 In
a few sentences write about what you
think would happen to a food factory if
its power were to shut off and there is no
way to get rid of its garbage.
SCIENCE STARTER

Based on your observations and prior knowledge write in your
journal what you think will happen when an egg is put into
vinegar for one day. Give reasons for your hypothesis.

Do the same thing for what would happen for two days?

Will it be destroyed? Will is grow larger, smaller, stay the same
size? Will the egg shell resist the vinegar?

After a couple of minutes you will discuss with your neighbors
and then we will discuss as a group.
EGGSPERT IN DIFFUSION
DIFFUSION & OSMOSIS
SPI 0707.1.5 (Diffusion)
After this lesson you will be able to: Explain
how materials move through simple diffusion.
 Cell
division allows organisms to grow and repair injuries.
 Think
of an organism like a factory. Just like a factory an
organism needs to be able to obtain energy, get
material in, and get rid of waste. So the cells of an
organism performs these functions.
 These
functions keep a cell healthy so they can divide.
CELLULAR GROWTH AND
DIVISION
 So
we know that cells need to get material into them
and also remove waste, but how do they do this?
 By
Diffusion!
The movement of
molecules from an area
in which they are highly
concentrated to an
area in which they are
less concentrated.
WHAT IS DIFFUSION?
DIFFUSION
 molecules
move
from areas of HIGH
concentration to
areas of LOW
concentration
 Diffusion
does NOT
require any energy
BrainPop
DIFFUSION OF WATER
 The
cells or organisms are surrounded by and filled
with fluids that are made mostly of water
 The
diffusion of water is so important to life processes
that it has been given a special name- Osmosis
 Observation
 Hypothesis
– Write in your science journal what you
think will happen to the egg by tomorrow. Will
water diffuse from the vinegar into the egg or will it
diffuse out of the egg into the vinegar? Why?
SCIENCE STARTER
 The
diffusion of water across a
semipermeable membrane.
 Semipermeable
means that only certain
substances can pass through
 Semipermeable
is sometimes called
selectively permeable
 Osmosis
requires NO ENERGY.
OSMOSIS
A
membrane that allows only certain
materials to cross it
 Materials
pass through pores in the
membrane
SELECTIVELY PERMEABLE
OSMOSIS
 WATER
molecules
move from areas of
HIGH concentration
to areas of LOW
concentration
Through
a
membrane!
ONLY
WATER!!!!
Osmosis
 Hypertonic-
a solution
that causes a cell to
shrink because of
Osmosis.
 Hypotonic-
a solution
that causes a cell to
swell because of
Osmosis.
 Isotonic-
a solution that
causes no change in the
size of the cell
OSMOSIS
 In
this picture a red
blood cell is put in a
glass of distilled
water. 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.
EQUILIBRIUM = molecules are evenly distributed
WHEN DO THE MOLECULES
STOP MOVING?
 Diffusion
is the movement of molecules
from an area of higher concentration to
an area of lesser concentration.
 Osmosis is the movement of water thru a
semi permeable membrane.
 Active transport requires energy.
(molecules move from an area of lesser
to higher concentration)
 Passive transport needs NO ENERGY!
(molecules move from an area of higher
to lesser concentration).
SUMMARY
 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
 A balance, or EQUILIBRIUM, must be
maintained.
WHY ARE OSMOSIS &
DIFFUSION IMPORTANT?