Transcript PPT
Osmosis
Diffusion of Water
Biology 11
Ms. Lowrie
Selectively Permeable Membrane
Isotonic Solution
Solute & water
concentration:
Equal inside and outside
cell
Water moves in and out
equally
Dynamic equilibrium
Cell size:
Stays the same
= solute
Hypotonic Solution
Solute concentration:
Higher INSIDE cell
Water concentration
Higher OUTSIDE cell
Water moves INTO cell
Cell size:
Grows
Think: hypo = hippo!
= solute
Hypertonic Solution
Solute concentration:
Higher OUTSIDE cell
Water concentration
Higher INSIDE cell
Water moves OUT OF cell
Cell size:
Shrinks
Think: hyper = sweat
= solute
Osmosis in Plant Cells
Turgor pressure
A type of water pressure
Applies only to plant cells
When is a plant rigid or
wilted?
Depends on water level in
vacuoles
Turgor Pressure
When high:
Vacuole(s) full
Pushes cytoplasm
against cell wall
Keeps plants rigid
Hypotonic
When low (due to
water loss):
Vacuole(s) shrink
Cytoplasm and cell
membrane pull
away from cell wall
Plant wilts
Hypertonic OR
isotonic
Dangerous Water Movement!
Animal
Hypotonic solution
May burst
“Lysed”
Plant
Hypertonic
Cell membrane
pulls away from cell
wall
“Plasmolysis”
Extra Questions
1. What determines whether water will
enter or leave a cell?
Concentration of solutes or water
2. Why will a goldfish die if it is placed in
salt water?
Hypertonic situation
Goldfish cells will give off water
Any Questions???
Let’s review!