Deck 3: Basic Embryology

Question 1

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)

Answer 1

A

Question 2

The neural tube develops from this layer.

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 zygote?

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

Answer 3

B

Question 4

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 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

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 8

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 9

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

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

Question 10

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 11

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 12

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 13

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 14

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

Question 15

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 16

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

Question 17

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 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

This develops into the epidermis of the skin.

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

Question 20

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 21

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

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

Question 22

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

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

Question 23

The gonads arise from what embryonic structure?

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

Question 24

Division of cells in a zygote is called

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

Question 25

Limb buds emerge in the human embryo about

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

Question 26

Conception occurs in the

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

Question 27

Somites differentiate into

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

Question 28

Approximately percent of all children have some birth defect.

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

Question 29

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 30

Which of the following is endodermal in origin?

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

Question 31

The sclerotome will develop into the

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

Question 32

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 33

Splanchnic mesoderm forms the

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

Question 34

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

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

Question 35

The middlemost embryonic germ layer to develop is

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

Question 36

Which of the following is the proper sequence for neurulation?

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

Question 37

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 38

Neural crest cells are derived from this germ layer.

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

Question 39

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

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

Question 40

The splanchnic mesoderm forms next to this layer.

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

Question 41

Which characteristic is not true of a blastocyst?

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

Question 42

The urinary bladder is derived from which embryonic layer?

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

Question 43

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

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

Question 44

In human embryos, the yolk sac is important because it

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

Question 45

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

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

Question 46

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

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

Question 47

A teratogen is

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

Question 48

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

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

Question 49

The expression ʺbreaking waterʺ during birthing refers to the

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

Question 50

The bodyʹs axis of development is determined by the

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

Question 51

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

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

Question 52

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

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

Question 53

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

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

Question 54

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

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

Question 55

Mesenchyme would refer to but not .

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

Question 56

The neural tube of the embryo develops into the

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

Question 57

Fertilization is to zygote as

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

Question 58

Implantation of the blastocyst on the uterine lining takes about

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

Question 59

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

Question 60

The term bilaminar disc refers to the embryonic and .

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

Question 61

Which of the following is not a germ layer?

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

Question 62

Conjoined twins occur as a result of

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

Question 63

The epiblast gives rise to the three primary germ layers.

Question 64

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

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

Question 65

Somatic mesoderm gives rise to all of the following except

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

Question 66

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

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

Question 67

Which of the following is not a property of mesenchyme?

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

Question 68

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

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

Question 69

Identical (monozygotic) twins are

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

Question 70

Another name for birth defect is

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

Question 71

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

Question 72

The correct sequence for embryonic development is

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

Question 73

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

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

Question 74

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

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

Question 75

Which of the following adult structures derives from neural crest?

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

Question 76

Which of the following appears latest in human development?

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

Question 77

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

Question 78

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

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

Question 79

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

Question 80

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