Potato and Osmosis Investigation

Potato and Osmosis Investigation

PLANNING: (P)

Some background Information: Water Potential and Living Plant Cells

Plant Cells in Pure Water: If plant cells are placed in pure water (a

hypotonic solution) water will initially move into the cells. After a

period of time the cells will become turgid. Turgor pressure is the

pressure exerted against the cell wall by contents of the cell. At

first most water movement is into the cell. As the turgor pressure

increases water will begin to diffuse out of the cell at a greater

rate, eventually equilibrium will be reached and water will enter and

leave the cell at the same rate.

Free Energy and Water Potential: Free energy can be simply defined as

the energy available (without temperature change) to do work. Chemical

potential of a substance is the free energy per mole of that

substance. Water potential is the chemical potential of water and is a

measure of the energy available for reaction or movement (Bidwell

1974:59). Water potential is important when studying osmosis because

it measures the ability of water to move, water always moves from

areas of high potential to areas of low water potential.

The formula for calculating water potential is:

Water Potential = Osmotic Potential + Pressure Potential

Water Potential in Plant Cells: Water will move by osmosis into and

out of cells due to differences in water potential between the cell

and its surroundings. Remember that water always moves from areas of

high potential to areas of low water potential.

Some Basic Principles:

· Water always moves from high water potential to low water potential.

· Water potential is...

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...diction did work

well because from my prediction and test I was able to match my ideas

and theories with the experiment, so that part was a success, I did

obtain anomalies as mentioned above and some improvements which could

be made are more accurate measurements with weight and length of

chips, make some changes with concentration levels of our sucrose

solution, this has been mention previously on pages 9 and 10 and more

time and care taken to improve on drying our potato chips; this my

reduce the weight of our chips and give more accurate weight

measurements when we do our final weigh in.

I think was experiment was a good for obtaining evidence and therefore

had no need to do a re-test of our potato chips, on a photocopied

sheet of my graph I have circled my anomaly results (sucrose

concentration level of 0.5M)