Embryology

1. Fertilization occurs when:
   a) The blastocyst attaches to the uterus
   b) The sperm and egg combine to form a zygote
   c) The embryo begins organ development
   d) The placenta forms

2. The zygote undergoes cleavage to form a:
   a) Blastocyst
   b) Morula
   c) Embryo
   d) Gastrula

3. The process by which the blastocyst attaches to the uterine lining is called:
   a) Fertilization
   b) Neurulation
   c) Implantation
   d) Gastrulation

4. The bilaminar germ disc consists of which two layers?
   a) Endoderm and mesoderm
   b) Ectoderm and mesoderm
   c) Epiblast and hypoblast
   d) Trophoblast and embryoblast

5. The trilaminar germ disc is formed during:
   a) Week 1
   b) Week 2
   c) Week 3
   d) Week 4

6. What is the name of the process that establishes the three germ layers?
   a) Neurulation
   b) Gastrulation
   c) Organogenesis
   d) Implantation

7. Which of the following is derived from the ectoderm?
   a) Kidneys
   b) Brain and spinal cord
   c) Heart and blood vessels
   d) Gastrointestinal lining

8. Which layer gives rise to muscles, bones, and the cardiovascular system?
   a) Ectoderm
   b) Mesoderm
   c) Endoderm
   d) Trophoblast

9. The primitive streak is important in:
   a) Brain development
   b) Neural tube formation
   c) Gastrulation
   d) Placental formation

10. The notochord forms from which germ layer?
    a) Ectoderm
    b) Mesoderm
    c) Endoderm
    d) Hypoblast

11. What is the function of the notochord?
    a) It induces neural tube formation
    b) It forms the placenta
    c) It develops into the lungs
    d) It produces red blood cells

12. The process of forming the neural tube is called:
    a) Gastrulation
    b) Neurulation
    c) Organogenesis
    d) Fertilization

13. Failure of the neural tube to close completely can lead to:
    a) Hydrocephalus
    b) Spina bifida
    c) Cleft palate
    d) Tetralogy of Fallot

14. Which of the following structures originates from the endoderm?
    a) Skeletal muscles
    b) Skin and hair
    c) Gastrointestinal tract
    d) Kidneys

15. The amnion is responsible for:
    a) Nourishing the embryo
    b) Forming the placenta
    c) Producing amniotic fluid
    d) Creating the neural crest

16. The yolk sac plays a crucial role in:
    a) Providing oxygen to the embryo
    b) Early blood cell formation
    c) Neural tube closure
    d) Lung development

17. The chorionic villi are essential for:
    a) Producing hormones
    b) Exchanging nutrients between mother and fetus
    c) Forming the neural tube
    d) Closing the primitive streak

18. The primary chorionic villus consists of:
    a) Cytotrophoblast only
    b) Syncytiotrophoblast only
    c) Both cytotrophoblast and syncytiotrophoblast
    d) Mesoderm and trophoblast

19. Which of the following forms the placenta?
    a) Hypoblast
    b) Amnion
    c) Trophoblast
    d) Neural tube

20. The intraembryonic mesoderm divides into:
    a) Amnion and yolk sac
    b) Paraxial, intermediate, and lateral mesoderm
    c) Neural tube and notochord
    d) Endoderm and ectoderm

21. The paraxial mesoderm forms:
    a) Liver and pancreas
    b) Muscles, bones, and dermis
    c) Lungs and intestines
    d) Placental tissues

22. The somites originate from which layer?
    a) Ectoderm
    b) Mesoderm
    c) Endoderm
    d) Trophoblast

23. Somites develop into:
    a) Kidneys and adrenal glands
    b) Neural crest cells
    c) Vertebrae and skeletal muscles
    d) Gastrointestinal tract

24. What is the first organ system to develop in the embryo?
    a) Nervous system
    b) Respiratory system
    c) Cardiovascular system
    d) Digestive system

25. The neural crest cells give rise to:
    a) Bones of the skull, melanocytes, and adrenal medulla
    b) Kidneys and bladder
    c) Skeletal muscles
    d) Pancreatic cells

26. What is a sacrococcygeal teratoma?
    a) A neural tube defect
    b) A tumor originating from primitive streak cells
    c) A disorder of the placenta
    d) A defect in amniotic fluid production

27. Which structure becomes the vertebral column?
    a) Primitive streak
    b) Notochord
    c) Chorionic villi
    d) Yolk sac

28. Choriocarcinoma is associated with abnormal development of:
    a) Placenta and trophoblasts
    b) Neural tube
    c) Endodermal cells
    d) Somites

29. Lateral folding of the embryo is important for:
    a) Heart formation
    b) Closure of the body wall and gut tube formation
    c) Formation of the neural tube
    d) Placental function

30. The extraembryonic mesoderm develops into:
    a) Blood vessels of the placenta
    b) The nervous system
    c) The liver and pancreas
    d) The skeletal system

Answer Key

1. b

2. b

3. c

4. c

5. c

6. b

7. b

8. b

9. c

10. b

11. a

12. b

13. b

14. c

15. c

16. b

17. b

18. c

19. c

20. b

21. b

22. b

23. c

24. c

25. a

26. b

27. b

28. a

29. b

30. a