Osmosis Flashcards
Define osmosis.
Osmosis is the passage of water from a region where it has a higher / more negative water potential to a region where it has a lower / less negative water potential through a selectively permeable membrane.
What is water potential measured in?
Units of pressure, usually kPa.
Under standard conditions of temperature and pressure, what water potential does pure water have?
Zero.
How will an addition of a solute affect the water potential of pure water?
It will lower its water potential.
If you add more solute to pure water…
The water potential of water becomes lower / more negative.
How can you find out the water potential of cells or tissues?
Place the cell / tissue in a series of solutions with different water potentials. Where there is no gain / loss of water, the water potential must be the same inside and outside of the cell / tissue.
What is a selectively permeable membrane?
A membrane permeable to water molecules put not larger molecules.
Define plasmolysis.
When the protoplast (living part of the cell) shrinks and pulls aways from the cell wall when a plant cell loses water by osmosis.
What happens if an animal cell is placed in solution with a more negative water potential?
The cell surface membrane cannot stretch to any great extent so the membrane will break, bursting the cell and releasing its contents.
How are animal cells prevented from bursting?
Animal cells usually live in a liquid which has the same water potential as the cells.
