🌿 UNIT VI: Reproduction 🌿
CH 2: Human Reproduction
Concepts: Fertilization, Embryo Development up to Blastocyst Formation and Implantation
1. Fertilization in humans usually occurs in the:
A. Ovary
B. Uterus
C. Cervix
D. Ampullary–isthmic junction of fallopian tube
Answer: D
Explanation: This region provides suitable conditions for fusion of gametes.
2. Fertilization is defined as:
A. Formation of gametes
B. Fusion of sperms
C. Fusion of male and female gametes
D. Implantation of embryo
Answer: C
Explanation: Fertilization involves fusion of sperm and ovum.
3. The product of fertilization is called:
A. Embryo
B. Morula
C. Blastocyst
D. Zygote
Answer: D
Explanation: Zygote is the first diploid cell formed after fertilization.
4. The chromosome number in human zygote is:
A. 23
B. 22
C. 46
D. 44
Answer: C
Explanation: Zygote is diploid with 46 chromosomes.
5. Functional maturation of sperm in female tract is called:
A. Spermiogenesis
B. Capacitation
C. Fertilization
D. Cleavage
Answer: B
Explanation: Capacitation enables sperm to fertilize ovum.
6. Which structure of sperm helps in penetrating egg coverings?
A. Tail
B. Middle piece
C. Acrosome
D. Nucleus
Answer: C
Explanation: Acrosome contains enzymes for penetration.
7. The egg coverings include:
A. Zona pellucida and corona radiata
B. Endometrium and chorion
C. Amnion and chorion
D. Myometrium and perimetrium
Answer: A
8. Which reaction prevents polyspermy?
A. Acrosomal reaction
B. Cortical reaction
C. Capacitation
D. Cleavage
Answer: B
Explanation: Cortical reaction blocks entry of additional sperms.
9. Fusion of male and female pronuclei is called:
A. Fertilization
B. Cleavage
C. Syngamy
D. Implantation
Answer: C
10. Fertilization restores:
A. Haploid condition
B. Diploid condition
C. Polyploidy
D. Triploidy
Answer: B
11. Which chromosome determines sex of child?
A. X chromosome of mother
B. X chromosome of father
C. Y chromosome of mother
D. X or Y chromosome of father
Answer: D
Explanation: Father contributes either X or Y sperm.
12. First division of zygote is:
A. Meiotic
B. Mitotic
C. Reductional
D. Amitotic
Answer: B
13. Repeated mitotic divisions of zygote are called:
A. Fertilization
B. Gametogenesis
C. Cleavage
D. Implantation
Answer: C
14. Cells formed during cleavage are called:
A. Blastocysts
B. Embryoblasts
C. Blastomeres
D. Trophoblasts
Answer: C
15. Cleavage occurs while zygote is:
A. Stationary in uterus
B. Moving through fallopian tube
C. Implanted in uterus
D. In ovary
Answer: B
16. The morula stage has approximately:
A. 4 cells
B. 8 cells
C. 16–32 cells
D. 64–128 cells
Answer: C
17. Morula enters the uterus after:
A. 1 day
B. 2 days
C. 3–4 days
D. 7–8 days
Answer: C
18. Morula is best described as:
A. Hollow ball of cells
B. Fluid-filled structure
C. Solid mass of cells
D. Differentiated embryo
Answer: C
19. Conversion of morula into blastocyst occurs in:
A. Ovary
B. Fallopian tube
C. Cervix
D. Uterus
Answer: D
20. Blastocyst is characterized by:
A. Solid structure
B. Fluid-filled cavity
C. Absence of differentiation
D. No outer layer
Answer: B
21. The cavity of blastocyst is called:
A. Blastopore
B. Blastocoel
C. Amniotic cavity
D. Coelom
Answer: B
22. The outer layer of blastocyst is:
A. Inner cell mass
B. Trophoblast
C. Endometrium
D. Chorion
Answer: B
23. Inner cell mass of blastocyst forms:
A. Placenta
B. Uterine wall
C. Embryo
D. Amnion only
Answer: C
24. Trophoblast later contributes to:
A. Embryo
B. Placenta
C. Amnion
D. Yolk sac
Answer: B
25. Implantation occurs approximately:
A. 1–2 days after fertilization
B. 3–4 days after fertilization
C. 6–7 days after fertilization
D. 14 days after fertilization
Answer: C
26. Implantation takes place in:
A. Ovary
B. Fallopian tube
C. Cervix
D. Uterus
Answer: D
27. Implantation occurs during:
A. Follicular phase
B. Ovulatory phase
C. Luteal phase
D. Menstrual phase
Answer: C
28. Which hormone prepares uterus for implantation?
A. Estrogen
B. FSH
C. LH
D. Progesterone
Answer: D
29. Implantation is initiated by:
A. Inner cell mass
B. Trophoblast
C. Ovum
D. Zygote
Answer: B
30. Endometrium becomes suitable for implantation due to:
A. Estrogen only
B. Progesterone
C. LH surge
D. FSH secretion
Answer: B
31. Implantation leads to:
A. Menstruation
B. Fertilization
C. Pregnancy
D. Ovulation
Answer: C
32. After implantation, the uterine lining is called:
A. Endometrium
B. Myometrium
C. Decidua
D. Chorion
Answer: C
33. Implantation prevents menstruation because:
A. Ovulation stops
B. Estrogen decreases
C. Progesterone remains high
D. LH surge occurs
Answer: C
34. Failure of implantation results in:
A. Pregnancy
B. Menopause
C. Menstruation
D. Ovulation
Answer: C
35. Placenta begins to develop from:
A. Inner cell mass only
B. Endometrium only
C. Trophoblast and uterine tissue
D. Ovum only
Answer: C
36. The stage suitable for implantation is:
A. Morula
B. Zygote
C. Blastocyst
D. Embryo
Answer: C
37. Which enzyme helps sperm penetrate zona pellucida?
A. Pepsin
B. Amylase
C. Acrosin
D. Trypsin
Answer: C
38. Which structure blocks polyspermy?
A. Zona pellucida
B. Corona radiata
C. Cortical granules
D. Trophoblast
Answer: C
39. Cleavage divisions are:
A. Unequal and meiotic
B. Equal and mitotic
C. Reductional
D. Amitotic
Answer: B
40. Embryonic development up to blastocyst occurs:
A. In ovary only
B. Entirely in uterus
C. During movement to uterus
D. After implantation only
Answer: C
41. Implantation normally occurs on:
A. Anterior uterine wall
B. Lower uterus
C. Upper posterior uterine wall
D. Cervix
Answer: C
42. Blastocyst remains free in uterus for:
A. 1 day
B. 2–3 days
C. 5–6 days
D. 10 days
Answer: B
43. Which process activates ovum after sperm entry?
A. Cleavage
B. Cortical reaction
C. Implantation
D. Capacitation
Answer: B
44. Which layer of blastocyst attaches to endometrium?
A. Inner cell mass
B. Amnion
C. Trophoblast
D. Blastocoel
Answer: C
45. Fertilization brings genetic variation because:
A. Gametes are diploid
B. Zygote is haploid
C. Gametes are genetically different
D. Cleavage is unequal
Answer: C
46. Blastocyst formation marks:
A. Beginning of pregnancy
B. End of fertilization
C. Readiness for implantation
D. End of cleavage
Answer: C
47. Implantation is possible only if:
A. Ovum is alive
B. Endometrium is thick and vascular
C. Estrogen is absent
D. LH level is high
Answer: B
48. Fertilization usually occurs within:
A. 6 hours of ovulation
B. 12 hours of ovulation
C. 24 hours of ovulation
D. 48 hours of ovulation
Answer: C
49. Which hormone maintains pregnancy after implantation?
A. Estrogen
B. Progesterone
C. FSH
D. LH
Answer: B
50. The correct sequence is:
A. Zygote → Blastocyst → Morula
B. Morula → Zygote → Blastocyst
C. Zygote → Morula → Blastocyst
D. Blastocyst → Morula → Zygote
Answer: C
