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 Table 47.2 to compare and contrast the mechanisms of action of emergency contraception and mifepristone to that of the pill. Which methods act as contraception and which act to terminate a pregnancy? Explain.

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?

The embryos of reptiles (including birds) and mammals have systems of extraembryonic membranes. What are the functions of these membranes, and how do fish and frog embryos survive without them?

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 the information in the graph to explain how the pill affects each of the following:(a) maturation of a follicle, (b) thickening of the uterine lining during the follicular phase, (c) probability of ovulation, and (d) volume of menstrual fluid.

Compare sperm formation with egg formation. In what ways are the processes similar? In what ways are they different?

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?Imagine that four different contraceptives are under development. One blocks ovulation, one blocks fertilization, one blocks cleavage, and one blocks implantation. In the United States, which contraceptive is likely to be the least controversial to bring to market? Why?

In general, what is the ploidy (n) state of human cells?

Which of the following statements about parthenogenesis is correct?

A hermaphrodite is an animal that __________.