MODEL PAPER 9 — BIOLOGY STD 12 Science — Question

Vaccination is the phenomenon of injection of killed or inactivated microbe to trigger the immune system to produce antibodies against a particular disease. Vaccination is the process of administering vaccines. Diseases can be prevented by vaccination. During vaccination inactivated or weakened microbes called as vaccines are introduced into the body. They trigger the production of antibodies. When disease-carrying microbes enter our body, self-protecting proteins called antibodies fight against the invader.
Immunisation is the protection of individuals from communicable diseases by administration of a suspension of dead micro- organisms. This is the stimulation of immune system in the body to produce memory cells which further can detect disease causing pathogens and immediately eliminate them before causing the disease.
Generally vaccines are of two types:
(a) Attenuated Vaccines: They are prepared from live organisms (generally pathogen is made weak to make it non virulent).
Examples: BCG and influenza vaccine.
(b) Killed Vaccines: They are prepared by killing the pathogenic organisms by heat or UV rays.
Examples: Polio and Rabies vaccines.