Immune System
T cell receptors (or TCR) on CD4+ T cells

recognize peptides not associated with MHC molecules
recognize peptides associated with MHC class II molecules
recognize peptides associated with MHC class I molecules
are secreted out into the environment to bind antigens

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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 the combination of different heavy and light chains that form the antigen binding site
Both (a) and (b)
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

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Immune System
Which of the following statements is false regarding 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 one marrow stem cells migrate to the thymus and develop into B cells
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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