Diffusion

The passive movement of molecules from a region of high concentration to a lower conentration

Simple diffusion:

Passive - energy comes from the natural, inbuilt motion of particles rather than ATP

• All particles are constantly in motion due to the kinetic energy that they possess
• The motion is random, with no set pattern to the way the particles move around
• Particles are constantly bouncing off one another as well as off other objects, for example, the sides of the vessel in which they are contained

Facilitated diffusion:

The movement of charged ions and polar molcules is made easier by transmembrane channels and carriers that span the membrane

• Is a passive process
• Relies only on the inbuilt motion (kinetic energy) of the diffusing molecules
• There is no external input of ATP from respiration
• It occurs down a concentration gradient,…