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24 Cards in this Set

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What is the purpose of lab 1A?
To investigate the processes of diffusion and osmosis in a dialysis tubing and investigate the effect of solute concentration on water potential as it relates to living plant tissues
What does Diffusion mean?
The random movement of molecules from an area of higher concentration of those molecules to an area of lower concentration
What does Osmosis mean?
The diffusion of water throgh a selectively permeable membrane from a region of higher water potential to a region of lower water potential
What is water potential?
The measure of free energy of water in a solution
What is active transport?
It moves substances against a concentration gradient, from regions of low concentration of that substance into regions of higher concentrations
What will you do in 1a?
You will measure diffusion of small molecules through dialysis tubing
What is dialysis?
The movement of a solute through a selectively permeable membrane
What will you do in 1C?
You will use potato cores placed in different molar concentrations of sucrose in order to determine the water potential of potato cells
Water Potential?
The movement of water into or out of plant cells
Where does water move to?
Water always move from an area of higher water potential to an area of lower water potential
What are the two physical factors water potential is affected by?
One factor is the addition of solute which lowers the water potential

The other factor is pressure potential where an increase in pressure raises the water potential
What is the movement of water into and out of a cell influenced by?
Solute Potential
What happens when water moves out of a cell?
The cell will shrink
What happens when water moves into an animal cell?
It will swell and maybe burst
What happens when water moves into a plant cell?
The presence of a cell wall prevents cells from bursting as water enters the cell
What happens when water enters a dialysis bag or a cell with a cell water?
Pressure will develop inside the bag or cell as water pushes against the bag or cell wall.
The pressure would cause the water to rise in an osmometer tube or increase the pressure on a cell wall.
What is the solute potential?
It is the effect that solutes have on a solution's overall water potential
What is pressure potential?
Pressure potential is usually positive in living cells; in dead xylem elements it is often negative.
What is the value of water potential?
The water potential value can be positive, zero or negative
What is the value of solute potential?
Solute potential is always negative
When in a solution and the inside of a potato cell is separated from pure water by a permeable cell membrane, what happens?
The water will move (by osmosis) from the surrounding water where water potential is higher into the cell where water potential is lower
What happens when water potential of the cell equals the water potential of the pure water outside the cell?
A dynamic equilibrium is reached and there will be no net water movement
what happens when you add solute to the water outside the potato cells?
the water potential of the solution surrounding the cells would decrease
What happens when enough solute is added to the water outside the cells?
Water will leave the cells, moving from an area of higher water potential to an area of lower water potential. The loss of the water from the cells will cause the cells to lose turgor. A continued loss of water will eventually cause the cell membrane to shrink away from the cell wall (plasmolysis)