Week 2: Making Babies
Week 2 lecture material pertaining to embryology
Questions and Answers
- 1.
Characteristics that are differentially expressed depending on whether the genetic material is inherited from the mother or father represent:
- A.
Genomic inheritance
- B.
Genomic imprinting
- C.
Chromosomal inheritance
- D.
Inheritance of contiguous gene complexes
- E.
Germline mosaicism
Correct Answer
B. Genomic imprintingExplanation
Genomic imprinting refers to the phenomenon where certain genes are expressed differently depending on whether they are inherited from the mother or the father. This is due to epigenetic modifications, such as DNA methylation, that occur during gametogenesis. These modifications result in the silencing or activation of specific genes in a parent-of-origin specific manner. Genomic imprinting plays a crucial role in development and can lead to diseases when disrupted. Therefore, the correct answer is genomic imprinting.Rate this question:
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- 2.
A 22 year old woman in her 8th week of pregnancy tells you that there is a history of neural tube defect in her family. What do you tell her?
- A.
She is young and has been taking folic acid so her baby is most likely completely normal
- B.
She should terminate the fetus and not have children
- C.
She is at no increased risk because she is otherwise healthy and has no other risk factors
- D.
She is at no increased risk because she is under 35 and the father's family has no history of neural tube defects
- E.
She is high risk and should have the baby evaluated using prenatal screening techniques
Correct Answer
E. She is high risk and should have the baby evaluated using prenatal screening techniquesExplanation
Based on the given information, the woman is at high risk due to a family history of neural tube defect. Therefore, it is recommended that she undergo prenatal screening techniques to evaluate the baby's condition and take appropriate measures if necessary.Rate this question:
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- 3.
The cytoplasm of the egg is capable of __________________ nuclei derived form adult tissues.
- A.
Inducing pluripotent stem cells in
- B.
Gene reprogramming
- C.
Silencing
- D.
Differential splicing of
- E.
Regenerating
Correct Answer
B. Gene reprogrammingExplanation
The cytoplasm of the egg has the ability to reprogram genes, which means it can change the expression of certain genes in a way that allows the development of pluripotent stem cells. Pluripotent stem cells have the potential to differentiate into any type of cell in the body, making them highly valuable for medical research and potential therapies. This reprogramming ability is unique to the cytoplasm of the egg and is not found in nuclei derived from adult tissues.Rate this question:
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- 4.
Future somite is derived from _____________ mesoderm formed to the side of the notochord.
Correct Answer
paraxialExplanation
The future somite is derived from paraxial mesoderm formed to the side of the notochord.Rate this question:
- 5.
Posterior remnants of the primitive streak cause
- A.
Sirenomelia
- B.
Sacroccoygeal teratomas
- C.
DiGeorge's Syndrome
- D.
Twinning
- E.
Piebald
Correct Answer
B. Sacroccoygeal teratomasExplanation
Sacroccoygeal teratomas are caused by posterior remnants of the primitive streak. The primitive streak is a structure that forms during embryonic development and is involved in the formation of the body's midline structures. When remnants of the primitive streak persist in the sacroccoygeal region, it can lead to the development of sacroccoygeal teratomas, which are tumors that contain tissues from all three germ layers. These tumors typically occur at the base of the tailbone and can vary in size and severity.Rate this question:
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- 6.
True or False: Splitting of early embryonic cells at the two cell stage is the most common way that identical twins are produced.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
False, this results in 2 placentas and 2 amniotic cavities almost never seen in identical twins; this pattern is diagnostic of fraternal twins.Rate this question:
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- 7.
A surge in ______ causes follicular rupture and ovulation.
Correct Answer
LH
lhExplanation
LH (luteinizing hormone) is responsible for causing follicular rupture and ovulation. It is a hormone released by the pituitary gland and plays a crucial role in the menstrual cycle. LH surge triggers the release of a mature egg from the ovary, which is essential for fertilization and conception to occur. Therefore, an increase in LH levels leads to follicular rupture and ovulation.Rate this question:
- 8.
A shifting of the forelimb one segment cranially might be due to abnormal expression of what gene?
- A.
BMPs
- B.
Sonic hedgehog
- C.
HOX genes
- D.
TGF-Beta
- E.
FGFs
Correct Answer
C. HOX genesExplanation
HOX genes are responsible for the regulation of body segment development during embryogenesis. Abnormal expression of HOX genes can lead to developmental abnormalities, including the shifting of the forelimb one segment cranially. Therefore, the abnormal expression of HOX genes is likely the cause of this abnormality. BMPs, sonic hedgehog, TGF-Beta, and FGFs are also involved in limb development, but they are not specifically associated with the shifting of the forelimb segment.Rate this question:
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- 9.
Homeobox genes are
- A.
Not expressed in flies
- B.
Only expressed in humans
- C.
Cause epithelial to mesenchymal transitions
- D.
Regulate migration of neural crest cells
- E.
Regulate patterning of cranial-caudal axis, including segmentation
Correct Answer
E. Regulate patterning of cranial-caudal axis, including segmentationExplanation
Homeobox genes are a group of genes that play a crucial role in the development of organisms. They are not expressed in flies or humans exclusively, nor do they cause epithelial to mesenchymal transitions. However, homeobox genes do regulate the migration of neural crest cells and are involved in the patterning of the cranial-caudal axis, including segmentation. This means that they are responsible for organizing the body plan and determining the placement of different body segments during embryonic development.Rate this question:
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- 10.
Which layer(s) of the embryonic disc is/are present at the end of the second week of development.?
- A.
Epiblast
- B.
Endoderm and mesoderm
- C.
Epiblast and hypoblast
- D.
Hypoblast and neural crest
- E.
Ectoderm and mesoderm
Correct Answer
C. Epiblast and hypoblastExplanation
At the end of the second week of development, both the epiblast and hypoblast layers are present in the embryonic disc. The epiblast is the upper layer of the disc and gives rise to the three primary germ layers: ectoderm, mesoderm, and endoderm. The hypoblast is the lower layer and contributes to the formation of the extraembryonic structures. These two layers play crucial roles in the early development of the embryo.Rate this question:
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- 11.
What initial morphological change occurs prior to gastrulation?
- A.
Migration of ectoderm to the midline
- B.
Formation of the notochord
- C.
Formation of the primitive streak
- D.
Separation of epiblast and hypoblast
- E.
Formation of morula
Correct Answer
C. Formation of the primitive streakExplanation
The formation of the primitive streak is the initial morphological change that occurs prior to gastrulation. The primitive streak is a structure that forms in the early embryo and serves as the site of cell migration and differentiation during gastrulation. It marks the beginning of the process where the three germ layers (ectoderm, mesoderm, and endoderm) form, which is a crucial step in embryonic development.Rate this question:
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- 12.
Melanocytes are derived from
- A.
Neural crest cells
- B.
Mesoderm
- C.
Endoderm
- D.
Ectoderm
- E.
Dermis
Correct Answer
A. Neural crest cellsExplanation
Melanocytes are pigment-producing cells that are responsible for the coloration of the skin, hair, and eyes. These cells are derived from neural crest cells, which are a group of cells that originate from the embryonic ectoderm. During development, neural crest cells migrate and differentiate into various cell types, including melanocytes. This explains why melanocytes are derived from neural crest cells rather than mesoderm, endoderm, ectoderm, or dermis.Rate this question:
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- 13.
What causes congenital megacolon?
- A.
Lack of sympathetic innervation to the bowel
- B.
Abnormal neural crest cell migration
- C.
Lack of formation of smooth muscle in the gut
- D.
Mutation in the c-kit receptor
- E.
Abnormal endoderm division
Correct Answer
B. Abnormal neural crest cell migrationExplanation
Congenital megacolon, also known as Hirschsprung's disease, is caused by abnormal neural crest cell migration. Neural crest cells are responsible for the formation of the enteric nervous system, which controls the movement of the intestines. In individuals with Hirschsprung's disease, these cells fail to migrate properly, leading to a lack of innervation in certain segments of the bowel. This results in a functional obstruction and the accumulation of stool, leading to the enlargement of the colon (megacolon).Rate this question:
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- 14.
Splitting of the lateral plate mesoderm forms
- A.
Yolk sac cavity
- B.
Aminotic cavity
- C.
Chorionic cavity
- D.
Intraembryonic cavity
- E.
Somites
Correct Answer
D. Intraembryonic cavityExplanation
The splitting of the lateral plate mesoderm forms the intraembryonic cavity. This cavity is located within the developing embryo and is surrounded by the layers of the lateral plate mesoderm. It is an important space where various organs and tissues will develop during embryogenesis. The formation of the intraembryonic cavity is a crucial step in the early development of the embryo, allowing for the proper organization and differentiation of cells and tissues.Rate this question:
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- 15.
What are the pons and cerebelleum derivatives of?
- A.
Telencephalon
- B.
Mesencephalon
- C.
Diencephalon
- D.
Rhombencephalon
- E.
Metencephalon
Correct Answer
E. MetencephalonExplanation
The pons and cerebellum are derivatives of the metencephalon. The metencephalon is one of the five major divisions of the developing brain, and it is responsible for the development of structures such as the pons and cerebellum. The pons is a structure located in the brainstem that helps to relay signals between different parts of the brain, while the cerebellum is involved in motor control, coordination, and balance.Rate this question:
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- 16.
It was determined that a woman had contracted rubella during her pregnancy which resulted in cardiac defects in her baby, during which point is it most likely that she contracted this disease?
- A.
1-5 weeks before fertilization
- B.
4-5 months after fertilization
- C.
6-7 months after fertilization
- D.
1-5 weeks after fertilization
- E.
3 months before fertilization
Correct Answer
D. 1-5 weeks after fertilizationExplanation
During the first 1-5 weeks after fertilization, the woman most likely contracted rubella. This is because rubella infection during this early stage of pregnancy is known to cause cardiac defects in the baby.Rate this question:
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- 17.
What forms bones of the face?
- A.
Neural crest cells from the 1st and 2nd pharyngeal arches
- B.
Primitive node
- C.
Paraxial mesoderm
- D.
Ectoderm
- E.
Gastrulation
Correct Answer
A. Neural crest cells from the 1st and 2nd pharyngeal archesExplanation
During embryonic development, the bones of the face are formed by neural crest cells from the 1st and 2nd pharyngeal arches. These neural crest cells migrate and differentiate into various types of cells, including osteoblasts, which are responsible for bone formation. The neural crest cells from these specific arches give rise to the bones of the face, such as the maxilla, mandible, and zygomatic bones. This process is crucial for the proper development and structure of the facial bones.Rate this question:
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- 18.
What forms the urogenital system?
- A.
Endoderm
- B.
Lateral plate mesoderm
- C.
Splachnic layer
- D.
Axial mesoderm
- E.
Intermediate mesoderm
Correct Answer
E. Intermediate mesodermExplanation
The urogenital system is formed from the intermediate mesoderm. This layer of mesoderm gives rise to the kidneys, gonads, and reproductive ducts. These structures are essential for the formation and function of the urinary and reproductive systems in the body. The other options, such as endoderm, lateral plate mesoderm, splachnic layer, and axial mesoderm, do not directly contribute to the formation of the urogenital system.Rate this question:
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- 19.
What forms placental vili to invade the uterus?
- A.
Blastocyst
- B.
Synctiotrophoblast
- C.
Cytotrophoblast
- D.
Epiblast
- E.
Hypoblast
Correct Answer
B. SynctiotrophoblastExplanation
The syncytiotrophoblast is responsible for invading the uterus during pregnancy. It forms the outer layer of the blastocyst and plays a crucial role in implantation. This specialized layer of cells secretes enzymes that help to break down the uterine lining, allowing the blastocyst to attach and establish a connection with the mother's blood supply. The syncytiotrophoblast also forms the outer layer of the placenta and is involved in nutrient and gas exchange between the mother and the developing fetus.Rate this question:
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- 20.
Which of the following factors does NOT affect fetal growth?
- A.
Glucose and insulin availability
- B.
Amino acids
- C.
Alcohol consumption and smoking
- D.
Genetic makeup of the baby
- E.
Number of ultrasounds taken
Correct Answer
E. Number of ultrasounds takenExplanation
The number of ultrasounds taken does not affect fetal growth. Ultrasounds are a diagnostic tool used to monitor the development and health of the baby during pregnancy, but they do not directly impact fetal growth. Factors such as glucose and insulin availability, amino acids, alcohol consumption and smoking, and the genetic makeup of the baby can all have significant effects on fetal growth and development.Rate this question:
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- 21.
An environmental agent that can cause developmental disruptions following maternal exposure is known as a ___________________.
Correct Answer
teratogenExplanation
A teratogen is an environmental agent that can cause developmental disruptions when a pregnant woman is exposed to it. These disruptions can result in birth defects or other abnormalities in the developing fetus. Teratogens can include substances such as drugs, chemicals, infections, or radiation. Maternal exposure to teratogens during critical periods of fetal development can have long-lasting effects on the child's health and development. It is important for pregnant women to be aware of potential teratogens and take necessary precautions to avoid exposure.Rate this question:
- 22.
Brown fat, quickening, and vernix caseosa appear during weeks:
- A.
17-20
- B.
1-10
- C.
21-26
- D.
35-38
- E.
9-14
Correct Answer
A. 17-20Explanation
During weeks 17-20 of pregnancy, brown fat, quickening (the first fetal movements felt by the mother), and vernix caseosa (a protective coating on the baby's skin) start to appear. These developments indicate the progression of the pregnancy and the growth and development of the fetus.Rate this question:
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- 23.
In a fetus, the sites of erythropoiesis move from
- A.
Spleen to liver to bone marrow
- B.
Placenta to liver to spleen
- C.
Liver to spleen to bone marrow
- D.
Bone marrow to spleen
- E.
Core bones to limbs
Correct Answer
C. Liver to spleen to bone marrowExplanation
During fetal development, erythropoiesis, the production of red blood cells, occurs in different organs. Initially, erythropoiesis takes place in the liver, where the fetus produces red blood cells. As the fetus continues to develop, the spleen becomes the primary site of erythropoiesis. Finally, towards the end of fetal development and after birth, erythropoiesis shifts to the bone marrow, which becomes the main site of red blood cell production in adults. Therefore, the correct sequence of erythropoiesis sites in a fetus is liver to spleen to bone marrow.Rate this question:
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- 24.
Around weeks ________ a fetus can be determined to be male or female via ultrasound.
- A.
14-16
- B.
3-5
- C.
9-12
- D.
1-8
- E.
5-10
Correct Answer
A. 14-16Explanation
Between weeks 14-16 of pregnancy, a fetus can be determined to be male or female via ultrasound. During this time, the external genitalia of the fetus has developed enough to be visible on the ultrasound image, allowing the healthcare provider to identify the gender. This is a common milestone in prenatal care and can be an exciting moment for expectant parents.Rate this question:
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- 25.
If born around week _____, a baby can survive.
- A.
6
- B.
12
- C.
16
- D.
20
- E.
26
Correct Answer
E. 26Explanation
Babies born around the 26th week of pregnancy have a higher chance of survival compared to those born earlier. At this stage, the baby's vital organs are more developed, allowing them to breathe on their own with medical assistance. They may still require intensive care and support, but their chances of survival and long-term health outcomes are significantly improved compared to babies born earlier in the pregnancy.Rate this question:
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