Final answer:
Not all active galaxies have large radio lobes; while this is a feature of some AGNs like radio galaxies, others may not exhibit such structures, making the statement false.
Step-by-step explanation:
The statement 'All active galaxies are observed to have large radio lobes extending from their nuclei' is false. Active galaxies, also known as active galactic nuclei (AGN), are characterized by a significant amount of energy produced in their nuclei. This energy is generated by the accretion of matter onto supermassive black holes, which can indeed lead to the formation of jets and lobes observable in radio waves. However, not all active galaxies exhibit such large radio lobes; it is a characteristic of a subset of AGNs known as radio galaxies. For example, Cygnus A is a prominent radio galaxy with large radio lobes, while other active galaxies might only display jets or even just central energy without large-scale radio structures. Therefore, the presence of large radio lobes is not a universal feature of all active galaxies.