Investigate the effect of salt concentration on the rate of water loss/gain by potato.

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                                               Biology coursework.

Investigate the effect of salt concentration on the rate of water loss/gain by potato.


Plan:

Investigate the effect of salt concentration on the rate of water loss/gain by potato.

Hypothesis:

I predict that the 0 M salt solution will make the potato gain weight because the water is at a higher concentration outside the potato so it moves in by osmosis.
I predict that in the 0.2 M solution the potato will neither gain nor lose weight because I think that the concentrations of water in and out of the potato are the same.
I predict that in the 0.4 M, 0.6 M, 0.8 M and 1.0 M solutions will lose weight because I think that the concentration outside the potato will be less concentrated than inside the potato so the water from inside the potato will move by osmosis.

Background Knowledge:

Osmosis – Osmosis is a special case of diffusion.

Outside the cell in the animation, there is a low concentration of solute molecules and a high concentration of water molecules. Inside the cell, there is a high concentration of solute molecules and a low concentration of water molecules.

The solute molecules can't diffuse out because the plasma membrane won't let them through. The water molecules however can diffuse in - this is osmosis. Osmosis can be defined as the passage of water molecules through a partially permeable membrane, from a region where they are in higher concentration to a region where they are in a lower concentration.

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Plasmolysis – Shrinkage of the cytoplasm of a plant cell, so that the cell membrane begins to tear away from the cell wall; caused by loss of water.

Diffusion – The movement of particles of gas, solvent or solute from an area of high concentration to an area of low concentration.

Active Transport - The movement of substances through cell membranes, using energy. The energy is in the form of ATP, which is first made by respiration. The substances are often moved against their concentration gradient.

Plant cell structure - Plant cells have a strong cell wall surrounding them. ...

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