Q.1 Which germ layer gives rise to the central nervous system?
Endoderm
Mesoderm
Ectoderm
Neural crest
Explanation - The ectoderm differentiates into the central nervous system, peripheral nervous system, and epidermis.
Correct answer is: Ectoderm
Q.2 The primitive streak first appears during which week of embryonic development?
1st week
2nd week
3rd week
4th week
Explanation - The primitive streak appears in the 3rd week of development and marks the beginning of gastrulation.
Correct answer is: 3rd week
Q.3 Which structure forms from the notochord?
Spinal cord
Vertebral bodies
Nucleus pulposus
Spinal nerves
Explanation - The notochord eventually degenerates, with remnants forming the nucleus pulposus of intervertebral discs.
Correct answer is: Nucleus pulposus
Q.4 Neural crest cells give rise to all of the following EXCEPT:
Melanocytes
Adrenal medulla
Cranial nerves
Kidney nephrons
Explanation - Kidney nephrons develop from intermediate mesoderm, not neural crest cells.
Correct answer is: Kidney nephrons
Q.5 Which of the following is a derivative of endoderm?
Liver
Heart
Kidney
Spinal cord
Explanation - The endoderm forms epithelial linings and organs such as the liver and pancreas.
Correct answer is: Liver
Q.6 Somites differentiate into all EXCEPT:
Dermis
Skeletal muscle
Vertebrae
Cardiac muscle
Explanation - Somites give rise to sclerotome (vertebrae), myotome (skeletal muscle), and dermatome (dermis). Cardiac muscle is derived from splanchnic mesoderm.
Correct answer is: Cardiac muscle
Q.7 The fetal portion of the placenta develops from:
Amnion
Yolk sac
Chorion frondosum
Decidua basalis
Explanation - The chorion frondosum is the fetal contribution to the placenta, while the decidua basalis is maternal.
Correct answer is: Chorion frondosum
Q.8 Which embryonic membrane contributes to the formation of the umbilical cord?
Yolk sac
Amnion
Allantois
Chorion
Explanation - The amnion surrounds the embryo and contributes to the umbilical cord formation.
Correct answer is: Amnion
Q.9 During which week does implantation of the blastocyst usually occur?
1st week
2nd week
3rd week
4th week
Explanation - Implantation typically begins at the end of the 1st week and is completed in the 2nd week.
Correct answer is: 2nd week
Q.10 Which of the following is a derivative of the neural tube?
Retina
Spinal cord
Adrenal medulla
Melanocytes
Explanation - The neural tube gives rise to the CNS, including the brain and spinal cord.
Correct answer is: Spinal cord
Q.11 Which vascular shunt in fetal circulation connects the pulmonary artery to the aorta?
Ductus venosus
Foramen ovale
Ductus arteriosus
Umbilical vein
Explanation - The ductus arteriosus shunts blood from the pulmonary artery to the aorta, bypassing fetal lungs.
Correct answer is: Ductus arteriosus
Q.12 Which pharyngeal arch gives rise to the maxilla and mandible?
First arch
Second arch
Third arch
Fourth arch
Explanation - The first pharyngeal arch forms the maxilla, mandible, malleus, and incus.
Correct answer is: First arch
Q.13 The cloaca divides into the urogenital sinus and rectum due to the formation of:
Urorectal septum
Allantois
Mesonephros
Pronephros
Explanation - The urorectal septum divides the cloaca into the urogenital sinus and rectum.
Correct answer is: Urorectal septum
Q.14 Which extraembryonic membrane forms blood cells in early development?
Chorion
Amnion
Yolk sac
Allantois
Explanation - The yolk sac serves as the primary site for hematopoiesis in early development.
Correct answer is: Yolk sac
Q.15 The heart begins to beat during which week of development?
2nd week
3rd week
4th week
5th week
Explanation - The primitive heart tube begins to beat by the 4th week of embryonic life.
Correct answer is: 4th week
Q.16 Which structure connects the yolk sac to the midgut in the embryo?
Vitelline duct
Allantois
Umbilical vein
Chorionic villi
Explanation - The vitelline duct connects the yolk sac to the embryonic midgut.
Correct answer is: Vitelline duct
Q.17 Which structure is derived from the second pharyngeal arch?
Maxilla
Stapes
Thyroid cartilage
Mandible
Explanation - The second pharyngeal arch gives rise to the stapes, styloid process, and parts of the hyoid bone.
Correct answer is: Stapes
Q.18 Which germ layer forms the epithelial lining of the gastrointestinal tract?
Ectoderm
Endoderm
Mesoderm
Neural crest
Explanation - The endoderm forms the epithelial lining of the GI tract, respiratory tract, and associated glands.
Correct answer is: Endoderm
Q.19 What is the function of the foramen ovale in fetal circulation?
Connects pulmonary artery to aorta
Connects right atrium to left atrium
Connects umbilical vein to IVC
Connects ductus venosus to portal vein
Explanation - The foramen ovale allows blood to pass from the right atrium to the left atrium, bypassing the lungs.
Correct answer is: Connects right atrium to left atrium
Q.20 Which embryonic structure gives rise to the diaphragm?
Septum transversum
Allantois
Yolk sac
Neural tube
Explanation - The septum transversum contributes to the central tendon of the diaphragm.
Correct answer is: Septum transversum
Q.21 The lens of the eye develops from which embryonic structure?
Surface ectoderm
Neural crest
Endoderm
Mesoderm
Explanation - The lens of the eye develops from surface ectoderm, while the retina comes from neuroectoderm.
Correct answer is: Surface ectoderm
Q.22 The adrenal cortex is derived from which embryonic layer?
Ectoderm
Neural crest
Mesoderm
Endoderm
Explanation - The adrenal cortex develops from mesoderm, while the adrenal medulla arises from neural crest cells.
Correct answer is: Mesoderm
Q.23 Which of the following is the first hematopoietic organ in the embryo?
Liver
Bone marrow
Yolk sac
Spleen
Explanation - The yolk sac is the initial site of hematopoiesis before the liver and bone marrow take over.
Correct answer is: Yolk sac
Q.24 Which process establishes the three germ layers in the embryo?
Fertilization
Cleavage
Gastrulation
Neurulation
Explanation - Gastrulation results in the formation of the ectoderm, mesoderm, and endoderm.
Correct answer is: Gastrulation
Q.25 The allantois in humans is primarily associated with:
Gas exchange
Formation of urinary bladder
Nutrition
Placental circulation
Explanation - In humans, the allantois contributes to the development of the urinary bladder.
Correct answer is: Formation of urinary bladder