The organic compounds that are structural elements in the cell walls of plants and bacteria are known as

The correct answer is carbohydrates.

Explanation:

The cell walls of bacteria are formed of peptidoglycan, also known as murein. This is constructed from the chains of polysaccharide cross-linked by unusual peptides comprising D-amino acids. However, the cell walls of bacteria are distinct from the cells walls of plants, as, in case of plants, the cell walls are formed of cellulose.  

Both the peptidoglycan and cellulose are the components of carbohydrates.  

a:

by the combination of an unlimited number of elements

thats a little if u want the answer just look it up on google thats what i do haha : )