Diffusion

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Diffusion

• Movement of Substances

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Imagine that you are in this situation. Your
mother broke a glass of perfume and you, who is
studying in the same room, gradually begin to
smell the scent of the perfume
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Diffusion

• Definition The net movement of solute particles
  from a region of higher concentration to a region
  of lower concentration, ie, down a concentration
  gradient.
• SI unit mol
• Other unit mass per unit volume

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In pictorial form
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Example of Diffusion

• Drop a piece of copper sulphate crystal into a
  gas jar full of water.
• Cover the jar and allow it to stand still for a
  few days.

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Factors involving rate of diffusion

• Concentration gradient
• Steeper gradient ? faster rate of diffusion
• Temperature
• Higher temperature ? faster rate of diffusion
• Size of particle
• Smaller particles ? faster rate of diffusion

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Factors involving rate of diffusion

• Rate of mixing
• Faster rate of mixing ? faster rate of diffusion

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Quiz Time!
Question 4 Question 3 Question 2 Question 1
Diffusion occurs when particles move from a
region of ___ concentration to a region of ___
concentration.
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Quiz Time!
Question 4 Question 3 Question 2 Question 1
What is a factor involving the rate of diffusion?
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Quiz Time!
Question 4 Question 3 Question 2 Question 1
Diffusion will occur until a ___ is achieved
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Quiz Time!
Question 4 Question 3 Question 2 Question 1
The difference in concentration between two
regions is known as the ___.
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You are wrong.
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Congratulations. You have completed the course on
diffusion!
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Osmosis

• Movement of Substances

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Osmosis

• Definition The net movement of solvent particles
  from a region of higher solvent/water potential
  to a region of lower solvent/water potential
  through a partially permeable membrane
• Water Potential Tendency of water to move down a
  concentration gradient and is measured in Pascals
  (Pa).

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Hypertonic, Isotonic and Hypotonic

• Osmosis

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Hypertonic, Isotonic and Hypotonic

• These terms can only be applied to animal cells
• Hypertonic water potential greater than solute
  concentration (eg. Distilled water)
• Isotonic water potential equal to solute
  concentration
• Hypertonic water potential lesser than solute
  concentration (eg. Honey)

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Effect of animal cell in hypotonic solution
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Effect of animal cell in hypertonic solution

• As the cell is placed in a solution hypertonic to
  its contents, water particles will leave its
  cytoplasm, pass the cell membrane due to osmosis.
• The cell shrinks and little spikes appear on the
  cell surface membrane
• This is known as crenation

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Effect of animal cell in hypertonic solution
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In a nutshell
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Effect of plant cells in solution with higher
water potential
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Effect of plant cells in solution with higher
water potential

• The cell wall is strong relatively inelastic. It
  prevents overexpansion of the cell by exerting an
  opposing pressure as water enters the cell. This
  prevents more water from entering the cell.
• When a plant cell expands, it becomes swollen or
  turgid. The turgidity of the cell with water is
  known as turgor.

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Effect of plant cells in solution with lower
water potential
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Police investigators were called to the scene and
after months of trying, they found john...
Dead... The question is, how did he die?
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What is your conclusion?

• He was placed in a hypertonic solution
• He was placed in a hypotonic solution
• He died from drowning
• His hat suffocated him

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You are wrong

• Head back to try again

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Suspects

• You start to line up the suspects. They are
• Mr I. M. Bottle
• Mr U. R. ? (Last name unknown People speculate
  that his last name is concentrated. Of course,
  another group of people think that his last name
  is mad.)
• Mr T. M. R.

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DM-3
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DM-3
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DM-3
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Suspects

• Who can you safely eliminate from this list of
  suspects
• I. M. Bottle
• U. R. ?.
• T. M. R. (Suspect says I AM VOLDEMORT!!!)

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Enter the LAIR!

• After many hours of investigation, you have found
  out that the killer was Mr. U. R. ?.
• A team of policemen rushed to arrest him
  however

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20 Hours Later
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Oh FINE! The first password is the unit water
potential is measure in, and the second is the
pressure exerted on the cell wall when a plant is
placed in a hypotonic solution
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Enter the LAIR!

• The answer is obviously simple. What is it?
• Pascals Turgid
• Pascals Turgor
• Kilograms Flacid
• Kilograms Turgor

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Meet the battle droids

• Just when you thought you could finally arrest
  him who would come but battle droids!

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Meet the battle droids

• Now what? The only way to defeat them is to yell
  the deactivation command.
• But what is this command?
• You think that it is the process where the
  vacuole of the plant cell shrinks and the
  cytoplasm pulls away from the cell wall the only
  problem is what is it?

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Meetthe battle droids

• Plasmolysis
• Crenation
• Swellation
• Turgor

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Well Done! The killer is apprehanded.