Transcript Passive Transport + Potato lab

Lesson 10
February 1st, 2011
Review of Passive Transport
Simple Diffusion
 Particles will move from an area of high concentration
to an area of low concentration until equilibrium is
met.
 Facilitated Diffusion
 Channels that allow larger particles to pass across the
membrane
 Osmosis
 the net movement of water across a selectively
permeable membrane from an area of high
concentration to an area of low concentration.
Terms used to describe solutions.
 Solution a homogeneous mixture composed of two or
more substances.
 A solute is dissolved in another substance, known as
a solvent.
 The solvent does the dissolving. Example: Water
 The following terms are used to compare two solutions
separated by a semi-permeable membrane.
 The water moving into or out of the cell is driven by
the osmotic pressure caused by concentration
gradients.
Isotonic solution – a solution of
equal solute concentration
 Equal parts of water move in
and out of the cell.
 The water pressure inside the
cell remains the same.
Hypertonic solution – a
solution that has higher solute
concentration than some other
solution
 Water will move from the area
of low concentration in the cell
to high concentration in the
solution
 The water pressure inside the
cell will decrease.
 Hypotonic solution – a
solution that has a lower solute
concentration than some other
solution.
 Water will move from the low
concentration solution to the
high concentration cell.
 The water pressure in the cell
will increase.
 Under normal conditions, osmosis does not occur into or
out of red blood cells. The cells maintain their normal
size and shape.
 If the solute has a lower concentration of solute than
blood serum (hypotonic solution), it may dilute the blood
serum until it is hypotonic to blood cell cytoplasm.
 If this occurs, osmosis will occur into the red blood cells,
causing the cells to swell and in some cases burst which
can be fatal as the cell can no longer transport oxygen.
This is called hemolysis.
 If the solute has a higher concentration of solute than
blood serum (hypertonic solution), it may concentrate
blood serum until it is hypertonic to blood cell
cytoplasm.
 Osmosis will occur out of the blood cells, causing the
blood cells to become small and scalloped shaped.
This shape is dangerous as the cells tend to stick
together and clog arteries and veins, which prevents
oxygen from reaching tissues. This condition is called
crenation, and may also be fatal.
Osmosis Lab
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1. Read over lab
Make the solutions needed.
Cut up, measure and weigh the potato slices.
Wait a few days
Weigh and measure the potato slices
Answer the questions