Weekly Pathology Exam - April 10, 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), not number.

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

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

Accepted Answer

Glutathione peroxidase — X-rays cause radiolytic decomposition of water into free radicals like OH•. Glutathione peroxidase is a key antioxidant enzyme that neutralizes free radicals and peroxides.

Question 4

A 68-year-old woman lost consciousness; two months later, a head CT scan showed a large cystic area in the left parietal lobe. Which pathologic process most likely occurred?

Accepted Answer

Liquefactive necrosis — Ischemic injury in the central nervous system (brain) characteristically results in liquefactive necrosis, which eventually leaves behind a cystic space or cavity.

Question 5

An experiment analyzes cells for enzyme activity associated with sustained cellular proliferation. Which of the following cells is most likely to have the highest telomerase activity?

Accepted Answer

Germ cells — Telomerase maintains telomere length and is highly active in germ cells and stem cells to allow for persistent division, whereas it is absent or low in most somatic cells.

Question 6

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

Accepted Answer

Apoptosis — The withdrawal of progesterone at the end of the menstrual cycle triggers programmed cell death (apoptosis) in the functional layer of the endometrium, leading to menstruation.

Question 7

After the birth of her first child, a woman breastfed for 1 year. Which process in the breast during pregnancy allowed her to breastfeed?

Accepted Answer

Hypertroxy and hyperplasia — Breast tissue undergoes both hyperplasia (increase in number of ducts/lobules) and hypertrophy (increase in size of cells) under hormonal influence during pregnancy/lactation.

Question 8

A nonpregnant uterus measures 7 x 4 x 3 cm, but at term measures 34 x 18 x 12 cm. Which cellular process contributed most to the increase in uterine size?

Accepted Answer

Hypertrophy — While both occur, the massive enlargement of the uterus during pregnancy is primarily due to the hypertrophy of smooth muscle cells (myometrium).

Question 9

A 28-year-old man with cystic fibrosis has a ΔF508 mutation in the CFTR gene. The misfolded protein is retained in which cellular location?

Accepted Answer

Endoplasmic reticulum — The ΔF508 mutation causes the CFTR protein to misfold. This defective protein is recognized by the ER quality control system and retained/degraded in the Endoplasmic Reticulum.

Question 10

What is the normal pH range of human blood?

Accepted Answer

7.35 – 7.45 — The physiological pH range of arterial blood is tightly regulated between 7.35 and 7.45.

Question 11

A patient with COPD has ABG results showing 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 (<7.35), indicating acidosis. The PaCO2 is high ( 45 mmHg), which explains the acidosis; therefore, it is respiratory acidosis.

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 (CO2) and kidneys (HCO3-).

Question 13

A diabetic patient presents with rapid, deep breathing (Kussmaul respirations). Which acid-base disorder is this compensatory mechanism addressing?

Accepted Answer

Metabolic Acidosis — Kussmaul breathing is a respiratory compensation for metabolic acidosis (like Diabetic Ketoacidosis) to 'blow off' CO2 and raise blood pH.

Question 14

What is the normal range for arterial PaCO2?

Accepted Answer

35-45 mmHg — The standard 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 H+ and Cl — Gastric secretions are rich in HCl. Significant vomiting leads to loss of hydrogen ions and chloride, resulting in a relative excess of bicarbonate and metabolic alkalosis.

Question 16

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

Accepted Answer

22-28 mEq/L — The normal clinical range for serum bicarbonate is typically 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 (CA) facilitates the rapid conversion of CO2 and H2O into H2CO3, which then dissociates into H+ and HCO3-.

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 ( 7.45), indicating alkalosis. The PaCO2 is low (<35 mmHg), which accounts for the alkalosis; thus, it is respiratory alkalosis.

Question 19

What is the formula for calculating anion gap?

Accepted Answer

Na+ - (Cl- + HCO3-) — The anion gap is calculated as the serum sodium concentration minus the sum of chloride and bicarbonate concentrations.

Question 20

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

Accepted Answer

Diabetic ketoacidosis — Diabetic ketoacidosis (DKA) results in the accumulation of ketoacids (unmeasured anions), which increases the anion gap. Diarrhea causes a normal anion gap acidosis.

Question 21

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

Accepted Answer

Respiratory Alkalosis — High altitude leads to hypoxemia, which causes hyperventilation. Excessive 'blowing off' of CO2 results in respiratory alkalosis.

Question 22

In familial retinoblastoma, what distinguishes its presentation from sporadic cases according to Knudson's hypothesis?

Accepted Answer

It presents earlier and is often bilateral — In the familial form, the first 'hit' is inherited in all cells; hence, only one somatic mutation is needed in a retinal cell, leading to multiple tumors and earlier onset.

Question 23

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

Accepted Answer

Binding of Rb to E2F — Hypophosphorylated Rb binds to E2F transcription factors, preventing the cell from progressing into the S phase.

Question 24

A tumor shows constitutive activation of growth signaling. Which mechanism is LEAST likely responsible?

Accepted Answer

Overexpression of p16 (INK4a) — p16 is a tumor suppressor that inhibits CDKs. Its overexpression would inhibit growth signaling, not activate it.

Question 25

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

Accepted Answer

Increasing tyrosine kinase activity — The t(9;22) Philadelphia chromosome creates the BCR-ABL fusion gene, which encodes a constitutively active tyrosine kinase that promotes uncontrolled proliferation.

Question 26

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

Accepted Answer

E-cadherin — E-cadherin mediates cell-cell contact inhibition. Loss of E-cadherin allows tumor 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

Tumor suppressors function like 'brakes'; one working copy is often sufficient — Tumor suppressor genes usually show a 'recessive' pattern at the cellular level (Knudson's Two-Hit Hypothesis), meaning one functional allele can still control the cell cycle.

Question 28

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

Accepted Answer

It prevents cells with DNA damage from proliferating — p53 senses DNA damage and induces cell cycle arrest (to allow repair) or apoptosis (if damage is irreparable), preventing the propagation of mutations.

Question 29

In late-stage tumors, TGF-β signaling often promotes metastasis. This occurs because:

Accepted Answer

The cell loses its growth-inhibitory response to TGF-β but retains other pathways like EMT — Late-stage cancers often become resistant to TGF-β-induced growth arrest but utilize TGF-β signaling to promote the epithelial-to-mesenchymal transition (EMT).

Question 30

A patient with Li-Fraumeni syndrome develops multiple tumors. The inherited defect involves:

Accepted Answer

TP53 — Li-Fraumeni syndrome is a rare autosomal dominant disorder caused by germline mutations in the TP53 tumor suppressor gene.

Question 31

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

Accepted Answer

Cyclin B-CDK1 — The Cyclin B-CDK1 complex (also known as Maturation Promoting Factor) triggers the transition into mitosis and processes like nuclear envelope breakdown.

Question 32

During tumor angiogenesis, MMP-9 performs multiple functions. Which combination of activities is CORRECT?

Accepted Answer

Degrades ECM and releases VEGF — Matrix metalloproteinases (MMPs) like MMP-9 degrade the extra-cellular matrix (ECM) to allow vessel sprouting and release sequestered growth factors like VEGF.

Question 33

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

Accepted Answer

Leaky, tortuous, and dilated vessels — Tumor vessels are structurally abnormal; they are often leaky, irregularly branched, and have haphazard blood flow due to the imbalance of pro-angiogenic factors.

Question 34

Normal p53 plays a role in preventing angiogenesis. Which mechanism explains this?

Accepted Answer

Induces synthesis of thrombospondin-1 — p53 stimulates the expression of anti-angiogenic molecules such as thrombospondin-1 and downregulates pro-angiogenic factors like VEGF.

Question 35

Three angiogenesis inhibitors—angiostatin, endostatin, and vasculostatin—share what common characteristic?

Accepted Answer

They are derived from cleavage of larger precursor proteins — Many endogenous angiogenesis inhibitors are fragments of proteins that have other functions (e.g., angiostatin is from plasminogen, endostatin is from collagen XVIII).

Question 36

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

Accepted Answer

Survival in the circulation — Survival in the bloodstream is very difficult for tumor cells due to shear stress, lack of adhesion (anoikis), and immune surveillance by NK cells.

Question 37

Loss of E-cadherin function promotes metastasis through which mechanism?

Accepted Answer

Reduced cell-cell adhesion — The loss of E-cadherin reduces the adhesiveness between epithelial cells, which is a prerequisite for cells to detach from the primary tumor.

Question 38

During ECM invasion, tumor cells must complete four sequential steps. Which is the FIRST step?

Accepted Answer

Loosening of cell-cell junctions — The cascade begins with the 'loosening up' of tumor cell-cell interactions (often via loss of E-cadherin), followed by degradation of ECM, attachment, and migration.

Question 39

Which lipoprotein is responsible for transporting dietary triglycerides from the intestines to tissues?

Accepted Answer

Chylomicrons — Chylomicrons are large lipoproteins synthesized in the small intestine that carry dietary (exogenous) lipids to the rest of the body.

Question 40

What is the primary function of HDL cholesterol?

Accepted Answer

Reverse cholesterol transport — HDL (High-Density Lipoprotein) picks up excess cholesterol from peripheral tissues and transports it back to the liver.

Question 41

Which hormone promotes lipogenesis and inhibits lipolysis?

Accepted Answer

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

Question 42

What is the genetic defect in familial hypercholesterolemia?

Accepted Answer

Defective LDL receptors — Familial hypercholesterolemia (Type IIa) is most commonly caused by mutations in the gene encoding the LDL receptor, preventing the clearance of LDL from plasma.

Question 43

Which clinical sign consists of yellowish nodules commonly found on the Achilles tendon in hypercholesterolemia?

Accepted Answer

Tendinous xanthoma — Tendinous xanthomas are cholesterol deposits in tendons, frequently the Achilles tendon, and are a hallmark of familial hypercholesterolemia.

Question 44

What is the primary metabolic pathway for fatty acid breakdown in mitochondria?

Accepted Answer

Beta-oxidation — Beta-oxidation is the catabolic process by which fatty acid molecules are broken down in the mitochondria to generate acetyl-CoA.

Question 45

The primary difference between Quality Control (QC) and Quality Assurance (QA) is:

Accepted Answer

QC monitors the testing process, QA monitors the entire laboratory system — QC (Quality Control) focuses on the analytical phase (the test itself), while QA (Quality Assurance) encompasses the entire process—pre-analytical, analytical, and post-analytical.

Question 46

Which type of control chart is most commonly used in Internal Quality Control?

Accepted Answer

Levy-Jennings chart — The Levey-Jennings chart is the standard tool used to plot QC data over time to identify trends, shifts, or random errors.

Question 47

In the pre-analytical phase, which factor is MOST critical for maintaining sample integrity?

Accepted Answer

Proper patient identification and sample labeling — Pre-analytical errors (like mislabeling) are the most frequent source of lab errors. Correct identification is foundational to quality.

Question 48

External Quality Assessment (EQA) primarily serves to:

Accepted Answer

Compare a lab's performance with other laboratories — EQA (or Proficiency Testing) involves an external agency sending 'blind' samples to laboratories to ensure their results are accurate and comparable to other labs.

Question 49

Which phase of quality control is responsible for the highest percentage of laboratory errors?

Accepted Answer

Pre-analytical phase — Statistically, the majority of errors (up to 70%) occur in the pre-analytical phase (collection, transport, handling).

Question 50

All the following are granulomatous diseases EXCEPT:

Accepted Answer

Acute Bronchitis — Acute bronchitis is characterized by acute inflammation (neutrophils), not granuloma formation. Tuberculosis, Leprosy, and Sarcoidosis are classic granulomatous diseases.

Weekly Pathology Exam - April 10, 2026 (Section A: MCQs)

Questions, Answers & Explanations