Potato in Salt Solution
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 permeable membrane from areas of high water potential (low solute concentrations) to regions of low water potential (high solute concentrations).
All plant cell membranes are partially permeable, which means they allow some some substances to penetrate them but not others.
Whether water enters the cell by osmosis will depend on the balance between external and internal solute and water potentials. If the solutions on each side of the partially permeable membrane are of equal water or solute potential, then there will be no net movement of...