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

By the combination of different heavy and light chains that form the antigen binding site
Antibody proteins can physically change their shape to bind different epitopes
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 one marrow stem cells migrate to the thymus and develop into B cells
B cells synthesize antibodies and put them on their cell surface
B cells can undergo class switching and produce a different antibody type
B cells that recognize high concentrations of antigens (self) in the absence of other signals undergo apoptosis in the bone marrow

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Immune System
The role of the M cell is to

pass bacteria or virus to underlying macrophages for processing and presentation of antigen
trap virus in mucus and prevent entry
induce apoptosis in virus-infected small intestinal epithelia cells
they use their cilia to propel mucus out of the small intestine

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