Enzymes are proteins
protein synthesis ocurs in the ribosomes
By definition: Facilitated diffusion<span> is the process of spontaneous passive transport of molecules or ions across a cell's membrane via specific transmembrane integral proteins.~Google
An example, the only I can really think of:
Polar and large molecules normally can't cross the lipid bi layer using simple diffusion, it usually has to be </span>Facilitated diffusion
Density-Dependent Factors. Which is a limiting factor that depends on population size.
I would have to say the second stage of life
