Weekly Pathology Exam - April 3, 2026 (Section A: MCQs)

Question 1

A 51-year-old man has a blood pressure of 150/95 mm Hg. If his hypertension remains untreated for years, which of the following cellular alterations would most likely be seen in his myocardium?

Accepted Answer

Hypertrophy — Cardiac muscle cells are permanent cells and cannot divide; therefore, they respond to increased workload (pressure overload from hypertension) by increasing in size (hypertrophy).

Question 2

A 38-year-old woman experienced severe abdominal pain with hypotension and shock. The mesentery shows focal, chalky white deposits. Which of the following events has most likely occurred?

Accepted Answer

Fat necrosis — Chalky white deposits in the mesentery are characteristic of fat necrosis, often seen in acute pancreatitis where released lipases break down triglycerides into fatty acids that complex with calcium (saponification).

Question 3

Cells are subjected to x-rays, resulting in cell injury by hydrolysis of water. Which of the following cellular enzymes protects the cells from this type of injury?

Accepted Answer

Glutathione peroxidase — Radiant energy produces free radicals via hydrolysis of water. Glutathione peroxidase is a key antioxidant enzyme that neutralizes free radicals like hydrogen peroxide.

Question 4

A 68-year-old woman suffered a stroke. Two months later, a head CT scan showed a large cystic area in the left parietal lobe. Which pathologic process occurred?

Accepted Answer

Liquefactive necrosis — Brain infarction typically results in liquefactive necrosis, which eventually leaves a cystic cavity after the debris is removed by macrophages.

Question 5

Which of the following cells is most likely to have the highest telomerase activity?

Accepted Answer

Germ cells — Germ cells and stem cells express high levels of telomerase to maintain telomere length and allow for continuous proliferation, unlike somatic cells.

Question 6

A 23-year-old woman experiences onset of menstrual bleeding. Which process is occurring in the endometrium just before the onset of bleeding?

Accepted Answer

Apoptosis — Withdrawal of progesterone at the end of the menstrual cycle triggers programmed cell death (apoptosis) in the functional layer of the endometrium.

Question 7

A 19-year-old woman breastfed her infant for a year. Which process in the breast during pregnancy allowed her to breastfeed?

Accepted Answer

Hormonal hyperplasia — Pregnancy induces hormonal hyperplasia of the glandular epithelium of the breast to prepare for lactation.

Question 8

A pregnant uterus increases in size from 7 cm to 34 cm at term. Which cellular processes contribute most to this increase?

Accepted Answer

Hypertrophy and hyperplasia — The massive enlargement of the uterus during pregnancy is due to both the enlargement of existing smooth muscle cells (hypertrophy) and the formation of new cells (hyperplasia).

Question 9

A mutation results in a misfolded CFTR protein (ΔF508) in cystic fibrosis. This protein is retained in which cellular location?

Accepted Answer

Endoplasmic reticulum — The ΔF508 mutation leads to misfolding of the CFTR protein, which is recognized by the ER quality control system and targeted for degradation before reaching the cell surface.

Question 10

What is the normal pH range of human blood?

Accepted Answer

7.35 - 7.45 — The physiological pH of arterial blood is strictly maintained between 7.35 and 7.45.

Question 11

A COPD patient has pH 7.28, PaCO2 58 mmHg, and HCO3- 26 mEq/L. What is the primary acid-base disorder?

Accepted Answer

Respiratory Acidosis — The pH is low (acidosis) and the PaCO2 is high (respiratory cause), typical for CO2 retention in COPD.

Question 12

Which buffer system is the PRIMARY extracellular buffer system in the body?

Accepted Answer

Bicarbonate buffer — The bicarbonate-carbonic acid system is the most important extracellular buffer because its components can be regulated by both the lungs and kidneys.

Question 13

A diabetic patient presents with Kussmaul respirations. Which acid-base disorder is this compensation addressing?

Accepted Answer

Metabolic Acidosis — Kussmaul breathing is deep, rapid respiration used to blow off CO2 to compensate for metabolic acidosis (common in DKA).

Question 14

What is the normal range for arterial PaCO2?

Accepted Answer

35-45 mmHg — The normal range for partial pressure of arterial carbon dioxide is 35 to 45 mmHg.

Question 15

A patient with severe vomiting develops metabolic alkalosis. Which mechanism explains this?

Accepted Answer

Loss of gastric HCL — Vomiting leads to the loss of hydrochloric acid (HCl) from the stomach, resulting in a net gain of bicarbonate in the blood.

Question 16

What is the normal range for serum bicarbonate (HCO3-)?

Accepted Answer

22-28 mEq/L — Normal serum bicarbonate levels generally range from 22 to 28 mEq/L.

Question 17

Which enzyme in renal tubular cells catalyzes the reaction between CO2 and water to form carbonic acid?

Accepted Answer

Carbonic anhydrase — Carbonic anhydrase facilitates the rapid interconversion of CO2 and water to bicarbonate and H+ ions.

Question 18

A patient has ABG results: pH 7.50, PaCO2 30 mmHg, HCO3- 23 mEq/L. What is the diagnosis?

Accepted Answer

Respiratory Alkalosis — The pH is high (alkalosis) and the PaCO2 is low (respiratory cause), often seen in hyperventilation.

Question 19

What is the formula for calculating the anion gap?

Accepted Answer

Na - (Cl + HCO3) — The anion gap is calculated by subtracting the sum of chloride and bicarbonate from the sodium concentration.

Question 20

Which condition is characterized by an increased anion gap metabolic acidosis?

Accepted Answer

Diabetic ketoacidosis — DKA involves the accumulation of unmeasured anions (ketoacids), leading to an elevated anion gap.

Question 21

A patient at high altitude develops dizziness and tingling. Which acid-base disorder is most likely?

Accepted Answer

Respiratory Alkalosis — High altitude causes hypoxia, which triggers hyperventilation to increase oxygen intake, leading to excessive loss of CO2 and respiratory alkalosis.

Question 22

In familial retinoblastoma, what distinguishes the presentation from sporadic cases?

Accepted Answer

Inheritance of one mutant allele (germline) — In familial cases, the first 'hit' is inherited in the germline, meaning all cells have one mutation; the second hit occurs somatically.

Question 23

Which event would MOST effectively prevent E2F-mediated transcription of S-phase genes?

Accepted Answer

Binding of hypophosphorylated Rb to E2F — Active (hypophosphorylated) Rb protein binds to E2F and prevents it from initiating the transcription of genes required for the S-phase.

Question 24

Constitutive activation of growth signaling despite absence of growth factors is LEAST likely caused by:

Accepted Answer

p53 mutation — p53 is a tumor suppressor involved in cell cycle arrest and apoptosis, not a growth factor signaling component like RAS, ABL, or receptors.

Question 25

In chronic myeloid leukemia, the BCR-ABL fusion protein drives malignancy primarily by:

Accepted Answer

Constitutive tyrosine kinase activity — The Philadelphia chromosome creates BCR-ABL, which acts as a constitutively active tyrosine kinase that drives uncontrolled cell proliferation.

Question 26

Tumor cells continue dividing despite contact with neighboring cells. Which protein's function is most likely compromised?

Accepted Answer

E-cadherin — E-cadherin mediates contact inhibition; its loss allows cells to ignore signals to stop growing when they touch other cells.

Question 27

Why must BOTH copies of a tumor suppressor gene be lost for tumor development, unlike oncogenes?

Accepted Answer

They are recessive at the cellular level — Tumor suppressor genes usually follow the 'two-hit' hypothesis where both alleles must be inactivated to lose the protective function.

Question 28

Which statement BEST explains why p53 is called the 'guardian of the genome'?

Accepted Answer

It prevents mutations by inducing G1 arrest or apoptosis — p53 senses DNA damage and initiates either repair (via G1 arrest) or apoptosis to prevent the propagation of mutations.

Question 29

In late-stage tumors, intact TGF-β signaling promotes metastasis because:

Accepted Answer

It induces epithelial-mesenchymal transition (EMT) — While TGF-β is growth-inhibitory in early stages, many cancers subvert this pathway in late stages to drive EMT and metastasis.

Question 30

Inherited defect in Li-Fraumeni syndrome involves:

Accepted Answer

VHL — Li-Fraumeni syndrome is characterized by a germline mutation in the TP53 gene, leading to various early-onset cancers.

Question 31

During mitosis, which cyclin-CDK complex is responsible for nuclear membrane breakdown?

Accepted Answer

Cyclin B-CDK1 — The Cyclin B-CDK1 complex (Mitosis-Promoting Factor) triggers the transition into M-phase, including nuclear envelope breakdown.

Question 32

Which scenario would MOST likely result in failed DNA damage repair followed by apoptosis?

Accepted Answer

Normal p53 and irreparable DNA damage — If DNA damage is too severe to be fixed, normal p53 upregulates BAX and other pro-apoptotic factors to eliminate the cell.

Question 33

In a tumor with loss of APC function, what is the immediate downstream effect?

Accepted Answer

Accumulation of β-catenin — APC normally facilitates the degradation of β-catenin; without APC, β-catenin translocates to the nucleus and activates growth-promoting genes.

Question 34

Which molecular mechanism explains the increased angiogenesis in von Hippel-Lindau (VHL) syndrome?

Accepted Answer

Stabilization of HIF-1α — VHL protein normally targets Hypoxia-Inducible Factor (HIF-1α) for degradation. Loss of VHL leads to HIF-1α accumulation and increased VEGF production.

Question 35

A tumor reaches 1.8 mm in diameter but fails to grow further. Which statement explains this?

Accepted Answer

Lack of angiogenesis (the 'angiogenic switch') — Tumors cannot grow larger than 1-2 mm without developing their own blood supply to provide nutrients and oxygen.

Question 36

During tumor angiogenesis, MMP-9 performs which combination of activities?

Accepted Answer

Degrades ECM and releases sequestered VEGF — Matrix metalloproteinase-9 (MMP-9) degrades extracellular matrix and releases biologically active VEGF to trigger the angiogenic switch.

Question 37

Which characteristic would MOST likely be observed in tumor vasculature compared to normal capillaries?

Accepted Answer

Leaky, dilated, and haphazardly connected vessels — Tumor vessels are notoriously abnormal, characterized by high permeability, tortuosity, and incomplete basement membranes.

Question 38

Normal p53 plays a role in preventing angiogenesis by:

Accepted Answer

Inducing the synthesis of thrombospondin-1 — Wild-type p53 stimulates the expression of anti-angiogenic molecules like thrombospondin-1.

Question 39

Angiostatin, endostatin, and vasculostatin share what common characteristic?

Accepted Answer

They are cleavage products of larger proteins — These are potent inhibitors of angiogenesis formed by the proteolytic cleavage of precursor proteins (e.g., plasminogen, collagen XVIII).

Question 40

Newly formed endothelial cells in tumor vessels contribute to growth by:

Accepted Answer

Secreting IGF and PDGF — Endothelial cells provide 'angiocrine' stimulation by secreting growth factors like Insulin-like Growth Factor (IGF) and Platelet-Derived Growth Factor (PDGF).

Question 41

At which stage of the metastatic cascade do MOST tumor cells fail?

Accepted Answer

Survival in the circulation — The bloodstream is a hostile environment for tumor cells due to shear stress and immune cells; very few circulating cells survive to form metastases.

Question 42

Loss of E-cadherin function promotes metastasis through:

Accepted Answer

Decreased cell-cell adhesion and release of β-catenin — Loss of E-cadherin reduces cell-cell stickiness and releases β-catenin, which travels to the nucleus to promote growth signaling.

Question 43

Breast cancer with high expression of CXCR4 and CCR7 is MOST likely to metastasize to:

Accepted Answer

Lymph nodes and Lung — These receptors respond to chemokines high in the lung and lymph nodes, directing the tissue-specific homing of breast cancer cells.

Question 44

During ECM invasion, which is the FIRST step?

Accepted Answer

Detachment of tumor cells from each other — The sequence of invasion is: 1. Loosening of cell-cell junctions, 2. Degradation of ECM, 3. Attachment to new ECM components, 4. Migration.

Question 45

Cleavage of basement membrane collagen IV and laminin by MMPs serves what purpose beyond degradation?

Accepted Answer

Generates chemotactic and angiogenic fragments — MMP cleavage products of the ECM often act as signals that promote tumor cell migration and stimulate new blood vessel growth.

Question 46

Which lipoprotein transports dietary triglycerides from the intestines to tissues?

Accepted Answer

Chylomicrons — Chylomicrons are formed in the intestinal mucosa and transport exogenous (dietary) lipids.

Question 47

What is the primary function of HDL cholesterol?

Accepted Answer

Transporting cholesterol to the liver — HDL is involved in reverse cholesterol transport, picking up excess cholesterol from peripheral tissues and returning it to the liver.

Question 48

Which enzyme breaks down triglycerides in adipose tissue during lipolysis?

Accepted Answer

Hormone-sensitive lipase — Hormone-sensitive lipase (HSL) catalyzes the breakdown of stored triglycerides into free fatty acids and glycerol.

Question 49

What happens to VLDL as it loses triglycerides to the tissues?

Accepted Answer

It becomes IDL then LDL — VLDL is converted into intermediate-density lipoprotein (IDL) and eventually low-density lipoprotein (LDL) as triglycerides are removed.

Question 50

Which hormone promotes lipogenesis and inhibits lipolysis?

Accepted Answer

Insulin — Insulin is an anabolic hormone that promotes fat storage (lipogenesis) and inhibits the breakdown of fats (lipolysis).

Weekly Pathology Exam - April 3, 2026 (Section A: MCQs)

Questions, Answers & Explanations