Figure 1
Osmosis makes plant cells swell up. The water moves into the plant vacuole and pushes against the cell wall. The cell wall stops the cell from bursting. This turgid state is useful as it gives the stem of the plant support. If the plant cell is lacking water, it wilts and the cell becomes flaccid as water has moved out of the cell. If a lot of water leaves the cell, the cytoplasm starts to peel away from the cell wall. The cell has undergone plasmolysis. (See figure 2)
Figure 2
Animal cells have no cell wall to stop them swelling so if they are placed in pure water, i.e. a hypertonic solution, they take in water by osmosis until they burst. (add something about blood cells and see fig 3)
Figure 3
The concentration of the solution that surrounds a cell will affect the state of the cell, due to osmosis. There are three possible concentrations of solution to consider:
- Isotonic solution a solution of equal concentration to a cell
- Hypertonic solution a solution of higher concentration than a cell
- Hypotonic solution a solution of lower or concentration than a cell
The effects of these solutions on cells are shown in this diagram below. (Figure 4)
Figure 4
Hypothesis ( need 3 short sentences)
For this particular investigation I think that the lower the concentration of the salt solution in the test tube the larger the mass of the potato will be. This is because the water molecules pass from a high concentration, i.e. in the water itself, to a low concentration, i.e. in the potato chip. Therefore, the potato chips in higher water concentrations will have a larger mass than in higher salt concentrations.
Risk Assessment
- Take care when cutting the potatoes with the cork borer.
- Clear work benches.
- Wash hands to prevent any contamination.
Method
- Wash Potatoes to remove any surface soil.
- Peel Potatoes to remove outer skin as this will act as a barrier.
- Cut the potatoes into cylinders of the same size using a cork borer i.e.
- Wash the potatoes again to remove any cell debris and other particles that may have attached to the surface.
- Carefully dry the potato chips with a paper towel.
- Measure and weigh each potato chip.
- Place the potato chips in labelled test tubes with various salt solutions.
- Time the submerged potato chips for exactly one hour.
- Drain the potatoes and dry off with a paper towel.
- Again measure and weigh each potato chip.
- Record results on a table below.
Results
