Hormonal control of ovulation.
- The LH surge triggering ovulation is caused by:
(a) High progesterone levels
(b) Sustained high estrogen levels
(c) Low inhibin-B
(d) FSH dominance
Answer: (b) Sustained high estrogen levels
Explanation: Estrogen from the dominant follicle exerts positive feedback on the pituitary at mid-cycle, causing the LH surge (≥200 pg/ml for 50 hours). - Which hormone directly stimulates the rupture of the Graafian follicle?
(a) Progesterone
(b) Estradiol
(c) Luteinizing Hormone (LH)
(d) Follicle-Stimulating Hormone (FSH)
Answer: (c) Luteinizing Hormone (LH)
Explanation: The LH surge induces enzymatic degradation of the follicular wall and oocyte maturation. - The “positive feedback loop” in ovulation involves:
(a) Estrogen → LH
(b) Progesterone → FSH
(c) Inhibin → GnRH
(d) Prolactin → Estrogen
Answer: (a) Estrogen → LH
Explanation: High late-follicular-phase estrogen stimulates LH secretion from the anterior pituitary via hypothalamic GnRH pulse amplification. - Which cell type produces androgens under LH stimulation?
(a) Granulosa cells
(b) Theca interna cells
(c) Corpus luteum cells
(d) Oogonia
Answer: (b) Theca interna cells
Explanation: Theca cells express LH receptors and convert cholesterol to androstenedione (androgen precursor for estrogen synthesis). - Ovulation typically occurs __ hours after the LH peak:
(a) 6–8 hours
(b) 24–36 hours
(c) 48–72 hours
(d) 5–7 days
Answer: (b) 24–36 hours
Explanation: The LH surge peaks 10–12 hours before ovulation, with ovulation occurring 24–36 hours after surge onset. - The primary function of mid-cycle FSH surge is to:
(a) Trigger follicular rupture
(b) Activate plasminogen for follicle wall digestion
(c) Stimulate LH receptor expression on granulosa cells
(d) Induce resumption of oocyte meiosis
Answer: (c) Stimulate LH receptor expression on granulosa cells
Explanation: FSH induces LH receptors on granulosa cells, enabling LH responsiveness for luteinization post-ovulation. - Which hormone inhibits FSH secretion during the follicular phase?
(a) Estrogen
(b) Inhibin-B
(c) Progesterone
(d) Activin
Answer: (b) Inhibin-B
Explanation: Inhibin-B from developing follicles selectively suppresses FSH (not LH) via pituitary action. - The hypothalamic hormone initiating the ovulatory cascade is:
(a) CRH
(b) TRH
(c) GnRH
(d) Dopamine
Answer: (c) GnRH
Explanation: Gonadotropin-releasing hormone (GnRH) pulses drive pituitary FSH/LH secretion throughout the cycle. - Which event is NOT associated with the LH surge?
(a) Completion of oocyte meiosis I
(b) Progesterone surge
(c) Follicular stigma formation
(d) Endometrial gland mitosis
Answer: (d) Endometrial gland mitosis
Explanation: Endometrial proliferation is estrogen-driven in the follicular phase; post-ovulation, progesterone causes secretory changes. - The “2-cell, 2-gonadotropin” theory explains:
(a) Corpus luteum regression
(b) Estrogen biosynthesis in follicles
(c) Oocyte maturation arrest
(d) Implantation window
Answer: (b) Estrogen biosynthesis in follicles
Explanation: LH stimulates theca cells to produce androgens; FSH stimulates granulosa cells to convert androgens to estrogens via aromatase. - Anovulation in PCOS is primarily due to:
(a) Insufficient GnRH pulses
(b) Elevated progesterone in follicular phase
(c) Absent LH surge
(d) Androgen suppression of follicular development
Answer: (d) Androgen suppression of follicular development
Explanation: Hyperandrogenism in PCOS arrests follicular growth at 5–10 mm, preventing dominant follicle selection. - Which enzyme is crucial for estrogen synthesis in granulosa cells?
(a) 5α-reductase
(b) Aromatase (CYP19)
(c) 17α-hydroxylase
(d) Cholesterol desmolase
Answer: (b) Aromatase (CYP19)
Explanation: Aromatase converts androstenedione/testosterone to estrone/estradiol, requiring FSH stimulation. - Ovulation prediction kits detect urinary surge of:
(a) Estradiol
(b) FSH
(c) LH
(d) Progesterone
Answer: (c) LH
Explanation: Urinary LH surge precedes ovulation by 24–48 hours, making it a reliable predictor. - The dominant follicle is selected on cycle day:
(a) 1–3
(b) 5–7
(c) 10–12
(d) 14–16
Answer: (b) 5–7
Explanation: By days 5–7, one follicle becomes FSH-responsive while others undergo atresia due to declining FSH. - Luteinization of granulosa cells post-ovulation requires:
(a) Suppression of inhibin
(b) Downregulation of FSH receptors
(c) LH-induced expression of steroidogenic enzymes
(d) Estrogen withdrawal
Answer: (c) LH-induced expression of steroidogenic enzymes
Explanation: LH upregulates P450scc and 3β-HSD in granulosa cells, enabling progesterone production in the corpus luteum. - Which hormone maintains the viability of the corpus luteum?
(a) hCG
(b) Prolactin
(c) Oxytocin
(d) Relaxin
Answer: (a) hCG
Explanation: In pregnancy, hCG from the blastocyst rescues the corpus luteum by mimicking LH action. - The “critical follicle size” for ovulation competence is:
(a) 5–8 mm
(b) 10–12 mm
(c) 18–25 mm
(d) 30–35 mm
Answer: (c) 18–25 mm
Explanation: Follicles must reach ~20 mm diameter to respond to the LH surge and ovulate. - Which factor induces meiotic resumption in the oocyte?
(a) Estrogen peak
(b) Progesterone surge
(c) LH-dependent MPF activation
(d) FSH-induced cAMP elevation
Answer: (c) LH-dependent MPF activation
Explanation: LH surge inhibits oocyte cAMP, activating Maturation Promoting Factor (MPF) to resume meiosis from prophase I. - Failure of positive feedback in menopause results from:
(a) Excess GnRH
(b) Loss of antral follicles
(c) Progesterone deficiency
(d) Inhibin excess
Answer: (b) Loss of antral follicles
Explanation: Ovarian follicle depletion eliminates estrogen production, preventing positive feedback and LH surges. - Kisspeptin neurons regulate ovulation by:
(a) Inhibiting prolactin release
(b) Stimulating GnRH pulse generator
(c) Directly suppressing FSH
(d) Degrading progesterone
Answer: (b) Stimulating GnRH pulse generator
Explanation: Kisspeptin from hypothalamic arcuate neurons is the primary activator of GnRH secretion. - Which contraceptive method prevents ovulation by suppressing mid-cycle LH surge?
(a) Copper IUD
(b) Combined oral pills
(c) Barrier methods
(d) Progestin-only pills
Answer: (b) Combined oral pills
Explanation: Ethinyl estradiol + progestin in COCPs suppress FSH/LH via negative feedback, inhibiting follicular development and LH surge. - The “luteal-placental shift” occurs at ~8 weeks when:
(a) Corpus luteum regresses
(b) Placenta becomes primary progesterone source
(c) Estrogen levels decline
(d) FSH surges resume
Answer: (b) Placenta becomes primary progesterone source
Explanation: Placental steroidogenesis supersedes corpus luteum function by week 8–10 of gestation. - Which hormone shows the earliest rise in the menstrual cycle?
(a) Estradiol
(b) Progesterone
(c) FSH
(d) LH
Answer: (c) FSH
Explanation: FSH rises in the late luteal/early follicular phase to recruit the next cohort of follicles. - Anovulation due to hyperprolactinemia results from:
(a) Direct inhibition of granulosa cells
(b) Suppression of hypothalamic GnRH
(c) Accelerated follicular atresia
(d) LH receptor downregulation
Answer: (b) Suppression of hypothalamic GnRH
Explanation: Elevated prolactin inhibits kisspeptin/GnRH pulse frequency via dopamine activation. - After ovulation, the collapsed follicle differentiates into corpus luteum under the influence of:
(a) FSH
(b) LH
(c) Estrogen
(d) Activin
Answer: (b) LH
Explanation: LH induces vascularization and luteinization of granulosa/theca cells to form progesterone-secreting corpus luteum.
Physiology of implanation,
- The “window of implantation” refers to the period when:
(a) Endometrium is maximally thick
(b) Progesterone levels peak
(c) Endometrium is receptive to blastocyst
(d) hCG secretion begins
Answer: (c) Endometrium is receptive to blastocyst
Explanation: A 4–6 day period (days 20–24 of cycle) when progesterone-primed endometrium expresses adhesion molecules (integrins, selectins) for blastocyst attachment. - Which hormone is CRITICAL for maintaining endometrial receptivity?
(a) Estrogen
(b) Progesterone
(c) FSH
(d) Prolactin
Answer: (b) Progesterone
Explanation: Progesterone induces endometrial stromal decidualization and glandular secretion essential for implantation. - The first step of implantation is:
(a) Trophoblast invasion
(b) Zona pellucida dissolution
(c) Apposition
(d) Syncytiotrophoblast formation
Answer: (c) Apposition
Explanation: Initial unstable contact between blastocyst and endometrial epithelium, mediated by L-selectin–trophoblast interactions. - hCG secretion begins:
(a) Before implantation
(b) During blastocyst adhesion
(c) After trophoblast invasion
(d) At gastrulation
Answer: (b) During blastocyst adhesion
Explanation: Trophoblasts secrete hCG upon contact with endometrium (day 7–8 post-fertilization), rescuing the corpus luteum. - Decidualization refers to:
(a) Oocyte maturation
(b) Endometrial stromal cell transformation
(c) Trophoblast differentiation
(d) Zygote cleavage
Answer: (b) Endometrial stromal cell transformation
Explanation: Progesterone-driven conversion of stromal fibroblasts to nutrient-rich decidual cells expressing IGFBP1 and prolactin. - Which molecule mediates blastocyst ADHESION to endometrium?
(a) Fibronectin
(b) Integrin αvβ3
(c) MMP-2
(d) Caspase-3
Answer: (b) Integrin αvβ3
Explanation: Expressed on endometrium during receptivity; binds osteopontin on trophoblast for stable attachment. - Trophoblast invasion into endometrium requires:
(a) Increased E-cadherin
(b) Matrix metalloproteinases (MMPs)
(c) Prostaglandin inhibition
(d) Estrogen surge
Answer: (b) Matrix metalloproteinases (MMPs)
Explanation: MMP-2/9 degrade endometrial extracellular matrix, enabling cytotrophoblast invasion. - The embryonic pole of blastocyst:
(a) Faces the endometrial lumen
(b) Contacts endometrium first
(c) Forms extraembryonic membranes
(d) Develops into placenta
Answer: (b) Contacts endometrium first
Explanation: The inner cell mass (embryonic pole) orients toward endometrium for implantation. - Which cytokine is crucial for maternal immune tolerance?
(a) IFN-γ
(b) TGF-β
(c) IL-2
(d) TNF-α
Answer: (b) TGF-β
Explanation: Suppresses T-cell responses and promotes regulatory T-cells to prevent fetal rejection. - Ectopic implantation most commonly occurs in:
(a) Ovary
(b) Cervix
(c) Fallopian tube
(d) Abdominal cavity
Answer: (c) Fallopian tube
Explanation: 95% of ectopic pregnancies implant in the ampullary region of fallopian tubes. - hCG prevents luteolysis by mimicking:
(a) FSH
(b) LH
(c) Progesterone
(d) Estrogen
Answer: (b) LH
Explanation: hCG binds LH receptors on corpus luteum, sustaining progesterone production until placental takeover (week 10). - Endometrial pinopodes are:
(a) Ciliated epithelial projections
(b) Apical protrusions for blastocyst uptake
(c) Immune cells
(d) Vascular structures
Answer: (b) Apical protrusions for blastocyst uptake
Explanation: Progesterone-induced pinopodes (days 20–21) absorb uterine fluid to facilitate blastocyst-endometrium contact. - Syncytiotrophoblast functions include all EXCEPT:
(a) hCG production
(b) Endometrial invasion
(c) Nutrient transport
(d) Embryonic organogenesis
Answer: (d) Embryonic organogenesis
Explanation: Syncytiotrophoblast handles implantation/hormones; organogenesis occurs in the embryonic disc. - Implantation completes when:
(a) Blastocyst hatches
(b) Trophoblast penetrates basal lamina
(c) Decidual reaction occurs
(d) hCG is detected
Answer: (b) Trophoblast penetrates basal lamina
Explanation: Invasion through endometrial epithelium and basal lamina embeds blastocyst by day 9–10. - Which factor prevents polyspermy but MUST be removed for implantation?
(a) Corona radiata
(b) Zona pellucida
(c) Cortical granules
(d) Acrosomal enzymes
Answer: (b) Zona pellucida
Explanation: Blastocyst “hatches” from zona pellucida (day 5) via proteases (e.g., strypsin) to implant. - Decidual NK cells promote implantation by:
(a) Killing trophoblasts
(b) Secreting angiogenic factors
(c) Producing progesterone
(d) Degrading MMPs
Answer: (b) Secreting angiogenic factors
Explanation: dNK cells release VEGF and angiopoietins to remodel spiral arteries for placental blood flow. - The “implantation bleed” occurs due to:
(a) Trophoblast erosion of capillaries
(b) Progesterone withdrawal
(c) Endometrial sloughing
(d) Ovarian rupture
Answer: (a) Trophoblast erosion of capillaries
Explanation: Minor bleeding when syncytiotrophoblasts invade endometrial vessels (day 20–24 cycle). - Which gene mutation causes implantation failure?
(a) BRCA1
(b) HOXA10
(c) CFTR
(d) SRY
Answer: (b) HOXA10
Explanation: HOXA10 (a homeobox gene) regulates endometrial receptivity; mutations cause subfertility. - Optimal embryo transfer timing in IVF targets:
(a) Proliferative phase
(b) Window of implantation
(c) Luteal regression
(d) Menstruation
Answer: (b) Window of implantation
Explanation: Embryos transferred on cycle days 19–21 to coincide with endometrial receptivity. - Leptin’s role in implantation includes:
(a) Inhibiting trophoblast invasion
(b) Promoting endometrial angiogenesis
(c) Suppressing integrin expression
(d) Degrading pinopodes
Answer: (b) Promoting endometrial angiogenesis
Explanation: Leptin upregulates VEGF and MMP-9, enhancing vascular remodeling for implantation. - Trophoblast differentiation into syncytiotrophoblast is driven by:
(a) Fusion of cytotrophoblast cells
(b) Endometrial TGF-β
(c) Estrogen stimulation
(d) hCG feedback
Answer: (a) Fusion of cytotrophoblast cells
Explanation: Cytotrophoblasts fuse under transcriptional control (e.g., syncytin-1) to form multinucleated syncytiotrophoblast. - Immunohistochemical marker of endometrial receptivity:
(a) Ki-67
(b) β-catenin
(c) αvβ3 integrin
(d) p53
Answer: (c) αvβ3 integrin
Explanation: Absence of αvβ3 integrin correlates with implantation failure; key adhesion molecule. - Implantation requires embryo to be at:
(a) Zygote stage
(b) Morula stage
(c) Blastocyst stage
(d) Gastrula stage
Answer: (c) Blastocyst stage
Explanation: Blastocyst (day 5) has differentiated trophectoderm for implantation and inner cell mass for embryo. - Which prostaglandin facilitates implantation?
(a) PGE1
(b) PGF2α
(c) Thromboxane A2
(d) Prostacyclin
Answer: (d) Prostacyclin
Explanation: PGI₂ promotes vasodilation and angiogenesis at implantation site via cAMP. - Primary cause of recurrent implantation failure:
(a) Low FSH
(b) Endometrial asynchrony
(c) High hCG
(d) Estrogen deficiency
Answer: (b) Endometrial asynchrony
Explanation: 80% of cases involve disrupted molecular receptivity (e.g., integrin defects, progesterone resistance).
Hormonal control of preganancy and lactation,
- The hormone detected by pregnancy tests is:
(a) Progesterone
(b) hPL
(c) hCG
(d) Relaxin
Answer: (c) hCG
Explanation: hCG (human chorionic gonadotropin) is secreted by syncytiotrophoblast cells 6–8 days post-fertilization. Its β-subunit is detected in urine/blood pregnancy tests. - Which hormone maintains the corpus luteum until 8–10 weeks of gestation?
(a) Progesterone
(b) Estrogen
(c) hCG
(d) hPL
Answer: (c) hCG
Explanation: hCG mimics LH, rescuing the corpus luteum to sustain progesterone/estrogen secretion until placental takeover. - Human Placental Lactogen (hPL) primarily antagonizes:
(a) Prolactin
(b) Glucagon
(c) Insulin
(d) Thyroxine
Answer: (c) Insulin
Explanation: hPL induces maternal insulin resistance to redirect glucose to the fetus, increasing the risk of gestational diabetes. - The “progesterone block” during pregnancy prevents:
(a) Implantation
(b) Uterine contractions
(c) Fetal organogenesis
(d) Ovulation
Answer: (b) Uterine contractions
Explanation: Progesterone suppresses myometrial gap junctions and oxytocin receptors, inhibiting contractions until labor. - Which hormone stimulates mammary duct development?
(a) Progesterone
(b) Estrogen
(c) hPL
(d) Relaxin
Answer: (b) Estrogen
Explanation: Estrogen promotes ductal branching; progesterone induces lobuloalveolar growth for milk production. - Milk ejection reflex is mediated by:
(a) Prolactin
(b) Oxytocin
(c) Dopamine
(d) Cortisol
Answer: (b) Oxytocin
Explanation: Oxytocin causes myoepithelial cell contraction in breasts, ejecting milk in response to suckling. - Elevated relaxin in pregnancy causes:
(a) Uterine hypertrophy
(b) Pelvic ligament relaxation
(c) Milk synthesis
(d) Fetal lung maturation
Answer: (b) Pelvic ligament relaxation
Explanation: Relaxin softens the cervix and pubic symphysis for parturition via collagen remodeling. - Prolactin secretion is inhibited by:
(a) TRH
(b) Dopamine
(c) Serotonin
(d) Estrogen
Answer: (b) Dopamine
Explanation: Hypothalamic dopamine (Prolactin-Inhibiting Factor) tonically suppresses prolactin release. - Which hormone spikes to initiate labor?
(a) Progesterone
(b) Estrogen
(c) Cortisol
(d) hCG
Answer: (b) Estrogen
Explanation: Late-pregnancy estrogen surge upregulates oxytocin receptors and prostaglandins, triggering contractions. - hPL is structurally similar to:
(a) Growth hormone
(b) Prolactin
(c) ACTH
(d) FSH
Answer: (a) Growth hormone
Explanation: hPL shares 96% homology with GH, explaining its lipolytic and anti-insulin effects. - Ferguson reflex during labor involves:
(a) Cervical stretch → oxytocin release
(b) Suckling → prolactin release
(c) Stress → cortisol surge
(d) Hypoglycemia → glucagon release
Answer: (a) Cervical stretch → oxytocin release
Explanation: Cervical dilation stimulates a neuroendocrine reflex, amplifying oxytocin for stronger contractions. - Surfactant synthesis in fetal lungs is enhanced by:
(a) Thyroxine
(b) Cortisol
(c) Insulin
(d) Estrogen
Answer: (b) Cortisol
Explanation: Glucocorticoids induce surfactant protein production via type II pneumocytes, preventing RDS. - The “lactogenesis II” phase requires:
(a) Progesterone withdrawal
(b) Estrogen surge
(c) hCG elevation
(d) FSH suppression
Answer: (a) Progesterone withdrawal
Explanation: Postpartum progesterone drop removes inhibition on prolactin, enabling milk secretion. - Which hormone regulates maternal calcium absorption for fetal skeletal development?
(a) Parathyroid hormone
(b) Calcitriol
(c) Calcitonin
(d) Thyroxine
Answer: (b) Calcitriol
Explanation: Placental 1α-hydroxylase increases active vitamin D (calcitriol), boosting intestinal calcium absorption. - Galactorrhea in non-pregnant women indicates hyperprolactinemia due to:
(a) Pituitary adenoma
(b) Adrenal insufficiency
(c) Hypothyroidism
(d) Ovarian failure
Answer: (a) Pituitary adenoma
Explanation: Prolactinomas (most common pituitary adenomas) cause inappropriate milk production and amenorrhea. - Progesterone synthesis in late pregnancy shifts from:
(a) Corpus luteum to placenta
(b) Placenta to fetal adrenals
(c) Maternal adrenals to ovaries
(d) Fetal liver to placenta
Answer: (a) Corpus luteum to placenta
Explanation: Placental syncytiotrophoblasts take over progesterone synthesis after 8–10 weeks (“luteoplacental shift”). - Colostrum differs from mature milk in having higher:
(a) Lactose
(b) Immunoglobulin A
(c) Lipids
(d) Water content
Answer: (b) Immunoglobulin A
Explanation: Colostrum is IgA-rich for passive immunity, with less fat/lactose than mature milk. - The hormone suppressing ovulation during lactation:
(a) Oxytocin
(b) Prolactin
(c) Estrogen
(d) hPL
Answer: (b) Prolactin
Explanation: High prolactin inhibits GnRH pulses, causing lactational amenorrhea (98% contraceptive efficacy if exclusive breastfeeding). - Which hormone increases maternal blood volume by 50%?
(a) Aldosterone
(b) Renin
(c) Erythropoietin
(d) hCG
Answer: (a) Aldosterone
Explanation: RAAS activation and placental CRH stimulate aldosterone, increasing plasma volume for uteroplacental perfusion. - Failure of milk ejection despite prolactin elevation indicates deficiency in:
(a) Dopamine
(b) Oxytocin
(c) Cortisol
(d) Progesterone
Answer: (b) Oxytocin
Explanation: Prolactin drives milk production; oxytocin is needed for milk ejection via myoepithelial contraction. - Placental CRH in late pregnancy:
(a) Suppresses fetal ACTH
(b) Induces uterine quiescence
(c) Triggers fetal cortisol surge
(d) Inhibits surfactant synthesis
Answer: (c) Triggers fetal cortisol surge
Explanation: Placental CRH stimulates fetal HPA axis, increasing cortisol for lung maturation and labor initiation. - Postpartum breast engorgement is caused by:
(a) Prolactin excess
(b) Oxytocin deficiency
(c) Vascular congestion
(d) Ductal obstruction
Answer: (c) Vascular congestion
Explanation: Sudden progesterone withdrawal causes vascular/lymphatic dilation before milk production stabilizes. - Hormonal basis of morning sickness:
(a) High hCG
(b) Low progesterone
(c) Estrogen deficiency
(d) Cortisol excess
Answer: (a) High hCG
Explanation: hCG peaks at 8–12 weeks, coinciding with nausea via stimulation of medullary chemoreceptor trigger zone. - Prolactin secretion is stimulated by:
(a) Suckling
(b) Dopamine agonists
(c) Bromocriptine
(d) Thyroxine
Answer: (a) Suckling
Explanation: Nipple stimulation suppresses dopamine and releases TRH/Serotonin, increasing prolactin. - Key hormone for cervical ripening in labor:
(a) Progesterone
(b) Prostaglandin F2α
(c) Relaxin
(d) Inhibin
Answer: (b) Prostaglandin F2α
Explanation: PGF2α softens the cervix via collagenase activation and water retention, facilitating dilation.
Spermatogenesis and its hormonal control.
- Which cell type directly stimulates Leydig cells to produce testosterone?
(a) Sertoli cells
(b) Spermatogonia
(c) Pituitary gonadotrophs
(d) Hypothalamic neurons
Answer: (c) Pituitary gonadotrophs
Explanation: Gonadotrophs in the anterior pituitary secrete Luteinizing Hormone (LH), which binds to Leydig cell receptors to trigger testosterone synthesis. - Androgen-Binding Protein (ABP) is produced by:
(a) Leydig cells
(b) Spermatocytes
(c) Sertoli cells
(d) Spermatids
Answer: (c) Sertoli cells
Explanation: Sertoli cells produce ABP under FSH stimulation, concentrating testosterone in seminiferous tubules to support spermatogenesis. - The primary role of FSH in spermatogenesis is:
(a) Stimulating testosterone secretion
(b) Inducing meiosis in spermatocytes
(c) Supporting Sertoli cell function
(d) Promoting spermiation
Answer: (c) Supporting Sertoli cell function
Explanation: FSH acts on Sertoli cells to promote nutrient supply, waste removal, and ABP synthesis, creating a microenvironment for germ cell development. - The blood-testis barrier is formed by:
(a) Tight junctions between Sertoli cells
(b) Basement membrane of seminiferous tubules
(c) Capillary endothelium
(d) Leydig cell processes
Answer: (a) Tight junctions between Sertoli cells
Explanation: Sertoli cells form tight junctions that compartmentalize the adluminal space, isolating developing germ cells from the immune system. - Which hormone exerts negative feedback on FSH secretion?
(a) Testosterone
(b) Inhibin-B
(c) Estradiol
(d) DHT
Answer: (b) Inhibin-B
Explanation: Inhibin-B, secreted by Sertoli cells, selectively suppresses FSH release via pituitary feedback. - Spermiogenesis involves:
(a) Mitotic division of spermatogonia
(b) Meiotic reduction division
(c) Transformation of spermatids to spermatozoa
(d) Spermiation into rete testis
Answer: (c) Transformation of spermatids to spermatozoa
Explanation: Spermiogenesis is the metamorphosis of round spermatids into motile sperm (acrosome formation, flagellum development). - The haploid cell formed after meiosis I is:
(a) Spermatogonium
(b) Primary spermatocyte
(c) Secondary spermatocyte
(d) Spermatid
Answer: (c) Secondary spermatocyte
Explanation: Meiosis I reduces diploid primary spermatocytes to haploid secondary spermatocytes. - Cryptorchidism impairs spermatogenesis primarily due to:
(a) Low FSH
(b) High scrotal temperature
(c) Androgen deficiency
(d) Absent inhibin
Answer: (b) High scrotal temperature
Explanation: Undescended testes experience core body temperature (37°C), disrupting enzyme activity critical for spermatogenesis (optimal at 34–35°C). - Testosterone synthesis in Leydig cells requires:
(a) FSH receptors
(b) LH receptors
(c) Inhibin receptors
(d) Estrogen receptors
Answer: (b) LH receptors
Explanation: LH binds G-protein-coupled receptors on Leydig cells, activating the cAMP-PKA pathway for testosterone production. - Which cell is diploid?
(a) Spermatid
(b) Secondary spermatocyte
(c) Spermatogonium
(d) Spermatozoon
Answer: (c) Spermatogonium
Explanation: Spermatogonia are diploid (2n) stem cells that undergo mitosis to maintain the germ cell pool. - Estradiol in males is derived from:
(a) Direct secretion by Leydig cells
(b) Aromatization of testosterone
(c) Sertoli cell metabolism
(d) Adrenal cortex
Answer: (b) Aromatization of testosterone
Explanation: Aromatase enzyme in Sertoli/adipose cells converts testosterone to estradiol, regulating gonadotropin release and bone health. - GnRH pulses from the hypothalamus:
(a) Directly stimulate spermatogenesis
(b) Inhibit prolactin release
(c) Trigger FSH/LH secretion
(d) Promote testosterone synthesis
Answer: (c) Trigger FSH/LH secretion
Explanation: GnRH acts on pituitary gonadotrophs to release FSH and LH in a pulsatile manner. - Which structure is shed during spermiation?
(a) Acrosome
(b) Flagellum
(c) Residual cytoplasm
(d) Mitochondrial sheath
Answer: (c) Residual cytoplasm
Explanation: Spermiation releases spermatozoa into the lumen after discarding excess cytoplasm via Sertoli cell phagocytosis. - Seasonal breeders like deer show active spermatogenesis in winter due to:
(a) Increased melatonin
(b) Reduced prolactin
(c) Elevated TSH
(d) Low cortisol
Answer: (a) Increased melatonin
Explanation: Melatonin (from pineal gland) stimulates GnRH release in response to short photoperiods (winter), activating reproduction. - Duration of spermatogenesis in humans is:
(a) ~24 days
(b) ~48 days
(c) ~64 days
(d) ~90 days
Answer: (c) ~64 days
Explanation: From spermatogonia to spermatozoa takes ~64 days, including mitosis, meiosis, and spermiogenesis. - Sertoli cells support germ cells by secreting all EXCEPT:
(a) Transferrin
(b) Anti-Müllerian Hormone (AMH)
(c) Testosterone
(d) Activin
Answer: (c) Testosterone
Explanation: Testosterone is produced by Leydig cells; Sertoli cells secrete ABP, AMH, inhibin, growth factors, and nutrients. - Kallmann syndrome causes infertility due to:
(a) Defective Sertoli cells
(b) Absent GnRH secretion
(c) Androgen receptor mutation
(d) 5α-reductase deficiency
Answer: (b) Absent GnRH secretion
Explanation: Kallmann syndrome (X-linked) involves impaired GnRH neuron migration, leading to low FSH/LH and arrested spermatogenesis. - Negative feedback on LH secretion is mediated by:
(a) Inhibin-B
(b) Estradiol
(c) Testosterone
(d) Both (b) and (c)
Answer: (d) Both (b) and (c)
Explanation: Testosterone (via androgen receptors) and estradiol (from aromatization) suppress hypothalamic GnRH and pituitary LH. - The role of the epididymis in sperm maturation includes:
(a) Capacitation
(b) Acrosome reaction
(c) Motility acquisition
(d) Meiotic division
Answer: (c) Motility acquisition
Explanation: Sperm gain motility and fertilization capacity during epididymal transit via protein modifications. - Spermatogonial stem cells express:
(a) c-Kit receptor
(b) FSHR
(c) LHR
(d) Aromatase
Answer: (a) c-Kit receptor
Explanation: c-Kit binds stem cell factor (from Sertoli cells), promoting spermatogonial self-renewal and differentiation. - Hormonal contraceptive for males targets:
(a) Testosterone + GnRH
(b) Testosterone + FSH
(c) Progesterone + estrogen
(d) Cortisol + prolactin
Answer: (a) Testosterone + GnRH
Explanation: Exogenous testosterone suppresses GnRH/FSH/LH, while GnRH analogs block endogenous pulses, halting spermatogenesis. - Spermatogenesis requires intratesticular testosterone at levels:
(a) Equal to serum
(b) 20–50× higher than serum
(c) 100× lower than serum
(d) Undetectable
Answer: (b) 20–50× higher than serum
Explanation: ABP concentrates testosterone in tubules at 20–50× serum levels, essential for meiosis and spermiogenesis. - Which enzyme converts testosterone to DHT in male reproductive tissues?
(a) Aromatase
(b) 5α-reductase
(c) 17β-HSD
(d) CYP17
Answer: (b) 5α-reductase
Explanation: 5α-reductase in prostate, skin, and genitalia produces potent DHT for external masculinization. - Varicocele-induced infertility involves:
(a) Oxidative stress in testes
(b) Low inhibin-B
(c) Elevated FSH
(d) All of the above
Answer: (d) All of the above
Explanation: Varicocele increases testicular temperature/ROS, reduces inhibin-B, and elevates FSH due to impaired spermatogenesis. - Complete spermatogenesis failure occurs in:
(a) Sertoli-cell-only syndrome
(b) Klinefelter syndrome
(c) Both (a) and (b)
(d) Kallmann syndrome
Answer: (c) Both (a) and (b)
Explanation:
- Sertoli-cell-only syndrome: Absent germ cells.
- Klinefelter syndrome (47,XXY): Hyalinized tubules and Leydig cell hyperplasia.
Both cause azoospermia.
Oogenesis and its hormonal control
- Oogenesis begins in females during:
(a) Puberty
(b) Fetal life
(c) Menarche
(d) Adulthood
Answer: (b) Fetal life
Explanation: Oogonia multiply by mitosis in the fetal ovary and become primary oocytes, which arrest in prophase I before birth. - The primary oocyte completes meiosis I just:
(a) Before birth
(b) At puberty
(c) Before ovulation
(d) After fertilization
Answer: (c) Before ovulation
Explanation: The LH surge triggers resumption of meiosis I just prior to ovulation, producing a secondary oocyte and the first polar body. - Which hormone directly triggers ovulation?
(a) FSH
(b) Estrogen
(c) LH
(d) Progesterone
Answer: (c) LH
Explanation: The LH surge causes rupture of the mature follicle and release of the secondary oocyte. - The granulosa cells of developing follicles produce:
(a) Testosterone
(b) Androstenedione
(c) Inhibin B
(d) LH
Answer: (c) Inhibin B
Explanation: Inhibin B is secreted by granulosa cells and inhibits FSH release through negative feedback. - The “zona pellucida” is synthesized by:
(a) Theca cells
(b) Oocyte itself
(c) Granulosa cells
(d) Corpus luteum
Answer: (b) Oocyte itself
Explanation: The oocyte produces glycoproteins (ZP1–ZP4) that form the zona pellucida, critical for sperm binding. - Meiosis II in oogenesis is completed:
(a) At ovulation
(b) After sperm penetration
(c) During follicular maturation
(d) At implantation
Answer: (b) After sperm penetration
Explanation: The secondary oocyte completes meiosis II only after fertilization occurs. - Dominant follicle selection occurs due to:
(a) Low FSH
(b) High LH
(c) Androgen dominance
(d) Estrogen feedback
Answer: (a) Low FSH
Explanation: The follicle with the highest FSH receptor sensitivity continues growing as FSH levels decline. - The corpus luteum primarily secretes:
(a) Estrogen and inhibin
(b) Progesterone and estrogen
(c) FSH and LH
(d) hCG and relaxin
Answer: (b) Progesterone and estrogen
Explanation: These hormones maintain the endometrium and support early pregnancy. - Antrum formation begins in the:
(a) Primordial follicle
(b) Primary follicle
(c) Secondary follicle
(d) Graafian follicle
Answer: (c) Secondary follicle
Explanation: Granulosa cells secrete fluid forming the antrum during the secondary follicle stage. - Positive feedback for the LH surge is mediated by:
(a) Low progesterone
(b) Sustained high estrogen
(c) Inhibin A
(d) Activin
Answer: (b) Sustained high estrogen
Explanation: High estrogen levels trigger positive feedback on the hypothalamus and pituitary, causing the LH surge. - The first polar body:
(a) Undergoes meiosis II
(b) Degenerates
(c) Is fertilized
(d) Forms the corpus luteum
Answer: (b) Degenerates
Explanation: The first polar body typically degenerates without dividing further. - Primordial follicles are arrested in:
(a) Prophase I
(b) Metaphase I
(c) Prophase II
(d) Metaphase II
Answer: (a) Prophase I
Explanation: Primary oocytes arrest in diplotene of prophase I until ovulation resumes meiosis. - Which hormone induces endometrial proliferation?
(a) Progesterone
(b) Estrogen
(c) LH
(d) Inhibin
Answer: (b) Estrogen
Explanation: Estrogen promotes thickening of the endometrium during the follicular phase. - Atresia affects:
(a) Only primordial follicles
(b) Dominant follicles
(c) All follicle stages except the dominant one
(d) Only corpus luteum
Answer: (c) All follicle stages except the dominant one
Explanation: Most follicles degenerate via atresia; only the dominant follicle survives to ovulate. - Menopause results from:
(a) Uterine aging
(b) Ovarian follicle depletion
(c) Pituitary failure
(d) Hypothalamic dysfunction
Answer: (b) Ovarian follicle depletion
Explanation: Depletion of follicles leads to loss of estrogen and increased FSH levels, resulting in menopause. - Theca interna cells produce:
(a) Progesterone
(b) Androgens
(c) Estradiol
(d) Inhibin
Answer: (b) Androgens
Explanation: Under LH influence, theca interna cells synthesize androgens for estrogen production by granulosa cells. - In PCOS, arrested follicular development is due to:
(a) Low LH
(b) High FSH
(c) Hyperandrogenism
(d) Estrogen deficiency
Answer: (c) Hyperandrogenism
Explanation: Excess androgens interfere with normal follicular development, causing cyst formation. - The “luteal-placental shift” occurs at:
(a) 4 weeks
(b) 8 weeks
(c) 12 weeks
(d) 20 weeks
Answer: (b) 8 weeks
Explanation: Around 8–10 weeks, the placenta takes over hormone production from the corpus luteum. - Ovulation occurs on day ___ of a 28-day cycle:
(a) 7
(b) 14
(c) 21
(d) 28
Answer: (b) 14
Explanation: In a 28-day cycle, ovulation typically occurs on day 14 after the LH surge. - Cumulus oophorus refers to:
(a) Theca cell layer
(b) Granulosa cells surrounding the oocyte
(c) Antral fluid
(d) Corpus albicans
Answer: (b) Granulosa cells surrounding the oocyte
Explanation: These granulosa cells help in oocyte release and transport during ovulation. - After ovulation, the ruptured follicle transforms into the corpus luteum under:
(a) FSH stimulation
(b) LH stimulation
(c) Estrogen withdrawal
(d) Progesterone surge
Answer: (b) LH stimulation
Explanation: LH triggers luteinization of follicular cells, forming the hormone-secreting corpus luteum. - Estrogen synthesis in follicles follows the:
(a) 1-cell, 1-gonadotropin model
(b) 2-cell, 2-gonadotropin model
(c) 3-cell model
(d) Autocrine model
Answer: (b) 2-cell, 2-gonadotropin model
Explanation: Theca cells (LH-sensitive) make androgens; granulosa cells (FSH-sensitive) convert them to estrogens. - Which hormone rescues the corpus luteum in pregnancy?
(a) Prolactin
(b) hPL
(c) hCG
(d) Relaxin
Answer: (c) hCG
Explanation: hCG maintains the corpus luteum during early pregnancy until the placenta takes over. - Primordial follicle activation requires:
(a) FSH
(b) AMH
(c) Kit ligand
(d) LH
Answer: (c) Kit ligand
Explanation: Kit ligand from granulosa cells binds to c-Kit receptors on oocytes, initiating follicle development. - Ovarian cycle events in correct sequence:
(a) Follicular → Luteal → Ovulation
(b) Luteal → Follicular → Ovulation
(c) Follicular → Ovulation → Luteal
(d) Ovulation → Follicular → Luteal
Answer: (c) Follicular → Ovulation → Luteal
Explanation:
- Follicular phase: Follicle matures (days 1–14)
- Ovulation: Oocyte release (~day 14)
- Luteal phase: Corpus luteum functions (days 15–28)
Control of fertility and population
- CuT 380A is a:
(a) Hormonal implant
(b) Non-hormonal IUD
(c) Oral contraceptive
(d) Barrier device
Answer: (b) Non-hormonal IUD
Explanation: CuT 380A releases copper ions that impair sperm motility and fertilization. It is effective for 10 years and does not contain hormones. - The primary mechanism of combined oral contraceptive pills (COCPs) is:
(a) Inducing anovulation
(b) Thickening cervical mucus
(c) Preventing implantation
(d) Inhibiting spermatogenesis
Answer: (a) Inducing anovulation
Explanation: COCPs (estrogen + progestin) suppress GnRH, inhibiting FSH/LH and preventing follicular development/ovulation. - “Saheli” is a:
(a) Weekly oral contraceptive
(b) Copper IUD
(c) Injectable contraceptive
(d) Emergency pill
Answer: (a) Weekly oral contraceptive
Explanation: Saheli (centchroman) is a non-steroidal, once-a-week pill developed in India. It acts as an estrogen receptor modulator. - The most effective permanent method of population control is:
(a) Vasectomy
(b) Tubectomy
(c) Lactational amenorrhea
(d) Condoms
Answer: (a) Vasectomy and (b) Tubectomy
Explanation: Vasectomy (male) and tubectomy (female) are surgical sterilization methods with >99% efficacy. - MTP is legal in India up to how many weeks?
(a) 12 weeks
(b) 20 weeks
(c) 24 weeks
(d) 28 weeks
Answer: (b) 20 weeks
Explanation: The Medical Termination of Pregnancy Act permits abortion until 20 weeks; up to 24 weeks under special cases (e.g., rape, fetal anomalies). - Progesterone-only pills (POPs) prevent pregnancy by:
(a) Inhibiting ovulation
(b) Thickening cervical mucus
(c) Both (a) and (b)
(d) Inducing endometrial atrophy
Answer: (c) Both (a) and (b)
Explanation: POPs primarily thicken cervical mucus and may suppress ovulation in a significant number of cycles. - Which contraceptive method also protects against HIV?
(a) Copper IUD
(b) Oral pills
(c) Male condom
(d) Diaphragm
Answer: (c) Male condom
Explanation: Male latex condoms provide a barrier that protects against HIV and other STIs, along with preventing pregnancy. - The “Two-Child Norm” in India aims to:
(a) Promote adoption
(b) Disqualify candidates with >2 children from panchayat elections
(c) Provide tax benefits
(d) Increase ART access
Answer: (b) Disqualify candidates with >2 children from panchayat elections
Explanation: Implemented in states like Rajasthan and Haryana to encourage smaller families in local government. - Injectables like Depo-Provera contain:
(a) Estrogen
(b) Progestin
(c) FSH
(d) GnRH
Answer: (b) Progestin
Explanation: Depo-Provera (medroxyprogesterone acetate) is a long-acting intramuscular progestin injection. - IVF involves fertilization:
(a) In the fallopian tube
(b) In a laboratory dish
(c) In the uterus
(d) In the ovary
Answer: (b) In a laboratory dish
Explanation: In Vitro Fertilization occurs outside the body; embryos are transferred to the uterus later. - Emergency contraception (morning-after pill) primarily:
(a) Aborts an implanted embryo
(b) Prevents fertilization or ovulation
(c) Causes uterine contractions
(d) Kills sperm
Answer: (b) Prevents fertilization or ovulation
Explanation: Pills like levonorgestrel delay ovulation or prevent fertilization when taken within 72 hours of intercourse. - “Population momentum” refers to:
(a) High birth rates due to young age structure
(b) Increased immigration
(c) Advanced medical facilities
(d) Government policies
Answer: (a) High birth rates due to young age structure
Explanation: Even with reduced fertility, a young population structure leads to continued population growth. - Which ART technique is used for male infertility?
(a) GIFT
(b) ZIFT
(c) ICSI
(d) IUI
Answer: (c) ICSI
Explanation: Intracytoplasmic Sperm Injection (ICSI) is used for severe male infertility by directly injecting a sperm into an egg. - India’s Total Fertility Rate (TFR) in 2023 is approximately:
(a) 1.8
(b) 2.0
(c) 2.7
(d) 3.5
Answer: (b) 2.0
Explanation: According to NFHS-5, India has achieved replacement-level fertility (TFR ~2.0). - The “World Population Day” is observed on:
(a) July 11
(b) September 26
(c) October 31
(d) December 10
Answer: (a) July 11
Explanation: Observed globally to raise awareness about population issues, started by the UN in 1989. - Which is a natural method of contraception?
(a) Diaphragm
(b) Basal Body Temperature (BBT) tracking
(c) Spermicide
(d) Vaginal ring
Answer: (b) Basal Body Temperature (BBT) tracking
Explanation: BBT method monitors ovulation through temperature changes to avoid fertile days. - Medical termination of pregnancy (MTP) before 7 weeks uses:
(a) Surgical curettage
(b) Mifepristone + Misoprostol
(c) RU-486 alone
(d) Methotrexate
Answer: (b) Mifepristone + Misoprostol
Explanation: This combination is effective and safe for early-stage medical abortion. - The primary goal of India’s National Population Policy (2000) is:
(a) One-child norm
(b) Two-child norm
(c) Voluntary family planning
(d) Compulsory sterilization
Answer: (c) Voluntary family planning
Explanation: NPP 2000 promotes informed choices and access to reproductive health services. - Which contraceptive is non-invasive and user-controlled?
(a) Implant
(b) Injectable
(c) Female condom
(d) Tubal ligation
Answer: (c) Female condom
Explanation: A barrier method controlled by the user, offering protection against pregnancy and STIs. - “Test-tube babies” involve:
(a) Surrogacy
(b) IVF
(c) Artificial insemination
(d) Cloning
Answer: (b) IVF
Explanation: IVF enables fertilization outside the body and implantation into the uterus. - Which Indian state first implemented the Population Control Bill (2021)?
(a) Kerala
(b) Uttar Pradesh
(c) Tamil Nadu
(d) Bihar
Answer: (b) Uttar Pradesh
Explanation: UP proposed incentives/disincentives under a draft population control bill. - Pradhan Mantri Matru Vandana Yojana (PMMVY) promotes:
(a) Early marriage
(b) Institutional deliveries
(c) Birth spacing
(d) Cash incentives for the first child
Answer: (d) Cash incentives for the first child
Explanation: PMMVY provides financial assistance to encourage maternal care and safe childbirth. - ZIFT differs from GIFT in that ZIFT involves:
(a) Transfer of gametes
(b) Transfer of zygote
(c) Donor eggs
(d) Surrogacy
Answer: (b) Transfer of zygote
Explanation: In ZIFT, a fertilized zygote is transferred to the fallopian tube, unlike gametes in GIFT. - Which factor most significantly reduces fertility rates?
(a) Economic development
(b) Religious beliefs
(c) Climate change
(d) Urbanization
Answer: (a) Economic development
Explanation: Higher education, female empowerment, and better income levels lead to smaller families. - “Mission Parivar Vikas” targets high TFR districts in:
(a) 7 states
(b) 15 states
(c) 22 states
(d) All states
Answer: (a) 7 states
Explanation: The mission focuses on districts in UP, Bihar, Rajasthan, MP, Chhattisgarh, Jharkhand, and Assam.
