Diffusion, Osmosis And Active Transport

Notes on diffusion, osmosis and active transport for GCSE science double award, maintenance of life module

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Diffusion
02/05/20
06
Diffusion is when something travels from an area of high
concentration to an area of low concentration. For example,
consider the scent from a hamburger...
The "scent particles" from
this hamburger are in high
concentration here:
Eventually they will
"diffuse" out into this area
of low concentration:

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Osmosis
02/05/20
06
Osmosis is a "special kind of diffusion". It's when water diffuses from a
concentrated area to a less concentrated area through a partially
permeable membrane (i.e. one that allows water to move through but not
anything else):
Water Sugar solution
In this example the water
molecules will move from left
to right (along the
concentration gradient) and
gradually dilute the sugar
solution.…read more

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Strong
sugar
solution
Potato cells
Medium
sugar
solution
Weak
sugar
solution…read more

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Active Transport
02/05/20
06
Active transport is when substances are absorbed _______ a
concentration gradient (like a ball being rolled ___ a hill).
This takes place in the opposite direction to normal _______.
This is how nitrates are taken in by root hair cells:
Root hair cell Root hair
already has a large cells "pull"
concentration of more nitrate
nitrate ions ions in
This process needs ________ (just like rolling a ball up a hill
would). This energy is provided by __________.…read more

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