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An epitope associates with which part of an antigen receptor or antibody? (A) the tail (B) the heavy-chain constant regions only (C) variable regions of a heavy chain and light chain (D) the light-chain constant regions only

Which statement best describes the difference between responses of effector B cells (plasma cells) and those of cytotoxic T cells? (A) \(\mathrm{B}\) cells confer active immunity; cytotoxic T cells confer passive immunity. (B) \(\mathrm{B}\) cells respond the first time a pathogen is present; cytotoxic T cells respond subsequent times. (C) B cells secrete antibodies against a pathogen; cytotoxic T cells kill pathogen-infected host cells. (D) \(B\) cells carry out the cell-mediated response; cytotoxic T cells carry out the humoral response.

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 (C) antigens. (C) An antigen can have different epitopes. (D) A liver or muscle cell makes one class of MHC molecule.

Vaccination increases the number of (A) different receptors that recognize a pathogen. (B) lymphocytes with receptors that can bind to the pathogen. (C) epitopes that the immune system can recognize. (D) MHC molecules that can present an antigen.a

SCleNTIFIC INQUIRY A major cause of septic shock is the presence of lipopolysaccharide(LPS) from bacteria in the blood. Suppose you have available purified LPS and several strains of mice, each with a mutation that inactivates a particular TLR gene. How might you use these mice to test the feasibility of treating septic shock with a drug that blocks TIR signaling?