Osmosis Flashcards
what is osmosis
diffusion of water molecules down the water potential gradient across a partially permeable membrane
what does water potential mean
measure of tendency of water molecules to diffuse from one region to another.
What solution has the highest water potential
Pure water
what lowers the water potential of a solvent
adding solute molecules. e.g adding sugars
what units are used for water potential
kPa kilopascals
why is water loss or gain more severe in animal cells
They dont have a supporting cell wall
what is the term for when water molecules enter an animal cell until its swoll and bursts
Cytolysis
what happens when an animal cell is placed in a solution of low water potential
water leaves the cell through partially permeable membrane and it will shrink and shrivel
Crenation- cell has became crenated, which is fatal
How come plant cells dont burst in high water potential solution
the strong cellulose wall prevents bursting when plant swells with water
What is the term for plants when placed in a solution of high water potential
Water enters plant through osmosis
Water enters vacuole and volume of plant increases
protoplast expands and pushes up cell wall increasing turgor pressure
Plant becomes rigid and firm- turgid.
Why is turgidity good for plants
Offers strength and support for plant, leaf can stand upright with leaves held out to catch sunlight.
What is the protoplast
contents of the cell except the cell wall
when does the protoplast shrink
During plasmolysis
what happens to the plant when placed in a solution of low water potential
-water leaves plant through partially permeable membrane through osmosis
-water leaves vacuole and decreases the volume of plant
-protoplast shrinks and stops exerting pressure on cell wall
-protoplast will eventually pull away from the cell wall
