Chapter 46, Problem 11
In the 1960s, the U.S. Food and Drug Administration approved a contraceptive that allowed women to plan desired pregnancies and prevent unwanted pregnancies. Oral hormonal contraception ('the pill') uses synthetic hormones similar in structure to progesterone and/or estradiol. What is the pill's mechanism of action? Which of the following is the most effective form of contraception? a. condom b. diaphragm c. withdrawal d. the pill
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Some stickleback fish develop protective spines, and other stickleback fish are spineless. Spine development is controlled by the expression of a gene known as Pitx1. The spineless phenotype is due to a mutation in Pitx1 that results in no expression of Pitx1 during development in regions where spines would otherwise form. When scientists compared the Pitx1 coding sequence in spined and spineless fish, they found this sequence was the same in both types of fish. Propose plausible hypotheses for the location of this mutation and for how it alters spine development.
The BMI z-score is a relative measure of body mass index (BMI) that takes into account age. Higher values represent heavier individuals for a given height. The table here shows the BMI z-score of pre- and post-pubertal girls at three ages. Which of the following conclusions can you draw from the data? a. At a given age, there are more girls with low BMI z-scores than with high BMI z-scores. b. At a given age, girls with high BMI z-scores are more likely to have begun puberty than girls with low BMI z-scores. c. Girls 11, 12, and 13 years of age are equally likely to have begun puberty. d. There is no relationship between BMI z-score and age of beginning puberty.
Type I diabetes is a form of diabetes that is due to the loss of insulin-producing cells of the pancreas. The potential of stem cells—in particular, induced pluripotent stem (iPS) cells—for therapy has gotten a lot of press. What are iPS cells? a. cells taken from early human embryos b. cells taken from the pancreas of people without diabetes c. cells derived by de-differentiating specialized adult cells d. cells derived by differentiating pancreas precursor cells
Type I diabetes is a form of diabetes that is due to the loss of insulin-producing cells of the pancreas. The potential of stem cells—in particular, induced pluripotent stem (iPS) cells—for therapy has gotten a lot of press. If researchers were attempting to stimulate the differentiation of iPS cells, which of the following would they most likely add to the cell-culture medium (the liquid surrounding the cells)? a. activin A, an extracellular signal protein b. Sox-2, a transcription factor active in early development c. Grb-2, an intracellular signal transduction protein d. lactase, an enzyme that catalyzes the breakdown of lactose
In the 1960s, the U.S. Food and Drug Administration approved a contraceptive that allowed women to plan desired pregnancies and prevent unwanted pregnancies. Oral hormonal contraception ('the pill') uses synthetic hormones similar in structure to progesterone and/or estradiol. What is the pill's mechanism of action? Use your knowledge of the hormonal regulation of reproduction to predict the effect of a daily synthetic progesterone pill on (a) pituitary secretion of LH and FSH, and (b) ovarian secretion of estradiol and progesterone.
In the 1960s, the U.S. Food and Drug Administration approved a contraceptive that allowed women to plan desired pregnancies and prevent unwanted pregnancies. Oral hormonal contraception ('the pill') uses synthetic hormones similar in structure to progesterone and/or estradiol. What is the pill's mechanism of action? Scientists confirmed the pill's mechanism of action by measuring plasma hormone levels in women before and after they went on the pill (* means P<0.05, ** means P<0.01, and *** means P<0.001). Do the data shown here support the hypothesis that the pill affects hormonal signaling?