Among all nucleated body cells, only B and T cells lose

Although pus is often seen simply as a sign of infection, it is also an indicator of immune defenses in action. Explain

How do the molecules that activate the vertebrate TLR signal transduction pathway differ from the ligands in most other pathways, such as those shown in Concept 11.2 (pp. 210214)?

Suppose humans were the major host for a bacterial species. What temperature would you predict would be optimal for growth of this species? Explain.

In what ways does innate immunity protect the mammalian digestive tract?

Sketch a B cell antigen receptor. Label the V and C regions of the light and heavy chains. Label the antigen-binding sites, disulfide bridges, and transmembrane region. Where are these features located relative to the V and C regions?

Explain two advantages of having memory cells when a pathogen is encountered for a second time

If both copies of a light-chain gene and a heavy-chain gene recombined in each (diploid) B cell, how would this affect B cell development?

Why is the adaptive immune response to an initial infection slower than the innate response?

If a child were born without a thymus, what cells and functions would be deficient? Explain

Treatment of antibodies with a particular protease clips the heavy chains in half, releasing the two arms of the Y-shaped molecule. How might the antibodies continue to function?

Suppose that a snake handler bitten by a particular venomous snake species was treated with antivenin. Why might the same treatment for a second such bite have different results?

Is immunological memory after a natural infection fundamentally different from immunological memory after vaccination? Explain.

In myasthenia gravis, antibodies bind to and block certain receptors on muscle cells, preventing muscle contraction. Is this disease best classified as an immunodeficiency disease, an autoimmune disease, or an allergic reaction? Explain

People with herpes simplex type 1 viruses often get mouth sores when they have a cold or similar infection. How might this location benefit the virus?

How would a macrophage deficiency likely affect a persons innate and adaptive defenses?

Is being infected with HIV the same as having AIDS? Explain

Which of these is not part of insect immunity? a. enzyme activation of microbe-killing chemicals b. activation of natural killer cells c. phagocytosis by hemocytes d. production of antimicrobial peptides e. a protective exoskeleton

An epitope associates with which part of an antigen receptor or antibody? a. the disulfide bridge b. the heavy-chain constant regions only c. variable regions of a heavy chain and light chain combined d. the light-chain constant regions only e. the tail

Which statement best describes the difference in responses of effector B cells (plasma cells) and cytotoxic T cells? a. B cells confer active immunity; cytotoxic T cells confer passive immunity. b. B cells kill pathogens directly; cytotoxic T cells kill host cells. 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. e. B cells respond the first time a pathogen is present; cytotoxic T cells respond subsequent times.

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

Which of the following should be the same in identical twins? a. the set of antibodies produced b. the set of MHC molecules produced c. the set of T cell antigen receptors produced d. the susceptibility to a particular virus e. the set of immune cells eliminated as self-reactive

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. macrophages specific for a pathogen. e. MHC molecules that can present an antigen.

Which of the following would not help a virus avoid triggering an adaptive immune response? a. having frequent mutations in genes for surface proteins b. infecting cells that produce very few MHC molecules c. producing proteins very similar to those of other viruses d. infecting and killing helper T cells e. building the viral shell from host proteins

Consider a pencil-shaped protein with two epitopes, Y (the eraser end) and Z (the point end). They are recognized by antibodies A1 and A2, respectively. Draw and label a picture showing the antibodies linking proteins into a complex that could trigger endocytosis by a macrophage.

Contrast Lamarcks idea for the inheritance of acquired characteristics, discussed on pp. 454455 of Concept 22.1, with the clonal selection of lymphocytes.

Describe one invertebrate defense mechanism and discuss how it is an evolutionary adaptation retained in vertebrates

A diagnostic test for tuberculosis (TB) involves injecting antigen (from the bacterium that causes TB) under the skin and then waiting a few days for a reaction to appear. This test is not useful for diagnosing TB in AIDS patients. Why?

Among all nucleated body cells, only B and T cells lose DNA during their development and maturation. In a short essay (100150 words), discuss the relationship between this loss and the theme of DNA as heritable biological information, focusing on similarities between cellular and organismal generations.