ICT IN BIOLOGY
DIFFUSION VS
OSMOSIS
YAASHINI A/P SELVARAJAHD20091034837
NATASHA KAUR A/P MINDAR SINGHD20091034839
AMARPREET KAUR A/ GURNAM SINGH D20091034873
KRISNAVIMALA A/P KRISHUAN D20091034821
GROUP MEMBERS
WHAT???
HOW???
DIFFERENCES???
SIMILARITIES????
HOW?
WHATZ TAT???
DIFFERENCES?
Any ideas??
OSMOSIS
OSMOTIC GRADIENT
- Difference in the [ ] of 2
solution EITHER side
semi-permeable membrane
Movement of H2O
molecules- [Higher] to
[lower] region [H2O] =
GRADIENT
Movement across the
semi-permeable membrane until (=) is
reached
when H2O molecules move from hypotonic
solution to a hypertonic solution.
Pressure that applied to solution -Prevent
inward flow of H2O
DIFFUSION
spontaneous or
random movemen
t of molecules
[Higher] to [lower
] solute
Transfer of kinetic
energy(K.E) take place due to the collisions
BETWEEN MOLECULES
K.E brings about a constant motion in
between the molecules
COLLIDING EACH
OTHER
SPEED RATE
dependent on the
K.E of the molecules
COMPARISON
DIF
FE
RE
NC
ES
• Nature of transport ( no membrane required)
• Flow from [higher] to [lower] of solute
• Flow from [lower] to [higher] of solvent
• Between gas molecules, solid-liquid or liquid-gas
• Relatively faster• Can spread over long
distance
• Nature of transport (presence of a semi-permeable membrane)
• Flow from [lower] to [higher] of solute
• Flow from [higher] to [lower] of solvent
• Only between two solvents
• Relatively slower (time-dependant process)
• Is limited to short distances
DIFFUSION OSMOSIS
SIMILARITIES
Occur in living and non-living systems
do not require any
external energy to drive the process
take place along the
concentration
gradient.
Passive transport
Osmosis Concept
1. Water molecules are always moving about
2. Net movement of WATER MOLECULES (Solvent) from a solution of [higher] of water to one with [lower] of water
3. Movement of WATER MOLCULES must be through a PARTIALLY PERMEABLE MEMBRANE
WATER POTENTIAL
Instead of using the word concentration for water…
We use WATER POTENTIAL
- Water potential is the measure of tendency for water to move from one place to another
- Water moves from High Water Potential to Low Water Potential
‘High’ Water Potential
‘Low’ Water Potential
Osmosis Concept (revised)
1. Net movement of WATER MOLECULES (Solvent) from a solution of higher concentration of water to one with lower concentration of water
2. Movement of WATER MOLCULES must be through a PARITALLY PERMEABLE MEMBRANE
water potentialwater potential
Legend Water
molecule
Solute molecule
Container B (Diluted Solute Solution)
66.6% Water Concentration
33.33% Solute Concentration
Container A (Concentrated Solute Solution)
20% Water Concentration
80% Solute Concentration
Partially Permeable Membrane
Remember Diffusion? Net Movement of particles down a concentration gradient from an area of higher concentration to an area of lower concentration!
It’s about the Word Play
Concentrated Solution (Sucrose for example)
Low Water Potential
Low concentration of Solvent
High concentration of Solute
Hypertonic compared to B
Dilute Solution
High Water Potential
High Concentration of Solvent
Low Concentration of Solute
Hypotonic compared to A
A B
80% sucrose
20% water
20% sucrose
80% water
Net
MISCONCEPTIONS
Issue Naive Idea* Scientific Idea
Concentration Students often base their predictions regarding the overall direction of osmosis on the concentration of the solute (e.g., 70% sugar, 20% sugar).
The concentration of water is the factor that determines the overall direction of osmosis, and H2O concentrations are
approximately inversely proportional to solute concentrations (e.g., 30% H2O,
80% H2O).Movement Common solute molecules
such as salt and sugar will diffuse through a semipermeable
membrane.
Only water and other small, neutral molecules (such as oxygen and carbon dioxide) can diffuse across a semipermeable membrane; sugar molecules and salt ions are too large and carry too much charge.
Constraints Osmosis will continue until equilibrium is reached, with equal concentrations of solute on both sides of the semi-permeable membrane.
Osmosis often fails to reach equilibrium levels because of other factors, such as pressure inside a plant cell or atmospheric pressure on a column of water.
Rate Students often miss questions about rate of reaction, presumably because this is rarely emphasized in texts and their mental model of molecular movement is not very robust.
The higher the temperature, the faster the rate of diffusion, all other things being equal.
TO RECALL…
HERE ARE THE ACTIVITIES
Semi-Permeable Membrane
A
10% sucrose solution
B
20% sucrose solution
Solution A is hypertonic solution
Solution B is hypotonic solution
“Osmosis taking place via the uni-direction movement of water molecules from A to B”
Spot the errors!
POE
Semi-Permeable Membrane
A
10% sucrose solution
Solution A is hypertonic
Solution B is hypotonic
“Osmosis taking place via the uni-direction movement of water molecules from A to B”
Spot the errors!
V
V
A
10% sucrose solution
B
20% sucrose solution
1. Semi-permeable membrane (Partially)
2. This is a hypertonic solution (need to be relative to something)
3. Molecules only move from high water potential to low water potential (It’s the net movement, molecules do not stop moving
anyway)
Misconceptions
2 20 drops of vanilla
QUESTION: Will you be able to smell the vanilla that is inside the balloon? Why or why not?
PURPOSE: • Can the students apply the concept of permeability? • Do students believe that a balloon can be semi-
permeable? • Do they believe that its semi-permeability will allow
them to smell the vanilla through the balloon?
TECHNIQUE TO OVERCOME MISCONCEPTION(DEMONSTRATION)
QUESTION: If freshener is sprayed in the front of the classroom, will the students in the back be able to smell it?PURPOSE:•Do the students believe that molecules are constantly in motion? •Do students believe that molecules want to spread out? •Are students aware of the movement of molecules from a high to low concentration?
Tick ( / ) for the picture related to osmosis process and tick ( X ) for the picture related to diffusion process.
Tick ( / ) for the picture related to osmosis process
and tick ( X ) for the picture related to diffusion process
PICTURE QUIZ
ATP ENER
GY
Water
ATP energy
Ink drop in solution
Gas Molecules
Blood cell Isotonic drink
Colour gas
Liquid moleculesGrape jusFish in hypotonic
SEMI-PERMEABLE MEMBRANE
Movement of moleculesMovement of substance
Solid moleculesNo semi-permeable membrane
Perfume
Semi-permeable membrane
Syrup drink
Tonicity
1 2 3
4 5
6 7 8
9 10 11
12
13
14
15
16
17 18
19
20
WO
RD
PU
ZZ
LE
DEFINITION
Down
2.condition achieved when molecules are evenly spread in an area3.when a solution as a greater concentration of particles4.turns color in the presence of starch5.the engulfing of large particles7.prefix that means "outside"9.the diffusion of water11.active transport will remove ___ ions, while taking in potassium ions12.channel ___ can help move things across the membrane16.organelle that helps remove excess water; ______ vacuole18.the outer boundary of the cell
Across1.type of transport that requires energy3.when a solution has a lesser concentration of particles6.type of transport that does not require energy8.prefix that means "inside"10.movement of molecules from high to low concentration13.a molecule composed of two hydrogens and one oxygen14.a solution that has an equal amount of particles15.membranes that let some things through, called selectively ______17.the maintaining of an internal balance19.word that means "cell"20.a difference in concentration creates a concentration ______
THANK YOU-KANY-