Final answer:
Passive immunity is acquired when an individual receives pre-formed antibodies from another source, such as the placenta or through breastfeeding, while active immunity is acquired when an individual's own immune system is activated to produce antibodies in response to an infection or vaccination.
Step-by-step explanation:
Passive immunity is acquired when an individual receives pre-formed antibodies from another source, such as the placenta or through breastfeeding. This can also occur through artificial means, such as the administration of antibodies through injection. One example of natural passive immunity is the transfer of antibodies from a mother to her newborn baby through breast milk, providing the baby with temporary immunity to certain diseases. Active immunity, on the other hand, is acquired when an individual's own immune system is activated to produce antibodies in response to an infection or vaccination. This can also be achieved through artificial means, such as receiving a vaccine that contains weakened or inactive forms of a pathogen, stimulating the immune system to produce a response and develop immunity.