This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “Structure of Antibodies – Set 2”.
1. Which two antibodies don’t have a hinge region among the following?
a) IgM, IgG
b) IgE, IgM
c) IgA, IgM
d) IgA, IgG
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Explanation: IgE and IgM don’t have hinge regions present in their structure, instead they have four constant regions in the heavy chain as CH1, CH2, CH3, CH4.
2. Which antibody/immunoglobulin is abundant in the human body?
a) IgE
b) IgG
c) IgA
d) IgM
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Explanation: IgG is the most abundant antibody present in the body. It has four isotypes IgG1, IgG2, IgG3, IgG4. Each of them has different, be it the function, affinity to activate complement pathway and in many other ways.
3. Which of the following immunoglobulin is synthesized first?
a) IgE
b) IgG
c) IgA
d) IgM
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Explanation: IgM is the first immunoglobulin that is synthesized. The reason behind this lies in the class switching process of the antibody. During class switching, the gene segment corresponding to IgM is present first.
4. Which of the following antibodies is present in breast milk?
a) IgE
b) IgG
c) IgA
d) IgM
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Explanation: IgA is the immunoglobulin that is present in breast milk. This way the infant gets the immunity from the mother. This provides passive and also long-lasting active immunity.
5. Which of the following antibodies acts against the allergic reaction?
a) IgE
b) IgG
c) IgA
d) IgM
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Explanation: IgE is the immunoglobulin which acts against the allergic reactions. It forms a complex with Mast cell leading to various interactions between their receptors.
6. Which of the following IgGs can pass through the placenta?
a) IgG1 and IgG2
b) IgG1 and IgG3
c) IgG2 and IgG3
d) IgG1 and IgG4
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Explanation: IgG1 and IgG3 are the two immunoglobulins which can pass through the placenta. These provide the immunity to the fetus.
7. Which of the following antibodies are present in tears and saliva?
a) IgE
b) IgG
c) IgA
d) IgM
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Explanation: IgA is the antibody present in the secretions like tears, saliva and some exocrine secretions also. This way it protects us from the pathogens and toxins which later might enter the mucosal surfaces.
8. Which of the following immunoglobulins can form a pentameric structure?
a) IgE
b) IgG
c) IgA
d) IgM
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Explanation: IgM is the only immunoglobulin/antibody which is capable of forming a pentameric structure. It has to undergo some conformational changes when involved in any reaction.
9. Which of the following antibodies has the highest valency?
a) IgE
b) IgG
c) IgA
d) IgM
View Answer
Explanation: IgM has the highest valency of 10. This is because of its pentameric structure. Each antibody has the valency of 2.
10. Which of the following antibodies acts as an opsonin?
a) IgE
b) IgG
c) IgA
d) IgM
View Answer
Explanation: IgG is the immunoglobulin that is involved directly in Opsonization. An opsonin is an antibody or some other substance. This binds to microorganisms or cells in order to enhance the phagocytosis.
Sanfoundry Global Education & Learning Series – Immunology.
To practice all areas of Immunology, here is complete set of 1000+ Multiple Choice Questions and Answers.
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