I hope ya'll are paying attention, here we go.
So the four things we need to cover are simple diffusion, facilitated diffusion, osmosis, and active transport.
Simple
Diffusion is basically the movement of a substance across a membrane on its own. It moves from a higher
concentration to a lower concentration. Think about when you start to smell perfume from accross the room and you look around wondering who sprayed it. The perfume wasn't sprayed anywhere near you but it reaches you because of diffusion.
Facilitated
Diffusion still moves from a high concentration to a low concentration across the membrane but it needs a little help from protiens to due so.
Osmosis is just diffusion specifically for water.
Active
Transport moves from a low
concentration to a high concentration (the opposite way of diffusion). It requires energy to make the transport pssible. Energy is required to move the substance against the
concentration.
(ATP=energy)