PotatoLabReport

Topics: Osmosis, Semipermeable membrane, Mass Pages: 5 (1275 words) Published: January 25, 2015
Shiva Kumar
Ms.Kelly
AP Biology
Period:5
September 29, 2014

Potato Lab Report: Effects of Sucrose Solutions on Potato Cells and Water Potential

Abstract: Osmosis is a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane. In this experiment, we learn about Osmosis and Diffusion through potato cores in different concentration of sucrose, (water, .2, .4, .6, .8, 1.0). We realized that the lower the concentration, the higher the potato cores weighed.

Introduction:All cells have membranes that are selectively permeable. In other words,they allow certain things in and certain substances are not allowed to enter the interior of the cell. The process by which water crosses membranes from region of high water concentration to regions of low water concentration is called Osmosis. Osmosis is the process whereby water moves across a cell membrane by diffusion. Diffusion takes place when the molecules of a substance tend to move from areas of higher concentration to areas of lower concentration. Cells must tightly control the process of osmosis otherwise they will die. Plants with too little water will wilt. This happens when water moves out of the cells by osmosis. Without this water there is little pressure inside the cell and the plant can no longer support itself against the pull of gravity.This experiment is to find out the water potential of potato cells . Water potential is the ability of water to move down gradient of water potential through partially permeable membrane until the gradient is constant.The purpose of this investigation is to see how a plant , in this case a potato , reacts to different concentrations of sucrose. Hypothesis:If we place potatoes in sucrose solutions then as the concentration goes up, the change in mass will go up as well. The higher the concentration the more mass we will lose. One formula we can reference is: Water Potential = Pressure Potential + Solute Potential

Materials and Supplies:
•Potato cores(3 per solution )
• Sucrose solution(.2,.4,.6,.8,1.0)
• Water
• Electronic balance scale
•Glass Jar
• Color dye
• Seran Wrap type of material

Procedures:
Gather 3 potato pieces
3 pieces for each solution
Get a jar and zero it on the scale
Place potato in each jar and weigh
Gather the six solutions
Put each solution in each jar
Put on wrap to stop evaporation
Wait till next day
weight for final results
Find mass difference by subtracting initial-final
Find percent change by dividing final mass by mass difference

Results and Data:

Contents in Beaker
Initial Mass
Final Mass
Mass Difference
Percent Change
1.0 M
7.52g
6.09g
-1.43g
-23.5
Distilled Water
6.92g
7.93g
1.01g
14.6
.2 M
6.86g
7.13g
.27g
3.93
.8 M
5.73g
4.72g
-1.01g
-17.6
.4 M
6.94g
5.95g
-.99g
-14.3
.6 M
7.74g
6.60g
-1.14g
-14.7

From what we can see on the graph there is a best fit line that can be drawn. But if we look at the .4 M solution we can see that it doesn't scale right with the rest of the points. You can see that there is a drastic dip down on .4 M , so that can conclude that we have some problems or errors in the procedure. The most likely error was that the potato was either too small or the surface area to volume ratio was off. If the potato was more equal to all the rest is would make a more linear look to the graph and the line of best fit would include more points closer to the actual line. The graph also proves our hypothesis as the Molarity of the solution increases from Distilled Water (0 Molarity) to the 1.0 M Sucrose solution ; the mass change and the weight of the potato go down in reaction to that.

Conclusion and Discussion:

Looking at the...

Cited: Literature:
Cellular Process Packet : Lab #4
Boseman Science Video
Exercise 2- Determine the Water Potential of Potato cells WorkSheet
Ap Biology Textbook
Lab Book
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