Osmosis. By this investigation, I tried to find out the changes in potato cylinders masses dependently on sucrose solution

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Investigation: Osmosis in potato cells, IB Biology

Osmosis in Plant Cells

Name:                                                                            Data: 11.11.2011

Time allocation: 2 hours                                                       I.B. Topic: 2

Data Collection and processing

Quantitative data:

Used solutions:

1.0 M = 20ml of 1M sucrose + 0 ml of water

0.8 M = 16ml of 1 M sucrose + 4ml of water

0.6 M = 12ml of 1 M sucrose + 8ml of water

0.4 M = 8ml of 1 M sucrose + 12ml of water

0.2 M = 4ml of 1 M sucrose + 16ml of water

Potato (a) and sweet potato (b) cylinders masses changes in different concentrations of sucrose:

a)

b)

Graph 1

Graph 2

Qualitative data:

  • Tube-pipe with 0.4 M solution wasn’t fully plugged with stopper.
  • Potato cylinders in 1.0 M, 0.8 M, 0.6 M, 0.4 M solutions were floating while in 0.2M and 0.0 M solutions it was fully on the bottom. On the other hand in 1.0M solution it was on the top, while in 0.8 M solution a bit lower, 0.6 M more lower etc. That’s because of density’s differences.
  • Levels of solutions looked different (it looked that volumes are not the same) (lowest in 0.6M and 0.2M solutions, highest in 0.4 M, 1.0 M solutions.). That’s probably because of different types of tube-pipes, differences in their sizes.
  • It was seen how potato cylinders were taking water inside in 0.0 M, 0.2 M and 0.6 M. It was bloating. I couldn’t see the any changes in 0.6 M. In 0.8M and 1.0 M potato cylinder looked like getting smaller. I can guess that it’s because of higher water potential in potato cylinder than in solution (water was diffusing from potato to solution).
  • We didn’t stir any of the solutions.
  • Potato cylinders weren’t completely dry while measuring its’ masses.
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Conclusions and evaluations

By this investigation, I tried to find out the changes in potato cylinders’ masses dependently on sucrose solution outside and hence – concentration of sucrose inside the potato, which has the same water potential as solution outside the cylinder. The data from this investigation shows that there are different results for potato and sweet potato cylinders. Therefore, we know that water potential (and concentration of sucrose) inside the potato and sweet potato cells is different. On the other hand, in both, by increasing outside solution concentration, water potential was gradually increasing in the cell. ...

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