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Chapter 51
What would happen if an NK cell killed a virally infected target cell by simply causing
the cell to burst, releasing all the cell contents into the tissues? (Figure 51.2)
Answer: The viruses would be liberated into the body where they could infect numerous
additional cells.
Jenner used cowpox virus to elicit an immune response against smallpox. What does this
tell us about the antigenic properties of the two viruses? (Page 1046)
Answer: The antigenic properties of the two viruses must be similar enough that
immunity to cowpox also enables protection against smallpox.
What does the common structure and mechanism of formation of Igs and TCRs suggest
about the evolution of B and T lymphocytes and these proteins? (Figure 51.15)
Answer: The common structure and mechanism of formation of B cell immunoglobulins
(Igs) and T-cell receptors (TCRs) suggests a common ancestral form of adaptive
immunity gave rise to the two cell lines existing today.
How would a high level of HCG present in a urine sample be indicated in this
agglutination test? (Figure 51.19)
Answer: A high level of HCG in a urine sample will block the binding of the antibody to
HCG-coated particles and prevent any agglutination.
Why were we able to eliminate smallpox virus using a vaccine but cannot eliminate
influenza? (Page 1063)
Answer: Influenza frequently alters its surface antigens making it impossible to produce
a vaccine with a long-term effect. Smallpox virus has a considerably more stable
structure.