What is the sex chromosome composition of a person with Klinefelter syndrome?
A. XXX
B. XO
C. XXY
D. XYY
E. YY
Answer: C
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Many men make antibodies to sperm, resulting in destruction of sperm to the point of sterility. What would be the likely origin of this autoimmune disease?
A. These antibodies are produced as a result of mutations in T lymphocytes, causing them to make large amounts of antibody. B. Antigens on sperm cells are similar to antigens on a variety of bacteria like Streptococcus. After a strep throat caused by Streptococcus, the immune system produces antibodies to streptococcal antigens, which then cross react with sperm antigens and destroy them. C. Since sperm are not made until after puberty, the immune system cannot scan the antigens on the sperm for immune tolerance. After sperm are made and the immune system sees them, they are recognized as foreign. D. T helper cells erroneously identify sperm cells as foreign invaders, triggering the T cytotoxic cells to start killing sperm.
Where does a fertilized egg typically implant?
a. Cervix b. Oviduct c. Vagina d. Ovary E. Uterine lining
Which chamber of the heart does the blood first enter when it returns from the pulmonary circuit?
a. the left ventricle b. the right ventricle c. the right atrium d. the left atrium
Which of the following animals generally has the lowest volume of urine production?
A) a vampire bat B) a salmon in fresh water C) a marine bony fish D) a shark inhabiting the Mississippi River