Finding the Water Potential of Potato Cells
Aim: Our aim was to discover the water potential of potatoes cells
using different concentrations of sucrose solution
Science:
Osmosis is 'the movement of water molecules from a region of higher
water potential to a region of lower water potential through a
semi-permeable membrane'
www.s-cool.co.uk
'Water can move between cells (unligninified) freely as the cell walls
are permeable. However its movement is controlled by a number of
factors, which are given names; solute potential ([IMAGE]), Pressure
potential (+ Matrix potential =0 normally)([IMAGE]) and water
potential ([IMAGE]).
Solute potential ([IMAGE]): this refers to the amount of substance
dissolved in the cytoplasm. This effects water movement because water
always moves from a less concentrated medium to a more concentrated
medium.
Pressure potential ([IMAGE]): this refers to the pressure exerted by
the cell walls. In a plant, the cell will fill with water until the
inner membrane is pushing on the outer membrane to the same force as
the wall is pushing back; they then are equal forces and cancel out.
Therefore there is no more movement of water.
Water potential ([IMAGE]): this is a figure worked out from the
equation; water potential = solute potential + pressure potential ([IMAGE]).
The figure represents the tendency of a cell to give out water.
http://www.restoringearth.co.uk/site/ossmosis.htm
Water moving out of cells causes them to lose turgor pressure - cell
membrane detaches from cell wall and shrinks (wilting) - plasmolysis
Water moving into cells causes them to become turgid, swollen -
deplasmolysis
http://biomicro.sdstate.edu/Hutchesh/bio101/Graphics/lab4/tsld011.htm
The is a dilute solution inside the potato cells due to it's cell sap,
this is a 'Dilute fluid found in the large central vacuole of many
plant cells. It is made up of water, amino acids, glucose, and salts.
The sap has many functions, including storage of useful materials, and
provides mechanical support for non-woody plants'
http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0029874.html
Prediction: From the research I have done into osmosis I have been
able to make some predictions about the results I will get.
If we say that the right hand side in picture 1 is the potato, and the
Diffusion and osmosis are necessary for the efficient transport of substances in and out of living cells. Diffusion is the most common and effective transportation process between cells and their surroundings, the movement of a substance along a concentration gradient from high to low, allowing essential nutrients and compounds to be transported without expending energy. Osmosis is a special kind of diffusion, specific to water. In order to observe diffusion and osmosis in real and artificial cells, a series of experiments was put together to observe how the surface area to volume ratio effects the rates of diffusion by using agar in different shapes with different ratios, next the rate of diffusion due to tonicity was observed using different solutions with different tonicities. And lastly live plant cells were submerged in different solutions with varying water potentials to observe how was potential effects the rate of osmosis and diffusion. It was concluded that the larger surface area to volume ratio, the faster rate of diffusion, the hypertonic solutions caused water to leave a cell and the hypotonic solutions allowed water to enter a cell, and that water potential will move from high to low in an attempt to maintain equilibrium.
Investigating Osmosis In A Potato Introduction: "Osmosis is typically defines as the flow of one constituent of a solution through a membrane while the other constituents are blocked and unable to pass through the membrane. Experimentation is necessary to determine which membranes permit selective flow, or osmosis, because not all membranes act in this way. Many membranes allow all or none of the constituents of a solution to pass through; only a few allow a selective flow. In a classic demonstration of osmosis, a vertical tube containing a solution of sugar, with its lower end closed off by a semi-permeable membrane, is placed in a container of water. As the water passes through the membrane into the tube, the level of sugar solution in the tube visibly rises.
The Effect of Water Concentration on the Mass of Potato Tissue Aim: The aim of this investigation is to discover the effect of water concentration on the mass of potato tissue, and also to investigate the movement of osmosis through potato tissue. Scientific Knowledge: When a substance such as a sugar dissolves in water, the sugar molecules attract some of the water molecules and stop them moving freely. This, in effect, reduces the concentration of water molecules.
Osmosis in Potato Tubes Osmosis: Osmosis is the movement of water molecules through a semi-permeable membrane from a high concentration to a low concentration. Diagram: [IMAGE] [IMAGE] Aim: To see the effects of different concentration of sugar solution on Osmosis in potato tubes. Key factor: In the investigation we change the sugar solution from: 0%-10%-20%-30%-40%-50% this is the independent variable; the dependant variable is the change in mass. Prediction: I predict that all the potato tubes in pure water or low concentration sugar solution will swell because water enters their cells by osmosis.
* Note the mass down in the table at the end of the first page.
Investigate the Osmosis of Potato Cells in Various Salt Solutions. Introduction I have been asked to investigate the effect of changing the concentration of a solution on the movement of water into and out of potato cells. I will be able to change the input of my experiment. The input variable is the concentration of the solution.
Water Potential of Potato Cells Aim: To demonstrate the Water Potential of Potato Cells. Objectives: · To show the water potential of potato cells using various measured concentrations of a sucrose solution and pieces of potato. · To record and analyse data to verify observed results. · The method and procedure was carried out as per instruction sheet. Observations: The experiment shows that the lower the concentration of the sugar solution, in the Petri dish, the mass of the potato increased.
the same way as it does potato. I would also widen the range of sugar
The variables I could change would be the temperature of the solution. The higher the temperature of the solution the more osmosis would occur. The surface area of the potato strip, the larger the surface area the more osmosis would occur as there would be more area exposed for osmosis to take place. The concentration of the solution will affect osmosis, the higher the concentration the less osmosis would take place. The duration of the experiment also affects how much water is gained/lost by osmosis as the longer the duration is, the more osmosis would take place (osmosis would stop as soon as it reaches an equilibrium of water content inside and outside the cell.
there would be no flow of water into or out of the cell so the cell
water in the potato, then the water will go out of the potato and into
Investigating the Water Potential of Celery Cells Aim = == I will be investigating the water potential of celery and to find out which solution will be isotonic with the celery cells, in other words equilibrium between the two no water will leave the cell, or enter. I will do this by following this method. Method 1.
To investigate the osmotic effect of changing the concentration of sucrose solution; distilled water, 20% sucrose solution, 40% sucrose solution, 60% sucrose solution on the change in mass of potato cylinder after 30 minutes of being in solution.
4. Put each group of potato discs in one of the 6 test tubes and watch