Answer:
It is both a barrier keeping unwanted things out, and a gate for nutrients to be brought in.
Answer:
Radical is an atom or a group of atoms of different elements that act as a single unit during chemical reaction.
Explanation:
For example: Hydrogen, Nitrogen,Nitride,Nitrate,Ammonium, etc.
The answer is D. multiple alleles
D because carbon, nitrogen, and oxygen are apart of like everything
