Download 1 HUMAN DEVELOPMENT MEDICAL EXAM 12/11/02 59 questions

HUMAN DEVELOPMENT MEDICAL EXAM 12/11/02
59 questions because Question 27 was deleted but credit was given if correct
FERTILIZATION
1. All of the following occur during capacitation EXCEPT:
a. sperm motility is activated.
*b. there is an influx of Na+, which is balanced by an efflux of H+.
c. calcium uptake is increased.
d. sperm lose cell surface glycoproteins.
2. During the acrosome reaction in mammalian sperm
a. sperm motility increases
*b. The inner acrosomal membrane becomes the outer boundary of the sperm head.
c. a protease is released by exocytosis
d. the sperm nucleus begins to decondense to form a pronucleus
3. The initial binding between mammalian sperm and eggs:
a. involves egg surface integrins.
b. is affected by pretreatment of the egg with N-linked glycohydrolases.
c. involves high energy sugar intermediates (UDP-sugars).
*d. involves only one of the three zona pellucida glycoproteins.
4. As a result of sperm egg plasma membrane fusion:
*a. cortical granule exocytosis is stimulated
b. the acrosome reaction is completed
c. the zona pellucida is released
d. the block to polyspermy is ended
5. Microvilli on the egg surface play an important role in incorporating the sperm during
fertilization. Based upon their structure, which drug would you think would block the
contribution of microvilli to incorporating the sperm into the egg?
*a. latrunculin, a microfilament inhibitor
b. colcemid, a microtubule inhibitor
c. puromycin, a protein synthesis inhibitor
d. tunicamycin, an inhibitor of the formation of N-glycosidic linkages
CLEAVAGE
6. By the stage of blastocyst formation (32-64 cell stage) blastomeres have become fully
committed to one of the following lineages:
a. mesoderm
*b. trophoblast
c. primitive streak.
d. neural derivatives
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7. The fate of a cell (as defined in developmental biology) is:
a. its capacity to change developmental programs when moved to an ectopic
location.
* b. the normal developmental pathway(s) it will take if left undisturbed.
c. always marked by easily detectable morphological differences between or among
cells.
d. defined following relocation to another part (ectopic site) of the developing
embryo.
8. The Mendelian concept of reciprocal inheritance is:
a. based on the expression of mitochondrial DNA.
b. based on the expression of some genes from only the maternal chromosome, and
of others only from the paternal chromosome.
c. that homologous genes (alleles) on the paternal autosomes are identical to those
on the maternal autosomes.
*d. the equivalent expression of a gene (allele) without regard to the parent of
origin.
9. Following fertilization, cleavage divisions in humans:
a. are slow so that cells can double in size with each cell cycle.
* b. take place within the oviduct.
c. do not start until the fertilized egg enters the uterine lumen.
d. synchronized so that each blastomere remains equivalent to the rest throughout
cleavage divisions (that is until hatching).
10. Immediately following compaction the cells of the blastula would be characterized as
having:
a. tight junctions among all cells.
b. cilia on the outer cells only.
*c. some cells which touch other cells but do not “see” the outside.
d. shed the surrounding zona pellucida.
GASTRULATION
11. At the end of gastrulation all of the following are true EXCEPT:
a. the neural tube has closed at both ends.
b. the laying down of the primary germ layers is complete.
*c. the embryo is bilaterally symmetrical at a molecular level.
d. the anterior-posterior axis of the embryo has been established.
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12. During gastrulation cells moving into and through the primitive streak:
*a. undergo cytoskeletal rearrangements, first displacing their cytoplasm basally
(toward the hypoblastic layer) and then rounding up and moving off.
b. up-regulate their cell adhesion molecules including members of the cadherin
family.
c. can only become notochord.
d. all of the above.
e. none of the above.
13. The descendants of the epiblast include:
a. the trophoblasts.
b. the primary yolk sac.
*c. the amnionic membrane.
d. inner cell mass.
14. Cells at the primitive node have cilia. The cilia are important in the process of
developing handedness (sidedness, right/left). This can be demonstrated by:
a. the occurrence of situs inversus in humans with a mutation in one of the dyneins.
b. the lack of left sided expression of Nodal when cilia are absent or non functional.
c. the heart appearing on the right side of the chest.
*d. all of the above.
e. none of the above.
EITHER b or d 15. Which of the following statements is true about the primitive node?
a. Cells that migrate through this structure give rise to the somites.
*b. Transplantation of the primitive node to an ectopic site can induce axis
formation.
c. In mammals (well mice anyway) the experiment described above would induce
only the anterior aspect of the embryonic axis.
*d. Cells that migrate through it contribute to head mesoderm (prechordal plate).
16. One important role of the hypoblast:
a. is to induce the neural lineage.
b. is to induce the migration of selected cells of the epiblast.
*c. is to orient the primitive streak.
d. is to form the definitive embryonic endoderm.
FLEXION
17. When flexion of the head and tail and lateral folding are complete:
a. the gut is completely segregated from the yolk sac.
b. the heart is still dorsal to the foregut.
c. the splanchnic mesoderm has yet to form a wall around the gut tube.
d. all viscera are retroperitoneal and have to secondarily move into the peritoneal
space.
*e. the embryonic tissues are completely segregated from the extraembryonic
membranes except at the umbilical cord (vitelline duct).
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18. You would predict that the cartilage, smooth muscle and blood vessels of the lung are
derived from:
a. endoderm.
b. ectoderm.
c. the somites.
*d. splanchnic mesoderm.
e. intermediate mesoderm.
19. The head fold:
a. rotates the heart to its position in the thoracic space.
b. rotates a component of the diaphragm into the thoracic space.
c. participates in narrowing the gut tube.
*d. all of the above.
20. The pericardial peritoneal canals permit communication between the primitive
pericardial cavity and the primitive abdominal cavity. The first step in closing these
canals is;
*a. the mesenchyme of the lateral body wall extends in the coronal plane and
divides the pericardial from the pleural cavities (pleuropericardial folds).
b. the invasion of the septum transversum by cells from the somites.
c. continued growth of the septum transversum.
d. the growth of cardiac tissue.
21. The tail fold:
a. moves the allantois closer to the connecting stalk.
b. narrows the gut tube at the posterior end.
c. rotates the cloaca to a ventral position.
*d. all of the above.
e. none of the above.
22. The intra embryonic coelom
a. is bounded by endoderm.
b. originates from the amnion cavity.
*c. originates from a space in the lateral plate mesoderm.
d. includes the yolk sac.
NEURULATION, NEURAL TUBE, NEURAL CREST
23. The action of noggin and chordin affect neural induction by:
a. inducing the expression of Nodal. Nodal is a prerequisite for neural induction in
the medial dorsal portion of the dorsal ectoderm.
*b. inhibiting expression of BMP-4 in the medial portion of the dorsal ectoderm and
thus preventing differentiation of epidermis.
c. inhibiting sonic hedgehog (Shh) and thus preventing the formation of the neural
plate.
d. inducing formation of the prechordal plate.
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24. An open posterior neuropore:
a. leads to a condition known as anencephaly
*b. results in spinal bifida
c. is always associated with cardiac bifida
d. is always fatal.
25. All of the following statements are correct regarding the events that occur when a
neuron is born EXCEPT:
a. The plane of division of progenitor cells in the ventricular zone influences its
fate.
b. The neuron will never again replicate its DNA
*c. the neuron looses its ability to migrate.
d. Just because a neuron has been born does not mean that it is destined to survive.
26. Rapid growth and bending of the embryo results in:
a. fusion of the neural folds.
b. a decrease in the volume of the brain vesicles.
c. degeneration of the neuroepithelium.
*d. development of a cephalic flexure.
DELETED – CREDIT GIVEN IF CORRECT 27. All of the following genes and
transcription factors are required for neural crest induction and subsequent migration
EXCEPT:
a. Wnt-6
b. slug
c. Pax3
*d. Ephrin
e. BMP-4
28. Heterotopic transplantation of quail neural crest cells into chick neural crest
migration pathways have revealed that:
a. all neural crest cells are pluripotent and can express all known neural crest
derivatives.
b. truncal neural crest cells form connective tissues when they are transplanted into
the vagal region of a younger host embryo.
c. neural crest cells from any region of the neuraxis will form the conotruncal
septum if they are transplanted adjacent to somites 1-3 early enough.
d. all of the above.
*e. none of the above.
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MESODERM
29. All of the following statements are correct concerning the formation of muscle tissue
in the body EXCEPT:
a. All skeletal muscles in the trunk are derived from somites.
*b. Limb musculature originates from the lateral plate mesoderm.
c. Smooth muscle tissue of the gastrointestinal tract develops mainly from the
splanchnic mesoderm.
d. Cardiac muscle develops from the splanchnic mesoderm surrounding the
endothelial heart tube.
30. The presomitic mesoderm (paraxial mesoderm before somites appear) carries
positional information or is said to be pre-patterned. This is evidenced by:
*a. retention of rib-bearing capability when thoracic paraxial presomitic mesoderm
is tranplanted to the cervical region.
b. loss of rib-bearing capability when thoracic paraxial presomitic mesoderm is
tranplanted to the cervical region.
c. loss of ability to differentiate at all following transposition to a different axial
level.
d. loss of ability for sclerotome to form vertebrate but retention of the ability of
myotome to make axial musculature appropriate for the original site (thoracic).
31. It can be demonstrated that the cranial (anterior) half of the somite is not identical to
the caudal (posterior) half. The evidence includes:
*a. only the caudal (posterior) half contains a protein that repels axonal growth
cones.
b. only the cranial half secretes an attractive signal to guide motor axons from the
spinal cord.
c. only the cranial half gives rise to the vertebral column.
d. only the posterior half gives rise to the axial muscles.
32. If somites are removed from the thoracic region:
a. no neural crest cells will migrate and hence no dorsal root ganglion cells will
form in this region.
b. no motor axons will grow out.
*c. neural crest cells destined to become sympathetic ganglion cells will migrate to
the right place but will be an unsegmented continuum in the region missing
somites.
d. all of the above.
e. none of the above.
33. Somites are added at regular intervals. This regularity requires:
a. a molecular clock.
b. signaling between Notch and Delta.
c. a wave of gene expression starting caudally and “moving” rostrally.
*d. all of the above.
e. none of the above.
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34. Signaling between Notch and Delta:
a. occurs when Notch protein is secreted by the signaling cell.
*b. involves the interaction of two transmembrane proteins.
c. occurs when Delta protein is secreted by the signaling cell.
d. occurs when Notch protein is “presented” to Delta via binding to extracellular
matrix elements.
ENDODERM – BOWEL LIVER PANCREAS
35. A previously healthy 13 year old white female is admitted to a hospital complaining
of severe sharp abdominal pain localize to the mid abdomen. For the previous two
months she had experienced periodic episodes of cramping periumbilical pain,
sometimes associated with a burning sensation. One day prior to admission, an
examination of the patient’s stool in the office of her pediatrician revealed the presence of
blood. On physical examination, the patient’s abdomen was found to be tender and
board-like. The complete blood count revealed 4-fold the normal number of white blood
cells with an excess of neutrophils. Peritonitis was diagnosed. Which of the following
causes is most likely to be the source of the patient’s problem?
*a. persistent vitelline duct
b. appendicitis
c. abdominal hernia
d. failure of midgut rotation
e. annular pancreas
36. An autopsy carried out on an infant that died on the fourth day of life reveals that the
cause of death was lipid pneumonia secondary to the aspiration of milk through a
tracheo-esophageal fistula above a stenotic region of the esophagus. The child had been
born at full-term as a result of an uneventful delivery. An examining pediatrician noted
good color and vital signs postpartum. Symptoms, which included regurgitation and
evident “choking” began during the child’s first feeding of breast milk. Which of the
following causes is most likely to be the source of the infant’s problem?
a. gastroesophageal reflux.
*b. failure of recanalization
c. reluctance of the mother to give birth
d. annular pancreas
e. failure of the stomach to rotate
37. Which of the following maternal conditions, might, if it had been noted and
diagnosed, could have led to medical intervention that would have saved the infant’s (in
the question above) life?
a. depression
b. vaccination against measles, mumps, and rubella
c. AIDS
d. persistent abdominal pain
*e. muffled fetal heart sounds due to polyhydramnios
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38. The midgut herniates into the umbilical cord because:
a. it is attracted by a temporary gradient of guidance molecules.
b. it is repelled by the liver.
c. it follows the growth of the superior mesenteric artery.
*d. its own rapid growth and that of the liver leave no space for it in the
developing peritoneal cavity.
e. it is drawn into the yolk sac by a patent vitelline duct.
39. The midgut:
*a. rotates a total of 270° counter clockwise during its herniation and subsequent
reduction (of the midgut hernia).
b. is primarily supplied by the inferior mesenteric artery.
c, extends buds that form the pancreas, liver, and biliary apparatus.
d. is partitioned by the rectovaginal septum.
e. the first region of the bowel to close.
40. Failure of which of the following processes is most likely to lead to volvulus
(twisting of gut with possible compromise of its blood supply)?
a. recanalization
b. apoptosis
c. rotation of the stomach
d. rotation of the midgut
*e. bowel becomes secondarily retroperitoneal
41. Which of the following is only in part a derivative of the primordial foregut?
a. tracheo-bronchial tree
b. liver
c. pancreas
d. stomach
*e. duodenum
FORMATION AND ROLE OF THE PLACENTA
42. The endometrium is “receptive”:
a. during its proliferative phase.
b. beginning at the time of ovulation.
c. largely due to the influence of human chorionic gonadotropin (hCG).
*d. 6 days following ovulation.
43. The cells of the blastocyst that adhere to the endometrial lining at implantation are:
a. inner cell mass.
*b. syncytiotrophoblast.
c. cytotrophoblast.
d. hypoblast.
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44. The trophoblast secretes human chorionic gonadotropin (hCG), which:
a. opens the window of receptivity.
*b. maintains the corpus luteum.
c. promotes rebuilding of the endometrium following menstruation.
d. is a matrix metalloproteinase (MMP).
45. Decidualization refers to:
a. shedding of the trophoblast.
b. the loss of the zona functionalis at menstruation.
*c. alterations in stromal cells of the endometrium.
d. the merging of the decidua capsularis with the
decidua parietalis.
46. During the stage of development pictured in this
figure, the levels of oxygen in the placenta are:
*a. low
b. high
Questions 47-49 refer to the drawing on the next page.
47. Select the correct label for the structure at I:
a. outer cytotrophoblastic shell
b. layer of syncytiotrophoblast
*c. chorionic plate
48. The leader at II indicates:
a. space filled with fetal blood.
*b. space filled with maternal blood.
c. decidua.
49. The leader at III indicates:
a. definitive yolk sac
b. amnion
*c. chorionic cavity
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QUESTIONS
47-49 (see
previous page)
CARDIOVASCULAR SYSTEM I
50. During organogenesis, blood vessels:
a. migrate into an organ once it develops.
*b. are formed within a developing organ.
c. are not subject to cell death.
d. are specified to become arteries and veins when they form.
51. The endocardial tubes:
*a. develop in the splanchnopleure.
b. give rise to the three layers of the heart.
c. produce cardiac jelly.
d. form a single tube prior to flexion.
52. During looping, the structure labled “A” in the drawing on
the right will give rise to:
a. The trabeculated portion of the right ventricle
*b. The trabeculated portion of the left ventricle.
c. the infundibulum
d. the aortic sac
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A
A
A
53. Which one of the following morphogenic events is a requirement for normal
separation of the common atrioventricular (AV) canal into right and left channels?
*a. The AV canal enlarges and is displaced to the right so that it communicates
with the right and left ventricles.
b. The bulboventricular flange (fold) forms and diverts blood from the left to the
right ventricle.
c. The truncus arteriosus must first become centered over both ventricles.
d. All of the above.
54. The ostium (foramen) secundum forms from perforations in the:
a. septum secundum.
*b. septum primum.
c. sinus venosus.
d. endocardial cushion.
55. The atrioventricular valves originate from the:
a, endocardial cushion.
b. primitive atria.
*c. ventricular myocardium.
d. bulbar ridges.
56. Persistent atrioventricular canal usually results from:
a. premature termination of neural crest cell migration.
b. displacement of the conotruncal swellings.
c. malformation of the muscular interventricular septum.
*d. malformation of the endocardial cushions.
57. The conotruncal septum arises from the:
a. ventricular myocardium.
b. moderator band.
*c. bulbar ridges.
d. endocardial cushion.
58. The aortic channel communicates with the:
*a. 3rd and 4th aortic arch.
b. 1st and 2nd aortic arch.
c. 2nd and 3rd aortic arch.
d. 5th aortic arch.
59. Tetralogy of Fallot is a malformation of:
a. the muscular interventricular septum.
b. cardiac looping.
c. bulboventricular flange.
*d. conotruncal septation.
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60. In the fetal circulation, superior vena cava blood is preferentially directed to the:
*a. right ventricle.
b. left atrium.
c. pulmonary vein.
d. ductus arteriosus.
61. ANSWER EITHER A OR B and provide a BRIEF answer. You may use phrases,
lists, drawings, but your answer must be both brief and be able to be read easily
(letters should be at least 5 mm in height). You do not have to provide every last
detail you only have to demonstrate an understanding of how (why) the structure
forms.
A. What events lead to formation of the coronary sinus?
End of 4th week, bilateral veins. Three veins develop that deliver (shunt)blood from
left side of embryo to the right horn of sinus venosus. Right horn enlarges; volume of
blood entering left horn diminishes, left horn reduced to the coronary sinus.
OR (only one answer will be graded)
B. How is the sinus venarum formed?
Three major veins deliver blood from left side of embryo to the right horn of sinus
venosus. Right horn enlarges, absorbed into right atrium, becomes smooth walled
sinus venarum.
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