Question

Identify the INCORRECT statement

• A. Epithelia are classified by the shape of the epithelial cells in the surface layer
• B. The shape of the cells in the surface layer of transitional epithelia is variable
• C. In pseudostratified epithelia all epithelial cells are in contact with the basement membrane
• D. Desmosomes are an effective barrier to the diffusion of substances across an epithelium

Hint:

Tight junctions prevent diffusion between cells, while desmosomes provide mechanical adhesion.

Answer 1

The Correct Option is D

Step 1: Epithelia are indeed classified based on the shape of cells present in the surface layer, so statement (a) is correct.
Step 2: Transitional epithelium shows variability in the shape of surface cells depending on stretching, so statement (b) is correct.
Step 3: In pseudostratified epithelium, all cells rest on the basement membrane, making statement (c) correct.
Step 4: Desmosomes function mainly in cell-to-cell adhesion and provide mechanical strength, but they do not act as barriers to diffusion. Tight junctions serve that function. Therefore, statement (d) is incorrect.