AP BIOLOGY

Detailed explanation-1: -There are two main functionally distinct classes of T cells: cytotoxic T cells kill infected cells directly by inducing them to undergo apoptosis, while helper T cells help activate B cells to make antibody responses and macrophages to destroy microorganisms that either invaded the macrophage or were ingested by it.

Detailed explanation-2: -T cells can wipe out infected or cancerous cells. They also direct the immune response by helping B lymphocytes to eliminate invading pathogens. B cells create antibodies. B lymphocytes, also called B cells, create a type of protein called an antibody.

Detailed explanation-3: -These two cell types can function independently or cooperatively to defend the body against pathogens. T-lymphocytes can be distinguished from other lymphocytes like B cells and natural killer cells (NK cells) by the presence of a T cell receptor (TCR) on the cell surface.

Detailed explanation-4: -While both B cells and T cells are involved in triggering the immune response, the main difference between the two is that T cells can only recognize viral antigens on the outside of infected cells and B cells can only identify the surface antigens of the infectious agents themselves.

Detailed explanation-5: -While T cells possess only a cell surface form of the antigen receptor and require MHC and a presenting cell for antigen recognition, B cells produce a secreted version of their antigen receptor (termed antibody or immunoglobulin) which can bind directly to antigen.