31) Near the end of the first trimester, deoxygenated blood flows from the developing embryo or fetus to the placenta through ________.

A) paired umbilical veins

B) the superior vena cava

C) one umbilical vein

D) three umbilical arteries

E) paired umbilical arteries

32) The conversion of mammary glands from resting to active states requires the presence of both placental hormones and ________.

A) oxytocin and insulin

B) progesterones and estrogens

C) human chorionic gonadotropin and parathyroid hormones

D) glucagon and somatostatin

E) growth hormones, prolactin, and thyroid hormones

33) Which statement regarding placental circulation is true?

A) Oxygenated maternal blood re-enters the mother’s venous system through chorionic villi.

B) Maternal and fetal blood mix near the placenta.

C) Deoxygenated maternal blood re-enters the mother’s venous system through small uterine veins.

D) Deoxygenated blood leaves the chorionic villi through umbilical arteries.

E) Oxygenated fetal blood enters the chorionic villi through umbilical arteries.

34) At which gestational age do basic heart structures, major blood vessels, lymph nodes, and ducts form?

A) month 6

B) month 8

C) month 4

D) month 7

E) month 2

35) Neural tube formation occurs during which gestational age?

A) 4 months

B) 2 weeks

C) 1 month

D) 9 weeks

E) 5 months

36) During pregnancy,

A) maternal respiratory rate decreases.

B) maternal blood volume decreases.

C) maternal nutrient requirements decrease significantly.

D) a woman’s glomerular filtration rate decreases by 20 percent.

E) maternal tidal volume increases.

37) When labor begins, the fetal pituitary gland secretes ________, which may be the actual trigger for the onset of labor.

A) prolactin

B) hCG

C) oxytocin

D) growth hormone

E) thyroxine

38) The last stage of labor is the

A) dilation stage.

B) expulsion stage.

C) placental stage.

D) decidual stage.

E) neonate stage.

39) The stage of labor during which the fetus begins to shift toward the cervical canal is the

A) emergence stage.

B) dilation stage.

C) placental stage.

D) expulsion stage.

E) fetal stage.

40) Which statement is true regarding conjoined twins?

A) Splitting of the inner cell mass may have occurred before gastrulation.

B) They are known as monozygotic twins.

C) Separation of the blastomeres early in cleavage may have occurred.

D) Splitting of the blastomeres or of the embryonic disc is not complete.

E) Two separate oocytes are fertilized at the same time.