Questions About Embryology: Fertilization, Growth, Placenta, and Pregnancy
Multiple-Choice Questions
Topic: Embryology – Fertilization, Growth, Placenta, Pregnancy
1. Where does fertilization typically occur in humans?
A) Uterus
B) Cervix
C) Vagina
D) Fallopian tube
E) Ovary
2. What is the result of the fusion of a sperm and an egg?
A) Embryo
B) Morula
C) Blastocyst
D) Zygote
E) Placenta
3. What structure forms after the zygote divides several times?
A) Ovum
B) Embryo
C) Morula
D) Placenta
E) Follicle
4. What is the name of the hollow ball of cells that implants into the uterus?
A) Blastula
B) Zygote
C) Morula
D) Gastrula
E) Blastocyst
5. Which hormone is detected in pregnancy tests?
A) Estrogen
B) Progesterone
C) Oxytocin
D) hCG
E) LH
6. What is the function of the placenta?
A) Digestion of food
B) Hormone production only
C) Waste elimination only
D) Nourishment and waste exchange between mother and fetus
E) Gas exchange in the mother
7. What does the umbilical cord connect?
A) Mother to ovary
B) Fetus to uterine wall
C) Fetus to placenta
D) Placenta to uterus
E) Embryo to cervix
8. When does implantation occur after fertilization?
A) Immediately
B) 12 hours later
C) 24 hours later
D) 6–7 days later
E) 2 weeks later
9. What is the outer layer of the blastocyst called?
A) Endoderm
B) Trophoblast
C) Ectoderm
D) Chorion
E) Zona pellucida
10. Which layer of the embryo forms the nervous system?
A) Endoderm
B) Mesoderm
C) Ectoderm
D) Trophoblast
E) Morula
11. Which germ layer gives rise to muscles and bones?
A) Endoderm
B) Mesoderm
C) Ectoderm
D) Blastoderm
E) Trophoblast
12. What does the endoderm primarily develop into?
A) Skin and hair
B) Muscles and bones
C) Lungs and digestive organs
D) Brain and spinal cord
E) Heart and kidneys
13. When is an embryo officially considered a fetus?
A) After 1 week
B) After 2 weeks
C) After 4 weeks
D) After 8 weeks
E) After 12 weeks
14. What is the role of amniotic fluid?
A) Nourishes the fetus
B) Helps fetal respiration
C) Cushions and protects the fetus
D) Removes waste
E) Forms bones
15. What hormone maintains the uterine lining in early pregnancy?
A) Estrogen
B) LH
C) Oxytocin
D) hCG
E) FSH
16. How long does human pregnancy typically last?
A) 30 weeks
B) 32 weeks
C) 36 weeks
D) 38 weeks
E) 40 weeks
17. Which structure prevents polyspermy (entry of multiple sperm)?
A) Chorion
B) Zona pellucida
C) Umbilical cord
D) Trophoblast
E) Placenta
18. What initiates labor contractions?
A) Estrogen
B) FSH
C) Oxytocin
D) Progesterone
E) LH
19. What structure is expelled after the baby is delivered?
A) Embryo
B) Morula
C) Placenta
D) Umbilical cord
E) Blastocyst
20. Which hormone promotes milk ejection?
A) Progesterone
B) Oxytocin
C) Prolactin
D) LH
E) Estrogen
21. What structure forms the fetal part of the placenta?
A) Chorion
B) Yolk sac
C) Amnion
D) Trophoblast
E) Uterus
22. Which embryonic membrane directly surrounds the embryo?
A) Amnion
B) Chorion
C) Yolk sac
D) Allantois
E) Placenta
23. When does organogenesis begin during development?
A) 1st week
B) 2nd week
C) 3rd week
D) 6th week
E) 10th week
24. What is the function of the yolk sac in humans?
A) Nutrition
B) Blood cell formation
C) Gas exchange
D) Hormone secretion
E) Digestion
25. Which of these structures is not derived from the mesoderm?
A) Heart
B) Muscles
C) Lungs
D) Kidneys
E) Skeleton
26. What does cleavage refer to in embryology?
A) Fertilization
B) Egg rupture
C) Mitotic division of the zygote
D) Implantation
E) Uterine contraction
27. What is the function of the chorionic villi?
A) Waste removal
B) Anchoring embryo to the uterus and nutrient exchange
C) Blood cell production
D) Gas storage
E) Hormone inhibition
28. Which of the following occurs during the first trimester?
A) Birth
B) Formation of organs
C) Weight gain
D) Contractions
E) Eyelid opening
29. Which hormone prepares the breasts for milk production?
A) LH
B) Oxytocin
C) Progesterone
D) Estrogen
E) Prolactin
30. What organ allows oxygen and nutrients to pass from mother to fetus?
A) Amnion
B) Chorion
C) Uterus
D) Placenta
E) Yolk sac
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Answers and Explanations
1. D – Fertilization usually happens in the fallopian tube.
2. D – The zygote is the first cell formed from sperm and egg fusion.
3. C – A morula is the early solid ball of cells formed by zygote division.
4. E – The blastocyst is the hollow ball of cells that implants.
5. D – hCG (human chorionic gonadotropin) is detected in pregnancy tests.
6. D – The placenta facilitates nutrient and waste exchange.
7. C – The umbilical cord connects the fetus to the placenta.
8. D – Implantation typically occurs 6–7 days after fertilization.
9. B – The trophoblast is the outer layer of the blastocyst.
10. C – The ectoderm gives rise to the nervous system.
11. B – The mesoderm forms muscles, bones, and the circulatory system.
12. C – The endoderm develops into the digestive tract and lungs.
13. D – At 8 weeks, the embryo is classified as a fetus.
14. C – Amniotic fluid cushions the fetus from impact.
15. D – hCG maintains the corpus luteum to keep producing progesterone.
16. E – Pregnancy lasts about 40 weeks from the last menstrual period.
17. B – The zona pellucida prevents more than one sperm from entering.
18. C – Oxytocin stimulates uterine contractions during labor.
19. C – The placenta is expelled after birth as the “afterbirth.”
20. B – Oxytocin causes milk ejection; prolactin produces milk.
21. A – The chorion forms the fetal side of the placenta.
22. A – The amnion is the innermost membrane surrounding the embryo.
23. C – Organogenesis begins around the third week of development.
24. B – The yolk sac is important in early blood formation in humans.
25. C – The lungs derive from the endoderm, not the mesoderm.
26. C – Cleavage refers to early mitotic divisions of the zygote.
27. B – Chorionic villi anchor the embryo and allow exchange with the mother’s blood.
28. B – Major organ systems begin forming in the first trimester.
29. E – Prolactin prepares the mammary glands for milk production.
30. D – The placenta transfers oxygen and nutrients to the fetus.
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