KMU Past Paper Practice

Question:

A pathologist examines a healing surgical wound. The defect has been cleared of necrotic material and now contains proliferating fibroblasts and newly formed vascular channels. Which event should follow to produce a stable mature scar?

Options:

Correct Answer:
Collagen deposition and matrix remodeling

Explanation: After angiogenesis and fibroblast proliferation, extracellular matrix deposition and remodeling convert granulation tissue into a stable collagenous scar.

Question:

Following tissue injury, macrophages accumulate within the wound. Experimental suppression of their repair-related secretory activity results in poor fibroblast recruitment and reduced formation of new vessels. Which function of macrophages has been impaired?

Options:

Correct Answer:
Release of repair-promoting mediators

Explanation: Macrophages coordinate repair by releasing growth factors and cytokines that promote angiogenesis, fibroblast migration, proliferation, and matrix synthesis.

Question:

A healing wound requires simultaneous development of new vessels and expansion of fibroblast populations. Which growth factor is capable of contributing to both fibroblast proliferation and angiogenesis?

Options:

Correct Answer:
FGF

Explanation: FGF supports fibroblast proliferation and also contributes to angiogenesis, allowing coordinated formation of connective tissue and its vascular supply.

Question:

During experimental wound healing, a mediator increases collagen synthesis while simultaneously reducing breakdown of newly deposited extracellular matrix. Which mediator best produces this coordinated fibrogenic response?

Options:

Correct Answer:
TGF-β

Explanation: TGF-β is strongly fibrogenic because it promotes ECM synthesis while reducing matrix degradation, favoring accumulation of collagen during scar formation.

Question:

A researcher blocks a growth-factor receptor on epithelial cells. Both EGF and another mediator can no longer stimulate proliferation of these cells. Which second mediator has most likely lost its effect?

Options:

Correct Answer:
TGF-α

Explanation: TGF-α and EGF both act through the EGF receptor, so receptor blockade prevents the proliferative response to either mediator.

Question:

Cells at the edge of an injured tissue receive a growth signal. Receptor activation is followed by PI3K–AKT signaling, which promotes survival and growth of cells participating in repair. What general principle does this illustrate?

Options:

Correct Answer:
Extracellular signals are converted into intracellular responses

Explanation: Growth-factor binding activates intracellular pathways such as PI3K–AKT, translating an external signal into survival, proliferation, migration, or matrix production.

Question:

A tissue specimen contains a matrix protein that provides elasticity rather than the major tensile strength of collagen. Into which ECM category should this protein be placed?

Options:

Correct Answer:
Fibrous structural proteins

Explanation: Elastin and collagen are fibrous structural proteins of the ECM; elastin provides elasticity, whereas collagen principally provides tensile strength.

Question:

In a healing wound, the extracellular matrix contains molecules that retain water and contribute to tissue resilience while organizing the ground substance around cells. Which group best performs this role?

Options:

Correct Answer:
Proteoglycans and glycosaminoglycans

Explanation: Proteoglycans and glycosaminoglycans form hydrated ground substance and contribute to matrix organization, hydration, and resilience.

Question:

An epithelial surface is injured, but its supporting basement membrane remains intact. Compared with an injury that destroys this framework, which outcome is favored by preservation of the matrix?

Options:

Correct Answer:
Restoration of normal tissue architecture

Explanation: An intact ECM framework provides the structural scaffold needed for organized regeneration; extensive matrix destruction instead favors repair by fibrosis.

Question:

A healing wound contains adequate collagen, but its fibers remain poorly organized. Which phase of repair is primarily defective?

Options:

Correct Answer:
Extracellular matrix remodeling

Explanation: Remodeling reorganizes deposited collagen and other matrix components, allowing the scar to mature and progressively acquire greater mechanical strength.

Question:

During scar maturation, collagen is being deposited while selected matrix components are simultaneously removed. Which relationship is essential for controlled remodeling?

Options:

Correct Answer:
Balance between collagen synthesis and matrix degradation

Explanation: Scar maturation requires controlled matrix synthesis by fibroblasts together with regulated degradation, mainly through the MMP–TIMP system.

Question:

A 30-year-old man has an uncomplicated healing laceration. Several weeks later, the scar has gained strength but remains mechanically weaker than the original uninjured tissue. Which process accounts for the increase in strength during this period?

Options:

Correct Answer:
Collagen reorganization and cross-linking

Explanation: Reorganization and cross-linking of collagen increase scar tensile strength during maturation, although healed tissue does not regain the full strength of uninjured tissue.

Question:

A malnourished patient develops delayed healing after surgery. Dietary assessment shows marked protein deficiency. Which repair process is most directly compromised by this deficiency?

Options:

Correct Answer:
Synthesis of structural matrix proteins

Explanation: Protein deficiency limits the substrates needed for production of collagen and other structural proteins, weakening connective-tissue repair.

Question:

A patient receiving prolonged systemic glucocorticoid therapy undergoes surgery. The wound heals slowly and forms a mechanically weak scar. Which combined effect best explains this finding?

Options:

Correct Answer:
Suppressed inflammation with reduced collagen production

Explanation: Glucocorticoids interfere with repair by suppressing the inflammatory response and reducing collagen synthesis, producing slower and weaker healing.

Question:

Two patients develop raised scars after similar skin injuries. In the first patient, the lesion remains limited to the area of injury. In the second, the lesion progressively grows into surrounding previously uninjured skin. Which abnormality is present in the second patient?

Options:

Correct Answer:
Keloid

Explanation: A keloid represents excessive scar formation that extends beyond the original wound, unlike a hypertrophic scar that remains confined to it.

Question:

A large skin wound develops excessive contraction during healing. The scar crosses a joint and subsequently restricts the range of movement. Which normal repair mechanism has become exaggerated?

Options:

Correct Answer:
Myofibroblast contraction

Explanation: Myofibroblasts normally reduce wound size by contraction; excessive activity produces a contracture that can restrict movement across a joint.

Question:

A patient with a chronic poorly perfused wound develops repeated breakdown of the skin surface rather than formation of a stable scar. Which abnormal outcome of deficient repair best describes this lesion?

Options:

Correct Answer:
Ulceration

Explanation: Deficient repair can result in ulceration when inadequate perfusion or other local factors prevent formation and maintenance of an intact healed surface.

Question:

A wound has developed excessive granulation tissue that projects above the adjacent skin. The wound fails to acquire a complete epithelial covering despite viable epithelial cells at its margins. Which mechanism best explains this failure?

Options:

Correct Answer:
Physical obstruction of epithelial migration

Explanation: Granulation tissue projecting above the wound surface prevents epithelial cells from migrating across the defect, thereby delaying re-epithelialization.

Question:

Newly deposited extracellular matrix in a wound binds growth factors close to the cells participating in repair. If this binding function were lost, which normal ECM role would be most directly impaired?

Options:

Correct Answer:
Maintaining a local reservoir of regulatory molecules

Explanation: The ECM binds and concentrates growth factors near target cells, creating a local reservoir that helps regulate cellular responses during repair.

Question:

A pathologist follows the evolution of a wound from early inflammation to its final appearance. Which sequence best represents successful repair by connective-tissue scar formation?

Options:

Correct Answer:
Inflammation → angiogenesis → fibroblast activity → matrix deposition → remodeling

Explanation: Scar repair proceeds through overlapping phases of inflammation, vascular formation, fibroblast activity, ECM deposition, and remodeling into a mature fibrous scar.