The effect of osmosis, diffusion, and the determination of osmotic concentration on potato parenchyma.

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The effect of osmosis, diffusion, and the determination of osmotic concentration on potato parenchyma.

Nicole Simone

Dr. Kelly- Bio I Lab


 

ABSTRACT

        I used the extract of a potato to observe the processes of osmosis and diffusion. I used a # 5 cork borer to cut the potato tuber cylinders from the potato. I cut the cylinders to be exactly 40 nm. I added a sucrose solution to the potato extract and incubated them for two hours. After the two hours were up the length was measured the potato extract weighed less.

        

INTRODUCTION

        Diffusion is the movement of molecules from a high concentration to a low concentration. The concentration gradient effects the rate of diffusion. The concentration gradient is the gradual difference in concentration over the distance between high and low regions. So the steeper your concentration gradient, the faster the rate of diffusion will occur. Temperature and molecular weight also directly effect the rate of diffusion. All molecules move faster at higher temperatures, but molecules with a larger molecular weight is much slower than small molecules at the same temperature.  Membranes that block or slow the passage of certain substances are expressed as being semi - permeable. This accounts for osmosis. Osmosis is the diffusion of water through a membrane. Osmosis occurs because certain molecules cannot cross the membrane. Hypotonic refers to more molecules being outside the cell, water enters the cell, and the cell expands. Isotomic refers to the same concentration of molecules inside and outside of the cell. No osmosis takes places during this phase. Hypertonic is when more molecules are outside the cell than inside the cell, and water leaves the cell, hence the cell shrinking. When the volume of sucrose increases in the beaker the cells of the potato will shrink and become hypertonic because water will leave the cells to dilute the outside solution. I do not think that the size of the potato will be affected if the cells lose water.

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MATERIALS AND METHODS

Dolphin, W.D. 2002. Biological Investigations.

        New York: McGraw-Hill.

There were no changes made to the lab.

RESULTS

        Our graph shows us the percent change for the class data, and the percent change for the table data. Table 1show us the molarity of sucrose solutions in moles / liter, for the four groups that did this experiment, the mean length, the standard deviation, and percent change. Table 2 shows us the same things for the class data.

DISCUSSION

        The osmotic concentration of the potato parenchyma for the table is 3.388. The osmotic concentration of the potato ...

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