Question

which of the following scenarios is the best example of naturally acquired active immunity? 1 point a fetus receives antibodies from its mother’s blood through the placenta. a person gets sick with the flu, recovers, and now has memory cells against that flu virus. a person receives an injection of antibodies after being exposed to a pathogen. a child is given a chickenpox vaccine at their doctor’s office. if a genetic disorder prevented a person’s b cells from being able to display antigen fragments on their surface after engulfing a pathogen, what would be the most likely consequence? 1 point the b cells would produce antibodies, but they would not match the pathogen. helper t cells would not be able to bind and release cytokines, preventing the b cell from completing its activation into a plasma cell. phagocytosis would destroy the b cell before it could be activated. the b cells would immediately transform into memory cells without t cell help

Explanation:

1. Naturally - acquired active immunity occurs when a person is exposed to a pathogen in the environment, gets sick, and the immune system generates memory cells. A fetus receiving antibodies from the mother is passive immunity. Injection of antibodies is artificial passive immunity, and vaccination is artificial active immunity. So a person getting sick with the flu, recovering, and having memory cells against the flu virus is naturally - acquired active immunity.
2. B cells display antigen fragments on their surface to interact with helper T cells. Helper T cells bind to these antigen - presenting B cells and release cytokines which are crucial for B cell activation into plasma cells. If B cells can't display antigen fragments, helper T cells won't be able to bind and release cytokines, preventing B cell activation.

Answer:

1. B. A person gets sick with the flu, recovers, and now has memory cells against that flu virus.
2. B. Helper T cells would not be able to bind and release cytokines, preventing the B cell from completing its activation into a plasma cell.