In: Biology
Answer 7:
Option 1- Natural acquired active immunity
Naturally acquired active immunity occurs when a person is exposed to a pathogen, develops disease, and as a result of primary immune response to the pathogen has acquired immunity.
Answer 8:
Option 4-All the definitions are matched correctly.
Answer 9:
Option1; True
ID50 means infectious dose when 50% of the exposed persons get
infected. Since Norovirus is very contagious, the ID dose will be
low. LD50 is Lethal Dose when 50% of those exposed succumb to
infection. As Norovirus is infectious but not serious (or lethal),
its LD50 must be very high.
Answer 10:
Option 2- False
Herd immunity describes the phenomena that individuals at risk are protected from the infection because they are surrounded by persons who are immune to the disease, thereby decreasing the chance of causative agent to spread among the herd. Even when the number of cases decline, the Herd immunity will remain intact and will become more strong by avoiding the re-emergence of the disease.