Ethiopian Medical Laboratory Science University Exit Exam Practice Questions (50 Items)

Part 1: Clinical Chemistry

Q1. A 45-year-old male patient presents with severe crushing chest pain radiating to his left arm. The clinician suspects an acute myocardial infarction (AMI). Which cardiac biomarker rises first within 1 to 3 hours following myocardial injury? A) Cardiac Troponin I (cTnI) B) Myoglobin C) Creatine Kinase-MB (CK-MB) D) Lactate Dehydrogenase (LDH)

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• Correct Answer: B
• Rationale: Myoglobin is a low-molecular-weight heme protein found in cardiac and skeletal muscle that is released rapidly into circulation (within 1–3 hours) following tissue injury, making it the earliest, though non-specific, marker for AMI.

Q2. During a routine fasting plasma glucose test, a laboratory technologist notes a sample sitting at room temperature as whole blood for over 3 hours without being centrifuged. What biochemical change occurs to the glucose concentration in this unseparated sample? A) It increases by 10% per hour B) It remains completely stable C) It decreases by approximately 5% to 7% per hour due to glycolysis D) It converts entirely into glycogen

• Correct Answer: C
• Rationale: In unseparated whole blood kept at room temperature, white and red blood cells metabolize glucose via glycolysis, reducing the measurable glucose concentration by roughly 5% to 7% every hour.

Q3. A patient diagnosed with chronic liver cirrhosis undergoes a routine chemistry panel. Which of the following serum protein electrophoresis profiles is characteristic of advanced liver cirrhosis? A) Polyclonal gammopathy with beta-gamma bridging B) Sharp spike in the monoclonal gamma region C) Marked elevation in the alpha-1 globulin band D) Total absence of the albumin band

• Correct Answer: A
• Rationale: Advanced cirrhosis causes a classic “beta-gamma bridging” pattern on serum protein electrophoresis because increased production of IgA and IgG blends the beta and gamma fractions together, obscuring the normal valley between them.

Q4. To verify the accuracy of a newly installed spectrophotometer in a regional hospital laboratory, the technologist measures light leakage outside the specified wavelength band. What is the technical term for this light error? A) Stray light B) Refracted light C) Monochromatic absorbance D) Transmitted scatter

• Correct Answer: A
• Rationale: Stray light refers to any light reaching the detector that falls outside the narrow bandpass selected by the monochromator, which can falsely lower absorbance readings at high concentrations.

Q5. A patient presents with generalized bone pain and recurrent kidney stones. Laboratory results reveal significantly elevated serum total calcium and decreased serum inorganic phosphorus. Which hormone is likely oversecreted? A) Calcitonin B) Thyroid Hormone (T4) C) Parathyroid Hormone (PTH) D) Insulin

• Correct Answer: C
• Rationale: Parathyroid hormone increases serum calcium by stimulating bone resorption and renal calcium reabsorption, while lowering serum phosphorus by inhibiting renal phosphate reabsorption.

Q6. When evaluating a patient’s lipid profile, the laboratory technician needs to calculate the LDL-Cholesterol level using the Friedewald formula. If Total Cholesterol is 240 mg/dL, HDL is 50 mg/dL, and Triglycerides are 150 mg/dL, what is the LDL-C value? A) 190 mg/dL B) 160 mg/dL C) 120 mg/dL D) 140 mg/dL

• Correct Answer: B
• Rationale: The Friedewald equation states: LDL-C=Total Cholesterol−HDL-C−(Triglycerides/5). Plugging in the values: 240−50−(150/5)=190−30=160 mg/dL.

Q7. Which blood collection tube contain an additive that acts as an antiglycolytic agent by inhibiting the enolase enzyme to preserve glucose levels? A) Light blue-top tube (Sodium citrate) B) Gray-top tube (Sodium fluoride) C) Lavender-top tube (EDTA) ) Green-top tube (Lithium heparin)

• Correct Answer: B
• Rationale: Sodium fluoride binds calcium to inhibit coagulation weakly, but primarily functions as an antiglycolytic agent by disrupting the enzyme enolase in the glycolytic pathway to stabilize glucose.

Q8. A clinical chemistry analyzer reports a critically high serum potassium level of 7.2 mEq/L. Upon visual inspection, the plasma sample appears dark red. What is the most appropriate next step for the laboratory professional? A) Report the critical value immediately to the physician B) Reject the sample due to in vitro hemolysis and request a redraw C) Dilute the sample 1:2 with saline and retest D) Re-centrifuge the tube for another 20 minutes

• Correct Answer: B
• Rationale: Intracellular potassium concentration is much higher than extracellular concentration. Hemolysis breaks red blood cells, releasing massive amounts of potassium into the serum, resulting in a falsely elevated value that requires sample rejection.

Q9. An arterial blood gas (ABG) sample is analyzed, revealing a pH of 7.25, a pCO2​ of 55 mmHg, and a HCO3−​ of 24 mEq/L. How should this acid-base disturbance be classified? A) Uncompensated Metabolic Acidosis B) Uncompensated Respiratory Acidosis C) Compensated Respiratory Alkalosis D) Fully Compensated Metabolic Alkalosis

• Correct Answer: B
• Rationale: A pH below 7.35 indicates acidosis. The elevated pCO2​ (above 45 mmHg) matches the acidic pH direction, while the normal bicarbonate (HCO3−​) shows that renal compensation has not yet occurred, confirming uncompensated respiratory acidosis.

Q10. Which enzyme is highly specific for hepatobiliary disease and is particularly elevated in patients presenting with post-hepatic obstructive jaundice? A) Alanine Aminotransferase (ALT) B) Alkaline Phosphatase (ALP) C) Amylase D) Creatine Kinase (CK)

• Correct Answer: B
• Rationale: Alkaline phosphatase is concentrated in the canalicular membranes of hepatocytes. Obstetric conditions or biliary tract blockages trigger increased synthesis and release of ALP, making it a key marker for obstructive liver disease.

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Part 2: Hematology

Q11. A complete blood count (CBC) from an anemic patient shows a Hemoglobin of 8 g/dL, a Total RBC count of 3.5×1012/L, and a Packed Cell Volume (PCV/Hematocrit) of 24%. What is the calculated Mean Cell Volume (MCV), and what morphological classification does it indicate? A) 68 fL; Microcytic B) 85 fL; Normocytic C) 110 fL; Macrocytic D) 75 fL; Macrocytic

• Correct Answer: A
• Rationale: MCV=(Hct in %×10)/RBC count=(24×10)/3.5=240/3.5=68.57 fL. An MCV below 80 fL is classified as microcytic.

Q12. A Wright-stained peripheral blood smear examination reveals numerous red blood cells containing small, round, dark-blue iron granules clustered near the periphery. What are these inclusions called? A) Howell-Jolly bodies B) Heinz bodies C) Pappenheimer bodies (Siderotic granules) D) Cabot rings

• Correct Answer: C
• Rationale: Pappenheimer bodies are abnormal iron granules found inside erythrocytes that appear as small, irregular, dark-blue inclusions on Romanowsky-stained smears, typical of sideroblastic anemia.

Q13. In automated hematology cell counters utilizing the Beckman Coulter principle, what electrical parameter changes as an individual blood cell passes through a tiny aperture to allow cell counting and sizing? A) Electrical resistance (impedance) increases B) Light scatter angle shifts C) Fluorescence intensity doubles D) Radiofrequency decreases

• Correct Answer: A
• Rationale: The electrical impedance principle relies on the fact that blood cells are poor electrical conductors. As they pass through an aperture, they displace conductive diluent, momentarily increasing electrical resistance in proportion to cell volume.

Q14. A patient suspected of having a hemoglobinopathy undergoes hemoglobin electrophoresis at an alkaline pH of 8.6. Which type of hemoglobin migrates fastest toward the anode during this procedure? A) Hemoglobin A (HbA) B) Hemoglobin F (HbF) C) Hemoglobin S (HbS) D) Hemoglobin C (HbC)

• Correct Answer: A
• Rationale: At an alkaline pH of 8.6, Hemoglobin A carries the strongest net negative charge among the common variants, causing it to migrate fastest toward the positive electrode (anode).

Q15. A laboratory professional performs a manual white blood cell count using a Neubauer hemocytometer. The total count obtained is extremely high, and the peripheral smear shows many nucleated red blood cells (nRBCs). How do nRBCs affect an automated total WBC count? A) They falsely decrease the total WBC count B) They have no effect on the count C) They falsely increase the total WBC count because automated analyzers count them as white blood cells D) They interfere with the platelet count only

• Correct Answer: C
• Rationale: Because nucleated red blood cells contain a nucleus and resist standard lysing agents similarly to leukocytes, automated cell counters often mistake them for lymphocytes, which falsely elevates the total WBC count.

Q16. A patient presents with unprovoked deep vein thrombosis. A coagulation profile is ordered, and the Prothrombin Time (PT) is normal, but the Activated Partial Thromboplastin Time (aPTT) is significantly prolonged. Which coagulation pathway is affected? A) Extrinsic pathway B) Intrinsic pathway C) Common pathway only D) Fibrinolytic pathway

• Correct Answer: B
• Rationale: The aPTT test assesses the integrity of the intrinsic coagulation pathway (Factors XII, XI, IX, VIII) and the common pathway, whereas the PT test measures the extrinsic pathway (Factor VII).

Q17. Which cytochemical stain is highly valuable for differentiating acute myeloid leukemia (AML) from acute lymphoblastic leukemia (ALL) by staining cytoplasmic granules in granulocytic cells? A) Periodic Acid-Schiff (PAS) B) Myeloperoxidase (MPO) C) Tartrate-Resistant Acid Phosphatase (TRAP) D) New Methylene Blue

• Correct Answer: B
• Rationale: Myeloperoxidase is an enzyme found in the primary granules of myeloid cells. Neutrophilic precursors test positive for MPO, whereas lymphoid cells are negative, making it useful for differentiating AML from ALL.

Q18. What is the standard anticoagulant concentration and ratio used in light blue-top collection tubes for routine coagulation testing like PT and aPTT? A) 3.2% Buffered Sodium Citrate at a 1:9 ratio of anticoagulant to blood B) 15% EDTA at a 1:4 ratio of anticoagulant to blood C) Lithium Heparin at a 1:1 ratio of anticoagulant to blood D) Ammonium oxalate at a 2:8 ratio of anticoagulant to blood

• Correct Answer: A
• Rationale: Coagulation assays require a precise 9:1 blood-to-anticoagulant ratio using 3.2% (0.109 M) buffered sodium citrate to preserve labile coagulation factors.

Q19. While reviewing a peripheral blood smear from a patient with severe anemia, the laboratory technician observes distinct crescent-shaped or sickle-shaped red blood cells with pointed ends. What molecular abnormality causes this morphological change? A) Substitution of valine for glutamic acid at position 6 of the beta-globin chain B) Total lack of alpha-globin chain synthesis C) Vitamin B12 deficiency altering nuclear maturation ) Excessive accumulation of cellular lead

• Correct Answer: A
• Rationale: Sickle cell anemia is caused by a point mutation where valine replaces glutamic acid at the sixth position of the beta-globin chain, causing hemoglobin polymerisation under low oxygen tension.

Q20. A manual reticulocyte count is performed by mixing equal volumes of whole blood with a supravital stain. Which of the following dyes is classified as a supravital stain used to visualize residual ribosomal RNA in reticulocytes? A) Leishman stain B) Wright-Giemsa stain C) New Methylene Blue D) Eosin Y

• Correct Answer: C
• Rationale: Reticulocytes contain residual ribosomal RNA that cannot be seen on standard dry smears. Supravital staining with un-fixed dyes like New Methylene Blue or Brilliant Cresyl Blue precipitates this RNA into a visible network.

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Part 3: Immunohematology (Blood Banking)

Q21. During forward blood grouping on a patient sample, agglutination is observed with Anti-A and Anti-B reagents. Reverse grouping shows no agglutination with A1 cells or B cells. What is the patient’s ABO blood type? A) Type O B) Type A C) Type B ) Type AB

• Correct Answer: D
• Rationale: Forward grouping detects antigens on red blood cells, so agglutination with both Anti-A and Anti-B indicates the presence of both A and B antigens. Reverse grouping checks for serum antibodies; the absence of agglutination confirms Type AB blood.

Q22. A crossmatch procedure is performed prior to a blood transfusion. The phase of the crossmatch that specifically detects clinically significant, warm-reacting IgG antibodies coating donor red blood cells is: A) Immediate spin phase B) Room temperature incubation phase C) Antihuman Globulin (AHG) phase D) 4°C cold phase

• Correct Answer: C
• Rationale: The Antihuman Globulin (AHG/Coombs) phase detects incomplete, non-agglutinating IgG antibodies and complement components that attach to red blood cells at warm body temperatures (37∘C).

Q23. A multi-parous pregnant woman who is Rh-negative delivers a healthy newborn who is Rh-positive. To prevent Rh isoimmunization, when should Rho(D) Immune Globulin (RhoGAM) be administered to the mother? A) Within 72 hours post-delivery B) Exactly 2 weeks before conception C) During active labor contractions only D) 48 hours before delivery

• Correct Answer: A
• Rationale: To prevent an Rh-negative mother from producing anti-D antibodies after exposure to Rh-positive fetal cells, RhoGAM must be administered within 72 hours of delivery or any potential fetomaternal hemorrhage event.

Q24. Which antigen system is notorious for causing delayed hemolytic transfusion reactions because its corresponding antibodies quickly drop below detectable levels in patient serum over time? A) Kell system B) Kidd system (Jka, Jkb) C) Duffy system (Fya, Fyb) D) Lewis system

• Correct Answer: B
• Rationale: Kidd system antibodies (Anti−Jka and Anti−Jkb) are notorious for dropping to undetectable levels after initial stimulation, leading to false-negative antibody screens and subsequent delayed hemolytic reactions upon re-exposure.

Q25. What is the primary clinical utility of the Direct Antihuman Globulin Test (DAT / Direct Coombs)? A) To screen donor serum for unexpected irregular antibodies B) To detect in vivo coating of patient red blood cells with antibodies or complement components C) To determine the specific ABO subgroup of a newborn D) To crossmatch platelets for a leukemia patient

• Correct Answer: B
• Rationale: The DAT determines whether antibodies or complement proteins have bound directly to red blood cells inside the body (in vivo), which is key for diagnosing autoimmune hemolytic anemia, hemolytic disease of the newborn, and hemolytic transfusion reactions.

Q26. A unit of packed red blood cells is collected in a CPDA-1 (Citrate-Phosphate-Dextrose-Adenine) anticoagulant-preservative bag. What is the maximum allowable storage shelf-life for this blood unit when kept at 1°C to 6°C? A) 21 days B) 35 days C) 42 days D) 56 days

• Correct Answer: B
• Rationale: CPDA-1 contains adenine, which helps red cells synthesize ATP during storage, extending the shelf life of packed red cells to 35 days when properly refrigerated at 1°C to 6°C.

Q27. During reverse ABO blood typing, a technologist observes unexpected weak agglutination with O cells and auto-control tubes at room temperature. This interference is most likely caused by: A) Rouleaux formation B) Cold-reactive autoantibodies (Cold agglutinins) C) High-titer IgG antibodies D) Bacterial contamination of reagents

• Correct Answer: B
• Rationale: Cold autoantibodies (often IgM with anti-I specificity) react best at temperatures below room temperature and can cause non-specific agglutination of all red cells, including O cells and the auto-control, during room-temperature testing.

Q28. What screening test must be performed on all blood donor units to minimize the risk of transmitting Chagas disease in endemic regions? A) Sputum culture for acid-fast bacilli B) Serological screening for Trypanosoma cruzi antibodies C) Molecular amplification for Plasmodium vivax D) Western Blotting for Hepatitis C

• Correct Answer: B
• Rationale: Chagas disease is caused by the parasite Trypanosoma cruzi and can be transmitted via blood transfusion. Donors from or exposed to endemic regions must be screened using validated serological assays.

Q29. A patient group is identified as “Weak D” positive through indirect antiglutination testing after initial negative typing with standard Anti-D reagent. How should a unit of blood from this individual be classified for donation purposes? A) Rh-negative B) Rh-positive C) ABO unclassifiable D) Bombay phenotype

• Correct Answer: B
• Rationale: Individuals with the Weak D phenotype express the D antigen at reduced levels. When acting as blood donors, their blood must be labeled Rh-positive because it can stimulate anti-D production in an Rh-negative recipient.

Q30. What dangerous phenomenon can occur if a unit of whole blood contaminated with viable donor T-lymphocytes is transfused into a severely immunocompromised recipient? A) Transfusion-Associated Circulatory Overload (TACO) B) Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD) C) Allergic anaphylactic reaction D) Acute intravascular hemolysis

• Correct Answer: B
• Rationale: TA-GVHD occurs when viable donor T-lymphocytes recognize an immunocompromised host’s tissues as foreign and mount an immune attack against them, a complication that can be prevented by blood irradiation.

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Part 4: Medical Microbiology

Q31. A cerebrospinal fluid (CSF) sample from a patient with suspected bacterial meningitis is received. Gram staining reveals Gram-negative, bean-shaped intracellular diplococci. Which organism is most likely responsible? A) Streptococcus pneumoniae B) Haemophilus influenzae C) Neisseria meningitidis D) Cryptococcus neoformans

• Correct Answer: C
• Rationale: Neisseria meningitidis characteristically appears as Gram-negative, kidney- or bean-shaped diplococci found inside polymorphonuclear leukocytes on CSF smear preparations.

Q32. A microbiology technologist performs a biochemical test to differentiate Staphylococcus aureus from coagulase-negative Staphylococci like Staphylococcus epidermidis. Which test is specific for identifying S. aureus? A) Catalase test B) Coagulase test C) Oxidase test D) Bacitracin susceptibility test

• Correct Answer: B
• Rationale: While all Staphylococci are catalase-positive, Staphylococcus aureus produces the enzyme coagulase, which clots plasma, distinguishing it from coagulase-negative species.

Q33. A sputum specimen undergoes Ziehl-Neelsen (ZN) staining. Under the oil-immersion objective, the technologist observes bright red, slender, beaded rods against a blue background. What structural component of the cell wall makes this organism acid-fast? A) High content of mycolic acids and lipids B) Thick peptidoglycan meshwork without lipids C) Presence of chitin fibers D) Outer lipopolysaccharide membrane

• Correct Answer: A
• Rationale: Mycobacteria possess a thick, waxy cell wall rich in mycolic acids and complex lipids. This structure resists decolorization by acid-alcohol after staining with carbolfuchsin, defining the acid-fast characteristic.

Q34. Which culture medium is formulated as both a selective and differential medium to isolate Gram-negative enteric bacilli while inhibiting Gram-positive organisms using bile salts and crystal violet? A) Blood Agar B) Chocolate Agar C) MacConkey Agar D) Lowenstein-Jensen Medium

• Correct Answer: C
• Rationale: MacConkey agar contains bile salts and crystal violet to inhibit the growth of Gram-positive bacteria (selective aspect) and includes lactose with a neutral red indicator to differentiate lactose fermenters from non-fermenters (differential aspect).

Q35. An antimicrobial susceptibility test using the Kirby-Bauer disk diffusion method is performed. The technologist notices that the Mueller-Hinton agar plates were poured too thick (depth > 4 mm). How does this technical error affect the resulting zones of inhibition? A) Zones of inhibition will be falsely larger B) Zones of inhibition will be falsely smaller C) The zones will turn completely irregular and asymmetrical D) There will be no effect on the zone sizes

• Correct Answer: B
• Rationale: If the agar depth is too thick, the drug must diffuse downward through more volume, reducing its lateral diffusion across the surface. This creates falsely smaller zones of inhibition and can lead to incorrect resistance classifications.

Q36. A professional works to isolate a fastidious respiratory pathogen. The organism grows well on Chocolate agar but fails to grow on standard blood agar unless cross-streaked next to a beta-hemolytic Staphylococcus aureus colony (satellitism). What organism exhibits this requirement for Factor V and Factor X? A) Haemophilus influenzae B) Klebsiella pneumoniae C) Streptococcus pyogenes ) Pseudomonas aeruginosa

• Correct Answer: A
• Rationale: Haemophilus influenzae is a fastidious bacterium that requires both Factor X (hemin) and Factor V (NAD) for growth. Chocolate agar provides both factors through lysed red cells, while blood agar only provides Factor X unless a satellite colony of S. aureus releases Factor V.

Q37. Which biochemical reaction profile is characteristic of Escherichia coli when cultured on Triple Sugar Iron (TSI) agar and evaluated in an IMViC test panel? A) TSI: Alk/Acid; IMViC: – / – / + / + B) TSI: Acid/Acid with gas; IMViC: + / + / – / – C) TSI: Alk/Acid with H2​S; IMViC: + / – / + / – D) TSI: Acid/Acid without gas; IMViC: – / + / – / +

• Correct Answer: B
• Rationale: E. coli is an enteric lactose fermenter that produces an Acid/Acid reaction with gas on TSI. Its classic IMViC profile is Indole positive (+), Methyl Red positive (+), Voges-Proskauer negative (-), and Citrate negative (-).

Q38. A throat swab from a child presenting with acute pharyngitis and a gray pseudomembrane reveals Gram-positive rods with club-shaped ends arranged in Chinese-letter formations. Which selective culture medium is best for isolating this suspected pathogen? A) Thayer-Martin Medium B) Cystine-Tellurite Blood Agar or Tinsdale Medium C) TCBS Agar D) Sabouraud Dextrose Agar

• Correct Answer: B
• Rationale: The clinical presentation and morphology suggest Corynebacterium diphtheriae. Tellurite-containing media select for this organism, reducing normal respiratory flora and turning colonies black or gray.

Q39. What is the standard operational temperature, pressure, and minimum holding time required to achieve absolute sterility inside a steam autoclave? A) 100°C at 10 psi for 45 minutes B) 121°C at 15 psi for 15 to 20 minutes C) 160°C at 0 psi for 2 hours D) 140°C at 20 psi for 5 minutes

• Correct Answer: B
• Rationale: Autoclaving relies on moist heat under pressure. The standard conditions to destroy all vegetative cells and highly resistant bacterial endospores are 121°C at 15 pounds of pressure per square inch (psi) for at least 15–20 minutes.

Q40. A fungal culture grows a mold with septate hyphae and a distinct conidiophore terminating in a vesicle covered with phialides producing chains of pigmented conidia, resembling a “dandelion”. What opportunistic fungus is this? A) Penicillium species B) Aspergillus species C) Mucor species D) Candida albicans

• Correct Answer: B
• Rationale: The characteristic microscopic structure showing a vesicle covered by phialides producing chains of conidia is diagnostic for Aspergillus species, a common cause of opportunistic fungal infections.

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Part 5: Parasitology

Q41. A stool examination from a patient presenting with chronic foul-smelling diarrhea, abdominal bloating, and flatulence reveals pear-shaped, binucleated trophozoites with four pairs of flagella and a distinct sucking disc. What is this parasite? A) Entamoeba histolytica B) Giardia duodenalis (lamblia) C) Balantidium coli D) Trichomonas vaginalis

• Correct Answer: B
• Rationale: The pear-shaped trophozoite with two nuclei, a sucking disc, and flagella is characteristic of Giardia lamblia, a flagellated protozoan that colonizes the upper small intestine and causes malabsorptive diarrhea.

Q42. During a routine microscopic examination of a wet mount stool sample, a laboratory technologist finds a large, oval helminth egg measuring roughly 140×80μm with a inconspicuous operculum at one end. This egg is typical of: A) Ascaris lumbricoides B) Fasciola hepatica C) Schistosoma mansoni D) Taenia saginata

• Correct Answer: B
• Rationale: Fasciola hepatica and Fasciolopsis buski produce large, operculated eggs that are passed in feces, making them distinct from common intestinal nematodes or cestodes.

Q43. A patient living near an irrigation dam project presents with hematuria and dysuria. Examination of a concentrated urine sediment reveals large, elongated helminth eggs characterized by a distinct terminal spine. What is the parasite? A) Schistosoma mansoni B) Schistosoma haematobium C) Schistosoma japonicum D) Trichuris chiura

• Correct Answer: B
• Rationale: Schistosoma haematobium adult worms inhabit the venous plexuses of the human urinary bladder, and its eggs, which feature a characteristic terminal spine, are excreted primarily in urine.

Q44. Which diagnostic method is considered the “gold standard” for quantifying the density of malaria parasites and identifying specific species variants in thick and thin blood films? A) Enzyme-Linked Immunosorbent Assay (ELISA) B) Giemsa-stained peripheral blood film microscopy C) Polymerase Chain Reaction (PCR) only D) Rapid Diagnostic Test (RDT) strips

• Correct Answer: B
• Rationale: Microscopic examination of Giemsa-stained thick and thin blood smears remains the reference method for malaria diagnosis because it allows for both species identification and parasite density quantification.

Q45. A stool wet mount preparation reveals a spherical protozoan cyst containing four nuclei, a small centrally located karyosome, and elongated chromatoid bars with rounded, blunt ends. This morphology matches: A) Entamoeba coli B) Entamoeba histolytica C) lodamoeba bütschlii D) Endolimax nana

• Correct Answer: B
• Rationale: Mature cysts of the pathogenic Entamoeba histolytica contain a maximum of four nuclei and can feature rod-like chromatoid bodies with characteristically blunt or rounded ends.

Q46. A mother brings her 6-year-old child to a clinic complaining that the child suffers from intense perianal itching, especially during the night. Which specimen collection method is most effective for diagnosing this suspected helminth infection? A) Concentrated formal-ether stool sedimentation B) Cellophane tape (Scotch tape) preparation applied to the perianal skin C) 24-hour urine collection D) Skin snip biopsy

• Correct Answer: B
• Rationale: Female Enterobius vermicularis (pinworm) worms migrate out of the anus at night to deposit eggs on the perianal skin rather than in the fecal stream, making a cellophane tape swab the preferred collection method.

Q47. A microfilarial parasite is detected in a blood smear collected from a patient living in a tropical region. The parasite features a sheath and does not have nuclei in the tip of its tail section. What is this species? A) Wuchereria bancrofti B) Brugia malayi C) Loa loa D) Onchocerca volvulus

• Correct Answer: A
• Rationale: Wuchereria bancrofti microfilariae are enveloped in a distinct sheath, and their tail sections taper smoothly without terminal nuclei, distinguishing them from Brugia or Loa loa.

Q48. Microscopic inspection of a stool sample reveals an oval, thin-shelled helminth egg with a clear space between the shell and an inner segmented embryo (morula stage) containing 4 to 8 cells. What parasite produces this egg? A) Hookworm species (Ancylostoma duodenale / Necator americanus) B) Strongyloides stercoralis C) Enterobius vermicularis D) Hymenolepis nana

• Correct Answer: A
• Rationale: Hookworm eggs are characterized by a thin, colorless shell surrounding a developing embryo that is typically at the multi-cell cleavage stage when passed in fresh stool.

Q49. A laboratory technologist examines a skin scraping lesion sample from an individual presenting with an ulcerated cutaneous sore. After Giemsa staining, tiny oval intracellular structures containing a nucleus and a distinct rod-like kinetoplast (amastigote stage) are found inside macrophages. What is the diagnosis? A) Toxoplasmosis B) Leishmaniasis C) African Trypanosomiasis ) Malaria

• Correct Answer: B
• Rationale: The amastigote form (Leishman-Donovan body), characterized by a nucleus and kinetoplast inside phagocytic mononuclear cells, is the diagnostic stage for Leishmania species infections.

Q50. Which intestinal cestode infection is contracted by consuming undercooked beef containing infectious cysticerci larval stages? A) Taenia solium B) Taenia saginata C) Diphyllobothrium latum D) Echinococcus granulosus

• Correct Answer: B
• Rationale: Taenia saginata is known as the beef tapeworm; its larval stage (Cysticercus bovis) develops in cattle tissues, and humans contract the intestinal tapeworm by eating undercooked, contaminated beef.