The Definition of Osmosis

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Biology Course Work

MyungJae BAEK (10Bio02)

Do NOT delete anything I have written in red.

Make any corrections in blue so I know what to re-read


Diffusion is the net movement of particles from an area of high concentration to an area of low concentration. Then what is osmosis? Basically, osmosis is the same action with diffusion but in water. To describe more precisely, osmosis is the net movement in water across partially permeable membrane, which mean the membrane allows the water to get through the membrane, but not solute molecules of ions (small substances cannot get through but not big substances)

The movement of particles in water also depends on the water concentration. For example, if the water concentration of the right side of membrane is higher than left side of the membrane, particles move to the left side. However, we don’t use the word ‘water concentration’ we use the term of ‘water potential’ instead of it. The way we say is very similar, as if water concentration is HIGH the water potential HIGH. On the contrary, if the water concentration is LOW, the water potential is LOW.

High water potential = High water concentration

Low water potential = Low water potential

You need to check this, as your information is incorrect

The shape of plant cell can be changed depends on the concentration of water. Since the plant cells are surrounded by a cell wall, which is fully permeable, it will let any molecules go through it. So osmosis will not happen. However, the cell membrane of plant cell is partially membrane. It means, if a plant cell in pure water, water will go through the cell membrane and it makes the cell to swell and rigid. If a plant cell is in pure water – water will enter the cell – correct your work - the cytoplasm and vacuole shrinking is incorrect. However the plant cell’s cell wall is very strong. What does the cell wall prevent happening to the cell? So the cell wall obstruct the water goes inside and swell the cell. However, plant cells are usually very strong, and firm to stay upright make sure that no wood in it. How the plant cells are firm, tight state of plant cell is called turgidity of plant cell.

If we put the cell this is not about animal cells in the pure water, the cytoplasm and the vacuole will shrink. Then the pushing movement to the cell wall is going to stop since the cell becomes floppy and drooping. This kind of condition is said to be flaccid. If the cytoplasm shrinks more and more to the centre of the cell, the cell wall will leave behind and tears the cell membrane away from the cell wall. This kind of condition is called plasmolysed. This condition usually kills cells because the cell membrane is tore. However, this kind of condition usually does not happen because plants cells are not often covered by strong solution.

The preliminary Experiment

The goal for this experiment is to see how osmosis on plant cell effect with different kind of solutions of different concentration of glucose. The change in mass of the potato in the solutions is the results for the experiment.

I’ll measure the mass instead of length, because it will be more accurate.






-7 or more beakers

-7 different glucose concentration solution

-Laptops (reporting)

-Electronic scale

-->Cut the potato pieces in the same size

--> Put the concentration glucose solutions in the beakers and label the beakers which solution is put

--> Put a potato piece in each beaker

--> 30minutes later take the potato out of beaker and measure the masses --> Record the result.


Controlled variables

• Solutions – The volume of the solutions should be same

- The temperature of the solutions should be the same

• Potato pieces – The length and width of potato pieces should be same.

• Time – Make sure the time of...
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