While the tadpoles of competing species may complete metamorphosis in as little as just a few short months, Bullfrog tadpoles can remain in the same state for as long as one to two years before they actually become adult frogs.
Two types of white blood cells called lymphocytes are vital to the specific immune response. Lymphocytes are produced in the bone marrow, and mature into one of several subtypes. The two most common are T cells and B cells. An antigen is a foreign material that triggers a response from T and B cells.
The theory called clonal selection says A. exposure to an antigen activates those T-and B-cells with receptors recognizing specific epitopes on the antigen B. the activation of T cells produces antibodies that recognize epitopes C. T cells are involved in the process by which antibodies are produced against epitopes. A.ntigen-antibody binding may result in all of the following except A. Agglutination of the antigens B. Complement activation C. Neutralization of the antigen D. Opsonization E. interleukin 2 production.