Investigation On Osmosis.

G.C.S.E Coursework Investigation On Osmosis.

Osmosis is as follows: When a solution is separated by a semi-permeable membrane from its pure solvent or from a more dilute solution, through the membrane and into the concentrated solution. The solvent is nearly always water. Theoretically the passage of the water would go on until the concentrations on both sides of the membrane were equal. It may seem paradoxical to say that the concentrated solution is exerting an osmotic pressure when it seems, to sucking water into itself. In the experiment described above, the pressure from the concentrated solution supports the column of fluid in the delivery tube above it. The pressure can also be demonstrated by partially filling a pig’s bladder with syrup, trying it tightly and immersing it in water. The osmotic pressure of the syrup causes water to pass in through the walls of the bladder, distending and sometimes bursting out by the outward pressure of the solution.

Explanation of osmosis.

It is not very clear why osmosis should occur, or what the properties is that make a membrane semi-permeable. One theory supposes that the membrane acts as a molecular sieve, having tiny pores in it that are too small to allow large molecules like sugar ( C6 H12 O 6 ) to pass through, but large enough to let the small water molecules (h2o) go trough. Another theory suggests that the solvent actually dissolves in the membrane and seeps through it by diffusion, while the solute molecules cannot dissolve in the membrane.

Biological importance of osmosis.

Osmosis, as described above, seems to have little bearing on biology. But many animal and plant membranes are semi-permeable and the living creatures may be bathed in solutions stronger or weaker than their own body fluids. Consequently, osmotic forces are set up. Osmosis in cells. Protoplasm itself is a semi-permeable at its boundaries and plays an important part in the passage of water into and out of the cells.

Suction pressure

When the cell is fully turgid the osmotic pressure of the vacuole equals the inward pressure of the cell wall and no more water can be taken up. In conditions where the inward pressure of the cell wall is less than the vacuolar osmotic pressure, the cell can still take up water by osmosis until the two opposite forces are equal. This “spare” osmotic pressure, for example osmotic pressure of the vacuole minus inward wall pressure, this is called suction pressure and in many cases this is the force which causes water to pass from cell to cell.

Introduction on the potato experiment.

I am going to carry out an investigation to see where osmosis takes place, What I am going to do is chop five pieces of potato’s the same mass, I will put all 5 pieces in a beaker with salt solution, then I will record the mass by using electronic scales (balance) after being in the salt solution every 2 minutes for 10 minutes and then I will record my results into a table.

Investigation on osmosis.

What are the variables ...