MLS 413 - Final Exam Questions and Answers Fully Solved Latest Update 2025-2026
affinity (antigen-antibody binding) - Answers the initial force of attraction that exists between Fab site
on an antibody molecule and a single epitope on an antigen
-strength of attraction depends on specificity of antibody for antigen (ex: cross reacting antigens have
lower affinity)
avidity (antigen-antibody binding) - Answers sum of attractive forces between an antigen and antibody;
the strength with which a multivalent antibody binds a multivalent antigen
precipitation - Answers when a soluble antigen is combined with a soluble antibody to produce insoluble
compounds that are visible
-requires antibody and antigen to have multiple binding sites for one another and equivalent
concentrations
agglutination - Answers visible aggregation of particles resulting from combination with specific
antibodies
-two step process: sensitization and lattice formation
-*sensitization*: antigen and antibody unite through binding of antigenic determinant sites (fast and
reversible)
-*lattice formation*: visble aggregates form as multiple antigen and antibody molecules bind to create a
stable lattice
-produced by antibodies called *agglutinins*
agglutination inhibition - Answers an agglutination rxn based on competition between antigen-coated
particles and soluble patient antigens for a limited number of antibody-combining sites
-lack of agglutination is a positive test result
-used to detect hapten antigens (illicit drugs)
precipitation curve - Answers -zone of equivalence
-prozone phenomenon
-postzone phenomenon
immunoturbidemetry - Answers a technique for determining the concentration of particles in a solution
based on the change in abs caused by a reduction in light intensity that occurs when an incident beam is
passed through a soln in which antigen-antibody complexes are forming
-measurement of ppt reactions
,nephelometry - Answers a technique for determining the concentration of particles in a solution by
measuring the light scattered at a particular angle from the incident beam as it passes through the
solution
-measurement of ppt reaction
-sens: 1010 micrograms Ab/mL
radial immunodiffusion (RID) - Answers serological test detecting the precipitate of Ag:Ab complexes in
which antigen is placed into a well and allowed to diffuse outward in all directions; precipitate formation
will be in a ring, and the thickness of the ring is proportional to the concentration of antigen
-*end point method*: allows reaction to go to completion, so the square of diameter is proportional to
antigen conc
-*kinetic method*: faster and measurement is taken before rxn is complete
-measurement of ppt reaction
immunofixation electrophoresis - Answers double diffusion technique where proteins in pt serum are
electrophoresed then Ab is applied directly to the gel. ppt forms where Ag-Ab combination has taken
place
-performed to visualize decr/incr production of Ab classes and to differentiated monoclonal and
polyclonal Igs
-variable sensitivity
-measurement of ppt reaction
ouchterlony diffusion - Answers double diffusion technique where wells are cut into gel and both Ag and
Ab diffuse out radially. a line of ppt forms where Ag and Ab meet in equiv amts
-3 possible patterns
-*identity*: if the Ag are identical they will react with the same Ab and the ppt line forms a continuous
arc
-*nonidentity*: Ag share no identical determinants and will react with different Abs and two crossed
lines are formed
-*partial identity*: Abs react with two similar Ag forming 2 lines and a spur that points to the similar Ag
direct agglutination - Answers patient serum is reacted with Ag that is naturally found on a particle to
test for Abs in pt serum
-ex: ABO typing and hemagglutination
, -agglutination indicated the presence of pt Ab to a natural Ag
passive (Indirect) agglutination - Answers uses particles that are coated with Ag that are not normally
found on their surfaces. Ag is attached to the carrier particle and agglutination occurs if pt Ab is present
-ex tests for: rheumatoid factor, Abs to viruses such as rubella, Abs to group A strept Ag
reverse passive agglutination - Answers Ab is attached to carrier particle and agglutination occurs if Ag is
present in pt sample
-common applications: rapid ID of Ag from infectious agents, detecting soluble Ag in urine, SF, and
serum
IgM agglutination rxn - Answers most efficient Ig with agglutination and best reacts between 4-27
degrees Celsius
IgG agglutination rxn - Answers often can't bridge the distance between particles because of their small
size so used with enhancement techniques and agglutinated best at 30-37 degrees celsius
-require use of second Ab, Coombs reagent which attached to Fc portion of IgG and helps to bridge gap
between RBCs so a visible agglutination reaction can occur
competitive immunoassay - Answers patient Ag competes with labeled Ag (Ag*) for limited Ab binding
sites. final detected signal is Ag*Ab
-inverse ratio, so the more pt Ag is present the less label is detected
noncompetitive/indirect ELISA for Ab detection - Answers excess solid phase Ag binds pt Ab and a
second labeled Ab (anti-human Ig) is added
-all pt Ab is allowed to bind
-amount of label is directly proportional to the amount of pt Ab present
homogenous enzyme immunoassay - Answers pt Ag and labelled Ag react with reagent Ab in solution.
enzyme label is inactivated when reagent Ag binds to Ab
-no physical separation step of bound and labeled Ag required
-pt Ag conc is directly proportional to the signal (measurable loss of enzyme activity)
-used to determine low-molecular-wt analytes in serum and urine
heterogenous enzyme immunoassay - Answers immunoassay in which enzyme is used as a label and
which requires a separation step to separate free from bound analyte.
-includes both competitive and noncompetitive immunoassay designs
affinity (antigen-antibody binding) - Answers the initial force of attraction that exists between Fab site
on an antibody molecule and a single epitope on an antigen
-strength of attraction depends on specificity of antibody for antigen (ex: cross reacting antigens have
lower affinity)
avidity (antigen-antibody binding) - Answers sum of attractive forces between an antigen and antibody;
the strength with which a multivalent antibody binds a multivalent antigen
precipitation - Answers when a soluble antigen is combined with a soluble antibody to produce insoluble
compounds that are visible
-requires antibody and antigen to have multiple binding sites for one another and equivalent
concentrations
agglutination - Answers visible aggregation of particles resulting from combination with specific
antibodies
-two step process: sensitization and lattice formation
-*sensitization*: antigen and antibody unite through binding of antigenic determinant sites (fast and
reversible)
-*lattice formation*: visble aggregates form as multiple antigen and antibody molecules bind to create a
stable lattice
-produced by antibodies called *agglutinins*
agglutination inhibition - Answers an agglutination rxn based on competition between antigen-coated
particles and soluble patient antigens for a limited number of antibody-combining sites
-lack of agglutination is a positive test result
-used to detect hapten antigens (illicit drugs)
precipitation curve - Answers -zone of equivalence
-prozone phenomenon
-postzone phenomenon
immunoturbidemetry - Answers a technique for determining the concentration of particles in a solution
based on the change in abs caused by a reduction in light intensity that occurs when an incident beam is
passed through a soln in which antigen-antibody complexes are forming
-measurement of ppt reactions
,nephelometry - Answers a technique for determining the concentration of particles in a solution by
measuring the light scattered at a particular angle from the incident beam as it passes through the
solution
-measurement of ppt reaction
-sens: 1010 micrograms Ab/mL
radial immunodiffusion (RID) - Answers serological test detecting the precipitate of Ag:Ab complexes in
which antigen is placed into a well and allowed to diffuse outward in all directions; precipitate formation
will be in a ring, and the thickness of the ring is proportional to the concentration of antigen
-*end point method*: allows reaction to go to completion, so the square of diameter is proportional to
antigen conc
-*kinetic method*: faster and measurement is taken before rxn is complete
-measurement of ppt reaction
immunofixation electrophoresis - Answers double diffusion technique where proteins in pt serum are
electrophoresed then Ab is applied directly to the gel. ppt forms where Ag-Ab combination has taken
place
-performed to visualize decr/incr production of Ab classes and to differentiated monoclonal and
polyclonal Igs
-variable sensitivity
-measurement of ppt reaction
ouchterlony diffusion - Answers double diffusion technique where wells are cut into gel and both Ag and
Ab diffuse out radially. a line of ppt forms where Ag and Ab meet in equiv amts
-3 possible patterns
-*identity*: if the Ag are identical they will react with the same Ab and the ppt line forms a continuous
arc
-*nonidentity*: Ag share no identical determinants and will react with different Abs and two crossed
lines are formed
-*partial identity*: Abs react with two similar Ag forming 2 lines and a spur that points to the similar Ag
direct agglutination - Answers patient serum is reacted with Ag that is naturally found on a particle to
test for Abs in pt serum
-ex: ABO typing and hemagglutination
, -agglutination indicated the presence of pt Ab to a natural Ag
passive (Indirect) agglutination - Answers uses particles that are coated with Ag that are not normally
found on their surfaces. Ag is attached to the carrier particle and agglutination occurs if pt Ab is present
-ex tests for: rheumatoid factor, Abs to viruses such as rubella, Abs to group A strept Ag
reverse passive agglutination - Answers Ab is attached to carrier particle and agglutination occurs if Ag is
present in pt sample
-common applications: rapid ID of Ag from infectious agents, detecting soluble Ag in urine, SF, and
serum
IgM agglutination rxn - Answers most efficient Ig with agglutination and best reacts between 4-27
degrees Celsius
IgG agglutination rxn - Answers often can't bridge the distance between particles because of their small
size so used with enhancement techniques and agglutinated best at 30-37 degrees celsius
-require use of second Ab, Coombs reagent which attached to Fc portion of IgG and helps to bridge gap
between RBCs so a visible agglutination reaction can occur
competitive immunoassay - Answers patient Ag competes with labeled Ag (Ag*) for limited Ab binding
sites. final detected signal is Ag*Ab
-inverse ratio, so the more pt Ag is present the less label is detected
noncompetitive/indirect ELISA for Ab detection - Answers excess solid phase Ag binds pt Ab and a
second labeled Ab (anti-human Ig) is added
-all pt Ab is allowed to bind
-amount of label is directly proportional to the amount of pt Ab present
homogenous enzyme immunoassay - Answers pt Ag and labelled Ag react with reagent Ab in solution.
enzyme label is inactivated when reagent Ag binds to Ab
-no physical separation step of bound and labeled Ag required
-pt Ag conc is directly proportional to the signal (measurable loss of enzyme activity)
-used to determine low-molecular-wt analytes in serum and urine
heterogenous enzyme immunoassay - Answers immunoassay in which enzyme is used as a label and
which requires a separation step to separate free from bound analyte.
-includes both competitive and noncompetitive immunoassay designs
