44. Animal Reproduction

Which of the following characterizes parthenogenesis? a. An individual may change its sex during its lifetime. b. Specialized groups of cells grow into new individuals. c. An organism is first a male and then a female. d. An egg develops without being fertilized.

What term describes the mode of asexual reproduction in which offspring develop from unfertilized eggs? a. parthenogenesis b. budding c. regeneration d. fission

In male mammals, excretory and reproductive systems share a. the vas deferens. b. the urethra. c. the seminal vesicle. d. the prostate.

In sperm competition, what is 'second-male advantage'? a. the observation that when females mate with two males, each male fertilizes the same number of eggs b. the observation that when females mate with two males, the second male fertilizes most of the eggs c. the observation that females routinely mate with at least two males before laying eggs or becoming pregnant d. the observation that accessory fluids prevent matings by second males—for example, by forming copulatory plugs

Which of the following statements regarding animal development is/are correct? Select True or False for each statement. T/F The neural tube forms after organogenesis is complete T/F The blastocyst is formed during cleavage T/F During cleavage, the zygote divides rapidly without growth, forming a mass of cells T/F Animals have two germ layers

Which of the following is properly paired? (A)seminiferous tubule—cervix (B)vas deferens—oviduct (C)corpus luteum—Sertoli cell (D)scrotum—clitoris

Peaks of LH and FSH production occur during a. the menstrual flow phase of the uterine cycle. b. the beginning of the follicular phase of the ovarian cycle. c. the period just before ovulation. d. the secretory phase of the uterine cycle.

True or false: The corpus luteum is retained upon implantation due to the presence of the hormone human chorionic gonadotropin (hCG).

During human gestation, rudiments of all organs develop a. in the first trimester. b. in the second trimester. c. in the third trimester. d. during the blastocyst stage.

Summarize the experimental evidence that Daphnia require three cues to trigger sexual reproduction. Discuss what these cues indicate about the environment.

Which of the following is a true statement? a. All mammals have menstrual cycles. b. The endometrial lining is shed in menstrual cycles but reabsorbed in estrous cycles. c. Estrous cycles are more frequent than menstrual cycles. d. Ovulation occurs before the endometrium thickens in estrous cycles.

Many frogs and mice are similar in size, yet a frog egg is vastly larger than a mouse egg. Propose a plausible explanation for this difference in the egg size.

For which of the following is the number the same in human males and females? a. interruptions in meiotic divisions b. functional gametes produced by meiosis c. meiotic divisions required to produce each gamete d. different cell types produced by meiosis

How do spermatogenesis and oogenesis in humans differ with respect to numbers of cells produced, gamete size, and timing of the second meiotic division?

Which statement about human reproduction is true? (A)Fertilization occurs in the vagina. (B)Spermatogenesis and oogenesis both require normal body temperature. (C)An oocyte completes meiosis after a sperm penetrates it. (D)The earliest stages of spermatogenesis occur closest to the lumen of the seminiferous tubules.

Give examples of negative and positive feedback in hormonal control of the human menstrual cycle. Why can a high estradiol level be considered a 'readiness' signal from a follicle?

Propose an experiment to test the hypothesis that cells from only one region of a frog blastula form the ectoderm. What results from this experiment would support this hypothesis?

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.

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

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?

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.

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? 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?