Certified Medical Laboratory Scientist (MLS)
Practice Exam Exam 2025-2026[Complete
Exam prep Questions with verified Answers]
100%Correct Answers
1. Which of the following anticoagulants is used for coagulation studies?
A. EDTA
B. Heparin
C. Sodium citrate
D. Potassium oxalate
Answer: C. Sodium citrate
Rationale: Sodium citrate binds calcium reversibly, preventing clotting and is
the preferred anticoagulant for coagulation tests.
2. A patient’s WBC count is elevated. This condition is known as:
A. Leukopenia
B. Leukocytosis
C. Thrombocytopenia
D. Erythrocytosis
Answer: B. Leukocytosis
Rationale: Leukocytosis refers to an elevated white blood cell count, often due
to infection, inflammation, or stress.
3. The primary function of hemoglobin is to:
A. Fight infections
B. Carry oxygen
C. Form clots
D. Store iron
,Answer: B. Carry oxygen
Rationale: Hemoglobin in red blood cells binds oxygen in the lungs and delivers
it to tissues.
4. Which laboratory test is used to monitor long-term glucose control in
diabetic patients?
A. Fasting blood glucose
B. Random glucose
C. Hemoglobin A1c
D. Oral glucose tolerance test
Answer: C. Hemoglobin A1c
Rationale: Hemoglobin A1c reflects average blood glucose over the past 2–3
months.
5. Which of the following is considered a Gram-positive bacterium?
A. Escherichia coli
B. Staphylococcus aureus
C. Pseudomonas aeruginosa
D. Neisseria meningitidis
Answer: B. Staphylococcus aureus
Rationale: Gram-positive bacteria retain the crystal violet stain due to their
thick peptidoglycan cell wall.
6. The most common cause of iron-deficiency anemia is:
A. Hemolysis
B. Chronic blood loss
C. Vitamin B12 deficiency
D. Bone marrow failure
Answer: B. Chronic blood loss
Rationale: Iron deficiency usually results from inadequate dietary intake or
chronic blood loss (e.g., gastrointestinal bleeding).
, 7. Which of the following enzymes is most specific for myocardial infarction?
A. AST
B. LDH
C. Troponin I
D. CK
Answer: C. Troponin I
Rationale: Troponin I is highly specific to cardiac muscle injury and is the
preferred biomarker for myocardial infarction.
8. In urinalysis, a “cast” indicates:
A. Bacterial infection
B. Hematuria
C. Kidney tubular disease
D. Liver dysfunction
Answer: C. Kidney tubular disease
Rationale: Casts are cylindrical structures formed in renal tubules, indicating
renal pathology.
9. Which type of leukocyte is primarily responsible for allergic reactions?
A. Neutrophils
B. Basophils
C. Monocytes
D. Lymphocytes
Answer: B. Basophils
Rationale: Basophils release histamine and play a key role in allergic responses.
10. Which method is most commonly used for bacterial identification in a
clinical lab?
A. ELISA
B. PCR
C. Gram stain
D. Western blot
Practice Exam Exam 2025-2026[Complete
Exam prep Questions with verified Answers]
100%Correct Answers
1. Which of the following anticoagulants is used for coagulation studies?
A. EDTA
B. Heparin
C. Sodium citrate
D. Potassium oxalate
Answer: C. Sodium citrate
Rationale: Sodium citrate binds calcium reversibly, preventing clotting and is
the preferred anticoagulant for coagulation tests.
2. A patient’s WBC count is elevated. This condition is known as:
A. Leukopenia
B. Leukocytosis
C. Thrombocytopenia
D. Erythrocytosis
Answer: B. Leukocytosis
Rationale: Leukocytosis refers to an elevated white blood cell count, often due
to infection, inflammation, or stress.
3. The primary function of hemoglobin is to:
A. Fight infections
B. Carry oxygen
C. Form clots
D. Store iron
,Answer: B. Carry oxygen
Rationale: Hemoglobin in red blood cells binds oxygen in the lungs and delivers
it to tissues.
4. Which laboratory test is used to monitor long-term glucose control in
diabetic patients?
A. Fasting blood glucose
B. Random glucose
C. Hemoglobin A1c
D. Oral glucose tolerance test
Answer: C. Hemoglobin A1c
Rationale: Hemoglobin A1c reflects average blood glucose over the past 2–3
months.
5. Which of the following is considered a Gram-positive bacterium?
A. Escherichia coli
B. Staphylococcus aureus
C. Pseudomonas aeruginosa
D. Neisseria meningitidis
Answer: B. Staphylococcus aureus
Rationale: Gram-positive bacteria retain the crystal violet stain due to their
thick peptidoglycan cell wall.
6. The most common cause of iron-deficiency anemia is:
A. Hemolysis
B. Chronic blood loss
C. Vitamin B12 deficiency
D. Bone marrow failure
Answer: B. Chronic blood loss
Rationale: Iron deficiency usually results from inadequate dietary intake or
chronic blood loss (e.g., gastrointestinal bleeding).
, 7. Which of the following enzymes is most specific for myocardial infarction?
A. AST
B. LDH
C. Troponin I
D. CK
Answer: C. Troponin I
Rationale: Troponin I is highly specific to cardiac muscle injury and is the
preferred biomarker for myocardial infarction.
8. In urinalysis, a “cast” indicates:
A. Bacterial infection
B. Hematuria
C. Kidney tubular disease
D. Liver dysfunction
Answer: C. Kidney tubular disease
Rationale: Casts are cylindrical structures formed in renal tubules, indicating
renal pathology.
9. Which type of leukocyte is primarily responsible for allergic reactions?
A. Neutrophils
B. Basophils
C. Monocytes
D. Lymphocytes
Answer: B. Basophils
Rationale: Basophils release histamine and play a key role in allergic responses.
10. Which method is most commonly used for bacterial identification in a
clinical lab?
A. ELISA
B. PCR
C. Gram stain
D. Western blot
