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Osmosis Notes
Osmosis
1. The Cell Membrane
a. Cells are not entirely closed off
from their surroundings.
b. The cell membrane has spaces
that allow certain materials like
oxygen, water, and carbon
dioxide to flow through.
c. It is important for these
molecules to go in and out of the
cell so that the cell can stay alive.
H2O
Osmosis
2. How it Works
a. Osmosis occurs when
water crosses over the cell
membrane.
b. Water will move from areas
of high concentration to areas
of low concentration. Does
that sound familiar? You
learned about diffusion in the
unit about particle motion.
c. Osmosis is the diffusion of
water across a cell
membrane.
Diffusion. Notice that the red molecules are
able to move across the membrane. This shows
diffusion.
Osmosis. Notice that the water on the right is
higher than on the left. The water diffused across
the membrane making this an example of
osmosis.
Osmosis
3. How it Works
A simple rule to remember is:
Salt is a solute, when it is concentrated inside or outside the
cell, it will draw the water in its direction. This is also why
you get thirsty after eating something salty.
Osmosis
Take a Look
Click the links below to learn a
little more about osmosis. Try
the practice quiz from the
Animation: How Osmosis Works
link when the video is over.
Animation: How Osmosis Works
Jake Teaches Osmosis
Adding Salt