Unformatted text preview: g the dermis from damage. Page 2 of 12 18. B. If an ulcer penetrated the walls of the intestine, this would allow the contents of the
gastrointestinal tract to enter the peritoneal cavity. Membranes surround this cavity, which
would prevent further transport of the gastrointestinal contents through the rest of the body.
An ulcer in the small intestine would not allow the contents to enter the lumen because this is
the normal place in which the contents are found.
19. B. The passage presents information about inflammatory bowel disease, including Crohn’s
disease and ulcerative colitis, the latter of which is associated with inflammation of the colon.
The item asks what process would be most disrupted by an inflammation in the colon. Since
the primary process that takes place in the colon is absorption of water, then the absorption of
water is the most likely process to be disrupted.
20. D. The immune system is designed to attack foreign material in the body. It avoids attacking
tissues of its own body because it suppresses cells that are specific to its own body’s antigens
(surface molecules that would otherwise initiate an immune response).
21. B. Inflammatory bowel disease appears to have a genetic component, but it does not show
clear evidence of Mendelian inheritance. This means that the trait cannot simply be
“recessive” since, if it were, it would show Mendelian inheritance patterns.
22. B. Assuming the genetic and autoimmune theories of inflammatory bowel disease are true,
then the gastrointestinal antigen being targeted must be located on the surface of proteins
encoded by the genes for the disease. Antigens are carried on the surface of cells, not on the
chromosomes, DNA segments, or RNA.
23. D. If the ulcers found in a diseased colon in UC were caused by a bacterium, it would be
expected that symptoms would be confined to the colon and its associated functions. If other
symptoms outside the GI tract were detected, a bacterial agent may not be the cause of the
24. D. According to the passage, rates of IBD are lower in developing countries that have higher...
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