Question 1

A prenatal diagnostic procedure to detect chromosomal abnormalities is:&#10;A) mitotic cleavage.&#10;B) bilateral symmetry.&#10;C) amniocentesis.&#10;D) folding.

Accepted Answer

A prenatal diagnostic procedure to detect chromosomal abnormalities is amniocentesis,where the amniotic fluid is removed and its fetal cells are grown for microscopic study of the chromosomes as well as sampled for determination of other fetal complications.After fertilization,the zygote then undergoes mitosis,or individual cell division,that splits it into more and more cells due to cleavage.During the beginning of the third week of prenatal development within the embryonic period,the primitive streak forms within the bilaminar disc.The primitive streak causes the disc to have bilateral symmetry,with a right half and left half.During the fourth week of prenatal development within the embryonic period,the embryonic disc undergoes embryonic folding,which places forming tissue types into their proper positions for further embryonic development.

Question 2

How many pairs of somites form the cuboidal segments of mesoderm within the embryo during the third week of prenatal development?&#10;A) 12&#10;B) 18&#10;C) 38&#10;D) 42

Accepted Answer

By the end of the third week,the mesoderm additionally differentiates and begins to divide on each side of the tube into 38 paired cuboidal segments of mesoderm,forming the somites.The somites develop in the following weeks of prenatal development,giving rise to most of the skeletal structures of the head,neck,and trunk,as well as the associated muscles and dermis of the skin.

Question 3

How many X-type chromosomes are necessary for the embryo to become of the female gender when present during prenatal development?&#10;A) One&#10;B) Two&#10;C) Three&#10;D) Four

Accepted Answer

The photographic analysis of a person's chromosomes is done by orderly arrangement of the pairs in a karyotype,with the sex known by the presence of either XX chromosomes for females or XY for males.

Question 4

The primitive streak forms in the embryonic disc during prenatal development,causing:&#10;A) initiation of palatal development.&#10;B) bilateral symmetry.&#10;C) fusion of the mandibular processes.&#10;D) disintegration of the oropharyngeal membrane.

Accepted Answer

The primitive streak causes the disc to have bilateral symmetry,with a right half and left half; most of the further development of each half of the embryo mirrors the other half.

Question 5

Which of the following statements concerning prenatal development is correct?&#10;A) Most congenital malformations occur during the last prenatal week.&#10;B) Maturation of existing structures occurs during the second to eighth week.&#10;C) Initiation of embryonic layers occurs during the first week.&#10;D) The fetus is the structure present during the embryonic period.

Accepted Answer

By the end of the first week of the preimplantation period,the blastocyst stops traveling and undergoes implantation and thus becomes embedded in the prepared endometrium,the innermost lining of the uterus on its back wall.After a week of cleavage,the blastocyst consists of a layer of peripheral cells,the trophoblast layer,and a small inner mass of embryonic cells,or the embryoblast layer.Any developmental disturbances occurring during the earlier embryonic period and not the later fetal period with its fetus may give rise to major congenital malformations of the embryo.Thus,the fetal period encompasses the beginning of the ninth week or third month continuing to the ninth month,with the maturation of existing structures occurring as the embryo enlarges to become a fetus.

Question 6

When does the blastocyte stop traveling and undergo implantation during prenatal development?&#10;A) First week&#10;B) Second week&#10;C) Third week&#10;D) Fourth week

Accepted Answer

By the end of the first week,the blastocyst stops traveling and undergoes implantation,thus becoming embedded in the prepared endometrium,the innermost lining of the uterus on its back wall.

Question 7

Which of the following structures initially forms during the third week of prenatal development?&#10;A) Primitive streak&#10;B) Embryoblast layer&#10;C) Bilaminar embryonic disc&#10;D) Trophoblast layer

Accepted Answer

During the beginning of the third week of prenatal development within the embryonic period,the primitive streak forms within the bilaminar disc.This furrowed,rod-shaped thickening in the middle of the disc results from an increased proliferation of cells in the midline area.After a week of cleavage,the blastocyst consists of a layer of peripheral cells,the trophoblast layer,and a small inner mass of embryonic cells,or embryoblast layer.The trophoblast layer later gives rise to important prenatal support tissue.The embryoblast layer later gives rise to the embryo during the prenatal period that follows,the embryonic period.

Question 8

In which of the following do the final stages of meiosis occur during prenatal development?&#10;A) Placenta&#10;B) Ovum&#10;C) Sperm&#10;D) Yolk sac

Accepted Answer

During fertilization,the final stages of meiosis occur in the ovum.The result of this process is the joining of the ovum's chromosomes with those of the sperm.This joining of chromosomes from both biologic parents forms a new individual with "shuffled" chromosomes.

Question 9

During prenatal development,the oropharyngeal membrane of the embryo:&#10;A) consists of three embryonic layers.&#10;B) is located superior to the first branchial arch.&#10;C) disintegrates during the third week of prenatal development.&#10;D) is located superior to the maxillary process.

Accepted Answer

At the cephalic end,the oropharyngeal membrane forms,which consists of only ectoderm externally and endoderm internally,without any intermediate mesoderm.This membrane is the location of the future primitive mouth or stomodeum of the embryo and thus the beginning of the digestive tract.It is located superior to the first branchial arch or mandibular arch.

Question 10

The neural crest cells migrate from which embryonic structures during prenatal development?&#10;A) Stomodeum&#10;B) First branchial arch&#10;C) Neural folds&#10;D) Frontonasal process

Accepted Answer

The neural crest cells migrate from the crests of the neural folds and then join the mesoderm to form mesenchyme.At the cephalic end,the oropharyngeal membrane forms,which consists of only ectoderm externally and endoderm internally,without any intermediate mesoderm.This membrane is the location of the future primitive mouth or stomodeum of the embryo and thus the beginning of the digestive tract.The first branchial arch,also called the first pharyngeal arch and mandibular arch,is the first of six arches that develops in fetal life.The frontonasal process is the midline unpaired embryonic structure that develops into the forehead.

Question 11

Which period of prenatal development is characterized by increased cellular differentiation?&#10;A) Unattached conceptus&#10;B) Embryonic period&#10;C) Preimplantation period&#10;D) Fetal period

Accepted Answer

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Question 12

What best characterizes the first week of prenatal development so that the blastocyst splits into smaller and more numerous cells?&#10;A) Implantation&#10;B) Mitotic cleavage&#10;C) Meiosis&#10;D) Fertilization

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Question 13

By the end of the first week of prenatal development,the blastula stops traveling and undergoes:&#10;A) implantation.&#10;B) migration.&#10;C) disintegration.&#10;D) amniocentesis.

Accepted Answer

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Question 14

Which of the following tissues listed will develop from the ectoderm layer of the embryo during prenatal development?&#10;A) Epidermis&#10;B) Liver&#10;C) Muscle&#10;D) Dermis

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Question 15

The folding of the embryo during prenatal development causes _____ to be on the _____.&#10;A) endoderm; inside of the embryo&#10;B) ectoderm; inside of endoderm&#10;C) endoderm; outside of the mesoderm&#10;D) mesoderm; outside of the ectoderm

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Question 16

Which of the following can occur that mainly involves the abnormal development of one or more structures from ectoderm within the embryonic period?&#10;A) Treacher Collins syndrome&#10;B) Ectodermal dysplasia&#10;C) Congenital syphilis&#10;D) Fetal alcohol syndrome

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Question 17

From which embryonic layer is mesoderm derived during prenatal development?&#10;A) Epiblast layer&#10;B) Hypoblast layer&#10;C) Endoderm&#10;D) Neuroectoderm

Accepted Answer

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Question 18

Found in early prenatal development,the neural tube will form in the future which of the following structures?&#10;A) Heart&#10;B) Spinal cord&#10;C) Face&#10;D) Digestive tract

Accepted Answer

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Question 19

What exact cells are localized to the neural plate of the embryo during the third week of prenatal development?&#10;A) Neuroectoderm&#10;B) Mesenchyme&#10;C) Somites&#10;D) Endoderm

Accepted Answer

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Question 20

During which week of prenatal development does the neural plate differentiate?&#10;A) Second week&#10;B) Third week&#10;C) Fourth week&#10;D) Fifth week

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Question 21

Implantation of the zygote may also occur outside the uterus during prenatal development with a(n):&#10;A) infection with rubella.&#10;B) infection with syphilis.&#10;C) ectopic pregnancy.&#10;D) case of ectodermal dysplasia.

Accepted Answer

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Question 22

What is the exact term for the process that affords the development of specific tissue structure or differing form due to embryonic cell migration and inductive interactions?&#10;A) Folding&#10;B) Morphogenesis&#10;C) Proliferation&#10;D) Appositional or interstitial growth

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Question 23

If there is failure of migration of the neural crest cells to the facial region during prenatal development,_____ can develop in the embryo.&#10;A) ectodermal dysplasia&#10;B) fetal alcohol syndrome&#10;C) Down syndrome&#10;D) Treacher Collins syndrome

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Question 24

What is the prenatal organ that joins the pregnant woman and the developing embryo during the second week of prenatal development?&#10;A) Placenta&#10;B) Amniotic cavity&#10;C) Yolk sac&#10;D) Primitive streak

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Question 25

What exact cells or structures develop from neuroectoderm and migrate from the neural folds to then join mesoderm to form mesenchyme during the third week of prenatal development?&#10;A) Somites&#10;B) Neural crest cells&#10;C) Mesoderm&#10;D) Yolk sac

Accepted Answer

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Deck 3: Prenatal Development