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

Question 1

What neurotransmitter is primarily associated with the euphoric feeling experienced during a 'runner's high'?

Accepted Answer

Endorphins — Endorphins are endogenous opioid peptides that are released during prolonged exercise, leading to feelings of pleasure and pain reduction, often described as 'runner's high'.

Question 2

Which neurotransmitter system is most implicated in the pathophysiology of anxiety disorders?

Accepted Answer

GABAergic system — Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system. Dysregulation of the GABAergic system is strongly linked to anxiety disorders.

Question 3

Where do neurons store the genetic information they use to code and build all the proteins required for their functions?

Accepted Answer

Nucleus — The nucleus of a neuron contains the cell's DNA, which holds the genetic blueprint for all proteins synthesized by the neuron.

Question 4

Which of the following are major inhibitory neurotransmitters, causing inhibitory postsynaptic potentials (IPSPs)?

Accepted Answer

GABA and Glycine — GABA (gamma-aminobutyric acid) and Glycine are the principal inhibitory neurotransmitters in the central nervous system, reducing neuronal excitability.

Question 5

The effect of tetrodotoxin (puffer fish poison) on axons demonstrates:

Accepted Answer

The necessity of sodium channels for action potential propagation. — Tetrodotoxin blocks voltage-gated sodium channels, preventing the influx of sodium ions necessary for the depolarization phase of the action potential, thus demonstrating their crucial role in axon conduction.

Question 6

Which neurotransmitter is most commonly associated with the regulation of mood, and its dysregulation is implicated in mood disorders like depression?

Accepted Answer

All of the above — Serotonin, dopamine, and norepinephrine are all neurotransmitters involved in mood regulation. Imbalances in any of these systems can contribute to mood disorders.

Question 7

Which of the following statements is NOT true regarding neurotransmitters?

Accepted Answer

Neurotransmitters are always excitatory. — Neurotransmitters can be either excitatory or inhibitory, depending on the type of receptor they bind to on the postsynaptic neuron. Therefore, the statement that they are always excitatory is false.

Question 8

Which neurotransmitter system is heavily involved in regulating sleep-wake cycles and is often implicated in insomnia?

Accepted Answer

Histaminergic system — Histamine acts as a wake-promoting neurotransmitter in the hypothalamus. Antihistamines, which block histamine receptors, can cause sedation and are often used to treat insomnia.

Question 9

Which neurotransmitter plays a critical role in mediating excitatory neurotransmission and is implicated in the hyperexcitability seen in certain seizure disorders?

Accepted Answer

Glutamate — Glutamate is the primary excitatory neurotransmitter in the central nervous system. An excess of glutamatergic activity or a deficit in GABAergic inhibition can lead to seizures.

Question 10

What is one of the primary functions of Dopamine in the brain?

Accepted Answer

Motivation, reward, and motor control — Dopamine is a key neurotransmitter in the brain's reward pathways, playing a significant role in motivation, pleasure, and motor control. It is also implicated in Parkinson's disease.

Question 11

What is one of the primary functions of Endorphins?

Accepted Answer

Pain relief and pleasure — Endorphins are natural painkillers produced by the body and contribute to feelings of well-being and pleasure, similar to opioids.

Question 12

Which neurotransmitter deficiency is strongly associated with Parkinson's disease?

Accepted Answer

Dopamine — Parkinson's disease is characterized by the degeneration of dopaminergic neurons in the substantia nigra, leading to a deficiency of dopamine and resulting in motor symptoms.

Question 13

A 28-year-old woman presents with fatigue and pallor. Complete blood count shows low haemoglobin level and peripheral blood film shows microcytic hypochromic red blood cells. What is the most likely diagnosis?

Accepted Answer

Iron deficiency anemia — Microcytic hypochromic red blood cells are characteristic of iron deficiency anemia, which is the most common cause of anemia in women of reproductive age due to blood loss (menstruation) and inadequate iron intake.

Question 14

The primary site of haematopoiesis in adults is:

Accepted Answer

Bone marrow — In healthy adults, the bone marrow is the primary site where all types of blood cells (red blood cells, white blood cells, and platelets) are produced through the process of hematopoiesis.

Question 15

Which blood cell type is primarily responsible for defence against parasitic infections and also plays a role in allergic reactions?

Accepted Answer

Eosinophils — Eosinophils are granulocytes that are particularly effective against parasitic infections and release mediators that contribute to allergic inflammation.

Question 16

Which clotting factor is deficient in Haemophilia A?

Accepted Answer

Factor VIII — Hemophilia A is an X-linked recessive disorder caused by a deficiency in functional Factor VIII of the coagulation cascade, leading to impaired blood clotting.

Question 17

A patient presents with recurrent infections, petechiae, and anaemia. A bone marrow biopsy shows reduced cellularity. What is the most likely diagnosis?

Accepted Answer

Aplastic anemia — Reduced cellularity in the bone marrow, along with pancytopenia (implied by recurrent infections, petechiae, and anemia), is characteristic of aplastic anemia, a condition where the bone marrow fails to produce sufficient blood cells.

Question 18

Haemopoiesis is the process of:

Accepted Answer

Formation and development of blood cells — Hematopoiesis is the complex biological process by which all types of blood cells, including white blood cells, red blood cells, and platelets, are formed and mature.

Question 19

A 62-year-old man presents with fatigue, fever and bruising. His full blood count shows WCC 40 × 10⁹/L with 25% circulating blasts, Hb 90 g/L and platelets 50 × 10⁹/L. Which investigation is required to definitively diagnose acute myeloid leukaemia?

Accepted Answer

Bone marrow biopsy and aspirate with cytochemical staining — While peripheral blood findings are suggestive, a bone marrow biopsy and aspirate are essential for definitive diagnosis of AML, allowing for assessment of cellularity, morphology, immunophenotyping, cytochemistry, and cytogenetics.

Question 20

Which cytochemical stain is most useful to confirm lymphoblasts in suspected ALL?

Accepted Answer

Periodic Acid-Schiff (PAS) — Periodic Acid-Schiff (PAS) staining typically shows cytoplasmic granules or diffuse positivity in lymphoblasts, helping to differentiate them from other myeloid blasts.

Question 21

A patient receiving chemotherapy shows a drop in neutrophil count. This condition is termed:

Accepted Answer

Neutropenia — Neutropenia is a medical term for a lower-than-normal number of neutrophils, a type of white blood cell, in the blood. Chemotherapy often causes neutropenia.

Question 22

Which chromosomal translocation is pathognomonic of chronic myeloid leukaemia?

Accepted Answer

t(9;22) — The Philadelphia chromosome, resulting from the reciprocal translocation t(9;22), is the hallmark of chronic myeloid leukemia (CML).

Question 23

Thrombopoietin primarily regulates the production of:

Accepted Answer

Platelets — Thrombopoietin (TPO) is the key hormone that stimulates the production of platelets (thrombocytes) from megakaryocytes in the bone marrow.

Question 24

Which of the following is a stem cell marker used to identify haematopoietic stem cells?

Accepted Answer

CD34 — CD34 is a cell surface glycoprotein that is expressed on hematopoietic stem cells and progenitors, making it a widely used marker for their identification and isolation.

Question 25

A 35-year-old man has no clinical evidence for bleeding and he feels fine. As part of a pre-operative workup for a hernia repair, laboratory studies show Hgb 14.8 g/dL, Hct 45%, MCV 96 fL, WBC count 8500/microliter, and platelet count 275,000/microliter. His prothrombin time is normal, but the partial thromboplastin time is prolonged. A deficiency of which of the following coagulation factors is most likely be associated with these findings?

Accepted Answer

Factor VIII — A prolonged PTT with a normal PT suggests a defect in the intrinsic pathway of coagulation. Factor VIII deficiency (Hemophilia A) or Factor IX deficiency (Hemophilia B) are the most common causes of isolated prolonged PTT.

Question 26

A 20-year-old man is actively bleeding from multiple sites during surgery. He has a CBC that shows a WBC count of 4500/microliter, Hgb 7.6 g/dL, Hct 23.9%, MCV 98 fL, and platelet count 75,000/microliter. His prothrombin time is 30 seconds and partial thromboplastin time 63 seconds. What is the best blood product to use for him in this situation?

Accepted Answer

Fresh frozen plasma — The patient has a prolonged PT and PTT, indicating a coagulopathy. Fresh frozen plasma (FFP) contains all clotting factors and is the most appropriate product to rapidly correct a broad range of clotting factor deficiencies in actively bleeding patients.

Question 27

A 31-year-old woman has oozing of blood from mucous membranes over the past 3 days. Laboratory studies show a platelet count of 10,000/microliter. She receives 6 units of platelets. An hour following this transfusion, her platelet count is 2,000/microliter. What is the most probable explanation for the change in pre- to post-transfusion platelet count?

Accepted Answer

Thrombotic microangiopathy (e.g., TTP/HUS) — A rapid drop in platelet count after transfusion, despite receiving platelets, suggests ongoing destruction of platelets. Thrombotic microangiopathies like TTP or HUS involve platelet consumption and can lead to this scenario.

Question 28

A 12-year-old boy has had multiple episodes of bleeding since infancy. It is characterized by hemarthroses and decreased joint mobility. His prothrombin time (PT) is normal, but the partial thromboplastin time (PTT) is elevated. When his plasma is mixed with normal plasma, the PTT is not elevated. His platelet count is normal. Which of the following is the most likely cause for his illness?

Accepted Answer

Congenital Factor VIII deficiency (Hemophilia A) — A normal PT, prolonged PTT, normal platelet count, and correction upon mixing with normal plasma are classic findings for a factor deficiency in the intrinsic pathway. Hemophilia A (Factor VIII deficiency) is the most common inherited disorder presenting with hemarthroses and is X-linked.

Question 29

A 64-year-old nursing home patient receiving tube feedings is admitted with fever of two days' duration accompanied by a cough productive of yellowish sputum. On admission his temperature is 37.4°C. A sputum gram stain shows 4+ gram positive diplococci. He is also found to have a total serum protein of 9.4 g/dl with serum albumin of 3.8 g/dl. Which of the following underlying diseases do these findings most strongly suggest that he has?

Accepted Answer

Aspiration pneumonia — The patient's presentation with fever, productive cough, and gram-positive diplococci on sputum gram stain is highly suggestive of pneumococcal pneumonia, a common bacterial infection, especially in elderly and debilitated individuals.

Question 30

A 44-year-old man has had congestive heart failure for 2 years. His serum ferritin is markedly elevated. His CBC shows WBC count 6300/microliter, Hgb 7.8 g/dL, Hct 22.6%, MCV 69 fL, and platelet count 177,000/microliter. A hemoglobin electrophoresis reveals 2% Hgb A, 8% Hgb A2, and 90% Hgb F. Which of the following hematologic conditions is he most likely to have?

Accepted Answer

Beta thalassemia major — The combination of microcytic anemia (low MCV), markedly elevated serum ferritin (indicating iron overload, not deficiency), and a high percentage of Hemoglobin F (HbF) with low HbA is characteristic of beta-thalassemia major or intermedia.

Question 31

A study of blood product therapy is done. One product is identified that carries the greatest risk for infection. This blood product has the shortest shelf life, and it must be used as quickly as possible for transfusion. Which of the following products is best described by these findings?

Accepted Answer

Platelets — Platelets have the shortest shelf life (typically 5 days at room temperature with agitation) and are at a higher risk for bacterial contamination and growth compared to red blood cells or plasma products, which are stored at colder temperatures.

Question 32

An 81-year-old previously healthy woman has had a 2 kg weight loss without dieting over the past 2 months. She reports no other problems. On examination there are no abnormal findings. Laboratory studies show a serum alkaline phosphatase of 200 U/L. Which of the following diseases is she most likely to have?

Accepted Answer

Metastatic breast cancer — A mildly elevated alkaline phosphatase in an elderly patient with weight loss and bone lesions can be suggestive of metastatic disease to the bone. While other options can cause elevated alkaline phosphatase, metastatic breast cancer is a strong consideration given the general presentation.

Question 33

A 17-year-old boy has developed a mild fever with sore throat over the past day. On physical examination he has generalized lymphadenopathy. Laboratory studies show a CD4 lymphocyte count of 375/microliter. He is most likely to be infected with which of the following agents?

Accepted Answer

Epstein-Barr virus (EBV) — Fever, sore throat, generalized lymphadenopathy, and atypical lymphocytes are classic symptoms of infectious mononucleosis, typically caused by Epstein-Barr virus (EBV). A CD4 count of 375 is not directly indicative of HIV without further context.

Question 34

A 62-year-old healthy woman has a pre-operative workup for an elective surgery. A serum glucose is ordered and is of 120 mg/dl. Four hours later that day, another glucose test is ordered unnecessarily, and the value is noted to be 124 mg/dl. Which of the following best explains the difference in these two values on this woman?

Accepted Answer

Normal diurnal variation and laboratory variability — A fasting glucose of 120 mg/dl is slightly elevated, but the subsequent value of 124 mg/dl, especially if not taken in a strictly fasting state or if there was a slight delay, can be attributed to normal variations and laboratory imprecision. It does not definitively indicate diabetes.

Question 35

A healthy 27 year old male donates blood. He completes the questionnaire and interview with no exclusions noted. The presence of which of the following infectious agents will not routinely tested for on his blood collected for transfusion?

Accepted Answer

West Nile virus — While routine screening for HIV, HCV, and HBV is standard for blood donations, testing for West Nile virus is not universally performed but may be implemented during outbreaks or in specific geographic regions.

Question 36

A 33-year-old woman has had multiple episodes of deep venous thrombosis over the past year. Last week she had a transient ischemic attack. On examination there are no abnormal findings. Laboratory studies show a prolonged prothrombin and partial thromboplastin time. When her plasma is mixed in a ratio of 1:1 with normal plasma, neither the PT nor the PTT normalize. Which of the following conditions is she most likely to have?

Accepted Answer

Antiphospholipid syndrome — Recurrent thrombosis (DVT, TIA), prolonged PT and PTT that do not correct with normal plasma are highly suggestive of antiphospholipid syndrome, particularly the presence of lupus anticoagulant.

Question 37

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

Accepted Answer

Chylomicrons — Chylomicrons are large lipoprotein particles assembled in the intestinal cells that transport dietary fats (triglycerides and cholesterol) from the small intestine into the lymphatic system and then into the bloodstream for distribution to peripheral tissues.

Question 38

What is the primary function of HDL cholesterol?

Accepted Answer

Reverse cholesterol transport (transport of cholesterol from peripheral tissues to the liver) — High-density lipoprotein (HDL) cholesterol, often referred to as 'good' cholesterol, plays a crucial role in reverse cholesterol transport, picking up excess cholesterol from peripheral tissues and transporting it back to the liver for elimination.

Question 39

Which enzyme is responsible for breaking down triglycerides in adipose tissue during lipolysis?

Accepted Answer

Hormone-sensitive lipase — Hormone-sensitive lipase (HSL) is the key enzyme in adipose tissue that hydrolyzes stored triglycerides into free fatty acids and glycerol, releasing them into circulation during periods of fasting or increased energy demand.

Question 40

What happens to VLDL as it loses triglycerides?

Accepted Answer

It is converted into LDL. — Very-low-density lipoprotein (VLDL) delivers triglycerides to peripheral tissues. As it loses triglycerides, it becomes denser and is progressively converted into intermediate-density lipoprotein (IDL) and then into low-density lipoprotein (LDL).

Question 41

Which hormone promotes lipogenesis (fat synthesis) and inhibits lipolysis (fat breakdown)?

Accepted Answer

Insulin — Insulin is a key anabolic hormone that promotes glucose uptake and storage, and it also stimulates lipogenesis and inhibits lipolysis, thus promoting fat storage.

Question 42

What is the genetic defect in familial hypercholesterolemia?

Accepted Answer

Deficiency in LDL receptor — Familial hypercholesterolemia is most commonly caused by mutations in the gene encoding the LDL receptor, leading to impaired clearance of LDL cholesterol from the bloodstream and consequently very high LDL levels.

Question 43

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

Accepted Answer

Xanthomas (specifically Tuberous xanthomas) — Xanthomas, particularly tuberous xanthomas on the Achilles tendon, are characteristic cutaneous manifestations of severe hyperlipidemia, especially familial hypercholesterolemia.

Question 44

What condition can severe hypertriglyceridemia lead to?

Accepted Answer

Acute pancreatitis — Severely elevated triglyceride levels (typically 1000 mg/dL) significantly increase the risk of acute pancreatitis due to the formation of chylomicron remnants that can obstruct pancreatic ducts.

Question 45

What is lipemia retinalis?

Accepted Answer

Cloudy appearance of the retina due to high triglyceride levels — Lipemia retinalis is a clinical finding where the retinal blood vessels appear milky white or creamy due to extremely high levels of triglycerides in the blood, which causes the plasma to become opaque.

Question 46

Which statin is commonly used to lower LDL cholesterol?

Accepted Answer

Atorvastatin — Atorvastatin is a potent statin medication widely prescribed for its efficacy in reducing low-density lipoprotein (LDL) cholesterol levels by inhibiting HMG-CoA reductase.

Question 47

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

Accepted Answer

Beta-oxidation — Beta-oxidation is the catabolic process occurring in the mitochondrial matrix that breaks down fatty acid chains into acetyl-CoA units, which then enter the citric acid cycle for energy production.

Question 48

Which apolipoprotein defect is responsible for familial dysbetalipoproteinemia?

Accepted Answer

ApoE — Familial dysbetalipoproteinemia (Type III hyperlipoproteinemia) is characterized by a defect in apolipoprotein E (ApoE), leading to impaired clearance of chylomicron remnants and very-low-density lipoprotein (VLDL) remnants.

Question 49

What is the chromosomal location of the RB gene?

Accepted Answer

13q14 — The RB1 gene, which encodes the retinoblastoma protein, is located on chromosome 13 at band q14 (13q14).

Question 50

According to Knudson's two-hit hypothesis, how many mutations are required to develop retinoblastoma?

Accepted Answer

Two — Knudson's two-hit hypothesis states that for tumor suppressor genes like RB, both alleles must be inactivated (mutated or lost) for the cancer to develop. In hereditary cases, one hit is inherited, and the second hit occurs somatically.

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

Questions, Answers & Explanations