KMU Past Paper Practice

Question:

A myocardial biopsy taken shortly after temporary coronary occlusion shows swollen cells with small clear cytoplasmic vacuoles. The plasma membranes remain intact and blood flow is restored promptly. What is the best interpretation of these morphological findings?

Correct Answer: Reversible hydropic cellular change

Explanation: Cellular swelling and cytoplasmic vacuolation with preserved membrane integrity are morphological manifestations of reversible injury.

Question:

During an episode of tissue hypoxia, oxidative phosphorylation decreases. The affected cells initially maintain some ATP production but accumulate acidic metabolic products. Which metabolic pathway is supporting this temporary ATP production?

Correct Answer: Anaerobic glycolysis

Explanation: When oxidative phosphorylation falls, cells temporarily generate ATP through anaerobic glycolysis, with accompanying lactic acid accumulation and reduced intracellular pH.

Question:

A hepatocyte subjected to prolonged metabolic stress develops progressive mitochondrial damage. Which cellular consequence most directly links this organelle injury with failure of energy-dependent cellular functions?

Correct Answer: Reduced ATP generation

Explanation: Mitochondria generate ATP by oxidative phosphorylation; their dysfunction therefore compromises ATP-dependent pumps and other energy-requiring cellular processes.

Question:

After exposure to an oxidizing chemical, hepatocytes show abnormal enzyme activity, altered structural proteins and damaged genetic material. Which common mechanism can account for injury to all three cellular targets?

Correct Answer: Reactive oxygen species activity

Explanation: Reactive oxygen species can modify proteins and damage DNA in addition to causing lipid peroxidation of cellular membranes.

Question:

A skeletal muscle cell exposed to a mild physical injury temporarily loses specialized function. Microscopy shows organelle swelling without major membrane disruption. Which outcome is most likely if the damaging stimulus is promptly removed?

Correct Answer: Restoration of normal cellular function

Explanation: Mild injury with organelle swelling but preserved critical membranes remains reversible, allowing recovery after removal of the stimulus.

Question:

Following severe cellular injury, the plasma membrane loses its ability to maintain normal ionic gradients. Sodium and calcium enter the cell while intracellular constituents begin to escape. Which function of the membrane has been critically compromised?

Correct Answer: Maintenance of selective permeability

Explanation: Plasma membrane integrity maintains ionic gradients and retains cellular contents; severe disruption causes uncontrolled ion movement and leakage.

Question:

A patient develops tissue hypoxia despite continued tissue perfusion. The affected cells receive metabolic substrates and retain removal of waste products during the early phase. Which feature distinguishes this situation from arterial ischemia?

Correct Answer: Blood flow to tissue is preserved

Explanation: Hypoxia refers to inadequate oxygen availability, whereas ischemia results from reduced blood flow and therefore also compromises substrate delivery and waste removal.

Question:

A tissue sample exposed to an injurious stimulus shows structural abnormalities on microscopic examination. The pathologist records the distribution and cellular appearance of these changes without addressing their cause. Which component of disease is primarily being documented?

Correct Answer: Morphology

Explanation: Morphology describes the structural alterations produced by disease, including changes visible grossly or microscopically.

Question:

A child has an inherited defect affecting a cellular enzyme. The abnormal protein alters cellular metabolism and eventually produces tissue dysfunction. In describing the disease, what does the sequence from abnormal protein to tissue dysfunction represent?

Correct Answer: Disease pathogenesis

Explanation: Pathogenesis is the sequence of cellular and tissue events through which an etiological factor produces the manifestations of disease.

Question:

A pathologist examines biopsy specimens to characterize structural abnormalities in diseased tissues, while another laboratory specialist evaluates abnormalities in blood and body fluids. Which pairing correctly describes these areas of pathology?

Correct Answer: Anatomic pathology and clinical pathology

Explanation: Anatomic pathology evaluates structural changes in cells and tissues, whereas clinical pathology evaluates disease through laboratory analysis of blood and other body fluids.

Question:

A cell exposed to prolonged injury can no longer maintain normal mitochondrial function. At the same time, plasma and organelle membranes develop severe structural defects. What is the most important implication of these combined findings?

Correct Answer: The cell has entered irreversible injury

Explanation: Persistent mitochondrial failure together with severe membrane damage represents the critical transition beyond which cellular recovery is no longer possible.

Question:

A cell under nutritional stress begins enclosing portions of its own cytoplasm and organelles within membrane-bound structures for subsequent lysosomal degradation. Which advantage does this response provide to the stressed cell?

Correct Answer: Recycles intracellular constituents for reuse

Explanation: Autophagy removes unnecessary or damaged intracellular material and permits recycling of degradation products during cellular stress.

Question:

At an inflammatory site, a macrophage surrounds a large fragment of damaged tissue and encloses it within a membrane-bound intracellular compartment. Which process describes the initial cellular uptake of this material?

Correct Answer: Phagocytosis

Explanation: Phagocytosis is the uptake of large extracellular particles; their later digestion after lysosomal fusion constitutes heterophagic processing.

Question:

A cell internalizes material from its surrounding environment by invagination of the plasma membrane and formation of intracellular vesicles. Both fluid-phase uptake and uptake of larger particles are examples of which broader cellular process?

Correct Answer: Endocytosis

Explanation: Endocytosis is the general process by which extracellular material is internalized into membrane-bound vesicles; pinocytosis and phagocytosis are specialized forms.

Question:

A macrophage has already internalized extracellular cellular debris. The resulting vesicle fuses with a lysosome containing hydrolytic enzymes. What is the principal function of this fusion?

Correct Answer: Degrade the engulfed material

Explanation: Lysosomal hydrolytic enzymes digest externally derived material after vesicle-lysosome fusion, completing the degradative component of heterophagy.

Question:

Two groups of hepatocytes are exposed to the same chemical for different durations. Cells exposed briefly recover, whereas prolonged exposure produces extensive structural damage. Which principle best explains this difference despite exposure to the same agent?

Correct Answer: Duration modifies the severity of cellular damage

Explanation: Cellular outcome depends not only on the nature of the insult but also on its severity and duration; prolonged exposure can convert reversible injury into irreversible damage.

Question:

A toxin causes mitochondrial dysfunction in a population of cells. ATP concentration falls progressively. Which cellular process is expected to become impaired because it directly requires ATP to maintain normal intracellular ionic composition?

Correct Answer: Membrane ion pumping

Explanation: ATP-dependent membrane pumps maintain normal sodium, potassium and calcium gradients; ATP depletion therefore disrupts intracellular ionic homeostasis.

Question:

Following restoration of circulation to an ischemic tissue, reactive oxygen species increase rapidly. Which combination of cellular targets is most vulnerable to this oxidative injury?

Correct Answer: Membrane lipids, proteins and DNA

Explanation: Reactive oxygen species cause lipid peroxidation, protein modification and DNA damage, making these three major targets of oxidative injury.

Question:

A drug is secreted into bile and reaches the intestine. Part of the substance is subsequently reabsorbed and returns to the liver through portal blood. Which pharmacological consequence can result from repeated cycling through this pathway?

Correct Answer: Prolongation of drug persistence in the body

Explanation: Enterohepatic circulation permits intestinal reabsorption after biliary secretion, delaying complete elimination and potentially prolonging drug effects.

Question:

A substance synthesized by the liver is secreted into bile, enters the intestine, and is largely returned to the liver after intestinal absorption. Which physiological substance best illustrates the importance of this recycling mechanism?

Correct Answer: Bile acids

Explanation: Bile acids are a physiological example of enterohepatic circulation, undergoing biliary secretion, intestinal reabsorption and return to the liver.