Simple diffusion is the process by which a substance moves across a cell membrane from an area of high concentration to an area of low concentration. Substances that move by simple diffusion are able to diffuse directly across the phospholipid bilayer of the cell membrane. These substances are generally small and neutral, as large or charged particles cannot cross the phospholipid bilayer. Some examples of molecules that move by simple diffusion are carbon dioxide and oxygen.
Facilitated diffusion is the process by which a substance moves across a cell membrane from an area of high concentration to an area of low concentration with the aid of a membrane protein. Substances that move by facilitated diffusion are not able to diffuse directly across the phospholipid bilayer of the cell membrane. These substances are generally large and/or charged. They therefore travel through a protein channel in the cell membrane along their concentration gradient. Some examples of substances that can move by facilitated diffusion are glucose, sodium ions and chloride ions.
The similarities between facilitated diffusion and simple diffusion are:
They both involve the movement of a substance across a cell membrane along its concentration gradient (from an area of high concentration to an area of low concentration).
They are both examples of passive transport, as neither requires energy from the cell to move the substance across the membrane.
The outer periphery of the inter-vertebral disk is composed of strong fibrous tissue called the Annulus fibrosus. This is a tough circular exterior of the inter-vertebral disc that surrounds the soft inner core, the nucleus pulposus. The outer portion is composed of a ring of ligament fibers that encases the inner core of the disc and securely connects the spinal vertebrae above and below the disc.
Answer: The name must include the genus and species of the new organism. [It must be written in italics with the species name lowercase]
