KMU Past Paper Practice

Question:

A 24-year-old man develops an infected wound. Plasma proteins become sequentially activated and ultimately generate a complex capable of producing pores in microbial membranes. Which sequence represents the terminal event responsible for this effect?

Correct Answer: C5b–C9

Explanation: C5b initiates assembly of C6–C9 to form the membrane attack complex, which creates membrane pores and can lyse susceptible microbes.

Question:

A patient develops marked pain and edema following acute tissue injury. A plasma-derived mediator generated through the kinin system is contributing to both findings. Which combination of actions best accounts for the presentation?

Correct Answer: Vasodilatation and increased permeability

Explanation: Bradykinin causes vasodilatation and increased vascular permeability and is also an important mediator of inflammatory pain.

Question:

During acute inflammation, tissue injury activates both plasma coagulation mechanisms and inflammatory pathways. Which statement best explains the relationship between these processes?

Correct Answer: Coagulation products may influence vascular and leukocyte responses

Explanation: Coagulation and inflammation are interconnected; products generated during clotting can influence vascular permeability and leukocyte activity.

Question:

A tissue sample obtained shortly after injury shows dilated arterioles and fluid leakage from small venules. The responsible mediator was stored within granules before the injury occurred. Which cell is the most important source of this mediator?

Correct Answer: Mast cell

Explanation: Mast cells store preformed histamine in granules and rapidly release it after injury, producing arteriolar dilatation and increased venular permeability.

Question:

An inflammatory cell is activated and releases arachidonic acid from its membrane phospholipids. The substrate then enters two major enzymatic pathways. Which pair correctly identifies these pathways?

Correct Answer: Cyclooxygenase and lipoxygenase pathways

Explanation: Arachidonic acid is metabolized through cyclooxygenase to form prostanoids and through lipoxygenase to form leukotrienes.

Question:

A mediator released from activated endothelial cells relaxes vascular smooth muscle. The same mediator can be generated by activated macrophages, where it contributes to microbial destruction. Which substance has these dual functions?

Correct Answer: Nitric oxide

Explanation: Endothelial nitric oxide produces vasodilatation, whereas macrophage-derived nitric oxide can participate in killing microorganisms.

Question:

At an infected site, leukocytes move from the vessel toward progressively higher concentrations of locally produced signaling proteins. These proteins also enhance leukocyte adhesion by activating integrins. Which mediator group is responsible?

Correct Answer: Chemokines

Explanation: Chemokines establish concentration gradients that direct leukocyte migration and also activate leukocyte integrins to promote firm endothelial adhesion.

Question:

A patient with acute inflammation develops endothelial activation that facilitates recruitment of circulating leukocytes. Which pair of macrophage-derived mediators most directly promotes this endothelial response?

Correct Answer: TNF and IL-1

Explanation: TNF and IL-1 activate vascular endothelium and increase adhesion molecule expression, thereby promoting leukocyte recruitment.

Question:

A patient develops a tense blister after a superficial burn. Microscopy shows separation within the superficial tissue by clear fluid containing very few inflammatory cells. Which process best explains this morphology?

Correct Answer: Accumulation of a cell-poor fluid exudate

Explanation: Serous inflammation produces a thin, watery, relatively cell-poor fluid and commonly forms blisters after mild superficial injury.

Question:

A patient with severe acute pericardial inflammation has leakage of large plasma proteins onto the serosal surface. Microscopy shows a dense eosinophilic network. Which event produced this appearance?

Correct Answer: Conversion of fibrinogen into fibrin

Explanation: Severe vascular leakage allows fibrinogen to escape into tissue, where conversion to fibrin produces the eosinophilic network of fibrinous inflammation.

Question:

A 32-year-old man has a localized bacterial infection. Histology shows a central area containing large numbers of neutrophils, liquefied necrotic tissue and edema fluid. Which gross lesion is expected to correspond to these findings?

Correct Answer: Localized abscess

Explanation: A localized collection of pus composed of neutrophils, necrotic debris and edema fluid forms an abscess, a characteristic pattern of suppurative inflammation.

Question:

Biopsy from the base of a long-standing mucosal surface defect shows macrophages, lymphocytes, plasma cells and proliferating fibroblasts. Which feature distinguishes this stage from an early acute lesion at the same site?

Correct Answer: Mononuclear inflammation with fibroblast proliferation

Explanation: A chronic ulcer develops mononuclear inflammatory infiltration and fibroblast proliferation, whereas the acute stage is dominated by neutrophils and vascular changes.

Question:

Following a brief inflammatory episode, vascular permeability returns to normal, inflammatory cells disappear, macrophages remove cellular debris and the tissue regains its original architecture. Which condition most strongly allowed this outcome?

Correct Answer: Limited injury in regenerating tissue

Explanation: Complete resolution is favored when tissue damage is limited, the injurious stimulus is removed and surviving cells can regenerate.

Question:

An inflammatory exudate rich in fibrin persists on a serosal surface rather than being completely removed. Fibroblasts and newly formed vessels subsequently grow into the exudate. Which process is occurring?

Correct Answer: Organization

Explanation: Ingrowth of fibroblasts and vessels into persistent fibrin is organization; this process can convert a fibrinous exudate into fibrous scar tissue.

Question:

A patient has persistent inflammation because the initiating stimulus remains in the tissue. A later biopsy shows mononuclear inflammatory cells together with tissue destruction and attempts at repair. Which outcome of the initial response is represented?

Correct Answer: Progression to chronic inflammation

Explanation: Persistence of the offending stimulus can convert acute inflammation into chronic inflammation characterized by mononuclear cells, tissue injury and repair.

Question:

A child experiences recurrent bacterial infections. Neutrophils reach infected tissues normally and can ingest microorganisms, but laboratory assessment demonstrates reduced complement-dependent coating of microbial surfaces. Which cellular step becomes less efficient as a result?

Correct Answer: Recognition for phagocytosis

Explanation: Complement-dependent opsonization coats microbial surfaces and facilitates their recognition by phagocytes, so defective coating reduces efficient ingestion.

Question:

A patient has an adequate number of circulating neutrophils, but very few reach sites of bacterial infection. The cells show impaired interaction with vascular endothelium despite otherwise normal microbial killing mechanisms. Which consequence is most likely?

Correct Answer: Persistence and spread of infection

Explanation: Defective leukocyte adhesion and migration prevent adequate neutrophil accumulation at infected sites, reducing microbial clearance and allowing infection to persist or spread.

Question:

Neutrophils from a patient with recurrent infections migrate normally and successfully engulf bacteria. However, viable microorganisms remain inside the cells after phagocytosis. Which functional abnormality best accounts for this finding?

Correct Answer: Failure of intracellular microbial killing

Explanation: Normal migration and ingestion with persistence of viable organisms localizes the defect to the intracellular killing stage of phagocyte function.

Question:

A patient mounts a strong neutrophilic response to infection. Microorganisms are eliminated, but adjacent viable tissue is damaged by substances released from activated leukocytes. Which pair is most directly responsible for this collateral injury?

Correct Answer: Reactive oxygen species and lysosomal enzymes

Explanation: ROS and lysosomal enzymes kill microbes but can injure host cells and extracellular matrix when released excessively into surrounding tissue.

Question:

Two patients have comparable tissue infections. One has an inadequate inflammatory response and develops persistent infection with delayed healing. The other clears the infection but develops substantial damage to surrounding normal tissue. Which principle best explains these contrasting outcomes?

Correct Answer: Inflammation requires an appropriately controlled host response

Explanation: Inadequate inflammation permits infection and delays healing, whereas excessive inflammation causes collateral tissue injury; effective defense therefore requires a balanced response.