The upper respiratory tract is lined with mucous membranes which secrete mucous. What is the purpose of mucous?
A) traps microbes and debris from the air we breathe
B) cools and dries, and traps microbes from the air we breathe
C) warms and humidifies, and traps microbes and debris from the air we breathe
D) warms and humidifies the air we breathe
E) cools and dries the air we breathe
Answer: C
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Below is a pedigree of a human genetic disease in which solid color indicates affected individuals. Assume that the disease is caused by a gene that can have the alleles A or a. What is/are the possible genotype(s) of person 3?
A) AA
B) Aa
C) Either AA or Aa
D) aa
E) Cannot be determined
An extremely rare occurrence in humans is a multiple pregnancy with the embryos at different stages due to fertilization weeks apart. What mechanism normally prevents this from happening?
A. The embryo's secretion of FSH and LH maintains the corpus luteum, keeping estradiol and progesterone high until the placenta takes over secretion of these hormones. B. The embryo's secretion of GnRH maintains the corpus luteum, keeping FSH and LH high until the placenta takes over secretion of these hormones. C. The embryo's secretion of hCG maintains the corpus luteum, keeping estradiol and progesterone high until the placenta takes over secretion of these hormones. D. The follicle's secretion of polar bodies maintains the fimbriae, keeping estradiol and progesterone high until the fallopian tube takes over secretion of these hormones.
Which of the following structures is NOT
found in mature sperm? a. nucleus b. acrosome with enzymes c. mitochondria d. microtubules in the tail e. ribosomes
Density-independent factors that limit
population growth include a. parasites. b. temperature. c. disease. d. competition. e. predation