Principles of Serologic Reactions – Precipitation and Agglutination

Question 1

What is the definition of serology?
A. Study of bacteria in blood
B. Study of antigen-antibody reactions in vitro
C. Study of immune cells in tissues
D. Study of viral replication

Answer 1

B

Question 2

Which antibody is most effective in precipitation reactions?
A. IgA
B. IgE
C. IgG
D. IgM

Answer 2

C

Question 3

What does the zone of equivalence in a precipitation reaction indicate?
A. Antibody excess
B. Antigen excess
C. Optimal antigen-antibody ratio
D. No reaction

Answer 3

C

Question 4

Which technique uses radial diffusion of antigen into antibody-containing gel?
A. Ouchterlony
B. James Oudin Test
C. Radial Immunodiffusion (RID)
D. Immunoelectrophoresis

Answer 4

C

Question 5

What is the most effective antibody in agglutination reactions?
A. IgA
B. IgE
C. IgG
D. IgM

Answer 5

D

Question 6

Which stage of serologic reaction involves visible complex formation like precipitation or agglutination?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary

Answer 6

B

Question 7

What term describes the strength of binding between a single antigenic determinant and an antibody site?
A. Avidity
B. Affinity
C. Specificity
D. Valency

Answer 7

B

Question 8

In the Ouchterlony test, crossed lines between wells indicate:
A. Identity
B. Partial identity
C. Non-identity
D. No reaction

Answer 8

C

Question 9

Which agglutination technique is used to detect antigens by attaching antibodies to particles?
A. Passive agglutination
B. Direct agglutination
C. Reverse passive agglutination
D. Coagglutination

Answer 9

C

Question 10

What is the purpose of using proteolytic enzymes in agglutination tests?
A. Increase antigen production
B. Enhance antibody affinity
C. Reduce zeta potential
D. Create antigen-antibody complexes

Answer 10

C

Question 11

What test uses Staphylococcus aureus binding to IgG’s Fc region for antigen detection?
A. Immunoelectrophoresis
B. Coagglutination
C. Agglutination inhibition
D. Ouchterlony

Answer 11

B

Question 12

In agglutination inhibition, a positive result means:
A. Agglutination occurs
B. No agglutination
C. Hemolysis
D. Precipitation

Answer 12

B

Question 13

What is the lattice formation in serologic reactions dependent on?
A. Molecular weight of antigen
B. Ionic charge of antibody
C. Ratio of antigen to antibody
D. pH of the medium

Answer 13

C

Question 14

What factor can affect the sensitivity of a precipitation reaction?
A. Temperature only
B. Antibody class only
C. Ionic strength of solution
D. Color of reactants

Answer 14

C

Question 15

What is the principle of the radial immunodiffusion (RID) test?
A. Antigen and antibody migrate toward each other
B. Antibody diffuses into agar containing antigen
C. Antigen diffuses into agar containing antibody
D. Electrophoresis of antigen

Answer 15

C

Question 16

Which immunodiffusion method can compare multiple antigen-antibody interactions simultaneously?
A. Radial Immunodiffusion
B. Ouchterlony Double Diffusion
C. Immunoelectrophoresis
D. Single Immunodiffusion

Answer 16

B

Question 17

What is the most commonly used support medium for precipitation reactions?
A. Cellulose
B. Agarose
C. Polyvinyl
D. Nitrocellulose

Answer 17

B

Question 18

In immunoelectrophoresis, what enhances the resolution of antigen separation?
A. Temperature control
B. Use of antibodies from different species
C. Application of electric current
D. Longer incubation

Answer 18

C

Question 19

What is the main advantage of agglutination over precipitation reactions?
A. Requires more antigen
B. Faster visible results
C. Requires electrophoresis
D. Only works with proteins

Answer 19

B

Question 20

Which test format is commonly used for detecting soluble antigens using coated latex beads?
A. Passive agglutination
B. Direct agglutination
C. Coagglutination
D. Precipitation ring test

Answer 20

A

Question 21

What does a line of identity in Ouchterlony double diffusion indicate?
A. Antigens are unrelated
B. Antigens share some epitopes
C. Antigens are immunologically identical
D. No antibodies are present

Answer 21

C

Question 22

In serologic testing, what is the role of zeta potential?
A. Increases antigen solubility
B. Enhances agglutination by attracting cells
C. Repels negatively charged cells
D. Forms immune complexes

Answer 22

C

Question 23

What is an indicator of a positive precipitation reaction in gel?
A. Color change
B. Visible ring or band
C. Hemolysis
D. Increase in temperature

Answer 23

B

Question 24

Which component is not necessary for a precipitation reaction to occur?
A. Antigen
B. Antibody
C. Enzyme label
D. Suitable medium (e.g., agar)

Answer 24

C

Question 25

What does high avidity indicate in an antigen-antibody interaction? A. Weak binding of one antibody site B. Strong overall binding of multiple sites C. No reaction will occur D. Reaction is irreversible

Answer 25

B

Question 26

Which of the following is a two-stage serologic reaction? A. Precipitation B. Agglutination C. Immunoelectrophoresis D. Both A and B

Answer 26

D

Question 27

Which method uses electric current to separate antigens before diffusion into antibody-containing gel? A. Ouchterlony B. Immunoelectrophoresis C. Radial Immunodiffusion D. Passive Agglutination

Answer 27

B

Question 28

What is indicated by a spur formation in Ouchterlony testing? A. Identity B. Non-identity C. Partial identity D. Inconclusive result

Answer 28

C

Question 29

What effect does antibody excess (prozone) have on serologic reactions? A. Enhances reaction B. No visible reaction C. Maximizes lattice formation D. Causes hemolysis

Answer 29

B

Question 30

Which of the following best describes the postzone effect? A. Excess antigen prevents lattice formation B. Excess antibody enhances agglutination C. No antigen present D. High temperature enhances reaction

Answer 30

A