Final answer:
The correct answer is D) Exotoxins originate internally, endotoxins externally. Exotoxins are proteins produced by pathogenic bacteria and secreted into the surrounding environment, targeting specific host cells. Endotoxins are part of the outer membrane of gram-negative bacteria and are released upon bacterial cell disintegration.
Step-by-step explanation:
The difference in source and origin for exotoxins and endotoxins is that exotoxins originate internally, while endotoxins originate externally in relation to the bacterial cell. Exotoxins are protein molecules that are produced internally by a variety of pathogenic bacteria, with many being produced by gram-positive pathogens, though some gram-negative pathogens also produce them. These toxins are secreted by the bacteria and have specific targets in the host cells they interact with. On the other hand, endotoxins are part of the outer membrane of gram-negative bacteria and are associated with the lipid A component of the lipopolysaccharide (LPS). Endotoxins are released when the bacteria die and the cell wall breaks apart. Thus, the correct answer to the student's question would be 'D) Exotoxins originate internally, endotoxins externally'.