Endotoxins are (select all that apply) Are often synthesized in an inactive form Part of the Gram-negative cell wall. Converted to toxoids for vaccine use. They are less potent than exotoxins. Produced by Gram-positive bacteria. Excreted from the cell. Lethal in small quantities. Composed of proteins. Destroyed by heat. Are made up of two subunits, A and B, where B specifically binds to the cell receptor. Etiology is the term used by microbiologists to describe the underlying cause of a disease.