Immune System
Polymorphonuclear leukocytes (or PMNs)

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

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

By rearrangements of the DNA encoding the variable regions of the heavy and light chains
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
Both (a) and (b)

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Immune System
The role of the M cell is to

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

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