<prompt> Following grows in the cell free medium except -aRickettsiaM lepraeSyphilisAll  <response>: Ans. is a i.e., Rickettsia; b i.e., M leprae; c i.e., Syphilis Obligate intracellular organisms . To grow in a medium which does not contain cells cell free medium, organism should be capable of ATP synthesis. . Obligate intracellular organisms are not capable of the metabolic pathways for ATP synthesis. . So, these organisms are dependent on the ATP of host cells. . As they require host cell ATP, they can not grow in the media which do not contain cells cell free media. . Such organisms are ? 1. Rickettsiae 2. Viruses 3. Pathogenic treponemes syphillis 4. Chlamydiae 5. M. leprae 