2.2.6 Diffusion & Osmosis Worksheet 1

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Name: _________________________
2.2.6 Movement of Substances Worksheet
Movement
Substances move in and out of cells in 2 ways
Diffusion
Movement of molecules ________ a region of ____________________________ to a region of
__________ concentration.
Active Transport
Movement of molecules from a less crowded (__________________________) to a more
crowded (______________________________) area WITH the use of energy.
Molecules are “carried" into or out of the cell using some of the cell's energy.
Movement in cells takes place through membranes
All the membranes in a cell act in the same way
Cell membranes – Mitochondrial membranes – Nuclear membranes – Chloroplast membranes
Permeability
Membranes can be
Permeable
– _____________________________________
Semi Permeable
– _____________________________________
Impermeable
– _____________________________________
Diffusion in everyday life

Smell of perfume

______________________

Stink bomb

Food colouring in water

______________________
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Name: _________________________
Osmosis
______________ is the movement of __________ across a semi-permeable membrane from a
region of ________ water concentration to a region of __________ water concentration

Osmosis is a special type of diffusion that
__________________________________

Osmosis is ______________
If pure water is separated from salt water the following occurs:

The __________ molecules move __________ in both
directions

The ________ molecules ____________ move out so
more water moves in to the salt solution

What you have is __________ moving from where there is
a ________ concentration of water to where there is a
__________ concentration of water this is osmosis
Osmosis and Animal Cells

Animal cells are only _____________________________________

If an animal cell is surrounded by a solution that is the ________ concentration as the
_________________ in the cell __________ will move in and out at the same rate and the cell
will ________________________

Many animals that live in the ______ have cytoplasm with a ______________ concentration to
________________

It is the function of our ______________ to make sure the fluid in our bodies that surrounds our
cells (extra cellular fluid) has a ____________ concentration
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Name: _________________________
Animal cells in a less concentrated solution
If an animal cell is in a solution that is ________ concentrated than its cytoplasm (i.e. if there is more
________________________ than ____________ the cell) the water from outside will move into the
cell and may cause it to __________ or die
Amoebas
Animal Cells in a more concentrated solution
If animal cells are in a solution that is ________ concentrated than their cytoplasm (i.e. if there is more
__________ in their cytoplasm than in the __________________________) then the water may leave
the animal cell and the cells _________________ and may die
Shrivelled Animal Cells
Osmosis and Plant Cells
o Plant cells have a ________________ which is surrounded by a ______________
o Cell walls are _____________________________ and will allow all substances in and out of
the cell
o If a plant cell is surrounded by a ________ concentrated solution then water from outside will
move ________ the cytoplasm and vacuole of plant cells
o This is how roots absorb water by ______________
Page 3 of 6
Name: _________________________
Water entering roots by osmosis
The ________ outside is less concentrated than the ________________ in the cytoplasm
Turgor
o When the outside water enters the plant cell the ______________ becomes bigger and the
_________________ swells
o This causes the ________________________ to be pushed out towards the ________________
o When cells are fully “swelled” like this with the membranes pushing against the cell wall they
are described as ____________
Turgid Cells
Turgor pressure
o This turgor pressure gives plants their _______________
o If plants did not have this they would ________
o Plants that don’t have ________ such as ______________ and ______________________ rely
on turgor pressure for strength
Plant cells in a more concentrated solution
If plant cells are surrounded by a ________ concentrated solution (for example if plant cells were
surrounded by __________________) the water inside the cell would move ______ to the more
concentrated solution outside
Page 4 of 6
Name: _________________________
Plasmolysis
o When this happens the cell wall stays ___________ but the membrane ___________________
away from it
o This is called ______________________
o Cells in this condition are called ________________________________ we can look at this
easily by placing a layer of red onion cells in salt water
Plasmolysed red onion cells
Osmosis and Food Preservation
o _______________ and __________ are the most common causes of food spoilage
o Both these cells are enclosed by a ________________
o If a food is placed in a sugary or salty solution then any bacteria or fungi present will ________
_________________________________ to the more concentrated solution outside
o When this happens the cells will _____________________ and the food will not become
contaminated with loads of bacteria and fungi
Examples
o Fish and Meat (bacon) may be stored in a salty solution
o Jams, marmalades and tinned fruits are stored in a sugary solution
Syllabus Can you? ...
 Define the term: Selectively permeable
 Explain the role of selectively permeable membranes.
 Define the terms: osmosis & diffusion
Page 5 of 6
Name: _________________________
 Give examples of diffusion and osmosis.
 Define the term: turgor.
 Explain turgidity in plant cells.
 Describe the application of high salt or sugar concentration in food preservation.
Page 6 of 6
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