Q43.2-1ITD. - Campbell Biology

Question

Assume that on average one out of every 10⁵B cells in the body is specific for antigen A on day 16 and that the number of B cells producing a specific antibody is proportional to the concentration of that antibody. What would you predict is the frequency of B cells specific for antigen A on day 36?

 

Step-by-Step Solution

Answer

On day 36, the frequency of B-cells would be approximately 5×10³ cells.

Step 1: Primary and secondary immune response

The primary response is the immunological response that occurs when the immune system encounters an infectious pathogen for the first time. A secondary immunological response, on the other hand, is triggered by a repeat encounter with the same antigen.

Step 2: Antibodies are produced by B cells

B cells are a type of white blood cell that plays an important role in adaptive immunity. These cells produce antigen-specific antibodies to destroy the antigens. For example, B cells produce antibodies A against antigen A and antibodies B against antigen B during an immune response.

Step 3: Frequency of B cells specific for antigen A on day 36

According to the graph, the frequency of B cells specific to antigen A is approximately 5×10³ because the number of B cells synthesizing specific antibodies is proportional to the antibody’s concentration.