Water Potential (kPa) 0.05 0.13 0.10 0.26 0.15 0.41 0.20 0.54 0.25 0.68 0.30 0.86 0.35 0.97 0.40 1.12 0.45 1.28 0.50 1.45 0.55 1.62 0.60 1.80 0.65 1.98 0.70 2.18 0.75 2.37 0.80 2.58 0.85 2.79 0.90 3.00 0.95 3.25 1.00 3.50 Conclusion: The mean % change in length of potato tissues increased by 2.22% in the 0.1M sucrose solution. This is because the water concentration of the sucrose solution was higher than that of the potato tissue. Water moved from the more concentrated water to the less concentrated potato tissues resulting in full turgor tissues with greater length. ...read more.

Conclusion

not to 0g but to 0.00g. This is to get more accurate results. There was one anomalous result, which was the 0.75M sucrose concentration; this was anomalous because it was way off from the line. Looking at my graph it should have been -0.6 or -0.7%. This may have been caused by human error, which was the making of the sucrose concentrations and measuring the potato chips, or one out of my six results could have been more inaccurate, and changed the average drastically. Or perhaps the potato chip was not cut accurately, or that part of the potatoes, cells did not loose/gain mass well. One or two of my results did vary a lot for the same concentration. The fact that a certain part of the potato may not be the same as another was shown as the chips all of the same length but we did not weigh them so they might not have been the same weight, or even close. I could extend my enquiry by testing the percentage change in mass with molarity using more concentrations and different kinds of potatoes. By this I mean using potatoes of different seasons, perhaps different types of potatoes. Then I could find out whether osmosis occurs with the same patterns and trends with any potato. ...read more.

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A clear account with good explanations but confusion over the use of some terms and no discussion of variables.

Marked by teacher Adam Roberts 20/05/2013

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