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To Find Out the Effect of Various Solutes On Living Cells

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Introduction

Peter O'Connor 9DV 4 May 2001 Biology Experiment Aim To find out the effect of various solutes on living cells Apparatus Test tubes, petri dish, test tube rack, knife, potato, distilled water, 1 M, 0.8 M, 0.6 M, 0.4 M, 0.2 M, salt solutions. Method Six test tubes were weighed, labelled and filled with equal amounts of different solutes. Test tube 1 was filled with distilled water. Test tube 2 was filled with 0.2 Molar salt solution. Test tube 3 was filled with 0.4 Molar salt solution. Test tube 4 was filled with 0.6 Molar salt solution. Test tube 5 was filled with 0.8 Molar salt solution and Test tube 6 was filled with 1 Molar salt solution. ...read more.

Middle

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. ...read more.

Conclusion

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. ...read more.

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