PRACTICE QUIZ ANSWERS - EMBRYOGENESIS, NERVOUS SYSTEM
I. Multiple Choice - Select
the one best answer to complete the statement or answer the question. Fill
in the blank space on the computer answer sheet that corresponds to the
letter of your choice. Only one answer is correct.
1. __D__The chorion
A. is lined by embryonic
somatic mesoderm.
B. is formed during the third
week of development after fertilization.
C. has a cavity (extra-embryonic
coelom) which is obliterated in later fetal life by the expansion of the
yolk sac.
D. is composed of the synctiotrophoblast,
cytotrophoblast, and extra-embryonic somatic mesoderm.
E. is connected to the embryo
via the connecting stalk, which is composed of ectoderm since it is external
to the embryo.
2. __C__ The neuroectoderm
A. is formed from ectodermal
cells in the midline of the embryo due to the presence of underlying paraxial
mesoderm.
B. gives rise to the neural
tube cells, which will form the sensory and autonomic ganglia of the peripheral
nervous system and the adrenal medulla.
C. is formed from the ectoderm
cranial (rostral) to the primitive knot (Henson's node) in the midline
of the embryo.
D. is formed after the head
and tail folds rotate the embryo.
E. is found in the neural
folds, which fuse together to form a tube composed of neural crest cells.
3. __B__ The yolk
sac
A. forms the foregut, midgut,
and hindgut during folding of the embryo in the second week post-fertilization.
B. has a diverticulum (outpouching)
from the hindgut, the allantois, which will later form a tube attached
to the urinary bladder.
C. is lined internally by
epiblast cells and covered externally by splanchnic mesoderm.
D. has a lower portion contained
within the umbilical cord of the fetus, which postnatally will form a definitive
structure.
E. is separated from the
chorion by the presence of the amniotic cavity during the second week of
development.
4. __D__ Cleavage
stages
A. directly result in the
formation of the blastocyst.
B. result in an increase
in total volume of the incipient embryo.
C. occur while the incipient
embryo is in the uterine cavity.
D. directly result in the
formation of the morula.
E. directly result in the
formation of the trophoblast.
5. __D__ The second
polar body
A. is formed just prior to
ovulation.
B. is formed in the secondary
oocyte as a result of the reduction first) division of meiosis.
C. contains 23 chromosomes
including a Y sex chromosome.
D. is formed as a result
of the completion of the second (duplication) division of meiosis.
E. contains 22 chromosomes
including a X sex chromosome.
6. __B__ The zona
pellucida
A. does not surround the
morula.
B. surrounds the primary
and secondary oocytes.
C. surrounds the blastocyst.
D. is never penetrated by
a sperm cell.
E. participates in the formation
of the trophoblast layer.
7. __C__ The extra-embryonic
mesoderm
A. is formed by epiblast
cells that migrate into the primitive streak.
B. forms a layer of the amnion
and yolk sac but not the chorion.
C. forms the lining of the
extra-embryonic coelom.
D. is formed by hypoblast
cells.
E. is formed by the synctiotrophoblast.
8. __A__ The notochord
A. is a mesodermal process
extending rostrally from the primitive knot.
B. directly forms most of
the definitive vertebral column.
C. induces the overlying
ectoderm cells to form the primitive streak.
D. is located beneath (ventral
to) the primitive streak.
E. degenerates completely
without forming any definitive structures.
9. __E__ Paraxial
mesoderm forms all of the following structures EXCEPT:
A. intercostal muscles
B. connective tissue in the
superficial fascia
C. rib one
D. dermis of the skin
E. thoracoacromial artery
10. __D__ Which of
the following is NOT associated with spinal nerve C4?
A. anterior root
B. posterior root
C. dorsal root ganglion
D. white ramus communicans
E. gray ramus communicans
11. __D__ Cardiac
branches of the vagus n. are primarily composed of ? fibers
A. somatic efferent
B. somatic afferent
C. visceral afferent
D. parasympathetic preganglionic
E. parasympathetic postganglionic
II. Multiple Completion.
Under the initial statement of each question are four statements that complete
or pertain to it. Read ALL statements carefully, and then choose the appropriate
answer.
Choose:
A=1,2, and 3;
B=1 and 3;
C=2 and 4;
D= 4 only;
E= all.
12. __D__ The postganglionic
neurons of the pre-aortic (pre-vertebral) ganglia
1. send postganglionic fibers
into spinal nerves in the abdominal region.
2. have postganglionic fibers
that are longer than parasympathetic postganglionic fibers.
3. are innervated by preganglionic
vagal fibers.
4. have postganglionic fibers
that travel with arterial branches of the aorta to innervate abdominal
viscera.
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