Competency-Based Question Bank: Human Reproduction

Section A: Competency-Based Multiple Choice Questions (Application & Analysis)

1. Analyze the hormonal graph: A woman visits a doctor with concerns about irregular cycles. Blood tests reveal that her LH levels remain consistently low throughout her cycle, with no mid-cycle surge. Which of the following consequences is inevitable in this cycle? a) Menstruation will not occur. b) The endometrium will not proliferate. c) Ovulation will not occur. d) The corpus luteum will persist indefinitely. Answer: c) Ovulation will not occur. Explanation: The "LH surge" is the essential signal that triggers the rupture of the Graafian follicle and the release of the secondary oocyte (ovulation). Without this surge, ovulation cannot happen.

2. Assertion (A): The second meiotic division in the human secondary oocyte is unequal. Reason (R): It ensures the retention of bulk cytoplasm in the ovum to support early embryonic development. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is not the correct explanation of A. c) A is true but R is false. d) A is false but R is true. Answer: a) Both A and R are true and R is the correct explanation of A. Explanation: Unequal cytokinesis concentrates all the nutrients and organelles into one large cell (the Ootid/Ovum), while the tiny Second Polar Body eventually degenerates.

3. Predict the Outcome: If the vasa efferentia in the male reproductive system are blocked, the gametes will not be transported from: a) Epididymis to Vas deferens. b) Testes to Epididymis. c) Rete testis to Epididymis. d) Vas deferens to Ejaculatory duct. Answer: c) Rete testis to Epididymis. Explanation: The sequence of ducts is: Seminiferous tubules -> Rete testis -> Vasa efferentia -> Epididymis. Blocking vasa efferentia prevents sperm from leaving the testis to reach the epididymis.

4. Clinical Application: A patient is diagnosed with oligospermia (low sperm count). The doctor suggests checking the temperature of his scrotum. What is the biological basis? a) High scrotal temperature kills Leydig cells. b) High scrotal temperature impairs spermatogenesis in seminiferous tubules. c) Low scrotal temperature causes thickening of semen. d) Temperature does not affect sperm count. Answer: b) High scrotal temperature impairs spermatogenesis... Explanation: Human testes are located in the scrotum because sperm production requires a temperature 2-2.5°C lower than the normal internal body temperature. High heat inhibits this process.

5. Calculate: How many secondary spermatocytes and secondary oocytes are required to form 100 spermatozoa and 100 ova respectively? a) 50 Secondary Spermatocytes, 100 Secondary Oocytes. b) 100 Secondary Spermatocytes, 100 Secondary Oocytes. c) 25 Secondary Spermatocytes, 100 Secondary Oocytes. d) 50 Secondary Spermatocytes, 50 Secondary Oocytes. Answer: a) 50 Secondary Spermatocytes, 100 Secondary Oocytes. Explanation:

• 1 Secondary Spermatocyte -> 2 Spermatozoa (100 / 2 = 50).
• 1 Secondary Oocyte -> 1 Ovum (100 / 1 = 100).

6. Assertion (A): The placenta is considered a hemochorial type in humans. Reason (R): Fetal blood mixes freely with maternal blood to ensure maximum nutrient transfer. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is not the correct explanation of A. c) A is true but R is false. d) A is true, but R is false. Answer: d) A is true, but R is false. Explanation: The human placenta is "Hemochorial" (maternal blood directly bathes the fetal chorion), but the bloods never mix. They remain separated by a thin membrane to prevent immune rejection and manage pressure differences.

7. Immunology link: Why is breastfeeding recommended for the first few months of an infant's life? a) It contains higher fat content. b) It contains IgA antibodies that provide passive immunity. c) It contains IgG antibodies. d) It contains oxytocin. Answer: b) It contains IgA antibodies that provide passive immunity. Explanation: Colostrum (first milk) is rich in IgA, which coats the infant's gut lining and protects the baby from infections while its own immune system is still developing.

8. Analyze the sequence: Sequence of layers a sperm must penetrate to fertilize the ovum? a) Plasma membrane -> Zona Pellucida -> Corona Radiata b) Corona Radiata -> Zona Pellucida -> Perivitelline space -> Plasma membrane c) Zona Pellucida -> Corona Radiata -> Plasma membrane d) Perivitelline space -> Corona Radiata -> Zona Pellucida Answer: b) Corona Radiata -> Zona Pellucida -> Perivitelline space -> Plasma membrane Explanation: The sperm first hits the outer cloud of follicular cells (Corona), then the jelly-like coat (Zona), enters the gap (Perivitelline), and finally fuses with the egg's membrane.

9. Case Analysis: A woman has strictly blocked fallopian tubes. Which ART method is strictly contra-indicated? a) IVF b) ICSI c) GIFT d) Surrogacy Answer: c) GIFT Explanation: GIFT (Gamete Intrafallopian Transfer) requires the egg and sperm to be placed in the tube to fertilize naturally. If the tubes are blocked, fertilization cannot occur.

10. Reasoning: Why does the corpus luteum degenerate if fertilization does not occur? a) Due to drop in FSH. b) Due to absence of hCG signal from the trophoblast. c) Due to high Prolactin. d) Due to Oxytocin. Answer: b) Due to the absence of hCG signal from the trophoblast. Explanation: If the egg is fertilized, the embryo's trophoblast secretes hCG, which keeps the corpus luteum alive to produce progesterone. No embryo = No hCG = Corpus luteum dies (becomes corpus albicans).

11. Identify the missing link: Hypothalamus -> GnRH -> Anterior Pituitary -> ____ -> Sertoli Cells -> Spermiogenesis. a) LH b) FSH c) Testosterone d) Inhibin Answer: b) FSH Explanation: Follicle Stimulating Hormone (FSH) acts on Sertoli cells to stimulate the maturation of sperm. LH acts on Leydig cells.

12. Assertion (A): Removal of ovaries in the first trimester of pregnancy leads to abortion. Reason (R): The placenta is not yet fully developed to take over progesterone secretion. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is not the correct explanation of A. c) A is true but R is false. d) A is false but R is true. Answer: a) Both A and R are true and R is the correct explanation of A. Explanation: During the first 10-12 weeks, the Corpus Luteum in the ovary is the primary source of progesterone needed to maintain the pregnancy. The placenta takes over this role only after the first trimester.

13. Comparative Analysis: Unlike spermatogenesis, oogenesis in humans: a) Is continuous. b) Involves equal cytokinesis. c) Is initiated during the embryonic development stage. d) Produces 4 functional gametes. Answer: c) Is initiated during the embryonic development stage. Explanation: Oogenesis begins in the female fetus (millions of oogonia are formed before birth). Spermatogenesis begins only at puberty.

14. Physiology: What triggers the "fetal ejection reflex"? a) Release of oxytocin from the fetal pituitary. b) Fully developed fetus and placenta. c) High Prolactin. d) Rupture of the sac. Answer: b) Fully developed fetus and placenta. Explanation: When the fetus is fully grown, it and the placenta release signals that cause mild uterine contractions, which then trigger the mother's pituitary to release Oxytocin (the positive feedback loop).

15. Critical Thinking: If the acrosome of a sperm is damaged but the sperm is still motile, what will be the result? a) The sperm will swim faster. b) It can fertilize but fusion will be delayed. c) The sperm will be unable to penetrate the zona pellucida. d) The sperm will die. Answer: c) The sperm will be unable to penetrate the zona pellucida. Explanation: The acrosome contains hydrolytic enzymes (hyaluronidase/acrosin) needed to digest the egg's protective coats. Without these, the sperm cannot reach the egg membrane.

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Section B: Case-Study & Source-Based Questions

Case Study 1: Intense Training

A 28-year-old athlete, Sarah, has amenorrhea. Her body fat is very low. LH/FSH are low.

16. Diagnose: Primary disruption likely occurring? Answer: (c) The Hypothalamus-Pituitary Axis. Low levels of both pituitary gonadotropins (LH/FSH) and ovarian hormones suggest the "master switch" (GnRH) is turned off.

17. Connect: Link between low body fat and cessation of cycle? Answer: Adipose tissue produces the hormone Leptin. Low body fat means very low Leptin. The hypothalamus senses low energy reserves and suppresses GnRH pulses to prevent an energy-expensive pregnancy during a time of "starvation" or extreme stress.

18. Evaluate: Sarah is at high risk for bone fractures. Why? Answer: Because her ovaries are not producing Estrogen. Estrogen is crucial for maintaining bone density by inhibiting bone resorption. Lack of estrogen (hypoestrogenism) leads to premature bone thinning.

Case Study 2: Polyspermy

Researchers add sperm to oocytes in a calcium-free medium. Multiple sperm enter (polyspermy).

19. Analyze: Which event requires calcium to trigger the "slow block"? Answer: (b) Cortical reaction. Calcium influx triggers the exocytosis of cortical granules.

20. Explain: Mechanism of the Cortical Reaction? Answer: Cortical granules release enzymes into the perivitelline space. These enzymes harden the Zona Pellucida and destroy the sperm receptors (ZP3), creating a chemical and physical barrier that prevents any more sperm from binding or entering.

Case Study 3: The Placental Barrier

A woman took a teratogen drug during the 5th week of pregnancy.

21. Reason: Why is the first trimester the most critical window? Answer: Because this is the phase of Organogenesis. All major organ systems (heart, limbs, brain) are being laid down. Small disruptions in cell division or signaling at this stage lead to major structural birth defects.

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Section C: Creating, Designing & Critical Thinking

22. Creating a Flowchart: Parturition feedback. Answer: Fully Developed Fetus/Placenta -> sends signals -> Mild Uterine Contractions (Fetal Ejection Reflex) -> stimulates -> Maternal Pituitary -> releases -> Oxytocin -> causes -> Stronger Uterine Contractions -> triggers -> More Oxytocin (Positive Feedback) -> leads to -> Expulsion of Baby.

23. Formulating a Hypothesis: Declining sperm count. Answer:

• Hypothesis: Increasing environmental exposure to "Endocrine Disruptors" (e.g., Phthalates in plastics or BPA) mimics estrogen in the male body. This provides negative feedback to the hypothalamus, reducing GnRH/FSH levels and impairing spermatogenesis in the seminiferous tubules.

24. Visualizing Development: Hormones during pregnancy. Answer:

• hCG: Peaks in the first trimester (to save the corpus luteum), then drops.
• Progesterone/Estrogen: Rise steadily throughout all 9 months (produced by CL first, then the Placenta) to maintain the uterine lining and suppress contractions.

25. Scenario Analysis (Infertility): Sperm die in cervical mucus. Answer:

• Diagnosis: This is Hostile Cervical Mucus (likely immunological, where the female produces antibodies against sperm).
• Solution: IUI (Intrauterine Insemination). Bypassing the cervix by washing the sperm and placing them directly into the uterus solves the problem.

26. Argumentation: "Placenta as multiple organs." Answer:

• As a Lung: Facilitates O2/CO2 exchange via diffusion.
• As a Kidney: Removes nitrogenous wastes (Urea) from fetal blood.
• As a Liver: Stores glycogen and detoxifies some substances.
• As an Endocrine Gland: Secretes hormones (hCG, hPL, Progesterone) to manage the pregnancy.

27. Designing a Public Health Plan: Rural Menstrual Hygiene. Answer:

• Education: Explain that menstruation is a normal biological sign of health, not a "curse" or "impurity".
• Infrastructure: Install incinerators in school toilets for safe disposal of pads.
• Health Outcome: Poor hygiene leads to Reproductive Tract Infections (RTIs) and Pelvic Inflammatory Disease (PID), which can cause long-term pain and infertility.