Methods of Transport in Cells :car: (Osmosis (What is a pertially…
Methods of Transport in Cells :car:
root hair cells
Mineral ions and water
) and in the gut (
absorbing nutrients into the blood stream
Acitve transport uses energy, unlike osmosis and diffusion!
Definition from CGP GCSE Biology Revision Guide:
"Diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration"
Happens in both
solutions and gasses
free to move
in these substances.
The process is
move around faster
because there is
causing an increase in the speed of the process.
Diagram of diffusion happening to a dye in water
"The bigger the concentration gradient (the difference in concentration), the faster the diffusion rate. A higher temperature will also give a faster diffusion rate because the particles have more energy, so move around faster."
Definition from CGP GCSE Biology Revision Guide
"Osmosis is the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration"
What is a
membrane I hear you ask?
A partially permeable membrane is a membrane with
very tiny holes
only small molecules
can pass through
Sugar molecules cannot pass through
because they are
. This is what makes it so useful for its perpose of osmosis.
Diagram demonstrating osmosis
If there are two liquids of exactly the same amount: a concentrated water and sugar solution, and clear water, naturally there are less water molecules in the sugar solution, because the sucrose molecules take up some of the space.
When a semi permeable membrane is placed in between these two substances, the
net movement of water molecules
is in the direcection of where there are less of them... in the sucrose solution. This is because the water molecules try to create an equilibrium of the number of molecules on both sides.
:star: This may sound tricky, but it is actually quite simple. look at the diagram link above :star:
:warning: Water molecules move in both directions because they are RANDOM. So you have to talk about the net flow or net movement of water molecules when talking abou the direction the travel in!