Advanced Placement (AP) Biology Practice Exam

What structures allow for easy communication between adjacent cells?

1. Cell junctions

2. Desmosomes

3. Gap junctions

4. All of the above

The correct answer is: Cell junctions

Communication between adjacent cells is primarily facilitated by specific structures known as cell junctions. These are specialized connections between cells that enable them to communicate and coordinate their activities. Among these junctions, gap junctions are particularly crucial, as they form channels that allow ions and small molecules to pass directly from one cell to another, facilitating rapid communication. Desmosomes, while important for mechanical stability and adhesion between cells, do not significantly contribute to communication in the way that gap junctions do. They primarily function to resist shear forces and hold cells together, particularly in tissues that experience stretching, such as skin or heart muscle. Therefore, while cell junctions encompass various structures that help in communication and adhesion, gap junctions specifically serve the role of enabling direct communication between cells. The answer focuses on the broader category of cell junctions, which includes both desmosomes and gap junctions, but the primary and most effective structures for facilitating communication are indeed the gap junctions. Thus, while it is accurate to identify cell junctions as facilitating communication, gap junctions are the specific structures that allow for easy transfer of information and materials between adjacent cells.