1.3 Osmosis Flashcards
what is osmosis
the diffusion of water across a membrane
define osmosis
The net movement of water molecules from a higher conc (of water) to a lower conc (of water), across a selectively permeable membrane, until equilibrium
what is the general water potential(Ψ) rule
water always moves from a high to low water potential.
What is the water potential(Ψ) of 100% pure water
Ψ = 0
(0 is the highest Ψ possible)
as an estimate, give the Ψ(kPa) of:
1. pure water
2. dilute solution
3. concentrated solution
- 0 kPa
- -200 kPa
- -500kPa
define: isotonic solution
a solution of equal solute concentration to a cell
define: hypertonic solution
a solution of higher solute concentration than a cell
define: hypotonic solution
a solution of lower solute concentration than a cell
effects of hypotonic solution on animal cell
- water enters
- cell swells and may lyse(burst)
effects of hypotonic solution on plant cell
- water enters
- cell swells and becomes turgid
effects of isotonic solution on animal cell
- no net movement of water
- cell normal size
effects of isotonic solution on plant cell
- no net movement of water
- cell normal size
effects of hypertonic solution on animal cell
- water leaves
- cell shrinks and CRENATES
what is it called when a cell shrinks in an ANIMAL CELL
crenation
effects of hypertonic solution on plant cell
- water leaves
- cytoplasm shrinks and PLASMOLYSES
(therefore flaccid)
what is it called when a PLANT CELL membrane shrinks away from its cell wall
Plasmolysis.
how do protoctistans such as amoeba which live surrounded by a HYPOTONIC solution prevent swelling or lyse?
expel water using contractile vacuoles
how do cells in marine environments which live surrounded by a HYPERTONIC solution reduce water potential?
actively pump ions into cells
how do non-woody plants keep cells hypertonic to the cell to allow osmosis
actively pump ions into cells
how is water potential of the cell calculated
Ψcell = Ψs +Ψp
what does Ψs stand for
solute potentual
(always -ve)
what does Ψp stand for
pressurre potential
(always +ve)
which has the highest water potential:
1. -400
2. -380
3. -360
3
which has the lowest water potential:
1. -400
2. -380
3. -360
1
