What is one of the differences between CD4+ and CD8+ T cells?a. CD4+ cells are immature, and CD8+ cells are mature.b. CD4+ cells are activated, and CD8+ cells are not.c. CD4+ cells interact with class II MHC proteins, and CD8+ cells interact with class I MHC proteins.d. CD4+ cells activate cell-mediated responses, and CD8+ cells activate humoral responses.

What is the difference between an epitope and an antigen?

Which of the following statements is true?(A) An antibody has one antigen-binding site. (B) A lymphocyte has receptors for a single antigen. (C) Every antigen has a single epitope. (D) A liver or muscle cell makes two classes of MHC molecule

Which of the following statements is not true?a. An antibody has more than one antigen-binding site.b. A lymphocyte has receptors for multiple different antigens.c. An antigen can have different epitopes.d. A liver or muscle cell makes one class of MHC molecule.

Which of the following best describes the difference in the way B cells and cytotoxic T cells deal with invaders?a. B cells confer active immunity; T cells confer passive immunity.b. B cells send out antibodies to attack; certain T cells can do the attacking themselves.c. T cells handle the primary immune response; B cells handle the secondary response.d. B cells are responsible for the cell-mediated immune response; T cells are responsible for the humoral immune response.

Which of the following should be the same in identical twins?a. the set of antibodies producedb. the set of MHC molecules producedc. the set of T cell antigen receptors producedd. the set of immune cells eliminated as self-reactive

Cytotoxic T cells are able to recognize infected body cells becausea. the infected cells display foreign antigens.b. the infected cells produce antigens.c. infected cells release antibodies into the blood.d. helper T cells destroy them first.

Explain how gene recombination leads to the production of vast numbers of different B-cell receptors.

Describe how HIV is transmitted and how immune system cells in an infected person are affected by HIV. What are the most effective means of preventing HIV transmission? Why is AIDS particularly deadly compared with other viral diseases?