The effects of osmosis in potato cells.

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John McArthur

Biology Science Investigation

Title:

The effects of osmosis in potato cells

Aim:

My aim for this experiment is to see the results of a potato tissue's mass difference, when placed in different concentrations of sugar solutions.

Osmosis is the passage of water molecules from a weaker solution into a stronger solution, through a partially permeable membrane. In this case, the tiny holes in the membrane of the potatoes will allow the water molecules to pass through in and out of the solution and the potato, depending on the concentration gradient of the two substances. So in this case, when the water concentration is lower in the tissue, the later will go inside the tissue of the potato, and the potato will gain mass. If there is very little different in the two water concentrations, there shouldn't be such a big change in mass. Also if there is a higher concentration of water in the potato, then the water will go out of the potato and into the liquid solution, as osmosis is the movement of water molecules from a region of high concentration to a region of low concentration, through a partially permeable membrane.

Planning

Variables:

There are many many variables that can be altered. These include:

  • Mass of chips in grams
  • Dimension of chip in cm
  • Strength of surcose solution in moles
  • Volume of sucrose solution in ml
  • Temperature of surcose solution in degree’s centigrate
  • Type of potatoe
  • Length of time  in hours
  • Location ie. Near a window,in shade etc.

Input Variable:

I will be changing the concentration of the sucrose solution.

Outcome variable:

There will be several cthings that change throughout the experiment. These are:

  • Mass of chips
  • Size of chips
  • Volume of sucrose solution

Control Variables:

I will be keeping the following things the same.

  • Mass of chips
  • Size of chips
  • Volume of sucrose solution
  • Temperature of sucrose solution
  • Type of potato
  • Location of experiment
  • Length of time experiment
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Prediction:

I predict that the weaker the solution is, the more solution the potato will absorb and the stronger the sugar solution the more water the potato will lose. Therefore, the weight of the potato at the end of the experiment will increase most in distilled water and decrease most in the strongest sugar solution.

I also believe that the apperance of the sample s that take in water eill be firmer and feel more rigid and the opposite for the samples that may lose water they shall become flaccid and feel very soft to the touch.

Apparatus:

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