Immune System
Polymorphonuclear leukocytes (or PMNs)

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

ANSWER DOWNLOAD EXAMIANS APP

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 rearrangements of the DNA encoding the variable regions of the heavy and light chains
By the combination of different heavy and light chains that form the antigen binding site
Both (a) and (b)

ANSWER DOWNLOAD EXAMIANS APP

Immune System
The role of the M cell is to

pass bacteria or virus to underlying macrophages for processing and presentation of antigen
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

ANSWER DOWNLOAD EXAMIANS APP

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

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

ANSWER DOWNLOAD EXAMIANS APP