Essential amino acids cannot be made by the body. As a result, they must come from food. The 9 essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
They gives us oxygen, they store carbon for us, and they provide materials for tools and shelter for us.
Viruses are not living organisms because they lack the ability to produce.
<span> species, genus, phylum</span>
