Final answer:
Passive diffusion is the energy-free movement of molecules from higher to lower concentration areas, which occurs for substances like gases and small lipids, but not for larger protein complexes that require active transport to pass through nuclear pores.
Step-by-step explanation:
Passive Diffusion through Nuclear Pores
Passive diffusion is a process where molecules proceed from a region of higher concentration to one of lower concentration without the use of cellular energy. This process is how certain small molecules and gases traverse the nuclear envelope through nuclear pores. Yet, it is important to clarify that the mechanism described in the provided information, which is energy-dependent, does not align with the definition of passive diffusion.
Overall, the nuclear envelope controls the passage of ions, molecules, and RNA between the nucleoplasm and cytoplasm via both passive and active transport methods. Passive diffusion plays a vital role in processes like O2 and CO2 exchange during respiration, but it is not analogous to the active transport of nuclear proteins as outlined in the reference.