Final answer:
IgG is the immunoglobulin involved in passive, natural immunity, transferred from mother to child through the placenta and also provided through breastfeeding in the form of secretory IgA.
Step-by-step explanation:
The immunoglobulin involved in passive, natural immunity is IgG.
Natural passive immunity is the process by which a mother transfers antibodies to her child, providing protection against certain infectious diseases. This type of immunity is critical for newborns, who have an undeveloped immune system. The primary immunoglobulin involved in this process is IgG, as it is the only antibody class capable of crossing the placenta from the mother's blood into the fetal bloodstream. By doing so, it provides the infant with immediate, though temporary, protection against the pathogens the mother has been exposed to. This protection lasts up to six months after birth. In addition to placental transfer, mothers can also pass secretory IgA to their infants through breastfeeding, which further contributes to the infant's passive, natural immunity by protecting mucosal surfaces against infection.
The antibody involved in passive, natural immunity is IgG. IgG is passed from a mother to her child through the placenta during pregnancy, providing temporary protection against infectious diseases. This is known as natural passive immunity.