Question 1

What is the first organ that develops in the fetus?

Accepted Answer

Answer reason: The embryonic heart forms early as a primitive heart tube around week 3 and begins beating by about day 22–23, making it the first functional organ. Early circulation is essential to deliver oxygen and nutrients to the rapidly developing embryo. While neural structures appear early, the heart is considered the first organ to develop and function.

Question 2

The umbilical cord contains?

Accepted Answer

Answer reason: A normal umbilical cord contains two umbilical arteries and one umbilical vein embedded in Wharton’s jelly. The arteries carry deoxygenated blood from the fetus to the placenta, while the single vein returns oxygenated blood to the fetus. This 2:1 configuration is standard; a single umbilical artery is an anomaly associated with congenital defects.

Question 3

Primitive streak appears in which week?

Accepted Answer

Answer reason: The primitive streak forms at the start of gastrulation, which begins in the third week of embryonic development. It appears on the dorsal surface of the epiblast and establishes the body axes while allowing epiblast cells to invaginate and form mesoderm and endoderm. Thus, its first appearance is during week 3.

Question 4

Notochord is derived from?

Accepted Answer

Answer reason: The notochord arises from axial mesoderm during gastrulation as cells migrate through the primitive node to form the notochordal process and plate, which then folds into the definitive notochord. It establishes the embryo’s midline and induces overlying ectoderm to form the neural plate. Endoderm forms gut-derived structures, ectoderm forms epidermis and neural tissue, and the trophoblast contributes to placental structures, not the embryonic notochord.

Question 5

Neural tube is formed from?

Accepted Answer

Answer reason: The neural tube arises from neuroectoderm during neurulation. Signals from the notochord induce ectoderm to form the neural plate, which folds and fuses to become the neural tube by week 4. Endoderm gives rise to gut and related structures, mesoderm forms muscle, bone, and notochord, and the yolk sac is extraembryonic.

Question 6

Failure of neural tube closure leads to?

Accepted Answer

Answer reason: Neural tube defects result from failure of neuropore closure in early embryogenesis. Failure of the caudal (posterior) neuropore closure produces spina bifida. Hydrocephalus is a CSF flow disorder and Down syndrome is a chromosomal anomaly. Anencephaly is due to failure of the rostral neuropore specifically, but the classic defect associated with neural tube closure failure is spina bifida.

Question 7

Which layer surrounds the umbilical cord?

Accepted Answer

Answer reason: The umbilical cord is covered by a continuation of the amniotic membrane. Beneath this amniotic covering is Wharton’s jelly, which protects the umbilical vessels. The chorion forms the outer fetal membrane and placenta, the decidua is the maternal endometrium of pregnancy, and the endometrium is the uterine lining outside of pregnancy.

Question 8

The inner cell mass develops into?

Accepted Answer

Answer reason: The inner cell mass (embryoblast) differentiates into epiblast and hypoblast; the epiblast gives rise to all three germ layers that form the embryo proper. The trophoblast, not the inner cell mass, forms the major fetal components of the placenta. While the yolk sac is an extraembryonic derivative largely from hypoblast, the best single answer describing the fate of the inner cell mass is the embryo proper.

Question 9

Period of organogenesis in embryo is?

Accepted Answer

Answer reason: Organogenesis (formation of the major organ systems from the three germ layers) occurs primarily during weeks 3 through 8 of embryonic development. This is the period of greatest susceptibility to teratogens because basic structures are being established. After week 8, the conceptus is termed a fetus and development is dominated by growth and functional maturation rather than new organ formation.

Question 10

Which organ is first develop in embryo?

Accepted Answer

Answer reason: The heart is the first functional organ to develop in the human embryo, with early heart tube formation and initiation of beating occurring around the 3rd to 4th week of gestation. This early cardiac activity is required to establish embryonic circulation to support rapid growth and organogenesis. Other organs such as lungs, liver, and kidneys develop later in the embryonic period and do not become functional as early as the heart.

Question 11

What is the first organ that develops in the fetus?

Accepted Answer

Answer reason: The heart is the first functional organ to develop in the embryo, with the primitive heart tube forming early and beginning to beat around week 3–4 of gestation. This early cardiovascular function is necessary to deliver oxygen and nutrients to rapidly developing tissues. While the neural tube forms very early as well, the question asks for the first organ to develop, and the heart is classically cited as the earliest developing and first functioning organ. Other organs listed (liver, lungs, kidneys) begin developing later and become functional much later in gestation.

Question 12

The lining of urinary bladder except trigone is derived from?

Accepted Answer

Answer reason: Most of the urinary bladder mucosal lining (urothelium), excluding the trigone, develops from endoderm of the urogenital sinus. The trigone is the key exception because it forms from incorporation of the mesonephric (Wolffian) ducts, which are mesoderm-derived. Therefore, for the bladder lining except trigone, the correct germ layer is endoderm. The other options do not represent the primary embryologic source for this portion of the bladder mucosa.

Question 13

The branch of anatomy dealing with embryos is?

Accepted Answer

Answer reason: Embryology is the branch of anatomy/biology that studies the development of the embryo and fetus from fertilization through organ formation and growth. In contrast, osteology studies bones, myology studies muscles, and arthrology studies joints. Therefore, the correct answer is Embryology.

Question 14

The thyroid gland develops from?

Accepted Answer

Answer reason: The thyroid primordium originates as an endodermal thickening in the floor of the primitive pharynx at the foramen cecum of the tongue. It then descends in the midline through the thyroglossal duct to reach its final pretracheal position. Branchial (pharyngeal) pouches primarily give rise to structures like the parathyroids and thymus, not the main thyroid gland. Therefore, the correct embryologic origin listed is the foramen cecum.

Question 15

The origin of the ovaries is from?

Accepted Answer

Answer reason: The ovaries develop from the genital (gonadal) ridge, which arises from intermediate mesoderm and is colonized by primordial germ cells to form the gonad. In females, this primitive gonad differentiates into the ovary. The genital tubercle forms external genital structures, while the Wolffian and Müllerian ducts form internal genital ducts (male and female tract derivatives) rather than the ovaries themselves.

Question 16

The 1st organ that develops in the foetus is?

Accepted Answer

Answer reason: The heart is the first functional organ to develop in the embryo, beginning to form very early and starting to beat around the 3rd week of gestation. Early circulation is critical to deliver oxygen and nutrients to rapidly growing tissues. The brain and other organs begin development early as well, but the cardiovascular system becomes functional first. Therefore, among the options, the heart is the best answer.

Question 17

The perimetrium of the uterus is derived from?

Accepted Answer

Answer reason: The perimetrium is the outer serosal covering of the uterus, which is derived from peritoneum (mesothelium). Serosal linings and most connective tissues develop from mesoderm. In contrast, endoderm primarily forms epithelial linings of the gut and associated organs, and ectoderm/neuroectoderm form skin and nervous system structures. Therefore, mesoderm is the correct germ-layer origin.

Question 18

Ear ossicles are derived from?

Accepted Answer

Answer reason: The middle ear ossicles develop from the first two pharyngeal (branchial) arches. The malleus and incus arise from Meckel cartilage of the 1st arch, while the stapes (especially its suprastructure) derives primarily from Reichert cartilage of the 2nd arch. Therefore, the correct choice is the first and second branchial arches.

Question 19

Cleft palate results due to failure of fusion of?

Accepted Answer

Answer reason: Cleft palate most commonly results from failure of fusion of the palatal shelves (lateral palatine processes), which are embryologic outgrowths of the maxillary prominences (maxillary processes). When these shelves fail to elevate and fuse with each other and with the nasal septum, an oronasal communication remains. Lateral nasal and mandibular processes are involved in facial/nasal/lower jaw formation rather than the secondary palate, and the frontal (frontonasal) process does not form the palatal shelves.

Question 20

Branchial arches are derived from?

Accepted Answer

Answer reason: Branchial (pharyngeal) arches are primarily formed by a mesenchymal core derived from mesoderm (and neural crest contributions), and they are lined externally by ectoderm and internally by endoderm. In standard embryology MCQs, the key derivation emphasized for the arches themselves is the mesodermal core with endodermal association (pharyngeal pouches). Among the provided options, "Endoderm and mesoderm" is the best match to the embryologic tissue origins involved. Options stating only one germ layer or ectoderm with mesoderm omit the essential endodermal component related to pharyngeal apparatus development.

Question 21

Zygote period is?

Accepted Answer

Answer reason: The zygote (germinal) period spans from fertilization through the first 2 weeks of development, ending with implantation and the beginning of gastrulation. Weeks 3–8 correspond to the embryonic period when organogenesis occurs. From about week 9 to birth is the fetal period characterized by growth and maturation. Therefore, 0–2 weeks best matches the zygote period.

Question 22

Formation of three primary germ layers is ____?

Accepted Answer

Answer reason: The three primary germ layers (ectoderm, mesoderm, and endoderm) are established during gastrulation, when the bilaminar embryonic disc reorganizes into a trilaminar disc. Neurulation occurs later and is the process of neural tube formation from ectoderm. Ovulation is release of an oocyte from the ovary and is unrelated to germ layer formation. Therefore, gastrulation is the best answer.

Question 23

Diaphragm develops from all except?

Accepted Answer

Answer reason: The diaphragm forms embryologically from four main components: septum transversum (central tendon), pleuroperitoneal membranes (close pericardioperitoneal canals), dorsal mesentery of the esophagus (crura), and muscular ingrowth from the lateral body walls. The yolk sac contributes to early hematopoiesis and primitive gut-related development but does not form part of the diaphragm. Therefore, "Yolk sac" is the exception.

Question 24

The decidua covering the implanted blastocyst is?

Accepted Answer

Answer reason: Decidua capsularis is the portion of the endometrium that overlies and covers the implanted blastocyst on the uterine cavity side. In contrast, decidua basalis lies between the conceptus and the myometrium and forms the maternal part of the placenta. Decidua parietalis lines the remainder of the uterine cavity away from the implantation site, while “decidua reflexa” is an older synonym often used for the capsularis. Therefore, the best answer is decidua capsularis.

Question 25

Laryngotracheal bud appears during which of following period of gestation?

Accepted Answer

Answer reason: The laryngotracheal (respiratory) diverticulum/bud arises from the ventral wall of the foregut early in embryogenesis, classically around the 4th week. It subsequently elongates and separates from the esophagus via formation of the tracheoesophageal septum. Weeks 5 and 7 are later developmental milestones, making 4th week the best answer.

Question 26

The most common site of hematopoiesis in a fetus is?

Accepted Answer

Answer reason: During fetal life, hematopoiesis shifts from the yolk sac early on to predominantly the liver in the mid-gestation period, making the liver the most common site in the fetus. The spleen contributes to hematopoiesis but is a secondary site compared with the liver. Bone marrow becomes the primary site near late gestation and after birth. Lymph nodes are mainly involved in lymphopoiesis and are not the principal fetal hematopoietic site.

Question 27

Which one of these is a Neural crest derivative?

Accepted Answer

Answer reason: Neural crest cells migrate widely and form multiple peripheral nervous system structures, including dorsal root (sensory spinal) ganglia. Adrenal cortex is mesoderm-derived (the adrenal medulla, not cortex, is neural crest-derived). Ventral horn cells are motor neurons from the neural tube, and there is no true "ventral root ganglion" (ventral roots carry motor fibers without a ganglion).

Question 28

A change in the amount of yolk and its distribution in the egg will affect?

Accepted Answer

Answer reason: The amount and distribution of yolk (e.g., isolecithal vs mesolecithal vs telolecithal eggs) determines how cleavage furrows can form and progress through the cytoplasm. Yolk is relatively inert and mechanically impedes cytokinesis, so heavily yolked regions cleave more slowly or incompletely, producing meroblastic cleavage patterns. These yolk-related effects alter the cleavage pattern (holoblastic vs meroblastic; equal vs unequal) rather than fertilization or zygote formation. The number of blastomeres at a given stage is mainly a consequence of cleavage timing/pattern and is not the primary direct effect tested here.

Question 29

A white sticky substance present on the fetus skin is called-?

Accepted Answer

Answer reason: Vernix caseosa is the white, cheesy, sticky protective coating on fetal/newborn skin produced by sebaceous glands and shed epithelial cells. It helps protect the fetus/newborn skin from maceration in amniotic fluid and provides barrier/antimicrobial benefits. The other options are incorrect: pruritis is itching, and “lucosites” (likely leukocytes) are white blood cells rather than a skin coating.

Question 30

When describing dizygotic twins to a couple, on which of the following would the nurse base the explanation?

Accepted Answer

Answer reason: Dizygotic (fraternal) twins result when two separate ova are ovulated and each is fertilized by a different sperm, producing two genetically distinct embryos. They typically have separate placentas and chorions, though placentas can appear fused if implantation sites are close. In contrast, sharing a common placenta/chorion is more characteristic of monozygotic (identical) twinning. Therefore, the defining feature is fertilization of two ova by separate sperm.

Question 31

Which of the following refers to the single cell that reproduces itself after conception?

Accepted Answer

Answer reason: A zygote is the single cell formed immediately after fertilization (conception) and it begins dividing by mitosis during cleavage. A blastocyst is a later multicellular stage with an inner cell mass and trophoblast. The trophoblast is the outer cell layer of the blastocyst that contributes to placenta formation, and a chromosome is a genetic structure, not the entire post-conception single cell.

Question 32

What is the first organ that develops in a fetus ...?

Accepted Answer

Answer reason: The heart is the first functional organ to develop in the embryo, beginning as a primitive heart tube that starts beating around week 5 of gestation (about day 22 post-fertilization). Early circulation is critical to deliver oxygen and nutrients to rapidly developing tissues. Other organs like lungs, liver, and kidneys begin forming early as well, but they become functional later than the heart’s initial activity.

Question 33

The placenta is formed by combination of?

Accepted Answer

Answer reason: The placenta has a maternal component (decidua basalis of the endometrium) and a fetal component (chorion frondosum, the villous chorion). The chorion frondosum develops chorionic villi that form the functional exchange surface, while the decidua basalis provides the maternal bed and blood supply. Decidua capsularis with chorion laeve corresponds to the smooth chorion (non-villous) and does not form the placenta.

Question 34

What is the first organ that develops in the fetus ...?

Accepted Answer

Answer reason: The heart is the first functional organ to develop in the embryo, beginning to form early in gestation and starting to beat around week 3–4. Early cardiac activity is essential to establish circulation and support rapid embryonic growth. The other listed organs (brain maturation, lungs, kidneys) develop later or become functional later compared with the early onset of cardiac function.

Question 35

The fertilized egg is called?

Accepted Answer

Answer reason: A fertilized egg, immediately after the sperm and ovum unite and form a single diploid cell, is termed a zygote. The term ovum refers to the unfertilized female gamete. As cell divisions proceed and implantation begins, the developing conceptus is referred to as an embryo (and later a fetus after the embryonic period). Therefore, the correct term for the fertilized egg is zygote.

Question 36

The first organ to develop in the human embryo is ?

Accepted Answer

Answer reason: The heart is the first functional organ to develop in the embryo, beginning to form early in the third week of gestation. It is also the first organ system to function, with cardiac activity detectable by about week 4 (often cited around day 22–23). Early circulation is essential to support rapid embryonic growth and organogenesis. The brain and other organs develop early as well, but they do not become functional before the cardiovascular system.

Question 37

At brith,the foetus is called?

Accepted Answer

Answer reason: At birth and through the first 28 days of life, a newborn is termed a neonate. A zygote is the single cell formed immediately after fertilization, a blastocyst is an early pre-implantation/implantation stage, and an embryo refers to early development up to about 8 weeks’ gestation. Therefore, the correct term at birth is neonate.

Question 38

Which vitamin deficiency causes neural tube defects?

Accepted Answer

Answer reason: Folic acid (vitamin B9) deficiency is strongly associated with neural tube defects such as spina bifida and anencephaly because folate is required for DNA synthesis and rapid cell division during early embryogenesis. The neural tube closes very early in pregnancy (around weeks 3–4), so inadequate maternal folate before conception and in early pregnancy increases risk. Periconceptional folic acid supplementation reduces the incidence of neural tube defects. While vitamin B12 is involved in folate metabolism, folate deficiency is the classic direct association tested.

Question 39

Structure connecting the foetus to placenta is ...?

Accepted Answer

Answer reason: The umbilical cord is the anatomical structure that physically connects the fetus to the placenta and contains the umbilical vessels (two arteries and one vein) for transport of oxygen, nutrients, and waste products. The amnion and chorion are fetal membranes that form the amniotic sac and contribute to placental structures but do not connect the fetus directly to the placenta as a conduit. The bulbourethral gland is a male reproductive gland and is unrelated to pregnancy.

Question 40

Which of the following event is post fertilisation event?

Accepted Answer

Answer reason: Post-fertilization events occur after the sperm and ovum fuse to form a zygote. Embryogenesis includes cleavage, blastocyst formation, implantation, and early organogenesis, all of which happen after fertilization. Gametogenesis and gamete transfer are pre-fertilization steps, while fertilisation itself is the event that precedes embryogenesis.

Question 41

Zygote first becomes a?

Accepted Answer

Answer reason: After fertilization, the zygote undergoes rapid mitotic cleavage divisions, forming a solid ball of cells called the morula (typically around day 3). The next major stage is formation of a fluid-filled cavity, producing the blastula/blastocyst (around day 4–5). “Embryo” and “foetus” are later developmental periods rather than the immediate post-zygote cleavage stage. Therefore, the first stage the zygote becomes is the morula.

Question 42

The first organ to form in the embryo is?

Accepted Answer

Answer reason: The heart is the first functional organ system to develop in the embryo, with the primitive heart tube forming early and beginning to beat around week 3–4 of gestation. This early cardiovascular development is necessary to establish circulation to support rapid embryonic growth. In contrast, organs like the liver and kidneys begin differentiating later and become fully functional later in fetal development.

Question 43

What is the first organ that develops in the fetus?

Accepted Answer

Answer reason: The heart is the first functional organ to develop in the embryo, with cardiac activity beginning very early (around the 3rd week), and a detectable heartbeat typically by about 5–6 weeks of gestation. Early establishment of circulation is essential to support rapid embryonic growth and organogenesis. In contrast, the lungs and kidneys mature later for postnatal function, and while the neural tube forms early, the question asks for the first organ that develops/starts functioning, which is the heart.

Question 44

The first organ develops in Foetus is?

Accepted Answer

Answer reason: The heart is the first functional organ to develop in the embryo, beginning as a primitive heart tube early in gestation and starting to beat around the 3rd to 4th week. Early establishment of circulation is essential to deliver oxygen and nutrients to rapidly developing tissues. While the brain and eyes begin developing very early as neural structures, the heart is classically taught as the first organ to develop and become functional.

Question 45

A baby before birth is called?

Accepted Answer

Answer reason: The term for a developing baby before birth is "fetus," typically used from about 8 weeks of gestation until delivery. "Neonate" refers to a newborn in the first 28 days after birth. "Infant" is generally used for a child from birth to 12 months, and "toddler" typically refers to ages 1–3 years.

Question 46

First cell of human life is ...?

Accepted Answer

Answer reason: The first cell of a new human individual is the zygote, formed at fertilization when the sperm and ovum fuse and their nuclei combine to create a single diploid cell. The egg (ovum) and sperm are haploid gametes and are not yet the new organism. “Embryo” refers to a later multicellular developmental stage after the zygote undergoes cleavage and implantation-related development.

Question 47

Which of the following germ layers fills the yolk sac?

Accepted Answer

Answer reason: Endoderm The yolk sac is lined by endoderm; in early development, endoderm forms the epithelial lining of the primitive gut and associated structures derived from it. The yolk sac is continuous with the embryonic gut via the vitelline (omphalomesenteric) duct, reflecting its endodermal lining. Ectoderm primarily forms surface ectoderm and neuroectoderm, while intraembryonic mesoderm contributes to muscle, bone, and connective tissues rather than lining the yolk sac.

Question 48

Which is First Site of Haemopoiesis?

Accepted Answer

Answer reason: Yolk sac The earliest hematopoiesis in embryonic development begins in the blood islands of the yolk sac (primitive hematopoiesis). The liver becomes the major hematopoietic organ later in fetal life, followed by spleen contribution. Bone marrow becomes the primary site near birth and in postnatal life, so it is not the first site.

Question 49

What is the first organ that develops in the fetus?

Accepted Answer

Answer reason: Heart The heart is the first functional organ to develop in the embryo, beginning very early in gestation, with cardiac activity detectable around weeks 5–6 of pregnancy. Early circulation is essential to support rapid growth and organogenesis by delivering oxygen and nutrients. The brain, lungs, and kidneys develop later in a way that depends on this early circulatory support.

Question 50

During which stage of gestation is the developing embryo most susceptible to major structural malformations due to teratogen exposure?

Accepted Answer

Answer reason: Organogenesis (17-60 days) Major structural malformations most commonly result from teratogen exposure during organogenesis, when the primary organ systems are forming (approximately weeks 3–8, i.e., days 17–60). During the earlier blastocyst stage, teratogenic effects are typically “all-or-none” (pregnancy loss or no defect) rather than specific anomalies. After organogenesis, exposures more often affect growth and functional maturation rather than causing major structural defects.

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What is the first organ that develops in the fetus?

The umbilical cord contains?

Primitive streak appears in which week?

Notochord is derived from?

Neural tube is formed from?

Failure of neural tube closure leads to?

Which layer surrounds the umbilical cord?

The inner cell mass develops into?

Period of organogenesis in embryo is?

Which organ is first develop in embryo?

What is the first organ that develops in the fetus?

The lining of urinary bladder except trigone is derived from?

The branch of anatomy dealing with embryos is?

The thyroid gland develops from?

The origin of the ovaries is from?

The 1st organ that develops in the foetus is?

The perimetrium of the uterus is derived from?

Ear ossicles are derived from?

Cleft palate results due to failure of fusion of?

Branchial arches are derived from?

Zygote period is?

Formation of three primary germ layers is ____?

Diaphragm develops from all except?

The decidua covering the implanted blastocyst is?

Laryngotracheal bud appears during which of following period of gestation?

The most common site of hematopoiesis in a fetus is?

Which one of these is a Neural crest derivative?

A change in the amount of yolk and its distribution in the egg will affect?

A white sticky substance present on the fetus skin is called-?

When describing dizygotic twins to a couple, on which of the following would the nurse base the explanation?

Which of the following refers to the single cell that reproduces itself after conception?

What is the first organ that develops in a fetus ...?

The placenta is formed by combination of?

What is the first organ that develops in the fetus ...?

The fertilized egg is called?

The first organ to develop in the human embryo is ?

At brith,the foetus is called?

Which vitamin deficiency causes neural tube defects?

Structure connecting the foetus to placenta is ...?

Which of the following event is post fertilisation event?

Zygote first becomes a?

The first organ to form in the embryo is?

What is the first organ that develops in the fetus?

The first organ develops in Foetus is?

A baby before birth is called?

First cell of human life is ...?

Which of the following germ layers fills the yolk sac?

Which is First Site of Haemopoiesis?

What is the first organ that develops in the fetus?

During which stage of gestation is the developing embryo most susceptible to major structural malformations due to teratogen exposure?

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