Fertilization MCQs With Answer is a targeted study resource for B. Pharm students preparing for reproductive biology, pharmacology, and therapeutics exams. This concise introduction covers molecular and cellular events of fertilization—sperm capacitation, acrosome reaction, zona pellucida binding, cortical granule exocytosis, pronuclear fusion—and clinical aspects such as timing, assisted reproductive technologies, and drug effects on fertility. These MCQs emphasize mechanisms, key proteins (IZUMO1, JUNO, ZP glycoproteins), polyspermy prevention, and pharmacological interventions relevant to pharmacists. Clear explanations and answer keys help reinforce learning, exam readiness, and application to drug therapy and contraceptive pharmacology. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Which event marks the completion of fertilization in humans?
- Fusion of male and female pronuclei
- Entry of sperm into the oocyte cytoplasm
- Activation of cortical granules
- Capacitation of sperm
Correct Answer: Fusion of male and female pronuclei
Q2. What is the primary biochemical change in sperm during capacitation?
- Increase in membrane cholesterol resulting in rigidity
- Decrease in membrane cholesterol and increased membrane fluidity
- DNA demethylation in sperm nucleus
- Release of acrosomal enzymes into seminal plasma
Correct Answer: Decrease in membrane cholesterol and increased membrane fluidity
Q3. Which glycoprotein of the zona pellucida primarily mediates species-specific sperm binding in humans?
- ZP4
- ZP2
- ZP3
- ZP1
Correct Answer: ZP3
Q4. IZUMO1 and JUNO proteins are critical for which fertilization step?
- Sperm capacitation in the epididymis
- Recognition and fusion of sperm and oocyte membranes
- Cortical granule exocytosis
Correct Answer: Recognition and fusion of sperm and oocyte membranes
Q5. The acrosome reaction is necessary for which action?
- Penetration of the oolemma directly without contacting zona pellucida
- Penetration of the zona pellucida by release of hydrolytic enzymes
- Fusion of pronuclei
- Activation of the uterine endometrium
Correct Answer: Penetration of the zona pellucida by release of hydrolytic enzymes
Q6. Which ion rise in the oocyte cytoplasm triggers cortical granule exocytosis?
- Potassium (K+)
- Chloride (Cl-)
- Calcium (Ca2+)
- Sodium (Na+)
Correct Answer: Calcium (Ca2+)
Q7. What is the pharmacological relevance of zona pellucida hardening after fertilization?
- It increases susceptibility to sperm-borne viruses
- It acts as a natural contraceptive preventing polyspermy
- It enhances implantation by increasing zona elasticity
- It decreases oocyte metabolic activity
Correct Answer: It acts as a natural contraceptive preventing polyspermy
Q8. Which mechanism primarily prevents polyspermy in mammals?
- Fast electrical block at the oolemma only
- Cortical granule exocytosis modifying the zona pellucida
- Immediate apoptosis of additional sperm
- Blocking sperm capacitation systemically
Correct Answer: Cortical granule exocytosis modifying the zona pellucida
Q9. Where does fertilization typically occur in the female reproductive tract?
- Uterine cavity
- Fimbrial end of the fallopian tube
- Isthmus of the fallopian tube
- Ampulla of the fallopian tube
Correct Answer: Ampulla of the fallopian tube
Q10. Which hormone secreted by the early embryo supports the corpus luteum and progesterone production?
- Luteinizing hormone (LH)
- Human chorionic gonadotropin (hCG)
- Prolactin
- Follicle-stimulating hormone (FSH)
Correct Answer: Human chorionic gonadotropin (hCG)
Q11. Which drug class can impair sperm capacitation and motility when taken chronically?
- Statins
- Beta-blockers
- Antibiotics like tetracyclines
- Anabolic steroids
Correct Answer: Anabolic steroids
Q12. In IVF procedures, which step mimics the natural acrosome reaction to allow sperm to penetrate the zona?
- Intracytoplasmic sperm injection (ICSI)
- Zona pellucida thickening
- Controlled ovarian hyperstimulation
- Sperm capacitation media and hyperactivation
Correct Answer: Sperm capacitation media and hyperactivation
Q13. Which of the following best describes intracytoplasmic sperm injection (ICSI)?
- Sperm are incubated with oocytes for natural fertilization
- A single sperm is injected directly into the oocyte cytoplasm
- Sperm are genetically modified before insemination
- Multiple sperm are injected to increase fertilization rate
Correct Answer: A single sperm is injected directly into the oocyte cytoplasm
Q14. Cortical granule contents act on which substrate to prevent further sperm binding?
- Oolemma receptors
- Zona pellucida glycoproteins
- Sperm plasma membrane proteins
- Follicular cell matrix
Correct Answer: Zona pellucida glycoproteins
Q15. Which molecule on the sperm is essential for fusion with the oocyte membrane?
- Acrosin
- IZUMO1
- Procollagen
- Progesterone receptor
Correct Answer: IZUMO1
Q16. JUNO is located on which cell during fertilization?
- Sperm plasma membrane
- Oocyte plasma membrane (oolemma)
- Zona pellucida
- Cumulus cells
Correct Answer: Oocyte plasma membrane (oolemma)
Q17. Which contraceptive mechanism directly prevents sperm capacitation?
- Intrauterine device (IUD) copper-induced sperm immobilization
- Combined oral contraceptives increasing estrogen
- Progesterone-only pills thickening cervical mucus
- Barrier methods like condoms
Correct Answer: Progesterone-only pills thickening cervical mucus
Q18. What is the physiological role of hyperactivation in sperm?
- To decrease mitochondrial ATP production
- To enhance progressive straight-line motility for rapid transit
- To increase flagellar force for zona penetration
- To induce sperm apoptosis before reaching oocyte
Correct Answer: To increase flagellar force for zona penetration
Q19. Which enzyme in the acrosome contributes to ZP digestion?
- Acrosin
- Lipase
- DNA polymerase
- Kinase
Correct Answer: Acrosin
Q20. Time window for fertilization after ovulation is approximately:
- 24 hours
- 72 hours
- 1 week
- 10 minutes
Correct Answer: 24 hours
Q21. Which condition is most likely associated with failed sperm-oocyte fusion despite normal sperm count?
- Defective acrosin activity
- Mutation in IZUMO1 or JUNO proteins
- Low testosterone levels
- High cervical mucus viscosity only
Correct Answer: Mutation in IZUMO1 or JUNO proteins
Q22. Which laboratory assay directly assesses fertilization competence during IVF?
- Sperm count by hemocytometer
- Zona penetration assay (hamster egg penetration test)
- Semen pH measurement
- Serum FSH level
Correct Answer: Zona penetration assay (hamster egg penetration test)
Q23. Which signaling molecule in oocyte activation induces cell cycle resumption?
- cGMP decrease only
- Calcium oscillations leading to calmodulin-dependent kinase activation
- ATP depletion
- Membrane hyperpolarization without secondary messengers
Correct Answer: Calcium oscillations leading to calmodulin-dependent kinase activation
Q24. Polyspermy would most likely result in which embryonic outcome?
- Normal diploid zygote
- Polyploidy and embryonic lethality
- Increased implantation success
- Enhanced placental function
Correct Answer: Polyploidy and embryonic lethality
Q25. Which drug used in assisted reproduction can trigger oocyte maturation by mimicking LH?
- Clomiphene citrate
- hCG (human chorionic gonadotropin)
- Metformin
- Progesterone
Correct Answer: hCG (human chorionic gonadotropin)
Q26. The zona pellucida protein primarily cleaved during cortical reaction to prevent sperm binding is:
- ZP1
- ZP2
- ZP3
- ZP4
Correct Answer: ZP2
Q27. Which process occurs first after sperm entry into the oocyte?
- First mitotic division
- Pronuclear formation and DNA decondensation
- Implantation into the uterine wall
- Blastocyst hatching
Correct Answer: Pronuclear formation and DNA decondensation
Q28. Which factor can reduce male fertility by damaging spermatogenesis?
- Antioxidants supplementation
- Exposure to alkylating chemotherapeutic agents
- Short-term fever under 24 hours
- Moderate exercise
Correct Answer: Exposure to alkylating chemotherapeutic agents
Q29. Which is a direct pharmacological antagonist of progesterone used in emergency contraception?
- Levonorgestrel
- Mifepristone (RU-486)
- Ethinylestradiol
- Clomiphene citrate
Correct Answer: Mifepristone (RU-486)
Q30. Which of the following describes the fast block to polyspermy seen in some species?
- Physical modification of the zona pellucida within minutes
- Immediate membrane depolarization of the oocyte preventing further sperm fusion
- Proteolytic cleavage of sperm receptors
- Secretion of anti-sperm antibodies
Correct Answer: Immediate membrane depolarization of the oocyte preventing further sperm fusion
Q31. What role does progesterone secreted by cumulus cells play in fertilization?
- Directly hardens the zona pellucida
- Acts as a chemoattractant and stimulates sperm hyperactivation
- Inhibits acrosome reaction
- Causes oocyte apoptosis
Correct Answer: Acts as a chemoattractant and stimulates sperm hyperactivation
Q32. Which condition is most likely to cause tubal factor infertility affecting fertilization?
- Endometrial hyperplasia
- Ectopic pregnancy history or pelvic inflammatory disease causing tubal scarring
- Polycystic ovary syndrome without tubal involvement
- Cervical stenosis only
Correct Answer: Ectopic pregnancy history or pelvic inflammatory disease causing tubal scarring
Q33. During IVF, zona pellucida thinning or artificial zona breach is performed to assist which process?
- Sperm production in male partner
- Embryo hatching and implantation
- Inhibition of cortical granule release
- Prevention of polyspermy
Correct Answer: Embryo hatching and implantation
Q34. Which intracellular change in the oocyte is responsible for resumption of meiosis II at fertilization?
- Increase in intracellular cAMP
- Decrease in intracellular Ca2+
- Increase in intracellular Ca2+ oscillations
- Activation of caspase cascade
Correct Answer: Increase in intracellular Ca2+ oscillations
Q35. Which test is commonly used to assess female ovarian reserve relevant to fertility planning?
- Serum anti-Müllerian hormone (AMH) level
- Serum LH test only
- Endometrial biopsy
- Hysterosalpingography for tubal patency only
Correct Answer: Serum anti-Müllerian hormone (AMH) level
Q36. Which drug can be used to induce ovulation by acting as an estrogen receptor modulator?
- Clomiphene citrate
- Progesterone-only pill
- Metformin as monotherapy
- Leuprolide acetate only for suppression
Correct Answer: Clomiphene citrate
Q37. Which event describes syngamy?
- Fusion of sperm and oocyte membranes before pronuclear formation
- Fusion of male and female pronuclei to form a zygotic nucleus
- Cleavage of the zygote into blastomeres
- Hatching of the blastocyst from the zona pellucida
Correct Answer: Fusion of male and female pronuclei to form a zygotic nucleus
Q38. Which contraceptive approach acts primarily by preventing ovulation?
- Copper IUD
- Combined oral contraceptive pills
- Barrier methods like diaphragm
- Spermicidal gels
Correct Answer: Combined oral contraceptive pills
Q39. How does a copper intrauterine device (IUD) mainly reduce fertilization?
- By releasing progesterone systemically
- By creating a local inflammatory reaction toxic to sperm
- By thickening cervical mucus exclusively
- By increasing luteal phase progesterone
Correct Answer: By creating a local inflammatory reaction toxic to sperm
Q40. Which molecular interaction is responsible for initial docking of sperm to the zona pellucida?
- Progesterone binding to sperm receptors
- ZP3 glycoprotein recognizing sperm surface proteins
- JUNO on sperm binding to oocyte glycoproteins
- hCG stimulating sperm motility
Correct Answer: ZP3 glycoprotein recognizing sperm surface proteins
Q41. Which factor secreted by the cumulus-oocyte complex facilitates sperm penetration?
- Hyaluronidase secreted by sperm interacting with cumulus matrix
- Estrogen secreted by uterus
- Inhibin from granulosa cells
- Prolactin from pituitary
Correct Answer: Hyaluronidase secreted by sperm interacting with cumulus matrix
Q42. Which abnormal fertilization event characterizes dispermic fertilization?
- Fertilization by a single haploid sperm
- Fertilization by two sperm leading to triploid zygote
- Fertilization without pronuclear formation
- Fertilization with immediate implantation
Correct Answer: Fertilization by two sperm leading to triploid zygote
Q43. Which medication used for cancer therapy is most likely to cause permanent ovarian failure?
- Antimetabolites like 5-FU
- Alkylating agents like cyclophosphamide
- Monoclonal antibodies only
- Tyrosine kinase inhibitors exclusively
Correct Answer: Alkylating agents like cyclophosphamide
Q44. What is the role of reactive oxygen species (ROS) in sperm function?
- Low levels are required for capacitation and acrosome reaction, while high levels cause damage
- ROS have no effect on sperm and are always detrimental
- ROS only enhance DNA repair in sperm
- High ROS always improve motility
Correct Answer: Low levels are required for capacitation and acrosome reaction, while high levels cause damage
Q45. Which technique bypasses the zona pellucida and can fertilize oocytes with defective zona recognition?
- Conventional IVF with co-incubation
- Intracytoplasmic sperm injection (ICSI)
- Zygote intrafallopian transfer (ZIFT)
- Intrauterine insemination (IUI)
Correct Answer: Intracytoplasmic sperm injection (ICSI)
Q46. Successful implantation typically occurs how many days after fertilization?
- 1–2 days
- 6–10 days
- 20–25 days
- Immediately within hours
Correct Answer: 6–10 days
Q47. Which maternal condition can alter the uterine environment and reduce chances of successful fertilization or implantation?
- Controlled hypothyroidism on stable therapy
- Severe uncontrolled diabetes mellitus
- Mild seasonal allergies
- Regular moderate exercise
Correct Answer: Severe uncontrolled diabetes mellitus
Q48. Which assay would a pharmacist recommend to monitor early pregnancy after ART to confirm implantation?
- Serum progesterone alone
- Serial quantitative serum hCG measurements
- Complete blood count weekly
- Urine glucose monitoring
Correct Answer: Serial quantitative serum hCG measurements
Q49. Which of the following best explains why advanced maternal age reduces fertilization success?
- Increased ovarian reserve and more oocytes
- Decline in oocyte quality, increased aneuploidy, and reduced ovarian reserve
- Faster oocyte meiosis completion improving embryo quality
- Better endometrial receptivity with age
Correct Answer: Decline in oocyte quality, increased aneuploidy, and reduced ovarian reserve
Q50. For B. Pharm students, why is understanding fertilization important in pharmacology?
- It has no relevance to drug therapy or safety
- It helps predict drug interactions in veterinary medicine only
- It informs drug effects on fertility, teratogenic risk, contraceptive mechanisms, and reproductive toxicology
- It only matters for basic anatomy courses
Correct Answer: It informs drug effects on fertility, teratogenic risk, contraceptive mechanisms, and reproductive toxicology
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