Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Junctions are areas between cells that either allow or prevent the movement of materials. Junctions are usually composed of numerous proteins, forming a large molecular complex. Gap junctions, desmosomes and tight junctions are three examples of junctions. Answer: junctions
Output:
What are the areas between cells that either allow or prevent the movement of materials called?