Licensure Exam Practice Test Questions

Medical Laboratory Scientist (MLS) Licensure Exam Practice Test Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

(All major subjects: Hematology, Clinical Chemistry, Immunology/Serology,

Microbiology, Blood Banking, and Urinalysis/Body Fluids)

• Which of the following cells is the precursor of macrophages in tissues?
• Lymphocyte
• Monocyte
• Neutrophil
• Eosinophil

Rationale: Monocytes circulate in blood and migrate into tissues to

differentiate into macrophages, responsible for phagocytosis and antigen presentation. 1 / 4

2. The main anticoagulant used for coagulation studies is:

A. EDTA

• Heparin
• Sodium citrate
• Oxalate

Rationale: Sodium citrate binds calcium reversibly, preserving coagulation

factors for accurate clotting tests.

3. The most common cause of microcytic, hypochromic anemia is:

• Iron deficiency anemia
• Thalassemia
• Anemia of chronic disease
• Sideroblastic anemia

Rationale: Iron deficiency reduces hemoglobin synthesis, producing small,

pale red cells.

• Which enzyme is most specific for myocardial infarction?

A. AST

B. LDH

C. CK-MB

D. ALP 2 / 4

Rationale: CK-MB (Creatine Kinase–Myocardial Band) rises within hours of

cardiac muscle injury and is cardiac-specific.

5. The presence of HBsAg in serum indicates:

• Current Hepatitis B infection
• Past infection
• Immunity
• False positive

Rationale: HBsAg (Hepatitis B surface antigen) is a marker of active

infection, either acute or chronic.

• A Gram-positive cocci in clusters is observed. The organism is catalase-

positive and coagulase-positive. The most likely organism is:

• Staphylococcus aureus
• Streptococcus pyogenes
• Staphylococcus epidermidis
• Streptococcus pneumoniae

Rationale: Catalase and coagulase positivity differentiates S. aureus from

other cocci.

• The universal donor for packed red blood cells is: 3 / 4

• O negative
• O positive
• AB positive
• AB negative

Rationale: O negative RBCs lack A, B, and Rh antigens, preventing

incompatibility reactions.

8. A urine sample with a fruity odor and positive ketones suggests:

• Diabetic ketoacidosis
• Urinary tract infection
• Liver disease
• Dehydration

Rationale: Ketone production due to fat metabolism in insulin deficiency

causes the fruity smell.

9. The normal WBC count range for adults is:

A. 2.0–5.0 ×10⁹/L

B. 4.0–11.0 ×10⁹/L

C. 12.0–16.0 ×10⁹/L

D. 1.0–3.0 ×10⁹/L

Rationale: Normal leukocyte count reflects adequate immune capacity

without leukocytosis or leukopenia.

• / 4