Question

(A) IgG (i) Allergic & parasitic infections
(B) IgM (ii) 1st antibody to appear in primary immune response
(C) IgA (iii) Most abundant antibody
(iv) Antibody present in saliva


(1) A-(iii); B-(ii); C-(iv)
(2) A-(iii); B-(ii); C-(i)
(3) A-(ii); B-(iii); C-(iv)
(4) A-(ii); B-(iv); C-(iii)

Answer 1

Answer:

$\bigstar\:\underline{\boxed{\bf{\red{Immunoglobulins:}}}}$

• Immunoglobulins are glycoproteins made up of four polypeptide chains (linked by disulphide bonds) - two heavy (h) (440 amino acids) and two light (L) (220 amino acids).
• Light and heavy chains are subdivided into variable and constant regions.
• They are mainly of five types as given below.

☢ Types of Immunoglobulins :

$\bigstar\:\underline{\boxed{\bf{\blue{Ig-G}}}}$

• Most abudant and predominant antibody in the secondary response.
• Only antibody to cross the placenta.
• Opsonizes i.e., enhance phagocytosis and fixes complement.

$\bigstar\:\underline{\boxed{\bf{\green{Ig-A}}}}$

• Secondary immunoglobulin
• Found in body secretions including saliva and tears.
• Does not fix complement.
• Available in colostrum and mother's milk.
• Fight against invading micro-organisms even before sensitized.

$\bigstar\:\underline{\boxed{\bf{\purple{Ig-M}}}}$

• Macroimmunoglobulin
• Produced early in the primary response.
• Most efficient in aggutination, complement fixation.
• Does not cross placenta.
• Antigen receptor on the surface of B cells.

$\bigstar\:\underline{\boxed{\bf{\orange{Ig-D}}}}$

• Umcertain.
• Functions as antigen receptor.
• Activates B-cells.

$\bigstar\:\underline{\boxed{\bf{\gray{Ig-E}}}}$

• Concentrated in mucous membranes, skin and lungs.
• Mediate immediate hypersensitivity.
• Does not fix complement.
• Main host defence against helminths infection.

____________________________

Correct Answer (1) :

(A) $\longrightarrow$ (iii)

(B) $\longrightarrow$ (ii)

(C) $\longrightarrow$ (iv)