Which of the following may explain why self-tolerance may fail?
A. A noncirculating antigen becomes exposed to the immune system.
B. Antibodies produced against foreign antigens cross-react with self-antigens.
C. Antibodies directed against other antibodies are produced.
D. All of the choices are correct.
Answer: D
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Polarized light is used by some butterflies to find a mate
Indicate whether the statement is true or false
Micturition
A. is another name for urination. B. is a reflex triggered by stretch receptors in the urinary bladder. C. requires contraction of the muscularis layer of the urinary bladder. D. requires the opening of two sphincters. E. All of the choices are correct.
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