Briefly explain why allergies, such as hay fever, are characterized as a hypersensitive immune ...

Answer to q. 1

Allergies are characterized by hypersensitive responses because this immune response is excessive and
causes damage to the host.

Answer to q. 2

A. The primary immune response is elicited upon first exposure to antigen. The secondary immune
response is elicited by secondary exposure to antigen. The secondary response is faster and greater
than the primary response. These observations are the basis of the significance of vaccination.
B. Passive immunity results from antibodies or specific immune cells delivered to a host from a
donor, e.g., from mother to fetus. Active immunity is when an individual exposed to antigen develops
antibodies and/or specific immune cells reactive with that antigen
C. Artificial immunity is induced by deliberate vaccination with a specific antigen. Natural immunity
is induced when a pathogen enters the body by natural encounters, such as a sneeze.