BIO 351 FINAL EXAM !
QUESTIONS AND VERIFIED
CORRECT ANSWER GRADED
A+ 100% GUARANTEED PASS
LATEST[2026-2027]
In the mammalian embryo, which structure is essential to set up the anterior-posterior axis? -
CORRECT ANSWER-Anterior visceral endoderm
A 25 year-old woman who is pregnant for the first time undergoes amniocentesis during the
25th week of pregnancy. This testing reveals an increased level of acetylcholinesterase in the
amniotic fluid. Acetylcholinesterase is normally produced in the CNS and cannot cross the blood
brain barrier. This test suggests which of the following fetal abnormalities? - CORRECT ANSWER-
Anencephaly-CORRECT, the neural tube is open in the head and exposed to amniotic fluid
The neural tube is regionalized by developmental gene regulation. Which of the following
correctly matches the gene and specified region? - CORRECT ANSWER-Shh - ventralizing the
neural tube-CORRECT, Shh is release by the notochord and ventralizes the neural tube
Your old pet cat has significant decline in hindlimb motor function, likely due to a loss of
neurons in the ventral lumbar spinal cord, similar to what occurs in ALS. You collect some cat
fibroblasts and dedifferentiate them into ES cells using a standard iPSC induction procedure. To
direct differentiation into ventral spinal cord motor neurons for transplantation into the spinal
cord, which of the following combinations would be most appropriate. - CORRECT ANSWER-
High [Shh], high [RA]
,Carbon monoxide has been demonstrated to disrupt thenormal formation of somites. If an
embryo is brieflyexposed to carbon monoxide during the earliest period ofsomitogenesis, the
formation of severalsomites can be disrupted. Which ofthe following vertebrae would be most
affected? - CORRECT ANSWER-Cervical (neck) vertebrae CORRECT, somitogenesis produces
spinal precursors from the most rostral to the most caudal, so the earliest somites formed will
form the cervical vertebrae.
Key components of the human segmentation clock are gradients and cycling gene expression
within the presomitic mesoderm. Gradients of ________________ from the caudal presomitic
mesoderm interact with cyclically expressed genes such as ___________________ to regulate
somitogenesis. - CORRECT ANSWER-FGF8, lunatic fringe
This individual has one of the most common autosomal recessive genetic diseases in the Puerto
Rican population. Vertebral segments are formed but completely FUSED. Which of the following
best matches the underlying cause of the vertebral fusion? - CORRECT ANSWER-Mutation in a
gene that generates the determination front - CORRECT, function of gene gradient and cycling
genes at the determination front are required for segmentation
The vertebrae are formed by resegmentation and fusion of the _________ compartment of a
somite and the _________ compartment of the immediately posterior/caudal somite. -
CORRECT ANSWER-caudal, rostral
The neural crest is derived from _______. An important step in neural crest induction is
activation of the __________ promoter. - CORRECT ANSWER-ectoderm, β-catenin
Why are craniofacial defects such as cleft palate or cleft lip a signal to physicians to look for
more serious defects such as heart abnormalities in newborns? - CORRECT ANSWER-These
organs all depend upon a common and important contribution from neural crest
The neural crest migrates from the __________ neural tube and then into in the skin along the
________ pathway to generate melanocytes. This explains why you have coloration defects as
seen in Waardenburg syndrome - CORRECT ANSWER-dorsal, dorsolateral
,You have surgically removed the anterior endoderm from a one day old chick embryo. The
embryo is subsequently cultured and you perform ISH for Tbx5. What do you predict will
happen? - CORRECT ANSWER-Tbx5 will not be expressed
Heart looping ________ . Finish the sentence. - CORRECT ANSWER-converts anterior-posterior
polarity to left-right polarity.
Axonal growth cones are highly dynamic structures that extend wave like extensions known as
lamellipodia and finger like extensions called ________. _____ are crucial intracellular signaling
molecules that translate extracellular signals into cytoskeletal changes within the growth cone. -
CORRECT ANSWER-Filopodia, Rho GTPase
You have deleted Bax from neural crest cells using a Wnt1:Cre line in mice. Which of the
following outcomes would you expect at birth in these mutant mice relative to controls? -
CORRECT ANSWER-Increased number of DRG neurons
The SCN9A gene produces a subunit of a sodium channel called NaV1.7. Mutations in SCN9A
cause a rare condition known as congenital insensitivity to pain that disrupts nociceptive neuron
action potential generation. You would like to generate a transgene for a viral vector that will
restore SCN9A expression in these patients. The promoter from which of the following genes
would be most appropriate for the transgene? - CORRECT ANSWER-TrkA
Spinal Muscular Atrophy (SMA) is a common life-threatening genetic disorder caused by the
death of spinal cord lower motor neurons. Mutations in the Survival Motor Neuron 1 (SMN1)
gene are frequently observed. A new gene replacement based therapeutic has been developed
using a viral vector that re-expresses SMN1. The compound AVXS-101, is now in clinical trials
(https://avexis.com/research-and-development ).
, You would like to improve the therapy by adding another gene to the viral vector. Which of the
following would be most likely to further enhance lower motor neuron survival? - CORRECT
ANSWER-Bcl-2 -Correct, this would improve cell survival
Recent studies of postmortem samples from patients diagnosed with autism spectrum disorders
noted patches of disorganized lamination in the upper layers of the cerebral cortex. The period
of cortical neurogenesis in humans begins at 42 days post-conception (dpc) and is complete by
~120 dpc. Which of the following times do you think cortical morphogenesis was most-likely
effected? - CORRECT ANSWER-100 dpc
Which of the following terms best describes the process by which myoblasts transform into
myofibers? - CORRECT ANSWER-Differentiation correct, differentiation is the generation of
specialized (often morphologically distinct) cell types from committed precursors
A developing embryo is treated with a toxin thatcompletely disrupts all neuromuscular
junctiondevelopment. You would expect muscle development inthis embryo to be halted at
which stage? - CORRECT ANSWER-Formation of secondary myotubes CORRECT. Formation of
secondary myotubes requires innervation at the neuromuscular junctions. The previous steps
do not required the innervation.
In a molecular genetic study, all stillborn fetuses are screened for mutations in Collagen Type II.
The result of mutations in this gene leads to a form of achondrogenesis. Which developmental
steps are most affected? - CORRECT ANSWER-Development of cartilage from sclerotome
CORRECT, Collagen type II is a key structural component of cartilage and disrupted cartilage
affects long bone growth. Bone formation is normal.
You work for MegaPharm, a startup pharmaceutical company. Your research shows that you
have identified a compound that inhibits osteoclasts. What would you expect if you treated
adult mice with this compound? - CORRECT ANSWER-Dense, heavy bone CORRECT, osteoclasts
digest bone. If you inhibit this process, the normal process of bone resorption is disrupted and
you would end up with dense and heavy bone.
QUESTIONS AND VERIFIED
CORRECT ANSWER GRADED
A+ 100% GUARANTEED PASS
LATEST[2026-2027]
In the mammalian embryo, which structure is essential to set up the anterior-posterior axis? -
CORRECT ANSWER-Anterior visceral endoderm
A 25 year-old woman who is pregnant for the first time undergoes amniocentesis during the
25th week of pregnancy. This testing reveals an increased level of acetylcholinesterase in the
amniotic fluid. Acetylcholinesterase is normally produced in the CNS and cannot cross the blood
brain barrier. This test suggests which of the following fetal abnormalities? - CORRECT ANSWER-
Anencephaly-CORRECT, the neural tube is open in the head and exposed to amniotic fluid
The neural tube is regionalized by developmental gene regulation. Which of the following
correctly matches the gene and specified region? - CORRECT ANSWER-Shh - ventralizing the
neural tube-CORRECT, Shh is release by the notochord and ventralizes the neural tube
Your old pet cat has significant decline in hindlimb motor function, likely due to a loss of
neurons in the ventral lumbar spinal cord, similar to what occurs in ALS. You collect some cat
fibroblasts and dedifferentiate them into ES cells using a standard iPSC induction procedure. To
direct differentiation into ventral spinal cord motor neurons for transplantation into the spinal
cord, which of the following combinations would be most appropriate. - CORRECT ANSWER-
High [Shh], high [RA]
,Carbon monoxide has been demonstrated to disrupt thenormal formation of somites. If an
embryo is brieflyexposed to carbon monoxide during the earliest period ofsomitogenesis, the
formation of severalsomites can be disrupted. Which ofthe following vertebrae would be most
affected? - CORRECT ANSWER-Cervical (neck) vertebrae CORRECT, somitogenesis produces
spinal precursors from the most rostral to the most caudal, so the earliest somites formed will
form the cervical vertebrae.
Key components of the human segmentation clock are gradients and cycling gene expression
within the presomitic mesoderm. Gradients of ________________ from the caudal presomitic
mesoderm interact with cyclically expressed genes such as ___________________ to regulate
somitogenesis. - CORRECT ANSWER-FGF8, lunatic fringe
This individual has one of the most common autosomal recessive genetic diseases in the Puerto
Rican population. Vertebral segments are formed but completely FUSED. Which of the following
best matches the underlying cause of the vertebral fusion? - CORRECT ANSWER-Mutation in a
gene that generates the determination front - CORRECT, function of gene gradient and cycling
genes at the determination front are required for segmentation
The vertebrae are formed by resegmentation and fusion of the _________ compartment of a
somite and the _________ compartment of the immediately posterior/caudal somite. -
CORRECT ANSWER-caudal, rostral
The neural crest is derived from _______. An important step in neural crest induction is
activation of the __________ promoter. - CORRECT ANSWER-ectoderm, β-catenin
Why are craniofacial defects such as cleft palate or cleft lip a signal to physicians to look for
more serious defects such as heart abnormalities in newborns? - CORRECT ANSWER-These
organs all depend upon a common and important contribution from neural crest
The neural crest migrates from the __________ neural tube and then into in the skin along the
________ pathway to generate melanocytes. This explains why you have coloration defects as
seen in Waardenburg syndrome - CORRECT ANSWER-dorsal, dorsolateral
,You have surgically removed the anterior endoderm from a one day old chick embryo. The
embryo is subsequently cultured and you perform ISH for Tbx5. What do you predict will
happen? - CORRECT ANSWER-Tbx5 will not be expressed
Heart looping ________ . Finish the sentence. - CORRECT ANSWER-converts anterior-posterior
polarity to left-right polarity.
Axonal growth cones are highly dynamic structures that extend wave like extensions known as
lamellipodia and finger like extensions called ________. _____ are crucial intracellular signaling
molecules that translate extracellular signals into cytoskeletal changes within the growth cone. -
CORRECT ANSWER-Filopodia, Rho GTPase
You have deleted Bax from neural crest cells using a Wnt1:Cre line in mice. Which of the
following outcomes would you expect at birth in these mutant mice relative to controls? -
CORRECT ANSWER-Increased number of DRG neurons
The SCN9A gene produces a subunit of a sodium channel called NaV1.7. Mutations in SCN9A
cause a rare condition known as congenital insensitivity to pain that disrupts nociceptive neuron
action potential generation. You would like to generate a transgene for a viral vector that will
restore SCN9A expression in these patients. The promoter from which of the following genes
would be most appropriate for the transgene? - CORRECT ANSWER-TrkA
Spinal Muscular Atrophy (SMA) is a common life-threatening genetic disorder caused by the
death of spinal cord lower motor neurons. Mutations in the Survival Motor Neuron 1 (SMN1)
gene are frequently observed. A new gene replacement based therapeutic has been developed
using a viral vector that re-expresses SMN1. The compound AVXS-101, is now in clinical trials
(https://avexis.com/research-and-development ).
, You would like to improve the therapy by adding another gene to the viral vector. Which of the
following would be most likely to further enhance lower motor neuron survival? - CORRECT
ANSWER-Bcl-2 -Correct, this would improve cell survival
Recent studies of postmortem samples from patients diagnosed with autism spectrum disorders
noted patches of disorganized lamination in the upper layers of the cerebral cortex. The period
of cortical neurogenesis in humans begins at 42 days post-conception (dpc) and is complete by
~120 dpc. Which of the following times do you think cortical morphogenesis was most-likely
effected? - CORRECT ANSWER-100 dpc
Which of the following terms best describes the process by which myoblasts transform into
myofibers? - CORRECT ANSWER-Differentiation correct, differentiation is the generation of
specialized (often morphologically distinct) cell types from committed precursors
A developing embryo is treated with a toxin thatcompletely disrupts all neuromuscular
junctiondevelopment. You would expect muscle development inthis embryo to be halted at
which stage? - CORRECT ANSWER-Formation of secondary myotubes CORRECT. Formation of
secondary myotubes requires innervation at the neuromuscular junctions. The previous steps
do not required the innervation.
In a molecular genetic study, all stillborn fetuses are screened for mutations in Collagen Type II.
The result of mutations in this gene leads to a form of achondrogenesis. Which developmental
steps are most affected? - CORRECT ANSWER-Development of cartilage from sclerotome
CORRECT, Collagen type II is a key structural component of cartilage and disrupted cartilage
affects long bone growth. Bone formation is normal.
You work for MegaPharm, a startup pharmaceutical company. Your research shows that you
have identified a compound that inhibits osteoclasts. What would you expect if you treated
adult mice with this compound? - CORRECT ANSWER-Dense, heavy bone CORRECT, osteoclasts
digest bone. If you inhibit this process, the normal process of bone resorption is disrupted and
you would end up with dense and heavy bone.
