Final answer:
It is true that B cells express only one allele for immunoglobulin heavy and light chains due to allelic exclusion, ensuring unique antigen-binding specificity for each B cell's antibodies.
Step-by-step explanation:
The student's question appears to relate to the expression of immunoglobulin alleles in B cells. The statement is true. Although each B cell has two alleles for the immunoglobulin heavy chain and two for the light chain, it only expresses one allele of each type due to a process known as allelic exclusion. This ensures that each B cell produces antibodies with a unique antigen-binding specificity. Antibody diversity is generated through a mechanism involving random recombination and mutation of gene segments encoding the variable regions of the antibody heavy and light chains. The antigen-binding specificity is determined by the variable domains, while the constant domains determine the antibody class and its immunological function. B cells undergo maturation in which they can eventually secrete large quantities of the antibody.