Question 1

Which of the following best describes the primary function of tight junctions in epithelial tissue?

Accepted Answer

They seal adjacent cells together to prevent the passage of molecules between them.

Question 2

A patient presents with woolly hair and progressive heart disease. Genetic analysis reveals mutations in plakoglobin and desmoplakin. Which cell structure is most likely affected?

Accepted Answer

Desmosomes

Question 3

Which of the following cell adhesion molecules is calcium-dependent and plays a critical role in embryonic development and tissue formation?

Accepted Answer

E-cadherin

Question 4

Which extracellular matrix protein is primarily responsible for providing tensile strength to tissues?

Accepted Answer

Collagen

Question 5

A mutation in which protein would most likely result in muscular dystrophy due to defects in the basal lamina?

Accepted Answer

Laminin

Question 6

Which of the following best explains why glycosylation is important for selectin function?

Accepted Answer

It enables selectins to interact with glycoproteins on other cells.

Question 7

Which of the following is a correct pairing of a cell junction and its associated cytoskeletal element?

Accepted Answer

Focal adhesion – actin microfilaments

Question 8

Which of the following statements about integrins is TRUE?

Accepted Answer

Integrins connect the extracellular matrix to the cytoskeleton.

Question 9

A researcher is studying a disease characterized by hypermobility and stretchy skin. Which extracellular matrix protein is most likely defective?

Accepted Answer

Collagen

Question 10

Which of the following best describes the role of fibronectin in wound healing?

Accepted Answer

It binds fibrin and helps platelets attach during clot formation.

Question 11

Which of the following equations best represents the relationship between the number of cell junctions ($$J$$), the number of cells ($$n$$), and the average number of junctions per cell ($$k) in a $$simple epithelial sheet?

Accepted Answer

$$J = \frac{n 	imes k}{2}$$

Question 12

Which of the following scenarios best illustrates the importance of cell adhesion molecules in infection?

Accepted Answer

A virus uses integrins to bind to the host cell and initiate endocytosis.

Question 13

Which of the following is a key difference between homotypic and heterotypic cell adhesion?

Accepted Answer

Homotypic adhesion involves the same adhesion molecule on both cells, while heterotypic adhesion involves different molecules.

Question 14

Which of the following best explains why loss of E-cadherin expression is often associated with cancer progression?

Accepted Answer

E-cadherin loss reduces cell-cell adhesion, allowing cells to detach and invade other tissues.

Question 15

Which of the following best describes the function of claudins in tight junctions?

Accepted Answer

They provide selectivity for cations and regulate paracellular transport.

Question 16

A patient with Ehlers-Danlos syndrome is found to have defects in collagen types I and III. Which of the following symptoms is most likely to be observed?

Accepted Answer

Hypermobility and fragile skin

Question 17

Which of the following best describes the role of elastin in connective tissue?

Accepted Answer

It allows tissues to return to their original shape after stretching.

Question 18

Which of the following is a consequence of increased collagen crosslinking with age?

Accepted Answer

Increased tissue stiffness and decreased flexibility

Question 19

Which of the following best explains why mutations in NCAM can lead to mental retardation?

Accepted Answer

NCAM is involved in neuronal development and growth, affecting synaptic connections.

Question 20

Which of the following best describes the function of gap junctions in animal cells?

Accepted Answer

They allow the exchange of ions and small molecules between adjacent cells.

Cell Junctions and Extracellular Structures: Structure, Function, and Disease

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