Osmosis 2.5.3 Flashcards
Define osmosis
Osmosis is the movement of water molecules from a high water potential to a low water potential, across a partially permeable membrane
Where does water diffuse from
It diffuses from a dilute to a concentrated solution.
Define water potential
A measure of the tendency of water molecules to diffuse from one region to another.
What is the water potential of pure water?
0
What happens to water potential as solutes are added?
It falls
When is a water potential gradient created?
When two regions of different water potentials are separated by a partially permeable membrane.
Why do water molecules have a low energy at low water potential?
As they are restricted by the presence of solutes, therefore cannot move as freely.
What is the osmotic concentration of an isotonic solution?
It is the same as the cytoplasm of the cell, therefore no net osmosis (equal)
What is the osmotic concentration of a hypertonic solution?
They have a lower water potential (higher pressure) than the cytoplasm, therefore net osmosis occurs out of the cell (cytoplasm).
What is the osmotic concentration of a hypotonic solution?
They have a higher water potential (lower pressure) than the cytoplasm, so net osmosis occurs into the cell (cytoplasm).
What effect does a hypertonic solution have on an animal cell?
Cause them to shrink - crenation.
What effect does a hypotonic solution have on an animal cell?
Cause them to burst - cytolysis
What is the function of the cell wall in osmosis?
Stops the cell from bursting when it absorbs water - as it is of high mechanical strength.
Describe the word turgid
Occurs in a plant cell during an increase in osmotic pressure, making the cell rigid.
Describe the word flaccid
Occurs when a plant loses too much water by osmosis and they become less rigid.
