Answer:
The best answer is R group. An R - group is a chemical group or side chain that is found attached to the central carbon in amino acids
Explanation:
Reaction. I hope this helped have a great day.
Well, it's obvious, because without a transport system, cells wouldn't have the nutrients and things they needed!! And waste wouldn't be able to circulate out of cells.
All elements are made of "atoms", and an atom is made up from 3 basic particles: Electrons are particles with a negative charge :)