Biology Diffusion Osmosis

Biology : Diffusion, Osmosis
particles
random motion
achieve even spacing
Diffusion
passive movement of particles from
an area of high concentration to an
area of low concentration
gradual movement : lots to fewer
natural tendency to spread out
liquids & gases
particles free to move
different gasses diffuse
smell
across membranes
small molecules
diffuse
glucose
amino acids
water
oxygen
membrane
holds cell together
allow stuff in & out
diffusion
osmosis
high to low concentration
go both ways through membrane
net overall flow high to low
stops big molecules
starch
protein
rate of diffusion
distance
less = quicker
concentration difference (gradient)
more particle on one side = quicker
surface area
greater = faster
Osmosis
movement of water molecules
across a partially permeable membrane
from a region of high water concentration
to a region of low water concentration
partially permeable membrane
very small holes
allows tiny molecules through
water
large molecules stopped
sucrose
water
pass both ways
random
steady net flow
into region of fewer water molecules
evens up water concentration
into stronger sugar solution
gets more dilute
type of diffusion
water in and out of cells
Tissue fluid
surrounds cells
contains
water
glucose
dissolved stuff
squeezed out of blood capillaries
cell / tissue fluid concentrations
different
outside more dilute
cell short on water
water into cell
cell dilute (lots water)
water drawn out of cell
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