Question

which of these cell junctions form a barrier to the passage of materials?
plasmodesmata
keratin fibers
desmosomes (anchoring junctions)
gap (communicating) junctions
tight junctions

part b
the primary role of ______ is to bind animal cells together.
plasmodesmata
gap (communicating) junctions
desmosomes
the cytoskeleton
tight junctions

Explanation:

For the first question, tight junctions seal adjacent epithelial cells in a narrow band just beneath their apical surface, forming a barrier that prevents leakage of materials between cells. Plasmodesmata are channels in plant cells for communication, keratin fibers are related to cell structure and protection, desmosomes are for cell - to - cell adhesion, and gap junctions allow communication between cells. For the second question, desmosomes are cell - to - cell adhesion structures that bind animal cells together. Plasmodesmata are in plant cells, gap junctions are for communication, the cytoskeleton provides structural support, and tight junctions are for forming barriers.

Answer:

Part A: E. tight junctions
Part B: C. desmosomes