Final answer:
Molecules move between the nucleus and the cytoplasm primarily through the nuclear pores.
Step-by-step explanation:
Molecules move between the nucleus and the cytoplasm through nuclear pores. The nuclear envelope, which houses these pores, controls the passage of ions, molecules, and RNA between the nucleoplasm and the cytoplasm, effectively acting as a gateway that regulates traffic in and out of the nucleus. It's worth mentioning that while vesicle transport such as endocytosis and exocytosis is crucial for moving macromolecules across the plasma membrane, it does not directly involve transport into or out of the nucleus. Instead, active transport processes, facilitated diffusion, and simple diffusion predominantly operate across the plasma membrane for different substances, each with its own specificity depending on factors like molecule size, polarity, and concentration gradients.