ch5 - osmosis

what is a solution

mixture made up of a solute (e.g. glucose), dissolved in a solvent (e.g. water)

What does water potential mean

pressure exerted by water molecules against a membrane (or container)

What symbol and unit is used for water potential

symbol - Ψ

unit measured in - kiloPascals (kPa)

What is the water potential of pure water

0 kPa

What happens to water potential when solutes dissolve in water

decreases/ the value for water potential becomes more negative as more solutes dissolve in water 

What does high water potential mean

solution has a high water concentration/ little solute dissolved in it

What does low water potential mean

solution has a low water concentration/ lots of solute dissolved in it

What is osmosis

net movement of water molecules down a water potential gradient (from area high water pot. to area of lower water pot.) across a partially permeable membrane until equilibrium is reached 

Is osmosis a passive or active process

passive process as it does not require added energy in the form of ATP hence molecules move due to kinetic energy

What is an isotonic solution

when water potential is the same in the solution and inside the cell hence there is no net movement of water into or out of the cell 

In isotonic solutions what happens to animal cells and plant cells

animal cells = stays the same size

plant cells = stays the same size

What is a hypotonic solution

when there is higher water potential outside the cell hence water molecules move into the cell

In hypotonic solutions what happens to animal cells and plant cells

animal cells = swell and burst 

plant cells = swell becoming turgid

Why do plant cells not burst in hypotonic solutions

Because plant cells have cell wall 

What is a hypertonic solution

when there is a lower water potential outside the cell hence water molecules move out the cell

In hypertonic solutions what happens to animal cells and plant cells

animal cells = shrink (crenation)

plant cells = shrink and become flaccid (plasmolysis)