Solute vs. Solvent
Solute:
The substance being dissolved

Solvent:
a liquid, gas, or solid capable of dissolving
another substance (Water is the universal
solvent)

Permeable vs. Impermeable



Permeable – substances can pass through
Impermeable – substances cannot pass
through
Semipermeable?
Semipermeable


A membrane that allows only certain
materials to cross it
Materials pass through pores in the
membrane
Diffusion


Movement of
molecules from an
area of high
concentration to an
area of lower
concentration
Example: skunk,
perfume, night after a
dinner at taco bell!
DEMO (Air Freshener)



What molecules moved?
What direction did the molecules move?
Location of molecules in the end?
DEMO (Food coloring)
1.
2.
3.
4.
5.
What molecules moved?
What direction did the molecules move?
Location of molecules in the end?
How did heat effect the movement of the
molecules?
How did cold effect the movement of the
molecules?
Diffusion
Draw a diagram of an example of diffusion
we saw in class.
Draw a diagram of an example of
diffusion we saw in class.
http://gened.emc.maricopa.edu/bio/bio181/
BIOBK/BioBooktransp.html
Factors that affect Diffusion



Temperature
Size of Particles
Concentration of Particles (number of
molecules of a substance in a given
volume )

www.goldiesroom.org/video_archive.htm
Define osmosis


The diffusion of water across a selectively
permeable membrane.
Semipermeable
Define osmosis
 Water
moves from a high
concentration of water
(less salt or sugar dissolved in it)
to a low concentration of water
(more salt or sugar dissolved in it).

This means that water would cross a selectively
permeable membrane from a dilute solution (less
dissolved in it) to a concentrated solution (more
dissolved in it).
Osmosis
A
B


Less saltmore water
→
More saltless water
The diffusion of
Water!
Which way is the
water moving?
 Which side is
higher in water
concentration?
Define osmosis
http://www.usd.edu/~bgoodman/Osmos.htm
Types of Solutions



Hypertonic Solution = higher concentration of
water in the cell than outside the cell
Hypotonic Solution = higher concentration of
water outside the cell than inside the cell
Isotonic Solution = equal concentrations of
water inside and outside the cell
Osmosis


Hypotonic Solutions:
contain a low concentration

of solute relative to another
solution (e.g. the cell's
cytoplasm).
When a cell is placed in a
hypotonic solution, the
water diffuses into the cell,
causing the cell to swell and
possibly explode.
http://www.tvdsb.
on.ca/westmin/scie
nce/sbi3a1/cells/os
mosis.htm
Osmosis


Hypertonic Solutions:
contain a high concentration
of solute relative to another
solution (e.g. the cell's
cytoplasm).
When a cell is placed in a
hypertonic solution, the water
diffuses out of the cell,
causing the cell to shrivel.
Osmosis


Isotonic Solutions: contain
the same concentration of
solute as an another solution
(e.g. the cell's cytoplasm).
When a cell is placed in an
isotonic solution, the water
diffuses into and out of the
cell at the same rate. The
fluid that surrounds the body
cells is isotonic.
Osmosis In Blood Cells
Hypotonic
Hypertonic
Define osmosis

In this picture a red blood cell
is put in a glass of distilled
water (all water with no salt or
sugar in it). Because there is a
higher concentration of water
outside the cell, water enters
the cell by OSMOSIS. In this
case too much water enters
and the cell swells to the point
of bursting open. In the end
pieces of cell membrane are
left in the water.
http://www.usd.edu/~bgoodman/Osmos.htm
Types of Solutions


A. Hypotonic
B. Hypertonic
Osmosis in Living Cells
Cellulose in
cell wall
Why are osmosis & diffusion
important?




All living things have certain requirements they
must satisfy in order to remain alive – maintain
homeostasis
These include exchanging gases (usually CO2
and O2), taking in water, minerals, and food,
and eliminating wastes.
These tasks happen at the cellular level.
Molecules move through the cell membrane by
diffusion
Why are osmosis & diffusion
important?
All living things have certain requirements
they must satisfy in order to remain alive.
These include exchanging gases (usually CO2
and O2), taking in water, minerals, and
food, and eliminating wastes.
These tasks ultimately occur at the cellular
level, and require that molecules move
through the membrane that surrounds the
cell.
Osmosis In Plant Cells
Review Osmosis & Diffusion
Here:
http://wappingersschools.org/WJH/t
eachers/science/Jim_Site/asignment
s/cells/diffusionetc/diffusion_osmosis
.html
Classify each osmosis diagram as
hypotonic, hypertonic, or isotonic solution.
A
B
C