Which of the following both prevents blood loss and the invasion of pathogens in vertebrates?
a. the formation of blood clots
c. humoral immunity
d. cell-mediated immunity
(2) Each T cell and each B cell binds only to one specific type of
(3) the term clonal in clonal selection refers to the fact that
a. a lymphocyte can be easily converted into a stem cell line for laboratory research
b. a single activated B cell produces many identical copies of antibody, which react to the antigen that activated the B cell.
c. an activated B cell can convert itself quickly into helper and killer T cells that are specific for the same antigen.
d. once activated, a specific lymphocyte makes many identical copies of itself.
(4) Why is only one of the lymphocytes in this diagram activated by the pathogen?
a. antigens move through the immune system by diffusion, so the lymphocyte closest to the site of infection binds the antigen first. Once a lymphocyte is activated, it produces chemicals that prevent the activation of other lymphocytes.
b. lymphocytes are only activated if all of their receptors are bound by antigens. In this case, there were only enough antigens to fully activate one cell.
c. your immune system contains many different lymphocytes, each displaying a different antigen-binding protein. In this case, the antigen only matched the binding protein on the cell that was activated.
d. lymphocytes can only be activated by chemical produced by the innate immune system. Only one of the cells in this diagram has been exposed to these chemicals.
(5) Memory cells
a. include B and T cells that remain in the body for long periods of time after the first exposure to a pathogen.
b. are macrophages that store copies of antibodies for decades.
c. make copies of T cells that remain active long after the primary response has ended.
d. become T cells during a secondary response to a pathogen
(6) A vaccine contains
b. active B cells.
d. active killer T cells.
(7) Interferons are though to “interfere” with viral infection because they
a. prevent virus particles from entering neighboring, uninfected cells.
b. create holes in the plasma membranes of infected cells.
c. attach to the DNA of viruses, preventing their replication.
d. prevent the function of natural killer cells, making it more difficult for the immune system to fight off an infection.
(8) Which of the following is likely to be first on the scene of a bacterial infection?
c. T helper cells.
d. killer T cells.
(9) The antibodies released by activated B cells specifically target
a. killer T cells.
(10) Which of the following areas of the human body is not the location of a major concentration of white blood cells?