CMLTE Clinical Chemistry & Instrumentation exam
practice questions and correct answers (verified
answers) plus rationales 2025/2026
1. Which of the following is the primary function of the liver in clinical chemistry?
A. Production of insulin
B. Detoxification of drugs and metabolites
C. Regulation of blood pressure
D. Filtration of urine
Answer: B. Detoxification of drugs and metabolites
Rationale: The liver metabolizes drugs and toxic substances, making them easier to excrete.
Insulin is produced by the pancreas, and blood filtration occurs in the kidneys.
2. The reagent commonly used in the Jaffe reaction for creatinine measurement is:
A. Picric acid
B. Phenol
C. Bromcresol green
D. Nessler’s reagent
Answer: A. Picric acid
Rationale: The Jaffe reaction is a colorimetric method in which creatinine reacts with picric acid
in an alkaline medium to form a colored complex.
3. Which of the following instruments measures absorbance of light in clinical chemistry?
A. Flame photometer
B. Spectrophotometer
C. Centrifuge
D. Electrophoresis apparatus
,Answer: B. Spectrophotometer
Rationale: Spectrophotometers quantify the concentration of substances by measuring light
absorbance at specific wavelengths.
4. What is the principle of an ion-selective electrode (ISE) used in electrolyte measurement?
A. Color change of a reagent
B. Generation of a voltage proportional to ion activity
C. Precipitation of ions
D. Absorption of light at a specific wavelength
Answer: B. Generation of a voltage proportional to ion activity
Rationale: ISEs measure the potential difference created by selective binding of ions to the
electrode membrane, which is proportional to ion concentration.
5. Which of the following is the most accurate method for glucose measurement in clinical
chemistry?
A. Benedict’s test
B. Glucose oxidase-peroxidase method
C. Fehling’s test
D. Seliwanoff’s test
Answer: B. Glucose oxidase-peroxidase method
Rationale: The glucose oxidase-peroxidase (GOD-POD) enzymatic method is highly specific and
widely used in automated clinical analyzers.
6. In spectrophotometry, Beer-Lambert law states that:
A. Absorbance is inversely proportional to concentration
B. Absorbance is directly proportional to concentration and path length
C. Transmittance is independent of concentration
D. Absorbance is constant for all wavelengths
Answer: B. Absorbance is directly proportional to concentration and path length
Rationale: According to Beer-Lambert law, A = εcl, where A is absorbance, ε is molar
absorptivity, c is concentration, and l is path length.
, 7. Which of the following is an enzyme commonly measured as a marker for myocardial
infarction?
A. AST (Aspartate transaminase)
B. ALP (Alkaline phosphatase)
C. CK-MB (Creatine kinase-MB)
D. Amylase
Answer: C. CK-MB (Creatine kinase-MB)
Rationale: CK-MB is specific for cardiac muscle damage and is a standard biomarker for
myocardial infarction.
8. The main purpose of calibration in clinical chemistry instruments is to:
A. Clean the instrument
B. Adjust the instrument to produce accurate results
C. Increase the speed of analysis
D. Reduce sample volume
Answer: B. Adjust the instrument to produce accurate results
Rationale: Calibration ensures that instrument readings correspond to known standard values,
improving accuracy and reliability of results.
9. Which electrolyte is measured using flame photometry?
A. Calcium and magnesium
B. Sodium and potassium
C. Chloride and bicarbonate
D. Phosphate and sulfate
Answer: B. Sodium and potassium
Rationale: Flame photometry determines the concentration of certain metal ions, especially
sodium and potassium, based on the emission of light at specific wavelengths.
10. Which of the following is a common interferent in bilirubin measurement?
A. Hemolysis
B. Lipemia
practice questions and correct answers (verified
answers) plus rationales 2025/2026
1. Which of the following is the primary function of the liver in clinical chemistry?
A. Production of insulin
B. Detoxification of drugs and metabolites
C. Regulation of blood pressure
D. Filtration of urine
Answer: B. Detoxification of drugs and metabolites
Rationale: The liver metabolizes drugs and toxic substances, making them easier to excrete.
Insulin is produced by the pancreas, and blood filtration occurs in the kidneys.
2. The reagent commonly used in the Jaffe reaction for creatinine measurement is:
A. Picric acid
B. Phenol
C. Bromcresol green
D. Nessler’s reagent
Answer: A. Picric acid
Rationale: The Jaffe reaction is a colorimetric method in which creatinine reacts with picric acid
in an alkaline medium to form a colored complex.
3. Which of the following instruments measures absorbance of light in clinical chemistry?
A. Flame photometer
B. Spectrophotometer
C. Centrifuge
D. Electrophoresis apparatus
,Answer: B. Spectrophotometer
Rationale: Spectrophotometers quantify the concentration of substances by measuring light
absorbance at specific wavelengths.
4. What is the principle of an ion-selective electrode (ISE) used in electrolyte measurement?
A. Color change of a reagent
B. Generation of a voltage proportional to ion activity
C. Precipitation of ions
D. Absorption of light at a specific wavelength
Answer: B. Generation of a voltage proportional to ion activity
Rationale: ISEs measure the potential difference created by selective binding of ions to the
electrode membrane, which is proportional to ion concentration.
5. Which of the following is the most accurate method for glucose measurement in clinical
chemistry?
A. Benedict’s test
B. Glucose oxidase-peroxidase method
C. Fehling’s test
D. Seliwanoff’s test
Answer: B. Glucose oxidase-peroxidase method
Rationale: The glucose oxidase-peroxidase (GOD-POD) enzymatic method is highly specific and
widely used in automated clinical analyzers.
6. In spectrophotometry, Beer-Lambert law states that:
A. Absorbance is inversely proportional to concentration
B. Absorbance is directly proportional to concentration and path length
C. Transmittance is independent of concentration
D. Absorbance is constant for all wavelengths
Answer: B. Absorbance is directly proportional to concentration and path length
Rationale: According to Beer-Lambert law, A = εcl, where A is absorbance, ε is molar
absorptivity, c is concentration, and l is path length.
, 7. Which of the following is an enzyme commonly measured as a marker for myocardial
infarction?
A. AST (Aspartate transaminase)
B. ALP (Alkaline phosphatase)
C. CK-MB (Creatine kinase-MB)
D. Amylase
Answer: C. CK-MB (Creatine kinase-MB)
Rationale: CK-MB is specific for cardiac muscle damage and is a standard biomarker for
myocardial infarction.
8. The main purpose of calibration in clinical chemistry instruments is to:
A. Clean the instrument
B. Adjust the instrument to produce accurate results
C. Increase the speed of analysis
D. Reduce sample volume
Answer: B. Adjust the instrument to produce accurate results
Rationale: Calibration ensures that instrument readings correspond to known standard values,
improving accuracy and reliability of results.
9. Which electrolyte is measured using flame photometry?
A. Calcium and magnesium
B. Sodium and potassium
C. Chloride and bicarbonate
D. Phosphate and sulfate
Answer: B. Sodium and potassium
Rationale: Flame photometry determines the concentration of certain metal ions, especially
sodium and potassium, based on the emission of light at specific wavelengths.
10. Which of the following is a common interferent in bilirubin measurement?
A. Hemolysis
B. Lipemia
