Answer:
Villus, plural villi, in anatomy any of the small, slender, vascular projections that increase the surface area of a membrane. ... The villi of the small intestine project into the intestinal cavity, greatly increasing the surface area for food absorption and adding digestive secretions.
The ER comes in two different morphological forms: smooth ER and rough ER
The first step begins with: A. the mouth.
Any light that exist was already emitted from somewhere. Any light that is absorbed, is destroyed, and is not emitted light; though, it may lead to light being emitted.