Question

multiple choice question
an extracellular junction that forms an impermeable barrier is called a(n)
tight junction
gap junction
adhesion junction

Explanation:

Tight junctions seal adjacent epithelial cells in a narrow band just beneath their apical surface. They limit the passage of molecules and ions through the space between cells, forming an impermeable barrier. Gap junctions allow for the direct passage of small molecules and electrical signals between cells, and adhesion junctions mainly function in cell - cell adhesion and maintaining tissue integrity, not in forming impermeable barriers.

Answer:

tight junction