Immune System
Numerous antibodies can be prepared, against one antigen, each binds to unique epitopes. How is this antibody diversity generated?

Antibody proteins can physically change their shape to bind different epitopes
By the combination of different heavy and light chains that form the antigen binding site
By rearrangements of the DNA encoding the variable regions of the heavy and light chains
Both (a) and (b)

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Immune System
Which of the following statements is false regarding B cells?

B cells that recognize high concentrations of antigens (self) in the absence of other signals undergo apoptosis in the bone marrow
B cells synthesize antibodies and put them on their cell surface
B cells can undergo class switching and produce a different antibody type
B one marrow stem cells migrate to the thymus and develop into B cells

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Immune System
Polymorphonuclear leukocytes (or PMNs)

can be attracted to the site of an infection following activation of complement
are derived from bone marrow stem cells
are a type of phagocyte that can engulf and kill bacteria
All of these

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