What gives an atom or ion the most stability
A. a valence shell filled with electrons
B. a valence shell incompletely filled with electrons.

When organisms convert from of energy, what usually results

Adigestive system that is a series of tubes beginning at the mouth and ending at the anus is a digestive system.

Amino acids contain the elements carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. of the 20 amino acids found in humans, 11 are called "nonessential" because they can be manufactured by the body when needed. which elements in these 11 amino acids are commonly obtained from the metabolism of sugar molecules?