KMU Past Paper Practice

Question:

A 28-year-old woman is examined during late pregnancy. The uterus is markedly enlarged compared with its pre-pregnancy size. The enlargement reflects both an increase in smooth-muscle cell size and hormone-driven proliferation of these cells. Which combination of adaptive responses best explains this finding?

Correct Answer:
Hypertrophy and hyperplasia

Explanation: Pregnancy produces physiological enlargement of uterine smooth muscle through increased cell size and increased cell number under hormonal stimulation.

Question:

A patient with prolonged immobilization develops marked reduction in skeletal muscle mass. Muscle fibers remain viable, and electron microscopy shows increased digestion of intracellular organelles within membrane-bound vacuoles. Which process is contributing to survival of these cells?

Correct Answer:
Autophagy

Explanation: Atrophic cells can digest their own organelles through autophagy, reducing cellular components while conserving nutrients needed for survival.

Question:

A bronchial biopsy from a patient exposed to chronic irritation shows replacement of the normal epithelial phenotype by a more resistant mature cell type. After the irritant is removed, normal epithelium gradually returns. Which cellular mechanism makes this reversal possible?

Correct Answer:
Reprogramming of tissue precursor cells

Explanation: Metaplasia results from altered differentiation of stem or precursor cells rather than direct transformation of one mature cell into another.

Question:

Cardiac myocytes exposed to sustained pressure overload enlarge and initially maintain cardiac output. Months later, the adaptive capacity is exceeded and cellular injury develops. Which principle is best illustrated by this sequence?

Correct Answer:
Persistent stress can exceed adaptive capacity

Explanation: Adaptation establishes a new steady state, but continuing or excessive stress may exceed the cell’s adaptive reserve and produce injury.

Question:

Electron microscopy of injured cells shows markedly swollen mitochondria with disruption of their internal structure. The cells subsequently fail to maintain energy-dependent ion gradients. Which functional consequence most directly follows this organelle injury?

Correct Answer:
Reduced ATP production

Explanation: Mitochondria generate most cellular ATP; severe structural damage therefore compromises energy production and contributes to loss of cellular homeostasis.

Question:

A cell exposed to severe irreversible injury loses calcium homeostasis. Intracellular calcium rises markedly, followed by progressive destruction of membranes, proteins and nuclear material. Which mechanism best links calcium accumulation with these structural changes?

Correct Answer:
Activation of destructive cellular enzymes

Explanation: Increased cytosolic calcium activates enzymes that damage membranes, cytoskeletal proteins and nucleic acids, promoting irreversible injury and necrosis.

Question:

Histological examination of an infarcted organ shows dead cells with intensely pink cytoplasm and nuclei that have become progressively pale until they are no longer visible. Which process is responsible for the nuclear appearance?

Correct Answer:
Enzymatic degradation of DNA

Explanation: Progressive fading and disappearance of the nucleus is karyolysis, caused by enzymatic degradation of nuclear DNA.

Question:

A pathologist compares two areas of cell death. In the first, tissue outlines remain recognizable for several days. In the second, the tissue has been rapidly converted into liquid debris. Which factor best explains this difference?

Correct Answer:
Balance between protein denaturation and enzymatic digestion

Explanation: Predominant protein denaturation preserves architecture in coagulative necrosis, whereas dominant enzymatic digestion produces liquefactive necrosis.

Question:

A lymph node biopsy from a patient with chronic granulomatous inflammation contains an amorphous granular area composed of fragmented cells. Unlike an infarct, the normal tissue architecture is completely lost within this region. Which necrotic pattern best fits this morphology?

Correct Answer:
Caseous necrosis

Explanation: Caseous necrosis shows amorphous granular cellular debris with complete loss of tissue architecture and commonly occurs within granulomatous inflammation.

Question:

Following severe irreversible injury, cells in a tissue rupture and release intracellular proteins into the extracellular space. An inflammatory infiltrate subsequently develops around the dead cells. Which event most directly initiates this surrounding reaction?

Correct Answer:
Loss of plasma membrane integrity

Explanation: Necrotic membrane disruption releases intracellular contents into surrounding tissue, provoking the characteristic inflammatory response.

Question:

During embryonic development, selected cells are removed to shape developing structures. The cells activate proteases, condense their chromatin and are rapidly cleared by neighboring cells. Which feature indicates that this is a regulated physiological process rather than accidental cell injury?

Correct Answer:
Orderly activation of intracellular proteases

Explanation: Apoptosis is an active regulated process driven by sequential caspase activation, allowing controlled elimination of selected cells.

Question:

A cell undergoing programmed death has already activated its executioner caspases. Shortly afterward, nuclear proteins and cytoskeletal components are cleaved and DNA fragmentation develops. Which role is performed by these enzymes?

Correct Answer:
Controlled dismantling of cellular structures

Explanation: Executioner caspases cleave key nuclear and cytoskeletal proteins and activate pathways that fragment DNA, producing orderly cellular dismantling.

Question:

A cell accumulates proteins that cannot fold correctly. When cellular repair mechanisms fail to restore normal protein structure, the cell activates a pathway leading to its controlled removal. Which type of stimulus has initiated this response?

Correct Answer:
Pathological intracellular stress

Explanation: Accumulation of irreparably misfolded proteins is a pathological intracellular stress that can activate the intrinsic apoptotic pathway.

Question:

A cytotoxic lymphocyte recognizes a damaged target cell and triggers its programmed elimination. Histology later shows disappearance of the individual target cell without significant injury to adjacent tissue. Which biological advantage is provided by this mode of cell death?

Correct Answer:
Selective removal with limited tissue damage

Explanation: Apoptosis removes selected abnormal or unwanted cells while containing their contents, thereby minimizing injury to surrounding tissue.

Question:

Following withdrawal of a hormonal stimulus, a hormone-dependent tissue decreases in size. Microscopy demonstrates removal of individual cells without membrane rupture or surrounding inflammation. Which process most directly contributes to the reduction in cell number?

Correct Answer:
Physiological apoptosis

Explanation: Hormone-dependent tissues may involute through physiological apoptosis when trophic hormonal stimulation is withdrawn.

Question:

A pathological cell population acquires a defect that markedly reduces programmed cell death while its rate of cell production remains unchanged. Over time, the population expands. Which principle best explains this observation?

Correct Answer:
Reduced apoptosis permits abnormal cell accumulation

Explanation: Tissue homeostasis depends on balancing cell production and removal; impaired apoptosis allows cells that should be eliminated to accumulate.

Question:

Cells obtained from an elderly individual show persistent molecular abnormalities despite functioning DNA-repair systems. The amount of unrepaired genetic injury has increased gradually over decades. Which mechanism of ageing is best demonstrated?

Correct Answer:
Accumulation of DNA damage over time

Explanation: Endogenous metabolism and environmental exposures continually damage DNA; incomplete repair allows genetic injury to accumulate during ageing.

Question:

An ageing cell remains viable but has reduced ability to respond to physiological stress. Studies show alteration of pathways that normally balance cellular growth with repair and maintenance according to nutrient availability. Which ageing mechanism is implicated?

Correct Answer:
Altered nutrient-sensing pathways

Explanation: Nutrient-sensing pathways regulate the balance between growth, metabolism, repair and stress resistance; their alteration contributes to cellular ageing.

Question:

Myocardial cells from an elderly patient contain fine yellow-brown cytoplasmic granules. The cells remain viable, and the pigment represents indigestible products generated during previous free-radical injury and lipid peroxidation. How should this finding be interpreted?

Correct Answer:
A marker of accumulated cellular wear

Explanation: Lipofuscin is a residual pigment reflecting previous oxidative and lipid damage; its presence marks accumulated cellular wear rather than cell death itself.

Question:

Two elderly patients experience the same moderate physiological stress. One recovers rapidly, while the other shows prolonged functional impairment despite having no acute tissue necrosis. Age-related changes have reduced the second patient’s ability to increase cellular performance when challenged. Which concept best explains this difference?

Correct Answer:
Reduced cellular functional reserve

Explanation: Accumulated molecular damage and declining maintenance mechanisms reduce the functional reserve of ageing cells, limiting their ability to adapt to stress.