Final answer:
A preparation of microorganisms that is administered to produce or artificially increase immunity is called a vaccine. Vaccines contain weakened or inactive forms of disease-causing microorganisms, which stimulate the immune system to develop immunity.
Step-by-step explanation:
A preparation of microorganisms that is administered to produce or artificially increase immunity to a particular disease is known as a vaccine. Vaccines contain weakened or inactive forms of the disease-causing microorganisms, which stimulate the immune system to mount a response and develop immunity. Vaccination triggers an immune response against the injected antigen, leading to the production of memory cells for long-term protection.