radical
1. (Science: chemistry) An atom or or electrically neutralgroup that has one or more unpaired electrons.
2. (Science: botany) Of leaves, clustered at the base of the stem.
The body is comprised of different elements with hydrogen, oxygen, carbon, and nitrogen as the major four. This tutorial will help you understand the chemical composition of the body. This will come in handy when considering the various interactions between cells and structures. ..