MEDICAL LABORATORY SCIENCE
REVIEW EXAM 2025/2026 QUESTIONS
AND ANSWERS 100% PASS.
What formulas correctly describes the relationship between absorbance and %T? - ANS A=
2-log %T
A = log 1/T
A = -log T
A solution that has a transmittance of 1.0 would have an absorbance of.. - ANS 2.0
In absorption spectrophotometry... - ANS Absorbance is directly proportional to
transmittance
Which wavelength would be absorbed strongly by a red-colored solution? - ANS 450 nm
A green colored solution would show highest transmittance at... - ANS 525 nm
A tech is performing an enzyme assay at 340 nm using a visible-range spectrophotometer. After
setting the wavelength and sdjusting the readout to zero %T with the light path blocked, a
cuvette with deionized whater is inserted. With the light path fully open and the 100% T control
at maximum, the instrument readout will not rise about 90%T. What is the most appropriate
first course of action? - ANS Replace the source lamp
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,Which type of monochromater produces the purest monochromatic light in the UV range? -
ANS A prism and variable exit slit
Which monochromator specification is required in order to measure the true absorbance of a
compound having a natural absorption bandwidth of 30 nm? - ANS 5-nm bandpass
Which photodetector is most sensitive to low levels of light? - ANS Photomultiplier tube
Which condition is a common cause of stray light? - ANS Dispersion from second-order
spectra
What is the most common cause of loss of linearity at high-analyte concentrations? -
ANS Stray light
Which type of filteris best for measuring stray light? - ANS Sharp cutoff
Which of the following materials is best suited for verifying the wavelength calibration of a
spectrophotometer? - ANS Holmium oxide glass
Why do many optical systems in chemistry analyzers utilize a reference light path? - ANS To
minimize error caused by source lamp fluctuation
Which component is required in a spectrophotometer in order to produce a spectral
absorbance curve? - ANS Photodiode array
The half-band width of a monochromator is defined by - ANS the range of the wavelengths
passed at 50% transmittance
The reagent blank corrects for absorbance caused by - ANS the color of reagents
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,A plasma sample is hemolyzed and turbid. What is required to perform a sample blank in order
to correct the measurement for the intrinsic absorbance of the sample when performing a
spectrophotometric assay? - ANS Substitute saline for the reagent
Which instrument requires a highly regulared DC power supply? - ANS A spectrophotometer
with a photomultiplier tube
Which statement regarding reflectometry is true? - ANS 100% reflectance is set with an
opaque film called a white reference
Bichromatic measurement of absorbance can correct for interfering substances if - ANS The
concentration of the interferent to absorbance is the same at both wavelengths
Which instrument requires a primary and secondary monochromator? - ANS Fluorometer
Which of the following statements about fluorometry is accurate? - ANS Unsaturated cyclic
molecules are often fluorescent
Which of the following components is not needed in a chemiluminescent immunoassay
analyzer? - ANS Source lamp
Which substance is used to generate the light signal in electochemiluminescence? -
ANS Ruthenium
Light scattering when the wavelength is greater than 10 times the particle diameter is described
by - ANS Rayleigh's law
Which statement regarding nephelometry is true? - ANS The detector response is directly
proportional to concentration
The purpose of the nebulizer in an atomic absorption spectrophotometer that uses a flame is to
- ANS convert ions to atoms
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, A flameless atomic absorption spectrophotometer dhydrates and atomizes a sample using -
ANS A graphite capillary furnace
When measuring lead in whole blood using atomic absorption spectrophotometry, what
reagent is required to obtain the needed sensitivity and precision? - ANS triton-X-100
Interference in atomic absorption spectrophotometery caused by differences in viscosity is
called - ANS Matrix effect
All of the following are required when measuring magnesium by atomic absorption
spectrophotometry except - ANS A 285 nm reference beam to correct for background
absorption
When measuring calcium by atomic absorption spectrophotometry, which is required -
ANS Lanthanum oxide to chelate phosphates
Ion selective analyzers using undiluted samples have what advantage over analyzers that use a
diluted sample - ANS Are not subject to pseudohyponatremia caused by high lipids
Select the equation describing the potential that develops at the surface of an ion-selective
electrode is determined by the - ANS Concentration of the potassium chloride filling solution
The term RT/nF in the Nernst equation defines the Slope of the electrode -
ANS Concentration of the potassium chloride filling solution
The ion-selective membrane used tho measure potassium is made of - ANS Valinomycin gel
The response of a sodium electrode to a to-fold increase in sodium concentration should be -
ANS An increase in potential of approximately 60 mV
4 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
REVIEW EXAM 2025/2026 QUESTIONS
AND ANSWERS 100% PASS.
What formulas correctly describes the relationship between absorbance and %T? - ANS A=
2-log %T
A = log 1/T
A = -log T
A solution that has a transmittance of 1.0 would have an absorbance of.. - ANS 2.0
In absorption spectrophotometry... - ANS Absorbance is directly proportional to
transmittance
Which wavelength would be absorbed strongly by a red-colored solution? - ANS 450 nm
A green colored solution would show highest transmittance at... - ANS 525 nm
A tech is performing an enzyme assay at 340 nm using a visible-range spectrophotometer. After
setting the wavelength and sdjusting the readout to zero %T with the light path blocked, a
cuvette with deionized whater is inserted. With the light path fully open and the 100% T control
at maximum, the instrument readout will not rise about 90%T. What is the most appropriate
first course of action? - ANS Replace the source lamp
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,Which type of monochromater produces the purest monochromatic light in the UV range? -
ANS A prism and variable exit slit
Which monochromator specification is required in order to measure the true absorbance of a
compound having a natural absorption bandwidth of 30 nm? - ANS 5-nm bandpass
Which photodetector is most sensitive to low levels of light? - ANS Photomultiplier tube
Which condition is a common cause of stray light? - ANS Dispersion from second-order
spectra
What is the most common cause of loss of linearity at high-analyte concentrations? -
ANS Stray light
Which type of filteris best for measuring stray light? - ANS Sharp cutoff
Which of the following materials is best suited for verifying the wavelength calibration of a
spectrophotometer? - ANS Holmium oxide glass
Why do many optical systems in chemistry analyzers utilize a reference light path? - ANS To
minimize error caused by source lamp fluctuation
Which component is required in a spectrophotometer in order to produce a spectral
absorbance curve? - ANS Photodiode array
The half-band width of a monochromator is defined by - ANS the range of the wavelengths
passed at 50% transmittance
The reagent blank corrects for absorbance caused by - ANS the color of reagents
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,A plasma sample is hemolyzed and turbid. What is required to perform a sample blank in order
to correct the measurement for the intrinsic absorbance of the sample when performing a
spectrophotometric assay? - ANS Substitute saline for the reagent
Which instrument requires a highly regulared DC power supply? - ANS A spectrophotometer
with a photomultiplier tube
Which statement regarding reflectometry is true? - ANS 100% reflectance is set with an
opaque film called a white reference
Bichromatic measurement of absorbance can correct for interfering substances if - ANS The
concentration of the interferent to absorbance is the same at both wavelengths
Which instrument requires a primary and secondary monochromator? - ANS Fluorometer
Which of the following statements about fluorometry is accurate? - ANS Unsaturated cyclic
molecules are often fluorescent
Which of the following components is not needed in a chemiluminescent immunoassay
analyzer? - ANS Source lamp
Which substance is used to generate the light signal in electochemiluminescence? -
ANS Ruthenium
Light scattering when the wavelength is greater than 10 times the particle diameter is described
by - ANS Rayleigh's law
Which statement regarding nephelometry is true? - ANS The detector response is directly
proportional to concentration
The purpose of the nebulizer in an atomic absorption spectrophotometer that uses a flame is to
- ANS convert ions to atoms
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, A flameless atomic absorption spectrophotometer dhydrates and atomizes a sample using -
ANS A graphite capillary furnace
When measuring lead in whole blood using atomic absorption spectrophotometry, what
reagent is required to obtain the needed sensitivity and precision? - ANS triton-X-100
Interference in atomic absorption spectrophotometery caused by differences in viscosity is
called - ANS Matrix effect
All of the following are required when measuring magnesium by atomic absorption
spectrophotometry except - ANS A 285 nm reference beam to correct for background
absorption
When measuring calcium by atomic absorption spectrophotometry, which is required -
ANS Lanthanum oxide to chelate phosphates
Ion selective analyzers using undiluted samples have what advantage over analyzers that use a
diluted sample - ANS Are not subject to pseudohyponatremia caused by high lipids
Select the equation describing the potential that develops at the surface of an ion-selective
electrode is determined by the - ANS Concentration of the potassium chloride filling solution
The term RT/nF in the Nernst equation defines the Slope of the electrode -
ANS Concentration of the potassium chloride filling solution
The ion-selective membrane used tho measure potassium is made of - ANS Valinomycin gel
The response of a sodium electrode to a to-fold increase in sodium concentration should be -
ANS An increase in potential of approximately 60 mV
4 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
