Well there are many but the surface of the earth is the material violin one outer core (if that makes sense
I think it is A but not 100% sure. Think of an enzyme like a key unlock the lock is the protein. And to activate getting inside your car or house you have to fit the key into the lock.
Mesophyll is a partí al reaction
A forest ecosystem can support a limited number of bears. This is because available energy is lost from one trophic level to the next. (flies, trout, then bears)
