In: Biology
Compare osmosis, simple diffusion, facilitated diffusion and active transport: A) describe their differences and B) explain when cells have to use each one.
Osmosis: It is the movement of solvent molecules through a semi-permeable membrane from a dilute to a concentrated region. It takes place along the concentration gradient.
Cells use osmosis to maintain the interanl fluid concentration. It can be done by either removing water by exosmosis or taking in water by endosmosis.
Facilitated diffusion: It is a process of
spontanoeus transport of molecules through a membrane by the help
of transmembrane integral proteins. It takes place along the
concentration gradient.
This process is required for the diffusion of large or polar
molecules across the membrane, which normally would not be able to
directly diffuse across the membrane.
Active transport: It is the energy-dependent
movement of ions across a semi-permeable membrane. Enzymes are
required for this process.
Cells perform active transport when they need to transport
molecules against their concentration gradient across a
membrane.