Chapter 3 movement of substances 2011

Chapter 3- Movement of substances

Chapter 3- Movement of substances

Kinetic Particle Theory

The kinetic particle theory states that

all matter is made up of in particles and that

these particles are in constant, random motion.

Diagram

Move about at great speeds

Slide over each other

Vibrate and rotate about a fixed position

Movement of particles

Far apartRandom

Close together Random

Close togetherRegular pattern

Arrangement of particles

GasLiquidSolidState

very weakstrongvery strongAttractive forces between particles

highlowvery lowKinetic energy of particles

GasLiquidSolidState

http://www.phschool.com/science/biology_place/labbench/lab1/intro.html

Explaining of key concepts with quiz and experiments to try.

http://www.nottingham.ac.uk/nursing/sonet/rlos/science/osmosis/index.html

Animations with narration

Some websites to explore… …







Diffusion-Examples Getting a whiff of KFC before

you step into the restaurant

Watching purple ribena slowly ‘colouring’ the glass of water

What will happen to the Lemon fragrance molecules after a few seconds? What region has a higher concentration of

lemon molecules?Lemon fragrance molecules

Starting point

Spraying lemon air freshner in a room

Describing what you have seen…

The 20 lemon fragrance molecules spreads out from the starting point of spraying until they are evenly spread in the room.

There is a higher concentration of lemon fragrance molecules from the point of spraying compared to the surroundings of a room.

This creates a concentration gradient between the two regions

Describing the process of DIFFUSIONDescribing the process of DIFFUSION

Difference in concentration between two regions is called

Region A Region B

Molecules (possess kinetic/movement energy) moving down a concentration gradient

Describing the process of DIFFUSION…

The 20 lemon fragrance molecules (possess kinetic energy as they are in random motion)

diffuse from a region of higher concentration

to a region of lower concentration, that is, down a concentration gradient until an equilibrium is reached.

When the lemon fragrance molecules are evenly spread, there is no net change in the system.

This is known as dynamic equilibrium

But does this mean that the lemon fragrance

molecules have stopped moving….?

Describing the process of DIFFUSION…

NOThe gas particles are still moving about as

they are always in constant and random

motion. [Kinetic Particle Theory]

Diffusion of red dye particlesDiffusion of red dye particles

http://rds.yahoo.com/_ylt=A0S020rc64JHmRABViajzbkF/SIG=12pujkgfv/EXP=1199848796/**http%3A//www.biologie.uni-hamburg.de/b-online/library/onlinebio/6_4.jpg

Define the process of DIFFUSION

Diffusion is the net movement ofparticles (atoms, ions or molecules)from a region of higher concentration toa region of lower concentration, i.e.down a concentration gradient.

The steeper the concentration gradient for a substance, the faster the rate of diffusion is for that substance.

20 potassium iodide ions

20 copper sulphate ions

permeable membrane

water

Note that:

• The left side of the beaker contains potassium iodide solution.

• The right side of the beaker contains copper sulphate solution.

Key

Potassium iodide ion

Copper sulphate ion

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Demonstrating Diffusion Across a Demonstrating Diffusion Across a Permeable Membrane Permeable Membrane

A permeable membrane allows solvent & solutes to pass through it.

A permeable membrane allows both the solvent (water) and the solutes (the dissolved substances i.e. potassium iodide and copper sulphate ions) to pass through.

Key

Movement of substances


Demonstrating Diffusion Across a Demonstrating Diffusion Across a Permeable MembranePermeable Membrane






• Even distribution of potassium iodide and copper sulphate ions throughout (Equal concentrations of all ions on both sides of the membrane).

• The net movement of particles (atoms, ions or molecules) from a region where they are of higher concentration to a region where they are of lower concentration, that is, down a concentration gradient, is called diffusion.


Recall concept on “Cell surface membrane” which is

found in all living cells Partially-permeable

membrane that forms a boundary between the cytoplasm of the cell and the outside.

Controls the passage of substances (small molecules) entering and exiting the cell

Diffusion in lungs

The cells of your lungs exchange oxygen and carbon dioxide through diffusion.

Diffusion in root hair cells

Plant cells such as root hair cells also take in oxygen and remove carbon dioxide through diffusion.

How can the rate of diffusion be affected?

1. Temperature Increase in temp. increases rate

2. Size of particles Small sizes diffuse faster than large ones

3. Thickness of the barrier Thicker walls, slower rate

4. Concentration gradient Greater concentration gradient, faster rate

5. Surface area Increase S.A., increase rate

Define osmosis

Osmosis is the movement of water molecules from a solution of higher water potential to a solution of lower water potential across a partially permeable membrane.

8 sucrose molecules

4 sucrose molecules

9 water molecules

18 water molecules

Key

Sucrose molecule

Water molecule

10% sucrose solution 5% sucrose

solution

Note that:

• Arm A contains more sucrose molecules per unit volume than arm B

• Arm A contains fewer water molecules per unit volume than arm B (Arm A has a lower water potential, arm B has a higher water potential).

A B

partially permeable membrane


Demonstrating Osmosis Across a Demonstrating Osmosis Across a Partially Permeable MembranePartially Permeable Membrane

A partially permeable membrane allows small molecules to pass through it.

Water Potential

Water potential is a measure of the tendency of water to move from one place to another.

The more diluted a solution, the higher the water potential.

Water always move from a solution with higher water potential to a solution with a lower one, i.e. down a water potential gradient.

A partially permeable membrane allows selected substances to pass through.

Key

Net movement of water molecules

A B A B



8 sucrose molecules

4 sucrose molecules

18 water molecules

9 water molecules

A B A B A Bdrop in level

rise in level



8 sucrose molecules

4 sucrose molecules

18 water molecules

9 water molecules

• Sucrose molecules cannot diffuse from A to B, water molecules diffuse from B to A.

• Level of solution A rises while B falls.

• The movement of water molecules from a solution of higher water potential to a solution of lower water potential through a partially permeable membrane is called osmosis.

A B A B A Bdrop in level

rise in level



Note: Only applicable to animal systems.Note: Only applicable to animal systems.

What is Hypotonic, Isotonic & Hypertonic?

A (low ) is hypertonic compared to B (high ).

C (high ) is hypotonic compared to B (low ).

low

high

(symbol to represent water potential)

Plant cell

Equal water potential inside and outside cell.

No net movement ofwater molecules

Higher water potential inside cell. Water

molecules move out of cell. Cytoplasm shrinks.

Cell becomes plasmolysed

Higher water potential outside cell. Water

molecules enter cell and exerts pressure on

the cell wall. Cell becomes turgid.

Animal cell

Isotonic soln:Equal water potential

inside and outside cell. No net movement of

water molecules

Hypertonic soln:Higher water potential

inside cell. Water molecules move out of cell.

Cell becomes crenated.

Hypotonic soln:Higher water potential

outside cell. Water molecules enter cell.

Cell bursts!

*Hypertonic, isotonic, hypotonic soln apply to animal systems only

Buzz Activity What happens when living cells require certain

substances that are of higher concentration inside the cell than they are in the external environment?

Active Transport

Active transport is the process in which energy is used to move the particles of a substance against a concentration gradient, that is, from a region of lower concentration to a region of higher concentration.

Energy is released during respiration in living cells.

Active transport in small intestine

Active transport in root hair cells

Calculating Surface Area: Volume Ratio

Cube A:

Sides - 1 cm

C:

Sides - 3 cm

SA 6 cm2 54 cm2

Volume 1 cm3 27 cm3

SA:VR 6:1 2:1

What does SA:VR mean to a What does SA:VR mean to a cell?cell?

Chapter 3 movement of substances 2011

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