AMT – Medical Laboratory Scientist (MLS) Certification Exam – QUESTIONS AND ANSWERS
| 2026/2027 LATEST UPDATE
SECTION 1: GENERAL LABORATORY
Questions 1–21
1. Which laboratory quality-control pattern is characterized by six or more consecutive
control results occurring on the same side of the established mean?
A) Shift
B) Trend
C) Random error
D) Carryover
Correct Answer: Shift
Rationale: A shift occurs when a series of control observations remains on one side of the
established mean, suggesting a persistent systematic change. A trend is a gradual movement
in one direction. Random error produces unpredictable variation, while carryover occurs
when material from one specimen influences a subsequent specimen.
2. Which calculation expresses standard deviation as a percentage of the mean?
A) Coefficient of variation
B) Reference interval
C) Mean deviation
D) Analytical sensitivity
Correct Answer: Coefficient of variation
Rationale: The coefficient of variation is calculated by dividing the standard deviation by the
mean and multiplying by 100. It allows comparison of imprecision between methods with
different means. Standard deviation alone describes absolute dispersion, whereas coefficient
of variation expresses dispersion relative to the magnitude of the measured values.
3. A laboratory method has a mean control value of 100 mg/dL and a standard
deviation of 5 mg/dL. What is the coefficient of variation?
A) 0.05%
B) 5%
C) 20%
D) 500%
Correct Answer: 5%
Rationale: Coefficient of variation equals standard deviation divided by the mean, multiplied
by 100. Here, 5 ÷ 100 × 100 equals 5%. The value therefore indicates that the method's
standard deviation represents 5% of its mean measurement, providing a useful measure of
relative imprecision.
, 4. Which organization establishes and enforces the Clinical Laboratory Improvement
Amendments requirements for laboratory testing in the United States?
A) OSHA
B) HIPAA
C) FDA
D) CMS
Correct Answer: CMS
Rationale: The Centers for Medicare & Medicaid Services administers CLIA requirements for
laboratory testing performed on human specimens. OSHA primarily addresses workplace
safety, HIPAA addresses protected health information, and the FDA regulates many medical
products and devices. CLIA establishes quality standards intended to ensure reliable
laboratory results.
5. Which information is most directly protected by HIPAA?
A) A patient's protected health information
B) The laboratory's reagent inventory
C) An analyzer's maintenance schedule
D) A centrifuge's operating speed
Correct Answer: A patient's protected health information
Rationale: HIPAA establishes requirements concerning protected health information and its
privacy and security. Patient-identifying laboratory results can constitute protected health
information. Reagent inventories, maintenance schedules, and equipment settings are
operational information and are not themselves the central subject of HIPAA's privacy
protections.
6. A chemical reagent bottle has an unfamiliar hazard symbol. What is the most
appropriate resource for determining its hazards and recommended precautions?
A) The laboratory's monthly workload report
B) The specimen accession log
C) The Safety Data Sheet
D) The patient chart
Correct Answer: The Safety Data Sheet
Rationale: A Safety Data Sheet provides standardized information about chemical hazards,
handling, storage, exposure controls, and emergency procedures. It is an essential laboratory
safety resource when working with hazardous chemicals. Patient records, workload reports,
and accession logs do not provide the required chemical-safety information.
7. Which microscope component primarily controls the amount of light reaching the
specimen?
A) Condenser iris diaphragm
, B) Ocular lens
C) Mechanical stage
D) Revolving nosepiece
Correct Answer: Condenser iris diaphragm
Rationale: The iris diaphragm regulates the diameter of the light beam entering the
specimen and therefore influences illumination and contrast. The ocular magnifies the
image, the stage supports the slide, and the nosepiece holds objective lenses. Proper
diaphragm adjustment is important for obtaining an appropriately illuminated microscopic
image.
8. Why is the oil-immersion objective used with immersion oil?
A) Oil decreases numerical aperture
B) Oil increases the refractive-index difference
C) Oil eliminates the need for focusing
D) Oil minimizes refraction between glass and the objective
Correct Answer: Oil minimizes refraction between glass and the objective
Rationale: Immersion oil has a refractive index similar to glass, reducing light refraction as
light passes from the slide into the objective. This permits more light to enter the objective
and improves resolving power. Oil does not eliminate focusing or decrease the objective's
numerical aperture.
9. Which specimen is generally preferred for coagulation testing?
A) Serum
B) Citrated plasma
C) EDTA plasma
D) Heparinized plasma
Correct Answer: Citrated plasma
Rationale: Sodium citrate is the anticoagulant routinely used for coagulation studies because
it reversibly binds calcium and permits controlled testing after recalcification. Serum lacks
clotting factors consumed during coagulation. EDTA and heparin interfere with coagulation
assays and therefore are inappropriate for routine PT and aPTT testing.
10. Which action is most likely to cause hemolysis during venipuncture?
A) Allowing alcohol to dry
B) Using an appropriately sized needle
C) Vigorous shaking of collected tubes
D) Properly mixing additive tubes
Correct Answer: Vigorous shaking of collected tubes
, Rationale: Vigorous shaking creates mechanical stress on erythrocytes and can produce
hemolysis. Additive tubes should instead be gently inverted according to the manufacturer's
instructions. Allowing alcohol to dry and selecting an appropriate needle reduce collection
problems, while proper gentle mixing promotes adequate additive distribution.
11. In the standard order of draw, which specimen is generally collected immediately
after blood cultures?
A) Light-blue citrate tube
B) Lavender EDTA tube
C) Gray fluoride/oxalate tube
D) Green heparin tube
Correct Answer: Light-blue citrate tube
Rationale: Blood cultures are generally collected first, followed by sodium citrate tubes for
coagulation studies. This sequence minimizes contamination from tube additives that could
alter test results. EDTA, heparin, and fluoride-containing tubes are collected later in the
standard sequence.
12. Which anticoagulant is used primarily for complete blood counts?
A) Sodium citrate
B) Sodium fluoride
C) EDTA
D) Lithium heparin
Correct Answer: EDTA
Rationale: EDTA preserves cellular morphology and prevents coagulation by chelating
calcium, making it the standard anticoagulant for hematology testing such as CBCs. Sodium
citrate is primarily used for coagulation studies. Fluoride is used principally to inhibit
glycolysis, while heparin is common for chemistry and blood-gas applications.
13. A blood specimen arrives unlabeled but the collector states that the patient's identity
is known. What should the laboratory do?
A) Test it because the collector confirmed the identity
B) Ask the collector to label it from memory
C) Compare it with the previous day's specimen
D) Reject the specimen according to identification policy
Correct Answer: Reject the specimen according to identification policy
Rationale: Patient identification errors can result in potentially serious clinical consequences,
especially with blood bank specimens. An unlabeled specimen generally cannot be safely
identified after collection merely through verbal confirmation. Laboratory identification
policies require appropriate labeling at collection and typically require rejection and
recollection when identification requirements are not met.
| 2026/2027 LATEST UPDATE
SECTION 1: GENERAL LABORATORY
Questions 1–21
1. Which laboratory quality-control pattern is characterized by six or more consecutive
control results occurring on the same side of the established mean?
A) Shift
B) Trend
C) Random error
D) Carryover
Correct Answer: Shift
Rationale: A shift occurs when a series of control observations remains on one side of the
established mean, suggesting a persistent systematic change. A trend is a gradual movement
in one direction. Random error produces unpredictable variation, while carryover occurs
when material from one specimen influences a subsequent specimen.
2. Which calculation expresses standard deviation as a percentage of the mean?
A) Coefficient of variation
B) Reference interval
C) Mean deviation
D) Analytical sensitivity
Correct Answer: Coefficient of variation
Rationale: The coefficient of variation is calculated by dividing the standard deviation by the
mean and multiplying by 100. It allows comparison of imprecision between methods with
different means. Standard deviation alone describes absolute dispersion, whereas coefficient
of variation expresses dispersion relative to the magnitude of the measured values.
3. A laboratory method has a mean control value of 100 mg/dL and a standard
deviation of 5 mg/dL. What is the coefficient of variation?
A) 0.05%
B) 5%
C) 20%
D) 500%
Correct Answer: 5%
Rationale: Coefficient of variation equals standard deviation divided by the mean, multiplied
by 100. Here, 5 ÷ 100 × 100 equals 5%. The value therefore indicates that the method's
standard deviation represents 5% of its mean measurement, providing a useful measure of
relative imprecision.
, 4. Which organization establishes and enforces the Clinical Laboratory Improvement
Amendments requirements for laboratory testing in the United States?
A) OSHA
B) HIPAA
C) FDA
D) CMS
Correct Answer: CMS
Rationale: The Centers for Medicare & Medicaid Services administers CLIA requirements for
laboratory testing performed on human specimens. OSHA primarily addresses workplace
safety, HIPAA addresses protected health information, and the FDA regulates many medical
products and devices. CLIA establishes quality standards intended to ensure reliable
laboratory results.
5. Which information is most directly protected by HIPAA?
A) A patient's protected health information
B) The laboratory's reagent inventory
C) An analyzer's maintenance schedule
D) A centrifuge's operating speed
Correct Answer: A patient's protected health information
Rationale: HIPAA establishes requirements concerning protected health information and its
privacy and security. Patient-identifying laboratory results can constitute protected health
information. Reagent inventories, maintenance schedules, and equipment settings are
operational information and are not themselves the central subject of HIPAA's privacy
protections.
6. A chemical reagent bottle has an unfamiliar hazard symbol. What is the most
appropriate resource for determining its hazards and recommended precautions?
A) The laboratory's monthly workload report
B) The specimen accession log
C) The Safety Data Sheet
D) The patient chart
Correct Answer: The Safety Data Sheet
Rationale: A Safety Data Sheet provides standardized information about chemical hazards,
handling, storage, exposure controls, and emergency procedures. It is an essential laboratory
safety resource when working with hazardous chemicals. Patient records, workload reports,
and accession logs do not provide the required chemical-safety information.
7. Which microscope component primarily controls the amount of light reaching the
specimen?
A) Condenser iris diaphragm
, B) Ocular lens
C) Mechanical stage
D) Revolving nosepiece
Correct Answer: Condenser iris diaphragm
Rationale: The iris diaphragm regulates the diameter of the light beam entering the
specimen and therefore influences illumination and contrast. The ocular magnifies the
image, the stage supports the slide, and the nosepiece holds objective lenses. Proper
diaphragm adjustment is important for obtaining an appropriately illuminated microscopic
image.
8. Why is the oil-immersion objective used with immersion oil?
A) Oil decreases numerical aperture
B) Oil increases the refractive-index difference
C) Oil eliminates the need for focusing
D) Oil minimizes refraction between glass and the objective
Correct Answer: Oil minimizes refraction between glass and the objective
Rationale: Immersion oil has a refractive index similar to glass, reducing light refraction as
light passes from the slide into the objective. This permits more light to enter the objective
and improves resolving power. Oil does not eliminate focusing or decrease the objective's
numerical aperture.
9. Which specimen is generally preferred for coagulation testing?
A) Serum
B) Citrated plasma
C) EDTA plasma
D) Heparinized plasma
Correct Answer: Citrated plasma
Rationale: Sodium citrate is the anticoagulant routinely used for coagulation studies because
it reversibly binds calcium and permits controlled testing after recalcification. Serum lacks
clotting factors consumed during coagulation. EDTA and heparin interfere with coagulation
assays and therefore are inappropriate for routine PT and aPTT testing.
10. Which action is most likely to cause hemolysis during venipuncture?
A) Allowing alcohol to dry
B) Using an appropriately sized needle
C) Vigorous shaking of collected tubes
D) Properly mixing additive tubes
Correct Answer: Vigorous shaking of collected tubes
, Rationale: Vigorous shaking creates mechanical stress on erythrocytes and can produce
hemolysis. Additive tubes should instead be gently inverted according to the manufacturer's
instructions. Allowing alcohol to dry and selecting an appropriate needle reduce collection
problems, while proper gentle mixing promotes adequate additive distribution.
11. In the standard order of draw, which specimen is generally collected immediately
after blood cultures?
A) Light-blue citrate tube
B) Lavender EDTA tube
C) Gray fluoride/oxalate tube
D) Green heparin tube
Correct Answer: Light-blue citrate tube
Rationale: Blood cultures are generally collected first, followed by sodium citrate tubes for
coagulation studies. This sequence minimizes contamination from tube additives that could
alter test results. EDTA, heparin, and fluoride-containing tubes are collected later in the
standard sequence.
12. Which anticoagulant is used primarily for complete blood counts?
A) Sodium citrate
B) Sodium fluoride
C) EDTA
D) Lithium heparin
Correct Answer: EDTA
Rationale: EDTA preserves cellular morphology and prevents coagulation by chelating
calcium, making it the standard anticoagulant for hematology testing such as CBCs. Sodium
citrate is primarily used for coagulation studies. Fluoride is used principally to inhibit
glycolysis, while heparin is common for chemistry and blood-gas applications.
13. A blood specimen arrives unlabeled but the collector states that the patient's identity
is known. What should the laboratory do?
A) Test it because the collector confirmed the identity
B) Ask the collector to label it from memory
C) Compare it with the previous day's specimen
D) Reject the specimen according to identification policy
Correct Answer: Reject the specimen according to identification policy
Rationale: Patient identification errors can result in potentially serious clinical consequences,
especially with blood bank specimens. An unlabeled specimen generally cannot be safely
identified after collection merely through verbal confirmation. Laboratory identification
policies require appropriate labeling at collection and typically require rejection and
recollection when identification requirements are not met.
