Deck 17: Reproduction

Question 1

Which of the following statements regarding male reproductive function is FALSE?

A) Sperm formed in the testes enter the epididymis before entering the vas deferens.
B) The seminal fluid is alkaline and rich in nutrients.
C) The Sertoli cells produce androgen-binding protein.
D) Sperm entering the epididymis are fully motile.
E) Most of the seminal volume is provided by the secretions of the seminal vesicles and prostate gland.

Answer 1

D

Question 2

Ejaculation of semen from the penis is caused by:

A) a parasympathetic reflex that contracts the seminal vesicles, epididymis, and vas deferens.
B) a somatic reflex that initiates sperm production and motility, and contracts skeletal muscle surrounding the vas deferens.
C) voluntary relaxation of the internal urethral sphincter, and sympathetic stimulation of smooth muscle contraction in the walls of the ureters and the urethra.
D) sympathetic nerve firing, which initiates smooth muscle contraction in the epididymis, vas deferens, ejaculatory ducts, prostate, and seminal vesicles.
E) parasympathetic stimulation of smooth muscle in the ureters, urinary bladder, and urethra.

Answer 2

D

Question 3

Which of the following would be most likely to occur in an adult male whose Sertoli cells have begun to produce excessive amounts of inhibin?

A) FSH secretion would be selectively inhibited, but LH secretion would be normal.
B) Spermatogenesis would be increased but testosterone secretion would be normal.
C) Spermatogenesis would be increased because testosterone production would be above normal.
D) Gonadotropin-releasing hormone levels and spermatogenesis would increase above normal.
E) Both FSH and LH secretion would rise above normal levels.

Answer 3

A

Question 4

Sexual differentiation of the embryo is normally determined by:

A) the number of chromosomes, with males having 22 pairs and females having an extra pair of XX chromosomes.
B) the presence of two X chromosomes, which causes the primordial testes to degrade.
C) the presence of one Y chromosome, which causes the primordial ovaries to degrade.
D) the presence of the Y chromosome, which directs the undifferentiated gonads to develop into testes (when there is one X chromosome present as well).
E) hormones produced by the placenta.

Question 5

In the differentiation of a normal female:

A) Müllerian inhibiting substance causes the Müllerian ducts to regress.
B) the uterus and fallopian tubes are formed from the Wolffian ducts.
C) female genitalia form in the absence of hormonal stimulation.
D) the gonads remain undifferentiated throughout fetal life.
E) the SRX protein present on X chromosomes makes the gonads differentiate into ovaries.

Question 6

As sperm travel from their site of production in the testes to the exterior, the sequence of ducts through which they will pass is:

A) rete testis; efferent ductules; vas deferens; ejaculatory duct; urethra.
B) efferent ductules; rete testis; vas deferens; ejaculatory duct; urethra.
C) rete testis; efferent ductules; vas deferens; urethra; ejaculatory duct.
D) rete testis; afferent ductules; ejaculatory duct; vas deferens; urethra.
E) rete testis; ejaculatory duct; efferent ductules; vas deferens; urethra.

Question 7

Which of the following male accessory reproductive organs secretes prostaglandins?

A) prostate gland
B) seminal vesicles
C) epididymis
D) bulbourethral glands
E) vas deferens

Question 8

Which is NOT a function of Sertoli cells?

A) forming a barrier between the blood and developing germ cells
B) secreting inhibin
C) nourishing developing sperm
D) converting estrogens into testosterone
E) phagocytizing defective sperm

Question 9

The process of spermatogenesis from primary spermatocyte to sperm:

A) takes about three weeks in the human.
B) occurs when a male is an embryo, ceasing at birth.
C) requires participation of Sertoli cells.
D) occurs in the epididymis.
E) occurs as the cells gradually travel between two closely attached Leydig cells.

Question 10

The onset of puberty is triggered by an increase in:

A) sensitivity of the gonads to pituitary gonadotropins.
B) sensitivity of the pituitary to GnRH.
C) GnRH secretion.
D) sensitivity of the hypothalamus to negative feedback by sex steroids.
E) sensitivity of the pituitary to negative feedback by sex steroids.

Question 11

Which of the following best describes a genetic male (XY) who lacks functional androgen receptors (androgen insensitivity syndrome)?

A) He will have normal male external genitalia.
B) He will have ovaries and female-appearing external genitalia but male secondary sex characteristics.
C) He will have female-appearing external genitalia and ovaries, but internal structures derived from the Wolffian ducts.
D) He will have male external genitalia but will have female-appearing internal structures derived from the Müllerian ducts.
E) He will have undescended testes, but female external genitalia and secondary sex characteristics.

Question 12

The androgen-binding protein functions to:

A) confer responsiveness of certain cells to male sex hormones.
B) transport androgens in the plasma.
C) bind and maintain high concentrations of testosterone in the seminiferous tubules.
D) transport testosterone across cell walls.
E) exert negative feedback on the production of testosterone by the Leydig cells.

Question 13

The fallopian tubes:

A) connect the uterus to the vagina.
B) carry sperm from the testes to the epididymis.
C) degenerate in females, due to the presence of Müllerian-inhibiting substance (MIS).
D) carry ova from the ovaries to the uterus.
E) develop from the embryonic Wolffian duct system.

Question 14

Sperm:

A) are stored in the vas deferens and the last part of the epididymis.
B) travel from the seminiferous tubules to the epididymis by the beating action of their flagellae.
C) travel through the vas deferens, then the ejaculatory duct, then the ureter during ejaculation.
D) are expelled from the penis through the ureter.
E) are no longer produced in individuals who have undergone a vasectomy.

Question 15

In the embryonic differentiation of a normal male:

A) undifferentiated gonads develop into testes during the fifth week of embryonic life.
B) the Wolffian ducts regress.
C) Mullerian inhibiting substance is absent.
D) testosterone directly stimulates development of the epididymis, vas deferens, and seminal vesicles.
E) testosterone directly stimulates development of the penis and scrotum.

Question 16

Which of the following is FALSE regarding erection of the penis?

A) It is a spinal reflex.
B) It is a result of sympathetic stimulation of vascular smooth muscle in the erectile tissue of the penis.
C) It can be triggered by stimulation of tactile receptors in the penis.
D) It is a result of arteriolar vasodilation and venous constriction of blood vessels in the penis.
E) It can be inhibited by input to the autonomic nerves from higher brain centers.

Question 17

With regard to reproduction, which is correct about SRY?

A) It is a protein that is normally coded for by a gene that is present on the Y chromosome.
B) It is a gene that codes for testosterone.
C) It is a protein that causes the degeneration of the Wolffian ducts.
D) It is a gene found in both males and females.
E) It is a protein normally coded for by a gene that is present on the X chromosome.

Question 18

Spermatogenesis:

A) begins with the mitotic division of spermatogonia.
B) results in four primary spermatocytes for every spermatogonium.
C) results in four spermatozoa for every primary spermatocyte.
D) is not complete until after an egg is fertilized, which initiates the second meiotic division.
E) takes place completely within the lumen of the seminiferous tubule.

Question 19

Which is TRUE regarding meiosis in a single germ cell?

A) It results in 2 cells with 46 chromosomes each.
B) It results in 4 cells with 23 chromosomes each.
C) It results in 4 cells with 23 pairs of chromosomes each.
D) It results in 4 cells with 46 chromosomes each.
E) It results in 4 cells with 46 pairs of chromosomes each.

Question 20

A female whose adrenal glands began secreting unusually high levels of androgen would probably have increased:

A) levels of spermatogenesis.
B) levels of LH secretion.
C) atrophy of skeletal muscles.
D) subcutaneous fat deposition.
E) growth of facial hair.

Question 21

Which of the following occurs at ovulation?

A) The first meiotic division of the oocyte completes and the dominant follicle ruptures.
B) The second meiotic division of the oocyte occurs.
C) The oocyte, along with its surrounding thecal layer, is expelled onto the ovarian surface.
D) The second meiotic division of the oocyte occurs and the dominant follicle ruptures.
E) The corpus luteum is expelled from the ovary and enters the fallopian tube.

Question 22

Which is TRUE during the luteal phase of the menstrual cycle?

A) Both estrogen and progesterone concentrations are kept low by negative feedback.
B) Estrogen concentration remains low, while progesterone concentration rises to a peak.
C) Progesterone concentration remains low, while estrogen concentration rises to a peak.
D) Progesterone concentration in the plasma is high, but estrogen concentration rises even higher.
E) Estrogen concentration in the plasma is high, but progesterone concentration rises even higher.

Question 23

Which is TRUE about the maturation of ovarian follicles?

A) Granulosa cells produce androgens, which stimulates follicle maturation.
B) Theca cells produce estrogen, which is converted to the androgens that stimulate follicle maturation.
C) On day 1 of the cycle, growing follicles have both FSH and LH receptors on granulosa cells.
D) Growing follicles produce estrogen, which further stimulates follicle maturation.
E) Follicle maturation is stimulated when FSH binds to theca cells and LH binds to granulosa cells.

Question 24

On day 14 of a typical 28 day menstrual cycle, LH concentration in the blood will be ________. The endometrium will be ________. Estrogen concentration in the blood is ________.

A) level; sloughing off; low
B) at or near a peak; near the end of the proliferative phase; relatively high
C) low but rising; in the secretory phase; high
D) at or near a peak; in the secretory phase; low
E) level; starting the proliferative phase; level but high

Question 25

The transition between the ________ and the ________ phases of the uterine cycle coincides with ________.

A) follicular; luteal; a rise in basal body temperature
B) proliferative; secretory; ovulation
C) menstrual; proliferative; ovulation
D) secretory; proliferative; selection of the dominant follicle
E) proliferative; secretory; menstruation

Question 26

On day 1 of the menstrual cycle, FSH levels will be ________. The follicle that will become dominant is in the ________ stage of maturation. Progesterone levels in blood are ________.

A) rising; primordial; low
B) rising; preantral to antral; low
C) rising; preantral to antral; high
D) falling; expanding; low
E) falling; atretic; high

Question 27

In the ovarian cycle, the dominant follicle:

A) undergoes atresia.
B) continues to grow beyond day 7 of the cycle, while the other developing follicles degenerate.
C) is selected on day 1 of the cycle, and no other follicles develop beyond that day.
D) is selected to continue growing at about the middle of the luteal phase.
E) ruptures during ovulation on day 21 of the cycle.

Question 28

Which is a TRUE statement about events occurring in the menstrual cycle?

A) Each peak in estrogen concentration is accompanied by an even greater peak in progesterone concentration.
B) FSH reaches its highest concentration 3 days before menstruation begins.
C) Progesterone is low during the first half of the cycle, and rises to a peak during the second half.
D) Ovulation occurs exactly in the middle of the follicular phase of the cycle.
E) The corpus luteum normally degenerates on day 14 of the cycle.

Question 29

If you start at the plasma membrane of an oocyte in a mature follicle and move outward, which is the correct order in which you would encounter the three structures listed below?

A) zona pellucida; granulosa cells; theca cells
B) zona pellucida; theca cells; granulosa cells
C) granulosa cells; zona pellucida; theca cells
D) granulosa cells; theca cells; zona pellucida
E) theca cells; zona pellucida; granulosa cells

Question 30

During the early part of the menstrual cycle, ________ acts on granulosa cells, which ________. ________ acts on theca cells, which ________.

A) LH; convert androgens to estrogens; FSH; synthesize androgens
B) LH; synthesize androgens; FSH; convert androgens to estrogens
C) FSH; convert androgens to estrogens; LH; synthesize androgens
D) FSH; synthesize androgens; LH; convert androgens to estrogens
E) progesterone; synthesize androgens; LH; secrete estrogens

Question 31

Shedding of the endometrial lining occurs:

A) because ovulation disrupts the growing follicle.
B) as a result of a fall in plasma levels of estradiol and progesterone.
C) a day after the LH surge.
D) because of an increase in the level of FSH.
E) because the nondominant follicles undergo atresia.

Question 32

Which of the following is NOT a result of the LH surge that occurs in the middle of the menstrual cycle?

A) The primary oocyte completes its first meiotic division.
B) Antrum size (fluid volume) and blood flow to the follicle increase markedly.
C) The granulosa cells begin releasing progesterone and decrease their release of estrogen.
D) Enzyme and prostaglandin synthesis by the granulosa cells increases, breaking down the follicular membranes.
E) The corpus luteum stops secreting hormones and degenerates.

Question 33

How does estradiol increase the likelihood that an egg will be fertilized?

A) It inhibits the motility of uterine smooth muscle.
B) It stimulates inhibin levels, which causes a surge of FSH.
C) It increases libido, or sex drive, in women.
D) It changes cervical mucus to a watery consistency that allows sperm to penetrate the cervix.
E) It stimulates LH receptors that help maintain a corpus luteum.

Question 34

Which of the following is NOT an action of estrogen?

A) stimulation of fat deposition under the skin in the breasts and hips
B) thickening epithelial lining of vagina
C) stimulation of myometrial contractions
D) stimulation of bone growth and strength
E) stimulation of growth of pubic hair

Question 35

Which is a function of LH?

A) It stimulates androgen production by theca cells.
B) It stimulates the growth of granulosa cells.
C) It stimulates production of inhibin by theca cells.
D) It stimulates estrogen production by theca cells.
E) It inhibits GnRH secretion by the hypothalamus during ovulation.

Question 36

The follicular phase of the ovarian cycle coincides with which phase or phases of the uterine cycle?

A) both the menstrual phase and the secretory phase
B) the secretory phase
C) both the follicular phase and the secretory phase
D) both the proliferative phase and the secretory phase
E) both the menstrual phase and the proliferative phase

Question 37

Which of the following does NOT normally produce androgens?

A) Leydig cells
B) theca cells
C) adrenal cortex cells
D) Sertoli cells

Question 38

Which of the following statements about estrogens in females is FALSE?

A) In low plasma concentration, estrogen inhibits pituitary secretion of LH and FSH.
B) In high plasma concentration, estrogen stimulates pituitary sensitivity to GnRH.
C) In the presence of high plasma concentration of progesterone, estrogen stimulates increased secretion of GnRH.
D) Estrogen secretion is required for the LH surge.
E) Estrogen stimulates follicular growth.

Question 39

Beginning on the first day of the menstrual cycle, the order of phases in the uterus is:

A) proliferative, secretory, menstrual.
B) secretory, proliferative, menstrual.
C) menstrual, secretory, proliferative.
D) menstrual, proliferative, secretory.
E) secretory, menstrual, proliferative.

Question 40

According to the two-cell mechanism of follicular estrogen synthesis:

A) granulosa cells synthesize an androgen, which the theca cells convert to estrogen.
B) Sertoli cells synthesize an androgen, which the granulosa cells convert to dihydrotestosterone.
C) theca cells synthesize an androgen, which luteal cells convert to estrogen.
D) production of progesterone by the corpus luteum requires cooperative interaction between two cell types.
E) theca cells synthesize an androgen, which the granulosa cells convert to estrogen.

Question 41

The acrosome reaction is triggered by:

A) deposition of sperm into the female reproductive tract.
B) capacitation of sperm.
C) estrogen.
D) binding of the heads of sperm to the zona pellucida.
E) the first meiotic reduction division of the ovum.

Question 42

Which is TRUE regarding fertilization and transport of an egg?

A) Fertilization occurs in the uterus, and must occur within 24-48 hours of ovulation.
B) Fertilization can occur any time with 7 days after ovulation, and it generally takes 10-14 days for the conceptus to reach the uterus.
C) Fertilization occurs in the fallopian tube, and it takes about 4 days for the conceptus to reach the uterus.
D) Fertilization must occur while the follicle is still attached to the ovary, and transport of the conceptus to the uterus takes 24-48 hours.
E) Fertilization occurs in the fallopian tube, and the conceptus must reach the uterus within 24-48 hours to implant, or it will die.

Question 43

Which is NOT true about the actions of progesterone?

A) It increases contractions and activity of the fallopian tube smooth muscle and cilia.
B) It induces thick, sticky mucus in the cervix.
C) It inhibits the milk-inducing effects of prolactin.
D) It increases body temperature.
E) It exerts negative feedback on the hypothalamus and anterior pituitary.

Question 44

Which is NOT a function of the hormone human placental lactogen in pregnancy?

A) inhibit glucose utilization by maternal tissues
B) promote breast growth
C) increase maternal metabolism of fatty acids
D) inhibit glucose utilization by maternal tissues and promote breast growth
E) prevents the corpus luteum from degenerating

Question 45

Which is TRUE about sperm delivery?

A) Most of the ejaculated sperm arrive in the vicinity of the ovum (if there is one).
B) Sperm transport through the cervix is made possible by actions of progesterone on the cervical mucus.
C) Of the several hundred million sperm in an ejaculation, only about 100 to 200 reach the fallopian tube.
D) Sperm are able to fertilize an egg from the instant they arrive in the female reproductive tract.
E) Sperm can survive for up to 2 weeks in the mucus of the cervix.

Question 46

Which of the following is a hormonal change that occurs near the end of a normal pregnancy?

A) Plasma progesterone levels decrease while the levels of estrogen continue to increase.
B) Estrogens stimulate connexin synthesis in the myometrium.
C) Plasma estrogen levels decrease while the levels of progesterone continue to increase.
D) Estrogen blocks the synthesis of oxytocin receptors on uterine smooth muscle.
E) There is a surge in the LH concentration.

Question 47

Which of the following is NOT a function of estrogen during pregnancy?

A) stimulation of myometrial growth
B) maintenance of the endometrium
C) stimulation of prolactin secretion
D) stimulation of breast development
E) stimulation of milk synthesis

Question 48

Which of the following statements regarding the control of parturition is FALSE?

A) Oxytocin secretion is stimulated by cervical dilation.
B) Coordinated uterine contractions cause the cervix to dilate.
C) Oxytocin decreases the expression of myometrial estrogen receptors.
D) Prostaglandins stimulate myometrial contractions.
E) Stretching of the myometrium is one signal that begins uterine contractions.

Question 49

Lactation normally does not occur during pregnancy because

A) the breast ducts do not develop until after a baby is born.
B) the high levels of estrogen and progesterone in maternal plasma inhibit prolactin effects on the breasts.
C) maternal plasma levels of prolactin are low during pregnancy.
D) high levels of androgens inhibit milk synthesis by the breasts.
E) the low levels of circulating estrogen and progesterone during pregnancy inhibit milk synthesis by the breasts.

Question 50

The blastocyst implants in the uterus on about the ________ day of the 28-day menstrual cycle. At this time, the endometrium is ________ and progesterone levels are _______.

A) 21st; thick and secretory; high
B) 28th; thick and secretory; low
C) 14th; thick and secretory; low
D) 28th; thin and proliferating; high
E) 21st; thin and proliferating; low

Question 51

Which is NOT a normal physiological consequence of pregnancy in a woman?

A) increased appetite
B) increased blood volume
C) hypoventilation
D) hyperventilation
E) cardiac output increases

Question 52

Which of the following statements is TRUE?

A) The mother and the fetus exchange nutrients by exchanging blood in the placenta.
B) Human chorionic gonadotropin maintains the corpus luteum.
C) Human chorionic gonadotropin levels are the highest at the end of pregnancy.
D) From the time of implantation through delivery, the corpus luteum is the major source of progesterone.
E) Maternal plasma progesterone levels decline in the weeks leading up to the birth of her baby.

Question 53

Which of the following does progesterone INHIBIT during pregnancy?

A) the sensitivity of the myometrium to stimuli that promote contraction
B) plugging of the uterus by thickened cervical mucus
C) growth of the mammary glands
D) secretion of estrogen
E) regression of the corpus luteum

Question 54

Which of these bests describes colostrum?

A) It is composed of dark-colored solid waste ejected from a fetus's bowels shortly after it is born.
B) It is a hormone secreted by the hypothalamus that inhibits prolactin secretion.
C) It is the watery remnant of breast milk that continues to be expelled from the breasts after a baby is weaned.
D) It is a watery, protein-rich fluid secreted from maternal breasts after delivery of a baby.
E) It is an estrogen-rich fluid that fills the antrum of a mature ovarian follicle.

Question 55

Which of the following statements regarding endocrine regulation of breast function in females is FALSE?

A) During puberty, ductal growth is stimulated by increasing estrogen levels in plasma.
B) During puberty, progesterone stimulates the growth of breast alveoli.
C) During pregnancy, the main source of plasma prolactin is secretion from the maternal anterior pituitary gland.
D) Prolactin is the main hormone mediating the milk ejection reflex.
E) Breast development fluctuates with changing blood concentrations of estrogen and progesterone during each menstrual cycle.

Question 56

Which is TRUE about hormonal control during pregnancy?

A) The corpus luteum must remain functional for 38 weeks, because it is the main source of estrogen and progesterone.
B) The placenta responds to estrogen and progesterone from the corpus luteum, but does not secrete them.
C) The placenta produces estrogen without any contribution from the fetal adrenal cortex.
D) The placenta is provided with androgens by the maternal ovaries and adrenal glands, and by the fetal adrenal glands.
E) The placenta secretes only steroid hormones, while fetal and maternal pituitary glands secrete pregnancy-specific protein hormones.

Question 57

Parturition:

A) is the delivery of the infant and placenta.
B) normally occurs between the 27th and 28th weeks of pregnancy.
C) is an example of negative feedback.
D) occurs within 24 to 48 hours of ovulation.
E) is a pathological condition in which a pregnant woman retains too much fluid (edema), and it can lead to seizures.

Question 58

Which is a TRUE statement about implantation of a blastocyst?

A) When it occurs outside the uterus, it is called a myopic pregancy.
B) It normally occurs midway through the luteal phase.
C) It is a result of digestion of myometrial cells by enzymes in the trophoblast.
D) It occurs at a time in the cycle when plasma estrogen concentration is higher than progesterone concentration.
E) It occurs at the same time as, and is caused by, the LH surge.

Question 59

The placenta is:

A) formed solely from the outermost layers of the embryonic trophoblast, and serves as an exchange organ between mother and fetus.
B) formed from interlocking fetal and maternal tissues, and allows the mother's blood to flow freely into the fetal circulation and back.
C) formed solely from the endometrial layer of the uterus, and allows the mother's blood to flow freely into the fetal circulation and back.
D) formed from interlocking fetal and maternal tissues, and serves as an exchange organ between mother and fetus.
E) formed from maternal circulatory stem cells, and serves as an exchange organ between mother and fetus.

Question 60

The implanting blastocyst "rescues" the corpus luteum by secreting:

A) large quantities of FSH and LH.
B) GnRH, which stimulates the pituitary gland to secrete FSH and LH.
C) human chorionic gonadotropin (hCG)
D) progesterone and estrogen.
E) cortisol.

Question 61

Following crossing-over in meiosis I, which of the following is NOT true?

A) Maternal and paternal chromatids will always orient to opposite poles of the cell, remaining segregated from one another.
B) Random orientation of maternal and parental chromatids to either pole of the cell allows mixing of these in resultant gametes.
C) It is extremely unlikely that all 23 maternal and paternal chromosomes will end up in the same gamete.
D) A resulting gamete may have millions of possible different combinations of maternal and paternal chromosomes.
E) Chromatid pairs lined up in the cell are separated so that half end up in each daughter cell when division occurs.

Question 62

The major source of estradiol and progesterone in a non-pregnant woman is the:

A) thyroid gland.
B) adrenal gland.
C) testis.
D) ovary.
E) uterus.

Question 63

When an embryo implants in the wall of the fallopian tube, it is called:

A) stillbirth.
B) erythroblastosis fetalis.
C) ectopic pregnancy.
D) endometriosis.
E) placenta previa.

Question 64

During in utero (fetal) development of the ovary, which of these occurs?

A) Cell division of primary oogonia results in the production of 2 to 4 million primary oocytes, which are present at birth.
B) Cell division of primary oogonia, which all complete the first meiotic division before birth.
C) Cell division of primary oogonia, which all complete both meiotic divisions before birth.
D) The mitotic division of primary and secondary oocytes produces cells with 23 chromosomes each.
E) A single primary oogonium remains dormant, which then undergoes rapid mitosis after birth.

Question 65

Which is LEAST important for supporting continuing lactation after a baby is born?

A) the suckling stimulus
B) emptying milk from the breast
C) the secretion of oxytocin
D) the secretion of prolactin
E) high levels of estrogen and progesterone

Question 66

Which of the following statement is FALSE regarding oxytocin?

A) It is secreted by the posterior pituitary.
B) It is synthesized by the hypothalamus and promotes contraction of myoepithelial cells in the breasts.
C) It facilitates the birth process.
D) It stimulates uterine contractions.
E) It stimulates synthesis of breast milk.

Question 67

Conversion of spermatids to spermatozoa involves cell division.

Question 68

Which of the following hormones is NOT secreted by the placenta during pregnancy?

A) human placental lactogen
B) androgens
C) estradiol
D) progesterone
E) inhibin

Question 69

Umbilical arteries:

A) deliver oxygen and nutrient-rich blood from the mother to the placenta.
B) deliver oxygen and nutrient-rich blood from the fetus to the placenta.
C) carry blood with low oxygen and high metabolic wastes away from the fetus to the placenta.
D) carry highly oxygenated blood from the placenta to the fetus.
E) carry blood with low oxygen and high metabolic wastes from the placenta to the mother's circulation.

Question 70

The time span over which sexual intercourse is most likely to result in conception is from ______ day(s) before ovulation to ______ day(s) after ovulation.

A) 0, 3
B) 1, 1
C) 2, 4
D) 1, 5
E) 5, 1

Question 71

Which of these results from the second meiotic division?

A) two diploid daughter cells with 46 chromosomes each
B) two haploid daughter cells with 23 chromosomes each
C) two diploid daughter cells with 23 chromosomes each
D) a single daughter cell with 46 chromosomes, and a polar body with no genetic material
E) two haploid daughter cells with 46 haploid chromosomes

Question 72

Prostaglandins are secreted in high concentration into semen by the prostate gland.

Question 73

Menopause:

A) is the cessation of menstrual cycles.
B) results in high plasma levels of estrogens.
C) occurs as a result of cessation of gonadotropin secretion.
D) is the cessation of ovulation while a baby is nursing.
E) is the pause in development of ovarian follicles occurring between the birth of a baby girl and when she reaches puberty.

Question 74

The products of the first meiotic division of spermatogenesis are spermatids.

Question 75

The part of the spermatozoan that enables it to swim through fluid is the acrosome.

Question 76

One way in which gametogenesis in males differs from gametogenesis in females is that mitosis of primordial germ cells occurs in males only during fetal life.

Question 77

The testes are located outside the abdomen because spermatogenesis requires a temperature lower than core body temperature.

Question 78

In the testis, spermatogenesis takes place in the seminiferous tubules and testosterone is produced by the Leydig cells.

Question 79

Meiosis results in germ cells with 23 maternal chromosomes in one daughter cell and 23 paternal chromosomes in the other.

Question 80

Implantation of a blastocyst:

A) normally occurs within the oviduct (fallopian tube).
B) normally begins around day 21 of the typical menstrual cycle.
C) occurs within 24 hours of fertilization of the oocyte.
D) takes place at a time in the typical menstrual cycle when estrogen concentration in the blood is higher than progesterone concentration in the blood.
E) requires the presence of high concentrations of follicle-stimulating hormone (FSH).