Final answer:
Lymphocytes that transform into plasma cells and secrete antibodies are known as B cells. These cells differentiate upon antigen exposure and become capable of producing large amounts of antibodies. T cells, alternatively, have different immune functions.
Step-by-step explanation:
Lymphocytes that transform into plasma cells and secrete antibodies are called B cells. B cells are a pivotal component of the adaptive immune system and play a crucial role in humoral immunity. They begin their life in the bone marrow and upon encountering an antigen, they transform and differentiate into plasma cells. Plasma cells are essentially activated B cells that have undergone a change to become antibody factories, secreting large quantities of antibodies to fight off pathogens. T cells, on the other hand, do not produce antibodies but rather perform functions such as helping B cells to mature and attacking infected or diseased cells directly.