1. surface area diffusion and osmosis

Monday 10 April 2023

Surface Area, Diffusion and Osmosis

Welcome back!

Tasks:

1.Holiday homework due on Thursday:1. All Quick Check and Review Qu’s from ch1

IN THE BACK OF YOUR BOOK OR ON PAPER

2. Microscope Practical Write-Up (“Exploring one of the....” from booklet

2.You could begin Ch2 qu’s at home if you want. Due in 3 weeks.


Surface Area, Diffusion and Osmosis

From p31


Surface Area to Volume Ratio

Make 3 cubes from Plastecine:

1x1x1 2x2x2 3x3x3



Cube dimensions

Surface Area / cm2 Volume / cm3

Surface Area to Volume

Ratio (SA/V)

1x1x1 6 1 6

2x2x2 24 8 3

3x3x3 54 27 2

As the volume of the cubes increases, then...



• What does this mean in reality?

• The bigger the object becomes, the less surface area there is available per unit volume


Task

• Complete:– Limitation to cell size: surface area to volume

ratio– From your booklet


Diffusion and Osmosis

• Recap your concept of particles:

• Draw Solid, Liquid and Gas

• Link



• Diffusion



• Diffusion

Evaporation of some particles

(not necessarily at BP)



• Diffusion

As time passes, the particles spread = diffusion



• Diffusion

There is a concentration gradient: particles have moved from an area of high concentration to low concentration



• Diffusion• Link 2

Diffusion = the spreading of particles (liquid or gas) from an area of higher concentration to an area of lower concentration



• Osmosis: diffusion of water in a cell

Cell Membrane

Higher

concentration of water

Lower

concentration of water



• Osmosis: diffusion of water in a cell

Cell Membrane

Lower

concentration of salt

Higher

concentration of salt



Conc of water

X

X

Osmosis = the spreading of water particles from an area of higher water concentration to an area of lower water concentration, or down the concentration gradient

Link 3


Diffusion and Equilibrium


Key Words

• Hypotonic Solution:– Contains more water and less solute (than

another solution)

• Hypertonic Solution– Contains less water and more solute (than

another solution)

• Isotonic Solution– Contains equal concentration of solute (to

another solution)


Osmosis and Equilibrium


Osmosis and Equilibrium in Cells


Answer these questions:

• Read p27-8– Write a definition for these terms:

• Diffusion• Osmosis• Hydrophilic• Lipophilic• Facilitated Diffusion

– Explain what happens to a cell if you put it into

• a Hypertonic Solution• A Hypotonic Solution

1. surface area diffusion and osmosis

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