The aim of this experiment is to investigate the movement of water into and out of plant cells by osmosis. The cells chosen for study will be taken from potato as they provide a ready supply of homogeneous material.

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Osmosis

Aim - The aim of this experiment is to investigate the movement of water into and out of plant cells by osmosis. The cells chosen for study will be taken from potato as they provide a ready supply of homogeneous material.

Osmosis is the diffusion of water molecules across a partially permeable membrane from a high concentration of water to a low concentration of water.

Movement of substances takes place through the cell membrane, which separates the different substances in the cell from its surroundings. This type of membrane allows small molecules such as water to pass through it, but it denies entry to large particles, such as glucose, to pass. This membrane is called a partially permeable membrane. The amount of water inside a cell is called water potential.

Variables that may affect the experiment (rate of osmosis) –

  • Concentration of Salt Solution
  • Size of the potato
  • Temperature of surroundings
  • Time

Prediction - Osmosis is the movement of water molecules, where water molecules diffuse from a highly concentrated region, to a region in which they are less concentrated. Therefore when potato is in a concentration of salt that is more than the concentration of water then the potato will decrease in size/mass. So if there was a salt solution of 5% and 10% the 10% solution would decrease in size/mass more than the 5% solution.

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Safety Precautions – I will take care when using the scalpel to cut up the potato, all stools will be under desks and safety goggles will be used if necessary.

Equipment –

  • Potatoes
  • A corer to core out the potato
  • Scalpel
  • Test tubes
  • Test tube holder
  • Solutions needed
  • Pins
  • Cling film
  • White tile
  • Weighing Scales

Method – First I got the potatoes needed and cored them out, we then cut lots up so they were all pretty much the same size/mass (if all the pieces of potato were not all similar, ...

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