D2.3 Water potential

Solvation with water

• particles in solute seperate from each other

• water partciles seperate from each toher

• seperated solute and partciles combine to make a solution

hypertonic

higher concentration of solute than water

• water moves from lower solute to higher solute concentraion

hypotonic

• higher water concentration than solute concentration

isotonic

equal concentration of water and solute

• equal movement in both directions

Osmosis

movement of water from high water pptential/ high solute concnetration to low water potential/low solute concnetration through a partailly permebale membrane (aquaporins)

Cell placed in hypertonic solution no cell wall

• water moves out

• cell shrinks

• crenation

Cell placed in hypotonic solution no cell wall

• water moves in

• swelling

• ulitamtely bursting

Preventing creanation and bursting without a cell wall

• cells have an organelle → contrative vacuole

• it collects water from inetriro of the cell and preiodcially empities it into the environment

Cell placed in hypotonic solution with cell wall

• usually plant cells are hypertonic compared to environment

• this creates turgor pressure which is essential for the cell to be rigid and stable

Water lost from plant cell

• cell mebrane and cytoplasm shrink away from the cell

• plasmolysis due to loss of tugor pressure

• long lasting plasmolysis → death

Isotonic solution

• IV solutions - so no water goes out of the cells or in to prevent creantion or bursting

• organ transplants immersed in isotinic solutions so no damage

Water potential

→ potential enrgy per unit volume in water

• measured in Kilopascals

• water potential is negative or zero (pure water)

• water potential = solute potential + pressure potential

• pressure potential = turgor pressure → generally positive in plants expect in xylem vessle

• solute potential - how much solute present. pure water = 0. Its always zero or negative

Water potentail and movement of water in a plant placed in a hypertonic solution

• outside lower solute potnetail (more negative) hence lower water potential then inside plant

• water moves out of the plant causing a decreased pressure potential

Water potentail and movement of water in a plant placed in a hypotonic solution

• lower solute potential in the plant hence lower water potentail

• water moves into the plant

• pressure potentail increases

• until the inside and environemnt have equal water potential