Salt Potato

Plants in the soil have their roots in a dilute solution of mineral ions. When they are suddenly flooded with seawater, concentration of which is 0.3 molar Sodium Chloride, they are observed to wilt and become flaccid.

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 tubers as they provide a ready supply of uniform material.

Any substance dissolved in water is called a solute; a solvent is a liquid that is able to dissolve another substance, called a solute, to form a solution.

The water content of plants varies depending on environmental conditions. In land plants it plays a vital role in structural support and mineral transport and thus a lack of water may lead to wilting or possibly death.

Water is mainly absorbed through the roots, which are covered in specially adapted root hair cells, with large surface areas and thin cell walls to aid absorption by osmosis. The evaporation of water through stomata on plant leaves causes a transpiration stream, causing the water to be drawn up through xylem vessels.

Osmosis is the flow of water molecules by diffusion through a partially pe

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10 molar concentration the changes in length appear to be consistent as a straight line, thereby suggesting that increases in solute potential will result in proportionally smaller increases in length.

· After the experiment has been completed all the apparatus will be properly placed away and all the potato cores will be disposed of.

The experiment was also limited by the accuracy of the top pan balance, which was to one decimal place, and the calibration of the ruler. Water loss can continue to such an extent that the cytoplasm, and attached cell membrane, contracts and detaches from the cell wall. This will be visible as an increase in length and mass of the potato cores.

Ideally all samples should have come from the same part of the potato, as this would have decreased the chances of variations in texture.

A variety of other similar plant roots could have also been placed through the same procedure in order for comparison.

· The length, mass and diameter of the potato cores, in order to allow for uniformity. These increases in size continued to decrease until the isotonic point was reached, where both the internal and external water potentials are the same.

· Cut 27 potato cores from the same large potato and place them onto a ceramic tile. This is because by increasing temperatures one is increasing the kinetic energy of the molecules and as a result the diffusion rate will also increase. This can be seen as a decreasing in length and mass from the original.

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