BIO 351 EXAM 3 QUESTIONS WITH CORRECT
ANSWERS 2026/2027
When and where are cardioprogenitors specified? - CORRECT ANSWER -Cardioprogenitors are
specified during early embryogenesis in the splanchnic mesoderm, which is derived from the
lateral plate mesoderm, and is known as the cardiogenic field or cardiogenic mesoderm.
What does the primary heart field form? - CORRECT ANSWER -The primary heart field forms the
initial scaffold and eventually the ventricle. The secondary heart field continues to create cells
and forms all the other structures.
What is the splanchnic mesoderm? - CORRECT ANSWER -The splanchnic mesoderm is the layer
that forms the circulatory system and the future gut wall. Cardiogenic cells are also formed from
this layer.
Where does cardiac primordia arise from? - CORRECT ANSWER -The splanchnic mesoderm.
What is linked to the ventral closure of the embryo? - CORRECT ANSWER -Migration of the
cardiac primordia an formation of the linear heart.
What is induced by rapid growth of the neural tube and somites? - CORRECT ANSWER -Ventral
closure.
What is the heart defect Dextrocardia? - CORRECT ANSWER -This is where the heart lies on the
right side of the thorax because it looped to the wrong side.
What other defect can cause the heart to be looped the wrong way? - CORRECT ANSWER -Situs
inversus, which causes complete asymmetry of all organs within the body.
,What is the heart defect Heterotaxy? - CORRECT ANSWER -This is where the heart is located on
the right side of the chest instead of the left side. This is random and usually fatal.
How are the chambers of the heart created after looping? - CORRECT ANSWER -Endocardial
cushions form on the dorsal and ventral walls of AV canal, which then meet and separate the AV
canal into the right and left channels and act as primitive valves for the heart.
How can malformations of the endocardial cushions affect the heart? - CORRECT ANSWER -This
can lead to atrial and ventricular septal defects, abnormal transposition in the great vessels, and
defects often associated with craniofacial defects.
When blood flows from the body to the heart (via the superior and inferior vena cava), what is
the correct order of flow within the heart? - CORRECT ANSWER -Right atrium, right ventricle,
pulmonary artery
Mutations in human TBX5 lead to a disorder called Holt-Oram syndrome. Which of the following
would you expect to the primary defects of this disorder based on its developmental function? -
CORRECT ANSWER -Upper limb and heart ventricular defects. Tbx5 is required both for
determination of the upper limbs and for ventricular formation.
From which embryonic germ layer does the lung primordium emerge? - CORRECT ANSWER -
Endoderm
What structures in the lung are the last to be formed during embryonic development? -
CORRECT ANSWER -Alevolar sacs (1st is trachea, 2nd is bronchi, 3rd is bronchioles)
What is unique about an amphibian's heart? - CORRECT ANSWER -It is three chambered with
there only being one ventricle, where deoxygenated blood from the right atrium mixes with
oxygenated blood from the lungs.
, How are bird and mammal hearts different from amphibian hearts? - CORRECT ANSWER -Birds
and mammals have a four-chambered heart with complete separation of the deoxygenated
blood going to the lungs and the oxygenated blood from the lungs going to the body.
In an developing embryo heart (day 21), name what each part, from anterior to posterior, will
eventually form in a mature heart (newborn). - CORRECT ANSWER -From top to bottom: Aortic
sac, conotruncal, right ventricle, left ventricle, right atrium, left atrium, atrioventricular (AV)
valve
What defect results from failure of the septum to separate the ventricle? - CORRECT ANSWER -
Ventricular Septal Defect (VSD). This leads to mixing of arterial and venous blood occurs in both
outflow tracts but especially in the pulmonary artery.
What genes regulate the formation of a 4-chambered heart? - CORRECT ANSWER -Tbx5, which,
in mammals, is initially expressed in the entire ventricular primordial heart field and then later
becomes restricted to the right atrium (RA), left atrium (LA), and left ventricle (LV).
What does restricting Tbx5 expression lead to? - CORRECT ANSWER -This leads to formation of
the right ventricle in a four-chambered heart. If expression is not restricited, a three-chambered
heart is created.
Where do the septa that separate the truncus arteriosus into the pulmonary artery and aorta
form from? - CORRECT ANSWER -They form from cells of the cardiac neural crest.
How does formation of the lung bud begin? - CORRECT ANSWER -The lung bud begins as an
outpouching from the foregut, forming the esophagus and trachea.
What is the homologous structure of lungs in the teleost (fish)? - CORRECT ANSWER -The swim
bladder
ANSWERS 2026/2027
When and where are cardioprogenitors specified? - CORRECT ANSWER -Cardioprogenitors are
specified during early embryogenesis in the splanchnic mesoderm, which is derived from the
lateral plate mesoderm, and is known as the cardiogenic field or cardiogenic mesoderm.
What does the primary heart field form? - CORRECT ANSWER -The primary heart field forms the
initial scaffold and eventually the ventricle. The secondary heart field continues to create cells
and forms all the other structures.
What is the splanchnic mesoderm? - CORRECT ANSWER -The splanchnic mesoderm is the layer
that forms the circulatory system and the future gut wall. Cardiogenic cells are also formed from
this layer.
Where does cardiac primordia arise from? - CORRECT ANSWER -The splanchnic mesoderm.
What is linked to the ventral closure of the embryo? - CORRECT ANSWER -Migration of the
cardiac primordia an formation of the linear heart.
What is induced by rapid growth of the neural tube and somites? - CORRECT ANSWER -Ventral
closure.
What is the heart defect Dextrocardia? - CORRECT ANSWER -This is where the heart lies on the
right side of the thorax because it looped to the wrong side.
What other defect can cause the heart to be looped the wrong way? - CORRECT ANSWER -Situs
inversus, which causes complete asymmetry of all organs within the body.
,What is the heart defect Heterotaxy? - CORRECT ANSWER -This is where the heart is located on
the right side of the chest instead of the left side. This is random and usually fatal.
How are the chambers of the heart created after looping? - CORRECT ANSWER -Endocardial
cushions form on the dorsal and ventral walls of AV canal, which then meet and separate the AV
canal into the right and left channels and act as primitive valves for the heart.
How can malformations of the endocardial cushions affect the heart? - CORRECT ANSWER -This
can lead to atrial and ventricular septal defects, abnormal transposition in the great vessels, and
defects often associated with craniofacial defects.
When blood flows from the body to the heart (via the superior and inferior vena cava), what is
the correct order of flow within the heart? - CORRECT ANSWER -Right atrium, right ventricle,
pulmonary artery
Mutations in human TBX5 lead to a disorder called Holt-Oram syndrome. Which of the following
would you expect to the primary defects of this disorder based on its developmental function? -
CORRECT ANSWER -Upper limb and heart ventricular defects. Tbx5 is required both for
determination of the upper limbs and for ventricular formation.
From which embryonic germ layer does the lung primordium emerge? - CORRECT ANSWER -
Endoderm
What structures in the lung are the last to be formed during embryonic development? -
CORRECT ANSWER -Alevolar sacs (1st is trachea, 2nd is bronchi, 3rd is bronchioles)
What is unique about an amphibian's heart? - CORRECT ANSWER -It is three chambered with
there only being one ventricle, where deoxygenated blood from the right atrium mixes with
oxygenated blood from the lungs.
, How are bird and mammal hearts different from amphibian hearts? - CORRECT ANSWER -Birds
and mammals have a four-chambered heart with complete separation of the deoxygenated
blood going to the lungs and the oxygenated blood from the lungs going to the body.
In an developing embryo heart (day 21), name what each part, from anterior to posterior, will
eventually form in a mature heart (newborn). - CORRECT ANSWER -From top to bottom: Aortic
sac, conotruncal, right ventricle, left ventricle, right atrium, left atrium, atrioventricular (AV)
valve
What defect results from failure of the septum to separate the ventricle? - CORRECT ANSWER -
Ventricular Septal Defect (VSD). This leads to mixing of arterial and venous blood occurs in both
outflow tracts but especially in the pulmonary artery.
What genes regulate the formation of a 4-chambered heart? - CORRECT ANSWER -Tbx5, which,
in mammals, is initially expressed in the entire ventricular primordial heart field and then later
becomes restricted to the right atrium (RA), left atrium (LA), and left ventricle (LV).
What does restricting Tbx5 expression lead to? - CORRECT ANSWER -This leads to formation of
the right ventricle in a four-chambered heart. If expression is not restricited, a three-chambered
heart is created.
Where do the septa that separate the truncus arteriosus into the pulmonary artery and aorta
form from? - CORRECT ANSWER -They form from cells of the cardiac neural crest.
How does formation of the lung bud begin? - CORRECT ANSWER -The lung bud begins as an
outpouching from the foregut, forming the esophagus and trachea.
What is the homologous structure of lungs in the teleost (fish)? - CORRECT ANSWER -The swim
bladder
