22. Which one of the following is a type of intercellular junction in animal cells?
    (1) Middle lamella (2) Plasmodesmata
    (3) Desmosomes (4) Glycocalyx

The correct answer is (3) Desmosomes, which are a type of intercellular junction found in animal cells. Desmosomes act like spot welds between adjacent cells, particularly epithelial cells, providing mechanical strength by anchoring intermediate filaments to the plasma membrane and connecting neighboring cells.​

• (1) Middle lamella is found in plant cells, acting as a cementing layer between adjacent plant cell walls.

• (2) Plasmodesmata are channels between plant cells for cytoplasmic communication.

• (4) Glycocalyx is a cell surface coating of carbohydrates, not a junction.

Overview: Types of Cell Junctions

Animal cells connect and communicate primarily via three junction types:

• Tight junctions: Seal adjacent cells tightly to prevent leakage.

• Gap junctions: Channels allowing molecule exchange.

• Desmosomes: Strong adhesion sites linking intermediate filaments of neighboring cells.​

Desmosomes: Structure and Function

Desmosomes resemble spot welds, holding cells together under mechanical stress. They use cadherin proteins to span the intercellular space and link to intracellular intermediate filaments, securing tissue integrity in skin, heart, and muscle.​

Summary Table

Conclusion

Desmosomes are the correct intercellular junction type for animal cells among the options, critical for maintaining mechanical cohesion of tissues