The farther layers of earths crust
The vertebrate endoskeleton is internal while an arthropod's exoskeleton is not
One consequence of CFCS pollution is increased rates of skin cancer in humans.
Cholofluorocarbons cause the breakdown of the ozone layer that protects the earth from the sun's ultraviolet radiation. Once in the atmosphere, CFCs drift slowly upward to the stratosphere, where they are brojken up by ultraviolet radiation, releasing the chlorine that catalytically destroys ozone.
Humans get amino acids from protiens in the food we eat. As we digest the food, the enzymes in our stomach and small intestines break down proteins into small amino acids. So technically, we do not make amino acids, we get amino acids from eating food high in protiens.