To Find Out the Effect of Various Solutes On Living Cells

Results

Graphs

This graph shows that the stronger concentration of molar solution the less weight the solution had after the 67 hour period.

This graph shows the lower molar solution concentration the more the potato pieces had expanded.

Conclusion

In this experiment, in a less concentrated salt solution the pieces of potato grew in size and in a more concentrated salt solution the pieces of potato shrank. This is due to a process called osmosis.

Osmosis is the movement of a solution across a semi-permeable membrane. A semi-permeable membrane is a thin porous wall that lets in some but not all of a liquid's components in. A plant's cell wall is a semi-permeable membrane.

The potato increased in size when it was left in distilled water because the concentration of salts within the potato was relatively higher than that within the distilled water. So, water would have travelled across the cell walls from the distilled water into the potato swelling the cells and making them larger and firmer. In higher concentrations of salt solutions, the pieces of potato shrank. This is because the salt concentrations in the potato pieces were relatively lower than in the salt solutions and so water would have travelled across the cell walls from the potato to the salt solutions. This made the potato cells less turgid, resulting in a smaller size and making the pieces of potato feel spongy. There was no difference in size of the potato when it was left in 0.4M salt solution. This suggests that there was little or no discernable movement of water, which in turn suggests that the concentration of salts in a potato is roughly the same as 0.4 M salt solution.

There is an anomaly in the results recorded in that although there were changes in size in 5 out of the 6 pieces of potato, there were no corresponding expected increases and decreases of weight. Apart from the potato put into the distilled water, all of the pieces of potato decreased in weight. This is probably due to the drying techniques used in this experiment.