The closer the shape of something is
to a perfect sphere, the more
effective the diffusion.
A larger surface
area to volume
ratio will allow
faster diffusion
rate.
Adaptations
Small intestine in mammals: has
a large surface area to allow
materials to transfer faster.
In small intestine, active transport is required to transfer
glucose to the villi, which go to the bloodstream and
transported around the body.
Gills in fish: only work when water is forced
across the membrane, by active transport.
Roots and leaves in plants: have a large surface area to
allow materials to transfer faster.
Root hair cells have a high surface area to allow diffusion to
happen faster.
Osmosis
Movement of water particles
Goes High to low concentration
Through a
semipermeable
membrane
Practical
Measure out 10 cm3 of the 1 M sugar solution and place into the first boiling tube (labelled 1 M sugar). Measure out 10 cm3
of 0.75 M sugar solution and place into the second boiling tube (labelled 0.75 M sugar). Repeat step 1 with 0.5M sugar, 0.25M
sugar and water so all 5 boiling tubes are filled with 10 cm3 solution. Using a cork borer, cut three potato cylinders of the
same diameter. Trim the cylinders so that they are all the same length. Accurately measure and record the length and mass
of each potato and record them in a table. Add one potato cylinder to each tube. Leave the potato cylinders in the boiling
tubes for a known time in the test tube rack. Remove the cylinders from the boiling tubes and carefully blot them dry with
the paper towels. Re-measure the length and mass of each cylinder.
Active Transport
Particles move from low concentration to high
concentration.