Deck 3: Basic Embryology

Question 1

Figure 3.1
Use the diagram above to answer the following questions.
Which letter indicates the zygote?

A) A
B) B
C) C
D) D
E) E

Answer 1

B

Question 2

What embryonic epiblast cells that remain on the surface of the trilaminar disc are ultimately called.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Answer 2

B

Question 3

Figure 3.1
Use the diagram above to answer the following questions.
Which letter indicates the oocyte?

A) A
B) B
C) C
D) D
E) E

Answer 3

A

Question 4

All major organs are present in rudimentary form.

A) 8 weeks (end of embryonic period)
B) 9-12 weeks (month 3)
C) 13-16 weeks (month 4)
D) 17-20 weeks (month 5)
E) 21-30 weeks (months 6 and 7)

Question 5

The ectoderm develops into the epithelium of the skin, whereas this layer gives rise to the epithelial lining of the gut tube.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 6

This develops into the lining of the gastrointestinal tract.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 7

Sex can be determined from the genitals.

A) 8 weeks (end of embryonic period)
B) 9-12 weeks (month 3)
C) 13-16 weeks (month 4)
D) 17-20 weeks (month 5)
E) 21-30 weeks (months 6 and 7)

Question 8

Figure 3.1
Use the diagram above to answer the following questions.
Which letter indicates the blastocyst?

A) A
B) B
C) C
D) D
E) E

Question 9

Eyes open and lungs develop.

A) 8 weeks (end of embryonic period)
B) 9-12 weeks (month 3)
C) 13-16 weeks (month 4)
D) 17-20 weeks (month 5)
E) 21-30 weeks (months 6 and 7)

Question 10

Limbs are complete.

A) 8 weeks (end of embryonic period)
B) 9-12 weeks (month 3)
C) 13-16 weeks (month 4)
D) 17-20 weeks (month 5)
E) 21-30 weeks (months 6 and 7)

Question 11

Figure 3.1
Use the diagram above to answer the following questions.
Which letter indicates the morula?

A) A
B) B
C) C
D) D
E) E

Question 12

The mesoderm located deep to the neural tube forms the kidneys and the gonads is the ________.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 13

Quickening occurs (mother feels fetus moving).

A) 8 weeks (end of embryonic period)
B) 9-12 weeks (month 3)
C) 13-16 weeks (month 4)
D) 17-20 weeks (month 5)
E) 21-30 weeks (months 6 and 7)

Question 14

The ribs and vertebrae form from this primary germ layer.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 15

This develops into the epidermis of the skin.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 16

Mucus-producing glands of the respiratory tract arise from this layer.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 17

The neural tube develops from this layer.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 18

This develops into the brain and spinal cord.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 19

Figure 3.1
Use the diagram above to answer the following questions.
Which letter indicates the uterus?

A) A
B) B
C) C
D) D
E) E

Question 20

The epiblast develops a primitive streak during days 14-15, the initial cells that ingress through the primitive streak become this germ layer.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 21

A transverse section through the 24-day embryo, dorsal to ventral, would first contact the

A) neural tube.
B) notochord.
C) somites.
D) myotomes.

Question 22

Which of the following is endodermal in origin?

A) liver
B) spleen
C) blood vessels
D) skin

Question 23

Somites differentiate into

A) the epidermis.
B) myotomes.
C) the gastrointestinal lining.
D) muscles.

Question 24

Blood vessels and the heart arise from this primary germ layer.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 25

The sclerotome will develop into the

A) peritoneum.
B) visceral serosa.
C) vertebrae.
D) heart.

Question 26

Division of cells in a zygote is called

A) blastulation.
B) cleavage.
C) gastrulation.
D) induction.

Question 27

Based on the proportions of the adult body, the 3-month fetus still shows disproportionately large

A) hands.
B) stomach.
C) head.
D) heart.

Question 28

Which of the following is the proper sequence for neurulation?

A) neural tube, neural plate, neural groove
B) neural groove, neural plate, neural tube
C) neural plate, neural groove, neural tube
D) neural groove, brain, neural tube

Question 29

The splanchnic mesoderm forms next to this layer.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 30

The embryonic notochord will eventually be replaced by the developing ________, leaving only remnants that persist as the nucleus pulposus of intervertebral discs.

A) spinal cord
B) pharynx
C) lateral muscle
D) vertebral column

Question 31

The middlemost embryonic germ layer to develop is

A) ectoderm.
B) endoderm.
C) mesoderm.
D) protoderm.

Question 32

This layer will give rise to the bones, ligaments and joints of the embryonic limbs.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 33

Conception occurs in the

A) lateral third of the uterine tube.
B) ovary.
C) peritoneal cavity.
D) uterine cavity.

Question 34

Approximately ________ percent of all children have some birth defect.

A) 0.01
B) 1
C) 3
D) 20

Question 35

The embryonic layer that invades the lining of the uterus and forms the placenta is the

A) trophoblast.
B) embryoblast.
C) inner cell mass.
D) endometrium.

Question 36

The dermis of the dorsal body region is derived from somites. However, the dermis of the ventral body region is derived from

A) endoderm.
B) ectoderm.
C) mesoderm-somites.
D) mesoderm-lateral plate.
E) intermediate mesoderm.

Question 37

Neural crest cells are derived from this germ layer.

A) endoderm
B) ectoderm
C) mesoderm-somites
D) mesoderm-lateral plate
E) intermediate mesoderm

Question 38

Splanchnic mesoderm forms the

A) heart.
B) notochord.
C) brain.
D) skin.

Question 39

The gonads arise from what embryonic structure?

A) notochord
B) endoderm
C) splanchnic mesoderm
D) intermediate mesoderm

Question 40

Limb buds emerge in the human embryo about

A) day 9.
B) day 15.
C) day 28.
D) day 60.

Question 41

The primary germ layer that ultimately forms the serous membranes of the peritoneum is

A) ectoderm.
B) mesoderm.
C) endoderm.
D) neural crest.

Question 42

Chemical, physical, or biological agents that can induce birth defects are called

A) mutagens.
B) teratogens.
C) free radicals.
D) carcinogens.

Question 43

The expression "breaking water" during birthing refers to the

A) amnion.
B) allantois.
C) chorion.
D) yolk sac.

Question 44

The urinary bladder is derived from which embryonic layer?

A) ectoderm
B) mesoderm
C) endoderm
D) neural crest

Question 45

The most common cause of mental retardation in the United States is

A) anencephaly.
B) spina bifida.
C) fetal alcohol syndrome.
D) thalidomide.

Question 46

A teratogen is

A) a deformed baby.
B) a specific sedative used in the 1950s in Europe.
C) a chemical agent, infectious agent or environmental factor that causes birth defects.
D) a stage of development in the mid-fetal period.

Question 47

Thalidomide, once used to alleviate morning sickness in pregnant women, resulted in

A) severe limb abnormalities.
B) heart defects.
C) mental retardation.
D) multiple births.

Question 48

The solid mass of cells that results from cleavage of the zygote is the

A) trophoblast.
B) blastocyst.
C) morula.
D) gastrula.

Question 49

The term bilaminar disc refers to the embryonic ________ and ________.

A) epidermis; dermis
B) ectoderm; mesoderm
C) epiblast; hypoblast
D) inner cell mass; trophoblast

Question 50

Most organ systems are fully formed and ready to function in the fetus by the sixth month. Which of the following systems is the exception to this generalization because it takes longer to finish development?

A) the circulatory system
B) the respiratory system
C) the urinary system
D) the integumentary system

Question 51

Fertilization is to zygote as

A) egg is to sperm.
B) oocyte is to ovary.
C) cleavage is to morula.
D) birth is to parturition.

Question 52

Implantation of the blastocyst on the uterine lining takes about

A) 1 week.
B) 2 weeks.
C) 3 weeks.
D) 4 weeks.

Question 53

Which of the following does not distinguish mesoderm from either endoderm or ectoderm?

A) It is a mesenchyme tissue.
B) It is derived from the epiblast.
C) It is the last of the three germ layers to develop.
D) Its cells can migrate widely within the embryo.

Question 54

The primary germ layer that ultimately produces the hair, fingernails, and toenails is

A) ectoderm.
B) mesoderm.
C) endoderm.
D) neural crest.

Question 55

Which characteristic is not true of a blastocyst?

A) It contains a fluid-filled cavity.
B) It develops 24-36 hours after conception.
C) It has an inner cell mass and an outer trophoblast.
D) It implants into the uterus.

Question 56

Male and female fetuses can first be distinguished by their genitalia at

A) 1 week.
B) 3 weeks.
C) 3 months.
D) 7 months.

Question 57

The neural tube of the embryo develops into the

A) spinal cord.
B) neural crest.
C) sensory neurons.
D) dorsal skin.

Question 58

The body's axis of development is determined by the

A) blastomeres.
B) epiblast.
C) notochord.
D) primitive streak.

Question 59

In human embryos, the yolk sac is important because it

A) stores yolk.
B) gives rise to earliest blood cells and blood vessels.
C) stores nitrogenous wastes.
D) allows for gas exchange through the placenta.

Question 60

Mesenchyme would refer to ________ but not ________.

A) mesoderm; ectoderm
B) ectoderm; mesoderm
C) endoderm; ectoderm
D) ectoderm; endoderm

Question 61

Somatic mesoderm gives rise to all of the following except

A) some bones.
B) some serous membranes.
C) dermis of the skin of the belly.
D) epidermis of the upper limb.

Question 62

Spina bifida results when the neural tube fails to close in the head.

Question 63

As a result of folding, the embryo acquires a tadpole shape by

A) day 9.
B) day 12.
C) day 15.
D) day 24.

Question 64

The outer membrane of the amniotic sac is called the amnion.

Question 65

The fetal period is the longer and later of the prenatal growth periods.

Question 66

Which of the following adult structures derives from neural crest?

A) all the nerve cells in the brain
B) all the nerve cells in the spinal cord
C) all the pigment-producing cells in the body
D) all bones

Question 67

The cavity in the mesoderm that ultimately develops into the peritoneal, pericardial, and pleural cavities is called:

A) an antrum.
B) a blastocoel.
C) a coelom.
D) a dermatome.

Question 68

The correct sequence for embryonic development is

A) zygote, blastocyst, morula.
B) zygote, morula, blastocyst.
C) blastocyst, morula, zygote.
D) zygote, fetus, embryo.

Question 69

If a mutation occurs in the hypoblast cells of a bilaminar embryo, one might expect birth defects to be present in the

A) blood cells or vessels.
B) brain and spinal cord.
C) hair and skin.
D) musculoskeletal system.

Question 70

Which of the following is not a property of mesenchyme?

A) It is present before birth.
B) Its cells migrate.
C) Its cells are star-shaped.
D) Its cells attach closely to one another and form sheets.

Question 71

Which of the following appears latest in human development?

A) limb buds
B) somites
C) heart
D) separate fingers

Question 72

The amniotic sac is derived from the epiblast, while the placenta develops from the

A) bilaminar disc.
B) hypoblast.
C) neural crest.
D) trophoblast.

Question 73

Production of surfactant begins during week 22-26 of the gestational period. Premature infants born after week 26 will

A) not survive.
B) will not need medical assistance for breathing.
C) will need medical assistance for breathing.
D) will be at increased risk for visual disorders and mental impairment.

Question 74

Conjoined twins occur as a result of

A) complete separation of cells in the early morula.
B) failure of the blastocyst to implant in the uterine lining.
C) incomplete division of the inner cell mass.
D) fertilization of the ovum by two different sperm

Question 75

The epiblast gives rise to the three primary germ layers.

Question 76

Which of the following is not a germ layer?

A) ectoderm
B) mesoderm
C) epidermis
D) endoderm

Question 77

Another name for birth defect is

A) birth illness.
B) teratogenesis.
C) congenital abnormality.
D) prenatal pathology.

Question 78

The inner cell mass will form the embryo, and the trophoblast will form the placenta.

Question 79

Identical (monozygotic) twins are

A) formed from splitting of the inner cell mass.
B) formed from splitting of the zygote.
C) formed from the release of two eggs.
D) formed from two sperm fertilizing one egg.

Question 80

The ability of one cell to influence the development of its neighboring cells is called

A) blastulation.
B) cleavage.
C) gastrulation.
D) induction.