Investigating Osmosis In Plant Cells

Fair Test: I must use the same kind of chips i.e the same potato, they must be relatively the same size and I must weigh them accurately both before and after the experiment. I must make sure that the volume of the sugar solution I put in each test tube is the same.

Equipment List

• 5 test tubes
• 5 equal potato chips (1 potato)
• A beaker
• 5 different sugar/water solutions (0%, 5%, 10%, 15% and 20%)
• A balance
• 25ml measuring cylinder
• Safety goggles
• A scalpel

Step By Step Instructions

• Firstly, get a test tube and some 0% sugar/water solution (tap water), I then measured 20ml of the solution and poured it into the test tube.
• Then accurately cut the potato into five equal chips using the scalpel, weigh them using the balance and record each chips individual mass.
• Get one of the chips and put it into the test tube with the 0% solution in it. Make sure you don’t forget which chip went into the solution.
• Put the test tube into the beaker so it is upright and no solution will be spilled.
• Repeat all the steps above 4 more times, each time use a different solution for example for the next experiment you would use 5% solution, for the third experiment use 10% solution and so on.
• After all this is complete, leave the test tubes for 24 hours.
• Take the chips from the test tubes and pat them dry, take the masses of all the chips and record them.

Analysis

From this experiment, I have learnt that osmosis occurs in plant cells when they are placed in a water solution. This occurs until the concentrations of

the two are the same as osmosis is the passage of water molecules from a weaker solution (a higher concentration) to a stronger solution (a lower concentration) via a partially permeable membrane. As you can see from my graph, the higher the concentration of the solution, the more the mass of the potato chip increased. This is because the solution was more concentrated than the chip so more water molecules have passed from the solution into the chip and therefore increasing its mass. When the solution is weaker in concentration, then the mass of the chip will decrease because the water molecules will pass out of the chip into the solution because the chip is more concentrated than the solution.

Evaluation

I think my experiment was quite reliable in that what I said in my prediction was proved to be correct. I could have improved my results my repeating the experiment and finding the average of my results. To verify that my results are fairly correct, I have included two other sets of results from other members of my class. In relate to this experiment and to prove my results further I could find at which point that the solutions are equal, I could use my graph as a rough guide. This would prove that osmosis occurs until both solutions are equal in concentration.