Weekly Pathology Exam - July 17, 2026 (Section A: MCQs)

Question 1

What neurotransmitter is associated with runner's high?

Accepted Answer

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

Question 2

What neurotransmitter is associated with anxiety disorders?

Accepted Answer

GABA — GABA (gamma-aminobutyric acid) is the primary inhibitory neurotransmitter in the central nervous system. Reduced GABAergic activity is strongly implicated in the pathophysiology of 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 carries the genetic code for all proteins. This information is transcribed into RNA and then translated into proteins in the cytoplasm.

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 mammalian central nervous system, mediating IPSPs.

Question 5

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

Accepted Answer

The importance of sodium channels in action potential propagation. — Tetrodotoxin blocks voltage-gated sodium channels. Its inhibitory effect on nerve impulse conduction highlights the critical role of sodium ions in the generation and propagation of action potentials along axons.

Question 6

What neurotransmitter is associated with mood disorders?

Accepted Answer

Serotonin — Serotonin is a key neurotransmitter involved in mood regulation. Dysregulation of serotonin pathways is a major factor in the development of mood disorders like depression and anxiety.

Question 7

Which of the following is not true?

Accepted Answer

All neurotransmitters are excitatory. — Neurotransmitters can be either excitatory or inhibitory, depending on the type of receptor they bind to and the ion channels they affect.

Question 8

What neurotransmitter is associated with insomnia?

Accepted Answer

Melatonin — While several neurotransmitters are involved in sleep regulation, melatonin is a hormone that plays a crucial role in the circadian rhythm and sleep-wake cycles. Dysregulation or deficiency of melatonin can contribute to insomnia.

Question 9

What neurotransmitter is associated with seizures?

Accepted Answer

Glutamate — Glutamate is the primary excitatory neurotransmitter in the brain. Excessive glutamatergic activity can lead to neuronal hyperexcitability and seizures.

Question 10

What is one of the functions of Dopamine?

Accepted Answer

Control of voluntary movement and reward pathways — Dopamine plays a crucial role in motor control, motivation, reward, and pleasure. Its deficiency is characteristic of Parkinson's disease, and its dysregulation is involved in addiction and schizophrenia.

Question 11

What is one of the functions of Endorphins?

Accepted Answer

Blocking pain signals and inducing euphoria — Endorphins are endogenous opioid peptides that act as natural painkillers and mood elevators, producing feelings of pleasure and well-being.

Question 12

What neurotransmitter is 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 in dopamine. This results in motor symptoms such as tremors, rigidity, and bradykinesia.

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 a classic finding in iron deficiency anemia, which is often caused by insufficient iron intake or increased blood loss, leading to fatigue and pallor.

Question 14

The primary site of haematopoiesis in adults is:

Accepted Answer

Bone marrow — In adults, the bone marrow is the primary site where all 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?

Accepted Answer

Eosinophils — Eosinophils play a key role in the immune response against helminthic (parasitic worm) infections and are also involved in allergic reactions.

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 clotting Factor VIII.

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 (indicated by recurrent infections, petechiae, and anemia), is characteristic of aplastic anemia, a condition where the bone marrow fails to produce enough blood cells.

Question 18

Haemopoiesis is the process of:

Accepted Answer

Production of blood cells — Hematopoiesis is the complex process by which all the cellular components of blood are formed from hematopoietic stem cells within the bone marrow.

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 aspiration and biopsy with cytochemical staining and immunophenotyping — While a peripheral blood smear shows blasts, a definitive diagnosis of acute myeloid leukemia (AML) requires examination of the bone marrow, including cytochemical stains (e.g., MPO) and immunophenotyping to confirm the myeloid lineage of the blasts and assess the percentage.

Question 20

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

Accepted Answer

Periodic Acid-Schiff (PAS) — The Periodic Acid-Schiff (PAS) stain is commonly used in the diagnosis of acute lymphoblastic leukemia (ALL) as it stains the granules within lymphoblasts, appearing as diffuse or block-like cytoplasmic positivity.

Question 21

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

Accepted Answer

Neutropenia — Neutropenia is a condition characterized by an abnormally low number of neutrophils, a type of white blood cell. Chemotherapy often suppresses bone marrow production, leading to neutropenia and an increased risk of infection.

Question 22

Which chromosomal translocation is pathognomonic of chronic myeloid leukaemia?

Accepted Answer

t(9;22) — The Philadelphia chromosome, a reciprocal translocation between chromosomes 9 and 22, t(9;22), is the hallmark genetic abnormality found in almost all cases of chronic myeloid leukemia (CML).

Question 23

Thrombopoietin primarily regulates the production of:

Accepted Answer

Platelets — Thrombopoietin is a cytokine that plays a critical role in the regulation of megakaryopoiesis and platelet production. It stimulates the proliferation and differentiation of megakaryocyte progenitors.

Question 24

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

Accepted Answer

CD34 — CD34 is a transmembrane glycoprotein that is expressed on hematopoietic stem and progenitor cells. It is a widely used marker for identifying and isolating these cells for transplantation and research.

Question 25

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 strenuous exercise, leading to feelings of euphoria and pain reduction, commonly described as 'runner's high'.

Question 26

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

Accepted Answer

GABA — GABA (gamma-aminobutyric acid) is the primary inhibitory neurotransmitter in the central nervous system. Reduced GABAergic activity is strongly implicated in the pathophysiology of anxiety disorders.

Question 27

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 carries the genetic code for all proteins. This information is transcribed into RNA and then translated into proteins in the cytoplasm.

Question 28

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 mammalian central nervous system, mediating IPSPs.

Question 29

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

Accepted Answer

The importance of sodium channels in action potential propagation. — Tetrodotoxin blocks voltage-gated sodium channels. Its inhibitory effect on nerve impulse conduction highlights the critical role of sodium ions in the generation and propagation of action potentials along axons.

Question 30

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

Accepted Answer

Serotonin — Serotonin is a key neurotransmitter involved in mood regulation. Dysregulation of serotonin pathways is a major factor in the development of mood disorders like depression and anxiety.

Question 31

Which of the following statements is NOT true regarding neurotransmitters?

Accepted Answer

All neurotransmitters are excitatory. — Neurotransmitters can be either excitatory or inhibitory, depending on the type of receptor they bind to and the ion channels they affect.

Question 32

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

Accepted Answer

Melatonin — While several neurotransmitters are involved in sleep regulation, melatonin is a hormone that plays a crucial role in the circadian rhythm and sleep-wake cycles. Dysregulation or deficiency of melatonin can contribute to insomnia.

Question 33

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 brain. Excessive glutamatergic activity can lead to neuronal hyperexcitability and seizures.

Question 34

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

Accepted Answer

Control of voluntary movement and reward pathways — Dopamine plays a crucial role in motor control, motivation, reward, and pleasure. Its deficiency is characteristic of Parkinson's disease, and its dysregulation is involved in addiction and schizophrenia.

Question 35

What is one of the primary functions of Endorphins?

Accepted Answer

Blocking pain signals and inducing euphoria — Endorphins are endogenous opioid peptides that act as natural painkillers and mood elevators, producing feelings of pleasure and well-being.

Question 36

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 in dopamine. This results in motor symptoms such as tremors, rigidity, and bradykinesia.

Question 37

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 normal PT and prolonged PTT, in the absence of bleeding, suggests a deficiency in an intrinsic pathway clotting factor. Factor VIII deficiency (Hemophilia A) is a common cause of isolated prolonged PTT.

Question 38

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 — This patient has evidence of coagulopathy (prolonged PT and PTT) and thrombocytopenia, along with significant anemia. Fresh frozen plasma (FFP) contains all clotting factors and can help correct the coagulopathy. Packed red blood cells would address the anemia, and platelets would address thrombocytopenia, but FFP is the most comprehensive choice for generalized bleeding due to coagulopathy and can also provide some volume expansion.

Question 39

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

Immune thrombocytopenic purpura (ITP) — Post-transfusion purpura (PTP) is a rare but serious complication characterized by a precipitous drop in platelet count 1-2 weeks after transfusion, typically due to an antibody against the HPA-1a platelet antigen. While the timing here is immediate, rapid destruction of transfused platelets suggests an immune-mediated process, and PTP fits this severe, non-response scenario.

Question 40

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

Hemophilia A — A normal PT, prolonged PTT, normal platelet count, and a history of hemarthroses strongly suggest a deficiency in an intrinsic pathway clotting factor. The fact that mixing with normal plasma corrects the PTT points towards a factor deficiency rather than an inhibitor. Hemophilia A (Factor VIII deficiency) is the most common inherited disorder causing these symptoms.

Question 41

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

Chronic obstructive pulmonary disease — The presence of gram-positive diplococci in sputum suggests bacterial pneumonia, commonly caused by Streptococcus pneumoniae. Patients with COPD are at increased risk for pneumonia due to impaired mucociliary clearance and weakened respiratory defenses. The elevated total protein and normal albumin might be related to the inflammatory response or underlying conditions, but the combination strongly points towards a complication of COPD.

Question 42

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 elevated Hgb F (90%) along with low MCV (69 fL) and severe anemia in a patient with chronic heart failure and elevated ferritin is highly suggestive of beta-thalassemia major. The elevated ferritin is due to increased iron absorption, common in thalassemia, and potential iron overload from repeated transfusions (though not explicitly mentioned, it's a consideration in severe cases). The low Hgb A2 is also consistent with beta-thalassemia.

Question 43

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 stored at room temperature, which increases the risk of bacterial contamination and subsequent infection compared to refrigerated blood products.

Question 44

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

Paget's disease of bone — A markedly elevated alkaline phosphatase (200 U/L) in an asymptomatic elderly woman, especially with potential for bone involvement, is highly suggestive of Paget's disease of bone. Weight loss could be incidental or related to other subtle issues, but the alkaline phosphatase is the key finding pointing to increased bone turnover.

Question 45

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) — The constellation of fever, sore throat, generalized lymphadenopathy, and a CD4 count of 375/microliter is highly suggestive of an acute viral infection. Epstein-Barr virus (EBV) is the most common cause of infectious mononucleosis, which presents with these symptoms and can cause a transient decrease in CD4 count.

Question 46

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 in glucose levels — A fasting glucose of 120 mg/dL is considered impaired fasting glucose. However, the subsequent measurement of 124 mg/dL, four hours later, without any specified reason for the test, likely reflects normal physiological variation and potentially a slight postprandial rise or diurnal fluctuation in blood glucose levels in a person who is not diabetic.

Question 47

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 screening for bloodborne pathogens is crucial, routine testing for West Nile virus in donated blood is not a standard practice in all regions or at all times, unlike HIV, HCV, and syphilis which are universally screened for.

Question 48

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 venous and arterial thrombosis (DVT and TIA) in a young woman, coupled with prolonged PT and PTT that do not correct with mixing studies, is highly suggestive of antiphospholipid syndrome. This syndrome is characterized by the presence of antiphospholipid antibodies that interfere with coagulation testing and increase the risk of thrombosis.

Question 49

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

Accepted Answer

Chylomicrons — Chylomicrons are large lipoprotein particles that are synthesized in the small intestine and transport dietary fats (triglycerides and cholesterol) to various tissues in the body.

Question 50

What is the primary function of HDL cholesterol?

Accepted Answer

Transport of cholesterol from peripheral tissues back to the liver. — HDL cholesterol, often referred to as 'good cholesterol,' plays a crucial role in reverse cholesterol transport by picking up excess cholesterol from peripheral tissues and transporting it back to the liver for excretion or reprocessing.

Weekly Pathology Exam - July 17, 2026 (Section A: MCQs)

Questions, Answers & Explanations