All MCAT Biology Resources
Example Questions
Example Question #1 :Fetal Circulation
What fetal organs is blood shunted away from during gestation?
The kidneys and spleen
The lungs and kidneys
The lungs and intestines
The lungs and liver
The liver and spleen
The lungs and liver
Oxygen diffuses from maternal blood to fetal blood through the placenta. Within the womb, the lungs are not able to work properly and so blood is rerouted through the foramen ovale and the ductus arteriosus. The liver is also underdeveloped, and not ready to perform the functions it will do in adulthood. The placenta takes over for the liver during gestation, and so blood is shunted away from the liver by the ductus venosus. This prevents oxygen that could be useful in other places from being wasted in the liver.
Example Question #1 :Fetal Circulation
The ductus arteriosus functions as a blood shunt during fetal development. Which circulatory components does the ductus arteriosus connect?
It shunts blood from the left atrium to the right atrium
It shunts blood from the right atrium to the left atrium
It shunts blood from the pulmonary artery to the aorta
It shunts blood from the aorta to the pulmonary artery
It shunts blood away from the fetal liver
It shunts blood from the pulmonary artery to the aorta
The ductus arteriosus shunts blood from the pulmonary artery to the aorta in order to bypass the lungs, since the fetal lungs are not active.
The foramen ovale shunts blood from the right atrium to the left atrium, serving as another method to bypass the lungs. The ductus venosus shunts blood away from the fetal liver. There is no shunt from the aorta to the pulmonary artery, and there is no shunt from the left atrium to the right atrium.
Example Question #52 :Biology
What is erythroblastosis fetalis?
The process by which fetal erythrocytes grow and mature
A fatal condition in which the zygote implants in an area other than the uterine lining
A severe estrogen deficiency, resulting in partially developed reproductive organs
A dangerous syndrome that can result from mother/baby Rh factor incompatibility
A syndrome in which the mother's hormones fail to engage, resulting in loss of pregnancy
A dangerous syndrome that can result from mother/baby Rh factor incompatibility
Erythroblastosis fetalis is a rare conditon in which the mother's anti-Rh antibodies enter the fetal bloodstream and attach to fetal erythrocytes. If not caught, it can result in "blue-baby syndrome." Erythroblastosis is only present in patients negative for the Rh factor, and carrying Rh positive fetuses.
Example Question #1 :Fetal Circulation
During what stage of pregnancy does a fetus's heart begin to beat?
Third trimester
First trimester
Fourth trimester
The fetus's heart does not begin to beat until after delivery.
Second trimester
First trimester
A pregnancy consists of three trimesters, each of which is approximately 12 weeks. The fetus's heart, brain, spinal cord, and other organs begin to form in approximately the fifth week of pregnancy—in the first trimester.
Example Question #1 :Gastrulation And Embryonic Germ Layers
The mesoderm germ layer eventually gives rise to the formation of the__________.
muscles
lining of the respiratory system
lining of the digestive system
nervous system
epidermis
muscles
中胚层产生肌肉等structures. The other answers are derived from the ectoderm or endoderm.
Example Question #51 :Biology
The thyroid gland arises from this embryonic layer__________.
I. neuroectoderm
II. ectoderm
III. mesoderm
IV. endoderm
V. ectoderm with contributions from mesoderm
IV
V
II
I
III
IV
Many of the glandular structures—both exocrine and endocrine—arise from endoderm. In particular, both the thyroid and parathyroid glands bud off from the pharyngeal mucosa, which of course is endodermal in character. Of course, like all tissues, there are mesodermal components of the gland in the way of connective tissues and blood vessels. The response indicating a mesodermal component invites you to make a wrong selection because you could remember that there are mesodermal-derived tissues everywhere, but you could not specifically recall the origin of the thyroid tissue, itself.
Example Question #1 :Gastrulation And Embryonic Germ Layers
Which of the following is NOT a major germ layer formed during gastrulation?
Endoderm
Mesoderm
Cytoderm
Ectoderm
Cytoderm
The correct answer is cytoderm.
There are three major germ layers formed during gastrulation: the ectoderm, mesoderm, and endoderm. Major structures form from these germ layers over the course of embryogenesis and development.
Example Question #22 :Developmental Physiology
A newly born child is having difficulty breathing and digesting food. A close medical examination has revealed an improperly formed inner lining to the digestive and respiratory systems. Which of the following is the most likely cause of the medical problem?
A disease affecting the ectoderm germ layer
An abnormality has occurred in the development of the endoderm
There is not enough information to determine a likely cause
Genetic abnormalities in both the mesoderm and ectoderm
A disruption of the mesoderm during development
An abnormality has occurred in the development of the endoderm
Gastrulation is the formation of the three layers of the embryo: ectoderm, endoderm, and mesoderm. The endoderm gives rise to the lining of the digestive system and respiratory system. A defect in these tissues suggests a problem of that germ layer during development. The ectoderm gives rise to the nervous system and epidermis. The mesoderm gives rise to the muscle and skeletal systems.
Example Question #1 :Gastrulation And Embryonic Germ Layers
The kidneys arise from which of the three embryonic germ layers?
Endoderm
Ectoderm
Notochord region
None of these choices are correct
Mesoderm
Mesoderm
The three embryonic germ layers are the ectoderm, mesoderm, and endoderm. The mesoderm gives rise to bone, muscle, the urinary system, and the kidneys. Ectoderm develops into the nervous system, dermis, hair, nails, eyes, and ears. The endoderm develops into the lining of internal organs, such as the lungs and the gastrointestinal tract. The notochord is not an embryonic layer and, like the kidneys, arises from the mesoderm.
Example Question #61 :Biology
What happens during the process of gastrulation?
The ectoderm differentiates into epithelial tissue
The three primary germ layers are created
The blastomeres undergo compaction
The epiblast and hypoblast are created
The cell divides into the eight-cell stage
The three primary germ layers are created
The process of gastrulation generates the three primary germ layers (ectoderm, endoderm, mesoderm). This is one of the most important steps of development.
The eight-cell stage signals the beginning of compaction, during which the cells of the blastula adhere to each other and prepare for further divisions. The epiblast and hypoblast are generated before gastrulation, but after implantation. Differentiation occurs long after the primary germ layers are formed.
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