CHAPTER 10: Precipitation and Agglutination Reactions

Question 1

In a precipitation reaction, how can the ideal antibody be characterized?
a. Low affinity and low avidity
b. High affinity and low avidity
c. High affinity and high avidity
d. Low affinity and high avidity

Answer 1

c. High affinity and high avidity

Question 2

Precipitation differs from agglutination in which way?
a. Precipitation can only be measured by an automated instrument.
b. Precipitation occurs with univalent antigen, whereas agglutination requires multivalent antigen.
c. Precipitation does not readily occur because few antibodies can form aggregates with antigen.
d. Precipitation involves a soluble antigen, whereas agglutination involves a particulate antigen.

Answer 2

d. Precipitation involves a soluble antigen, whereas agglutination involves a particulate antigen.

Question 3

When soluble antigens diffuse in a gel that contains antibody, in which zone does optimum precipitation occur?
a. Prozone
b. Zone of equivalence
c. Postzone
d. Prezone

Answer 3

b. Zone of equivalence

Question 4

Which of the following statements apply to rate nephelometry?
a. Readings are taken before equivalence is reached.
b. It is more sensitive than turbidity.
c. Measurements are time dependent.
d. All of the above.

Answer 4

d. All of the above.

Question 5

Which of the following is characteristic of the endpoint method of RID?
a. Readings are taken before equivalence.
b. Concentration is directly in proportion to the square of the diameter.
c. The diameter is plotted against the log of the concentration.
d. It is primarily a qualitative rather than a quantitative method.

Answer 5

b. Concentration is directly in proportion to the square of the diameter.

Question 6

In which zone might an antibody-screening test be false negative?
a. Prozone
b. Zone of equivalence
c. Postzone
d. None of the above

Answer 6

a. Prozone

Question 7

How does measurement of turbidity differ from nephelometry?
a. Turbidity measures the increase in light after it passes through a solution.
b. Nephelometry measures light that is scattered at an angle.
c. Turbidity deals with univalent antigens only.
d. Nephelometry is not affected by large particles falling out of solution.

Answer 7

b. Nephelometry measures light that is scattered at an angle.

Question 8

Which of the following refers to the force of attraction between an antibody and a single antigenic determinant?
a. Affinity
b. Avidity
c. Van der Waals attraction
d. Covalence

Answer 8

a. Affinity

Question 9

Immunofixation electrophoresis differs from immunoelectrophoresis in which way?
a. Electrophoresis takes place after diffusion has occurred in immunofixation electrophoresis.
b. Better separation of proteins with the same electrophoretic mobilities is obtained in immunoelectrophoresis.
c. In immunofixation electrophoresis, antibody is directly applied to the gel instead of being placed in a trough.
d. Immunoelectrophoresis is a much faster procedure.

Answer 9

c. In immunofixation electrophoresis, antibody is directly applied to the gel instead of being placed in a trough.

Question 10

If crossed lines result in an Ouchterlony immunodiffusion reaction with antigens 1 and 2, what does this indicate?
a. Antigens 1 and 2 are identical.
b. Antigen 2 is simpler than antigen 1.
c. Antigen 2 is more complex than antigen 1.
d. The two antigens are unrelated.

Answer 10

d. The two antigens are unrelated.

Question 11

Which technique represents a single-diffusion reaction?
a. Radial immunodiffusion
b. Ouchterlony diffusion
c. Immunoelectrophoresis
d. Immunofixation electrophoresis

Answer 11

a. Radial immunodiffusion

Question 12

Which best describes the law of mass action?
a. Once antigen-antibody binding takes place, it is irreversible.
b. The equilibrium constant depends only on the forward reaction.
c. The equilibrium constant is related to strength of antigen-antibody binding.
d. If an antibody has a high avidity, it will dissociate from antigen easily.

Answer 12

c. The equilibrium constant is related to strength of antigen-antibody binding.

Question 13

Agglutination of dyed bacterial cells represents which type of reaction?
a. Direct agglutination
b. Passive agglutination
c. Reverse passive agglutination
d. Agglutination inhibition

Answer 13

a. Direct agglutination

Question 14

If a single IgM molecule can bind many more antigens than a molecule of IgG, which of the following is higher?
a. Affinity
b. Initial force of attraction
c. Avidity
d. Initial sensitization

Answer 14

c. Avidity

Question 15

Agglutination inhibition could best be used for which of the following types of antigens?
a. Large cellular antigens such as erythrocytes
b. Soluble haptens
c. Bacterial cells
d. Coated latex particles

Answer 15

b. Soluble haptens

Question 16

Which of the following correctly describes reverse passive agglutination?
a. It is a negative test.
b. It can be used to detect autoantibodies.
c. It is used for identification of antigens.
d. It is used to detect sensitization of red blood cells.

Answer 16

c. It is used for identification of antigens.

Question 17

Reactions involving IgG may need to be enhanced for which reason?
a. It is only active at 25°C.
b. It may be too small to produce lattice formation.
c. It has only one antigen-binding site.
d. It is only able to produce visible precipitation reactions.

Answer 17

b. It may be too small to produce lattice formation.

Question 18

For which of the following tests is a lack of agglutination a positive reaction?
a. Hemagglutination
b. Passive agglutination
c. Reverse passive agglutination
d. Agglutination inhibition

Answer 18

d. Agglutination inhibition

Question 19

Typing of RBCs with reagent antiserum represents which type of reaction?
a. Direct hemagglutination
b. Passive hemagglutination
c. Hemagglutination inhibition
d. Reverse passive hemagglutination

Answer 19

a. Direct hemagglutination

Question 20

In a particle-counting immunoassay using reagent antibody attached to latex particles, if the particle count in solution is very low, what does this mean about the presence of patient antigen?
a. The patient has no antigen present.
b. The patient has a very small amount of antigen.
c. The patient has a large amount of antigen present.
d. The test is invalid.

Answer 20

c. The patient has a large amount of antigen present.