Osmosis
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INTRODUCTION
Osmosis is defined as the movement of water from an area of high concentration of water to an area of low concentration of water. “Kinetic molecular theory of matter this theory states that all matter whether it exists as a liquid, gas, or solid in a state of constant motion. The molecules that make up the matter are always moving in random fashion.” (lab # 5 pg. 1) “Passive Transport the transport of molecule without requiring the cell to expend any energy. This causes molecules to bump into each other and move in new directions diffusion is the result of this contact. (Johnson, Michael pp. 55) Random movement of molecules to an area of lower concentration from an area of higher concentration is known as Osmosis. “Not all substances diffuse readily into and out of living cell”. (Johnson, Michael pp. 55) Plasma membrane is known as selectively permeable. Semi-permeable membranes are very thin layers of material (cell membranes are semi-permeable) which allow some things to pass through them but prevent other things from passing through what is know as diffusion. Isotonic solute concentrations inside and outside cells are equal. Therefore no net movement of water into or out of cell. Hypotonic solution is low in solutes high in water molecules compared to a hypertonic solution. Hypertonic is high in solutes low in water molecules. Active transport is the transport of specific solutes across plasma membranes against the concentration gradient through use of cellular energy. (Johnson, Michael pp. 55)
Hypothesis
When putting sucrose solutions into liquid containing water one of three things will happen. The cells that are in a control environment will become hypotonic, hypertonic and isotonic.
Materials and Methods
beaker
water
sucrose
scale
artificial cells
thread
clock
pen
paper
Experiment
This experiment follows the flow of water into or out of the cells. Cells are the dialysis tubes that are being used.
Pieces of dialysis tubing were folded over twice and tied twice at each end with tread.
Five cells were made. Each cell contained two different fluids inside except for cells five and one. They both contained 15ml of tap water.
The class constructed cells from dialysis tubing with different concentrations of sucrose solutions, which will be placed in the cells.
Sucrose cannot diffuse through the tubing, but water can. The cells were placed in different environments for sixty minutes.
The amount of sucrose and water that was put in cells and beakers, 1 and cell 5 had 15 ml. of tap water and cell 1 , 2 , 3, and 4 beakers had 200 ml. of tap water , cell 5 had 200 ml. of 60% of solution cell 2 had 20% , 3 had 40% and cell 4 had 60% of sucrose. (Lab report handout page 5)
Results Table #1 Osmosis Raw Data
Weight in grams
Time min
Cell 1
Cell 2
Cell 3
Cell 4
Cell 5
16.3
15.3
13.9
13.0
11.8
10.9
10.4
In cells two, three, and four, the concentration of solute is higher in the beaker than in the cell. Cell three with 40% sucrose gained a little more rapid than cell two that had 20% sucrose in it.
Cell five started with tap water and was put in the beaker with 60% sucrose which made the water molecules from the beaker will tent to penetrate the cell in order to dilute the high concentration of solute within.
Change of weight in grams from the initial weight table #2
Time minis
Cell 1
Cell 2
Cell 3
Cell 4
Cell 5
-2.4
-3.3
-4.5
-5.4
-5.9
The table above indicates the change in weight from the initial weight for each cell and each time interval. As notice from the above information from table number 2, cell number 5 weighs the least. Due to the mal- function of cell 2 which would have gain weight and not lost, cell 5 would have lost the most weight. The leakage in cell 2 tubing, gives an example of the importance of controls. “Whenever possible proper controls should be set up to ensure that any changes in results in the experiment are due to thing being tested and not anything else.” But never the less from the first initial weight cell number five has been in the negatives and remained in that direction through the entire experiment. Cell number 4 weighs the most. The numbers went up fast and then slowly began to decline. In cells, three, and four, the concentration of solute is lower in the beaker than in the cell. The amount of sucrose that was put in cells they had different amount of sucrose cell four had 60%sucrose in it that gained more weight rapidly between intervals. Cell three with 40% sucrose expanded a little less rapid than cell two that had 20% sucrose that had