Final answer:
Acquired immunity, which consists of active and passive types, is a crucial aspect of the body's defense mechanism developed either through a response to a pathogen or by receiving antibodies from another individual.
Step-by-step explanation:
Acquired immunity is a defense mechanism in the body that develops after exposure to various pathogens. It consists of two types: active immunity and passive immunity, both of which can be naturally or artificially induced.
Active immunity occurs when an individual's own immune system responds to a pathogen by producing memory B cells and memory T cells, which provide long-term protection.
An example of this would be the immunity that develops following an illness like chickenpox or through vaccination such as the flu shot, which uses a weakened form of a virus to stimulate the immune system.
On the other hand, passive immunity is provided when a person is given antibodies from another individual, such as the antibodies a baby receives from its mother through the placenta or breast milk.
This type of immunity is immediate but temporary, as the antibodies will eventually degrade, and the individual has not produced their own memory cells.