Question 1

Which of the following best describes the main event that distinguishes the embryonic period from the fetal period during prenatal development?

Accepted Answer

The appearance of rudimentary versions of major organs.

Question 2

During fertilization, what is the primary function of the acrosome reaction?

Accepted Answer

To release digestive enzymes that allow sperm to penetrate the zona pellucida.

Question 3

If two sperm fertilize a single oocyte simultaneously, what is the likely outcome?

Accepted Answer

The resulting zygote will have 69 chromosomes and will not survive.

Question 4

Which hormone is primarily responsible for maintaining the corpus luteum during the first trimester of pregnancy?

Accepted Answer

Human chorionic gonadotropin (hCG)

Question 5

What is the main function of the trophoblast cells in the blastocyst?

Accepted Answer

To form the chorion and contribute to placenta formation.

Question 6

Which extraembryonic membrane is the first to develop and is important for early blood cell and vessel formation?

Accepted Answer

Yolk sac

Question 7

During gastrulation, which germ layer forms as epiblast cells migrate through the primitive streak and displace the hypoblast?

Accepted Answer

Endoderm

Question 8

Which structure is responsible for inducing the formation of the neural tube during embryonic development?

Accepted Answer

Notochord

Question 9

A pregnant woman is found to have high blood glucose levels during her second trimester. Which hormone is most likely contributing to her increased insulin resistance?

Accepted Answer

Human placental lactogen (HPL)

Question 10

Which of the following best explains why maternal and fetal blood do not mix directly in the placenta?

Accepted Answer

The chorionic villi contain fetal blood vessels that are separated from maternal blood by a thin barrier.

Question 11

Which of the following is a critical function of the hormone relaxin during pregnancy?

Accepted Answer

Promoting blood vessel growth in the uterus

Question 12

During which stage of labor does the cervix become fully dilated to 10 cm?

Accepted Answer

Dilation stage

Question 13

Which positive feedback mechanism is responsible for the intensification of uterine contractions during true labor?

Accepted Answer

Stretching of the cervix stimulates oxytocin release, which increases uterine contractions.

Question 14

Which of the following is a direct result of the first breath taken by a neonate after birth?

Accepted Answer

A drop in pulmonary resistance and increased blood flow to the lungs.

Question 15

Which hormone is primarily responsible for stimulating milk ejection (letdown) from the mammary glands during breastfeeding?

Accepted Answer

Oxytocin

Question 16

A mutation prevents the development of the syncytiotrophoblast layer in a blastocyst. Which of the following is the most likely consequence?

Accepted Answer

Implantation would fail due to lack of hCG production and inability to maintain the corpus luteum.

Question 17

Which of the following best describes the role of the amnion during embryonic development?

Accepted Answer

It encloses the embryo in a fluid-filled sac, protecting it from drying out and mechanical injury.

Question 18

Which primary germ layer gives rise to the lining of the gastrointestinal, respiratory, and urinary tracts?

Accepted Answer

Endoderm

Question 19

Which of the following is a reason why pregnant women are more susceptible to urinary tract infections (UTIs)?

Accepted Answer

Dilation of the ureters and renal pelvis, along with compression by the uterus, leads to urine stasis.

Question 20

Which of the following best explains why detection of significant levels of hCG in urine is a reliable test for pregnancy?

Accepted Answer

hCG is produced by the syncytiotrophoblast only after implantation has occurred.

Human Development: Prenatal Period, Pregnancy, and Postnatal Changes

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