{ "chapter": "Reproduction", "count": 100, "answerIndex": "zero-based", "notice": "Original practice items including related concept variants; not official examination questions.", "questions": [ { "id": "lh-surge-ovulation", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Which hormonal event most directly triggers ovulation in a typical menstrual cycle?", "options": [ "A surge in luteinising hormone", "A permanent fall in FSH from birth", "A sudden rise in ADH", "Release of thyroxine from the ovary" ], "answer": 0, "explanation": "High oestrogen from the mature follicle produces positive feedback that generates an LH surge, triggering ovulation." }, { "id": "progesterone-withdrawal", "chapter": "Reproduction", "difficulty": "Standard", "stem": "If fertilisation does not occur, degeneration of the corpus luteum promotes menstruation mainly through a fall in:", "options": [ "Testosterone only", "Progesterone and oestrogen", "ADH and aldosterone", "Insulin and glucagon" ], "answer": 1, "explanation": "The corpus luteum supports the endometrium by secreting progesterone and oestrogen. Their decline causes the uterine lining to break down." }, { "id": "acrosome-reaction", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Failure of the acrosome reaction would most directly prevent a sperm from:", "options": [ "Producing ATP in mitochondria", "Completing meiosis in the testes", "Penetrating the egg's surrounding layers", "Carrying a haploid nucleus" ], "answer": 2, "explanation": "The acrosome releases enzymes that help the sperm pass through the egg's protective extracellular layers before membrane fusion." }, { "id": "placental-barrier", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Maternal and fetal blood normally remain in separate circulations at the placenta. Exchange is still efficient because:", "options": [ "Every fetal capillary opens into a maternal artery", "Only hormones cross the placenta", "Fetal blood contains no plasma", "The exchange barrier is thin and richly supplied with vessels" ], "answer": 3, "explanation": "A thin placental barrier and extensive blood supply maintain short diffusion distances and concentration gradients without direct mixing of the two bloodstreams." }, { "id": "reproduction-meiosis-outcome", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "A diploid germ cell completes meiosis. Which outcome follows most directly?", "options": [ "Haploid cells with varied allele combinations are produced", "Testosterone secretion increases", "Sperm development is supported", "Ovarian follicles grow and secrete increasing oestrogen" ], "answer": 0, "explanation": "Haploid cells with varied allele combinations are produced. Two divisions follow one DNA replication, with crossing over and independent assortment." }, { "id": "reproduction-meiosis-cause", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Which change most directly explains this observation: haploid cells with varied allele combinations are produced?", "options": [ "LH stimulates interstitial cells in the testes", "A diploid germ cell completes meiosis", "FSH and testosterone act on seminiferous tubules", "FSH rises during the early ovarian cycle" ], "answer": 1, "explanation": "Haploid cells with varied allele combinations are produced. Two divisions follow one DNA replication, with crossing over and independent assortment." }, { "id": "reproduction-meiosis-mechanism", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "After a diploid germ cell completes meiosis, which explanation best links the change to its outcome?", "options": [ "LH receptor signalling promotes steroid synthesis in Leydig cells", "Sertoli cells respond by nurturing germ cells and regulating spermatogenesis", "Two divisions follow one DNA replication, with crossing over and independent assortment", "FSH stimulates granulosa-cell proliferation and follicular development" ], "answer": 2, "explanation": "Haploid cells with varied allele combinations are produced. Two divisions follow one DNA replication, with crossing over and independent assortment." }, { "id": "reproduction-testosterone-outcome", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "After LH stimulates interstitial cells in the testes, which observation is most likely?", "options": [ "Sperm development is supported", "A surge of LH triggers ovulation", "Ovarian follicles grow and secrete increasing oestrogen", "Testosterone secretion increases" ], "answer": 3, "explanation": "Testosterone secretion increases. LH receptor signalling promotes steroid synthesis in Leydig cells." }, { "id": "reproduction-testosterone-cause", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "A learner records that testosterone secretion increases. Which preceding event best accounts for it?", "options": [ "LH stimulates interstitial cells in the testes", "FSH rises during the early ovarian cycle", "FSH and testosterone act on seminiferous tubules", "Sustained high oestrogen creates positive feedback near mid-cycle" ], "answer": 0, "explanation": "Testosterone secretion increases. LH receptor signalling promotes steroid synthesis in Leydig cells." }, { "id": "reproduction-testosterone-mechanism", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "After LH stimulates interstitial cells in the testes, which explanation best links the change to its outcome?", "options": [ "Sertoli cells respond by nurturing germ cells and regulating spermatogenesis", "LH receptor signalling promotes steroid synthesis in Leydig cells", "Hypothalamic and pituitary stimulation abruptly increases gonadotropin release", "FSH stimulates granulosa-cell proliferation and follicular development" ], "answer": 1, "explanation": "Testosterone secretion increases. LH receptor signalling promotes steroid synthesis in Leydig cells." }, { "id": "reproduction-testosterone-integrated", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: LH stimulates interstitial cells in the testes?", "options": [ "Ovarian follicles grow and secrete increasing oestrogen — FSH stimulates granulosa-cell proliferation and follicular development", "Sperm development is supported — Sertoli cells respond by nurturing germ cells and regulating spermatogenesis", "Testosterone secretion increases — LH receptor signalling promotes steroid synthesis in Leydig cells", "A surge of LH triggers ovulation — Hypothalamic and pituitary stimulation abruptly increases gonadotropin release" ], "answer": 2, "explanation": "Testosterone secretion increases. LH receptor signalling promotes steroid synthesis in Leydig cells." }, { "id": "reproduction-fsh-sperm-outcome", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "A student models this change: FSH and testosterone act on seminiferous tubules. What should the model predict first?", "options": [ "Ovarian follicles grow and secrete increasing oestrogen", "A surge of LH triggers ovulation", "A diploid zygote with a new allele combination forms", "Sperm development is supported" ], "answer": 3, "explanation": "Sperm development is supported. Sertoli cells respond by nurturing germ cells and regulating spermatogenesis." }, { "id": "reproduction-fsh-sperm-cause", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "What is the most likely cause when sperm development is supported?", "options": [ "FSH and testosterone act on seminiferous tubules", "Sustained high oestrogen creates positive feedback near mid-cycle", "A sperm nucleus fuses with the egg nucleus", "FSH rises during the early ovarian cycle" ], "answer": 0, "explanation": "Sperm development is supported. Sertoli cells respond by nurturing germ cells and regulating spermatogenesis." }, { "id": "reproduction-fsh-sperm-mechanism", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "After FSH and testosterone act on seminiferous tubules, which explanation best links the change to its outcome?", "options": [ "FSH stimulates granulosa-cell proliferation and follicular development", "Sertoli cells respond by nurturing germ cells and regulating spermatogenesis", "Hypothalamic and pituitary stimulation abruptly increases gonadotropin release", "Two haploid chromosome sets unite during fertilization" ], "answer": 1, "explanation": "Sperm development is supported. Sertoli cells respond by nurturing germ cells and regulating spermatogenesis." }, { "id": "reproduction-fsh-sperm-integrated", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: FSH and testosterone act on seminiferous tubules?", "options": [ "Ovarian follicles grow and secrete increasing oestrogen — FSH stimulates granulosa-cell proliferation and follicular development", "A surge of LH triggers ovulation — Hypothalamic and pituitary stimulation abruptly increases gonadotropin release", "Sperm development is supported — Sertoli cells respond by nurturing germ cells and regulating spermatogenesis", "A diploid zygote with a new allele combination forms — Two haploid chromosome sets unite during fertilization" ], "answer": 2, "explanation": "Sperm development is supported. Sertoli cells respond by nurturing germ cells and regulating spermatogenesis." }, { "id": "reproduction-follicle-outcome", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Which immediate result is most consistent with this condition: FSH rises during the early ovarian cycle?", "options": [ "A surge of LH triggers ovulation", "A diploid zygote with a new allele combination forms", "The acrosome releases hydrolytic enzymes", "Ovarian follicles grow and secrete increasing oestrogen" ], "answer": 3, "explanation": "Ovarian follicles grow and secrete increasing oestrogen. FSH stimulates granulosa-cell proliferation and follicular development." }, { "id": "reproduction-follicle-cause", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Which condition would most specifically produce this result: ovarian follicles grow and secrete increasing oestrogen?", "options": [ "FSH rises during the early ovarian cycle", "Sustained high oestrogen creates positive feedback near mid-cycle", "A sperm nucleus fuses with the egg nucleus", "A capacitated sperm binds the egg's surrounding glycoprotein layer" ], "answer": 0, "explanation": "Ovarian follicles grow and secrete increasing oestrogen. FSH stimulates granulosa-cell proliferation and follicular development." }, { "id": "reproduction-follicle-mechanism", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "After FSH rises during the early ovarian cycle, which explanation best links the change to its outcome?", "options": [ "Hypothalamic and pituitary stimulation abruptly increases gonadotropin release", "FSH stimulates granulosa-cell proliferation and follicular development", "Two haploid chromosome sets unite during fertilization", "Membrane fusion at the sperm head initiates exocytosis that aids penetration" ], "answer": 1, "explanation": "Ovarian follicles grow and secrete increasing oestrogen. FSH stimulates granulosa-cell proliferation and follicular development." }, { "id": "reproduction-follicle-integrated", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: FSH rises during the early ovarian cycle?", "options": [ "A surge of LH triggers ovulation — Hypothalamic and pituitary stimulation abruptly increases gonadotropin release", "A diploid zygote with a new allele combination forms — Two haploid chromosome sets unite during fertilization", "Ovarian follicles grow and secrete increasing oestrogen — FSH stimulates granulosa-cell proliferation and follicular development", "The acrosome releases hydrolytic enzymes — Membrane fusion at the sperm head initiates exocytosis that aids penetration" ], "answer": 2, "explanation": "Ovarian follicles grow and secrete increasing oestrogen. FSH stimulates granulosa-cell proliferation and follicular development." }, { "id": "reproduction-lh-surge-outcome", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Sustained high oestrogen creates positive feedback near mid-cycle. Which outcome follows most directly?", "options": [ "Further sperm entry is blocked", "A diploid zygote with a new allele combination forms", "The acrosome releases hydrolytic enzymes", "A surge of LH triggers ovulation" ], "answer": 3, "explanation": "A surge of LH triggers ovulation. Hypothalamic and pituitary stimulation abruptly increases gonadotropin release." }, { "id": "reproduction-lh-surge-cause", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Which change most directly explains this observation: a surge of LH triggers ovulation?", "options": [ "Sustained high oestrogen creates positive feedback near mid-cycle", "A sperm nucleus fuses with the egg nucleus", "A capacitated sperm binds the egg's surrounding glycoprotein layer", "One sperm fuses with the egg membrane" ], "answer": 0, "explanation": "A surge of LH triggers ovulation. Hypothalamic and pituitary stimulation abruptly increases gonadotropin release." }, { "id": "reproduction-lh-surge-mechanism", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "After sustained high oestrogen creates positive feedback near mid-cycle, which explanation best links the change to its outcome?", "options": [ "Two haploid chromosome sets unite during fertilization", "Hypothalamic and pituitary stimulation abruptly increases gonadotropin release", "Membrane fusion at the sperm head initiates exocytosis that aids penetration", "A calcium wave triggers cortical granules to modify and harden the extracellular coat" ], "answer": 1, "explanation": "A surge of LH triggers ovulation. Hypothalamic and pituitary stimulation abruptly increases gonadotropin release." }, { "id": "reproduction-lh-surge-integrated", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: sustained high oestrogen creates positive feedback near mid-cycle?", "options": [ "A diploid zygote with a new allele combination forms — Two haploid chromosome sets unite during fertilization", "The acrosome releases hydrolytic enzymes — Membrane fusion at the sperm head initiates exocytosis that aids penetration", "A surge of LH triggers ovulation — Hypothalamic and pituitary stimulation abruptly increases gonadotropin release", "Further sperm entry is blocked — A calcium wave triggers cortical granules to modify and harden the extracellular coat" ], "answer": 2, "explanation": "A surge of LH triggers ovulation. Hypothalamic and pituitary stimulation abruptly increases gonadotropin release." }, { "id": "reproduction-fertilization-outcome", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "After a sperm nucleus fuses with the egg nucleus, which observation is most likely?", "options": [ "The acrosome releases hydrolytic enzymes", "Many smaller blastomeres form within the original volume", "Further sperm entry is blocked", "A diploid zygote with a new allele combination forms" ], "answer": 3, "explanation": "A diploid zygote with a new allele combination forms. Two haploid chromosome sets unite during fertilization." }, { "id": "reproduction-fertilization-cause", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "A learner records that a diploid zygote with a new allele combination forms. Which preceding event best accounts for it?", "options": [ "A sperm nucleus fuses with the egg nucleus", "One sperm fuses with the egg membrane", "A capacitated sperm binds the egg's surrounding glycoprotein layer", "The zygote undergoes rapid mitotic cleavage without overall growth" ], "answer": 0, "explanation": "A diploid zygote with a new allele combination forms. Two haploid chromosome sets unite during fertilization." }, { "id": "reproduction-fertilization-mechanism", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "After a sperm nucleus fuses with the egg nucleus, which explanation best links the change to its outcome?", "options": [ "Membrane fusion at the sperm head initiates exocytosis that aids penetration", "Two haploid chromosome sets unite during fertilization", "Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus", "A calcium wave triggers cortical granules to modify and harden the extracellular coat" ], "answer": 1, "explanation": "A diploid zygote with a new allele combination forms. Two haploid chromosome sets unite during fertilization." }, { "id": "reproduction-fertilization-integrated", "chapter": "Reproduction", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a sperm nucleus fuses with the egg nucleus?", "options": [ "Further sperm entry is blocked — A calcium wave triggers cortical granules to modify and harden the extracellular coat", "The acrosome releases hydrolytic enzymes — Membrane fusion at the sperm head initiates exocytosis that aids penetration", "A diploid zygote with a new allele combination forms — Two haploid chromosome sets unite during fertilization", "Many smaller blastomeres form within the original volume — Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus" ], "answer": 2, "explanation": "A diploid zygote with a new allele combination forms. Two haploid chromosome sets unite during fertilization." }, { "id": "reproduction-acrosome-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "A student models this change: A capacitated sperm binds the egg's surrounding glycoprotein layer. What should the model predict first?", "options": [ "Further sperm entry is blocked", "Many smaller blastomeres form within the original volume", "It embeds in the uterine lining", "The acrosome releases hydrolytic enzymes" ], "answer": 3, "explanation": "The acrosome releases hydrolytic enzymes. Membrane fusion at the sperm head initiates exocytosis that aids penetration." }, { "id": "reproduction-acrosome-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "What is the most likely cause when the acrosome releases hydrolytic enzymes?", "options": [ "A capacitated sperm binds the egg's surrounding glycoprotein layer", "The zygote undergoes rapid mitotic cleavage without overall growth", "A healthy blastocyst contacts a receptive endometrium", "One sperm fuses with the egg membrane" ], "answer": 0, "explanation": "The acrosome releases hydrolytic enzymes. Membrane fusion at the sperm head initiates exocytosis that aids penetration." }, { "id": "reproduction-acrosome-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After a capacitated sperm binds the egg's surrounding glycoprotein layer, which explanation best links the change to its outcome?", "options": [ "A calcium wave triggers cortical granules to modify and harden the extracellular coat", "Membrane fusion at the sperm head initiates exocytosis that aids penetration", "Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus", "Trophoblast cells adhere, invade and begin forming the fetal part of the placenta" ], "answer": 1, "explanation": "The acrosome releases hydrolytic enzymes. Membrane fusion at the sperm head initiates exocytosis that aids penetration." }, { "id": "reproduction-cortical-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: One sperm fuses with the egg membrane?", "options": [ "Many smaller blastomeres form within the original volume", "It embeds in the uterine lining", "Further sperm entry is blocked", "The corpus luteum persists and continues progesterone secretion" ], "answer": 2, "explanation": "Further sperm entry is blocked. A calcium wave triggers cortical granules to modify and harden the extracellular coat." }, { "id": "reproduction-cortical-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: further sperm entry is blocked?", "options": [ "Early trophoblast cells secrete human chorionic gonadotropin", "The zygote undergoes rapid mitotic cleavage without overall growth", "A healthy blastocyst contacts a receptive endometrium", "One sperm fuses with the egg membrane" ], "answer": 3, "explanation": "Further sperm entry is blocked. A calcium wave triggers cortical granules to modify and harden the extracellular coat." }, { "id": "reproduction-cortical-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After one sperm fuses with the egg membrane, which explanation best links the change to its outcome?", "options": [ "A calcium wave triggers cortical granules to modify and harden the extracellular coat", "Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus", "Trophoblast cells adhere, invade and begin forming the fetal part of the placenta", "hCG acts like LH and prevents luteal degeneration in early pregnancy" ], "answer": 0, "explanation": "Further sperm entry is blocked. A calcium wave triggers cortical granules to modify and harden the extracellular coat." }, { "id": "reproduction-cortical-integrated", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: one sperm fuses with the egg membrane?", "options": [ "Many smaller blastomeres form within the original volume — Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus", "Further sperm entry is blocked — A calcium wave triggers cortical granules to modify and harden the extracellular coat", "It embeds in the uterine lining — Trophoblast cells adhere, invade and begin forming the fetal part of the placenta", "The corpus luteum persists and continues progesterone secretion — hCG acts like LH and prevents luteal degeneration in early pregnancy" ], "answer": 1, "explanation": "Further sperm entry is blocked. A calcium wave triggers cortical granules to modify and harden the extracellular coat." }, { "id": "reproduction-cleavage-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "The zygote undergoes rapid mitotic cleavage without overall growth. Which outcome follows most directly?", "options": [ "The corpus luteum persists and continues progesterone secretion", "It embeds in the uterine lining", "Many smaller blastomeres form within the original volume", "The endometrium stays thick and uterine contractions are restrained" ], "answer": 2, "explanation": "Many smaller blastomeres form within the original volume. Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus." }, { "id": "reproduction-cleavage-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which change most directly explains this observation: many smaller blastomeres form within the original volume?", "options": [ "A healthy blastocyst contacts a receptive endometrium", "Progesterone remains high after ovulation", "Early trophoblast cells secrete human chorionic gonadotropin", "The zygote undergoes rapid mitotic cleavage without overall growth" ], "answer": 3, "explanation": "Many smaller blastomeres form within the original volume. Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus." }, { "id": "reproduction-cleavage-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After the zygote undergoes rapid mitotic cleavage without overall growth, which explanation best links the change to its outcome?", "options": [ "Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus", "hCG acts like LH and prevents luteal degeneration in early pregnancy", "Trophoblast cells adhere, invade and begin forming the fetal part of the placenta", "The steroid maintains secretory uterine tissue suitable for implantation" ], "answer": 0, "explanation": "Many smaller blastomeres form within the original volume. Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus." }, { "id": "reproduction-cleavage-integrated", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: the zygote undergoes rapid mitotic cleavage without overall growth?", "options": [ "It embeds in the uterine lining — Trophoblast cells adhere, invade and begin forming the fetal part of the placenta", "Many smaller blastomeres form within the original volume — Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus", "The endometrium stays thick and uterine contractions are restrained — The steroid maintains secretory uterine tissue suitable for implantation", "The corpus luteum persists and continues progesterone secretion — hCG acts like LH and prevents luteal degeneration in early pregnancy" ], "answer": 1, "explanation": "Many smaller blastomeres form within the original volume. Repeated S and M phases partition cytoplasm as the embryo travels toward the uterus." }, { "id": "reproduction-implantation-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After a healthy blastocyst contacts a receptive endometrium, which observation is most likely?", "options": [ "The corpus luteum persists and continues progesterone secretion", "The endometrium stays thick and uterine contractions are restrained", "It embeds in the uterine lining", "Gases, nutrients and wastes exchange efficiently without normal direct blood mixing" ], "answer": 2, "explanation": "It embeds in the uterine lining. Trophoblast cells adhere, invade and begin forming the fetal part of the placenta." }, { "id": "reproduction-implantation-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "A learner records that it embeds in the uterine lining. Which preceding event best accounts for it?", "options": [ "Early trophoblast cells secrete human chorionic gonadotropin", "Progesterone remains high after ovulation", "Maternal and fetal blood flow closely on opposite sides of thin placental villi", "A healthy blastocyst contacts a receptive endometrium" ], "answer": 3, "explanation": "It embeds in the uterine lining. Trophoblast cells adhere, invade and begin forming the fetal part of the placenta." }, { "id": "reproduction-implantation-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After a healthy blastocyst contacts a receptive endometrium, which explanation best links the change to its outcome?", "options": [ "Trophoblast cells adhere, invade and begin forming the fetal part of the placenta", "The steroid maintains secretory uterine tissue suitable for implantation", "Large area, short distance and maintained concentration gradients favour diffusion and transport", "hCG acts like LH and prevents luteal degeneration in early pregnancy" ], "answer": 0, "explanation": "It embeds in the uterine lining. Trophoblast cells adhere, invade and begin forming the fetal part of the placenta." }, { "id": "reproduction-implantation-integrated", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a healthy blastocyst contacts a receptive endometrium?", "options": [ "The corpus luteum persists and continues progesterone secretion — hCG acts like LH and prevents luteal degeneration in early pregnancy", "It embeds in the uterine lining — Trophoblast cells adhere, invade and begin forming the fetal part of the placenta", "The endometrium stays thick and uterine contractions are restrained — The steroid maintains secretory uterine tissue suitable for implantation", "Gases, nutrients and wastes exchange efficiently without normal direct blood mixing — Large area, short distance and maintained concentration gradients favour diffusion and transport" ], "answer": 1, "explanation": "It embeds in the uterine lining. Trophoblast cells adhere, invade and begin forming the fetal part of the placenta." }, { "id": "reproduction-hcg-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "A student models this change: Early trophoblast cells secrete human chorionic gonadotropin. What should the model predict first?", "options": [ "The endometrium stays thick and uterine contractions are restrained", "Gases, nutrients and wastes exchange efficiently without normal direct blood mixing", "The corpus luteum persists and continues progesterone secretion", "Relatively deoxygenated blood and wastes reach the exchange surface" ], "answer": 2, "explanation": "The corpus luteum persists and continues progesterone secretion. hCG acts like LH and prevents luteal degeneration in early pregnancy." }, { "id": "reproduction-hcg-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "What is the most likely cause when the corpus luteum persists and continues progesterone secretion?", "options": [ "Progesterone remains high after ovulation", "Maternal and fetal blood flow closely on opposite sides of thin placental villi", "Fetal blood travels through umbilical arteries toward the placenta", "Early trophoblast cells secrete human chorionic gonadotropin" ], "answer": 3, "explanation": "The corpus luteum persists and continues progesterone secretion. hCG acts like LH and prevents luteal degeneration in early pregnancy." }, { "id": "reproduction-hcg-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After early trophoblast cells secrete human chorionic gonadotropin, which explanation best links the change to its outcome?", "options": [ "hCG acts like LH and prevents luteal degeneration in early pregnancy", "The steroid maintains secretory uterine tissue suitable for implantation", "Large area, short distance and maintained concentration gradients favour diffusion and transport", "The arteries carry blood away from the fetal heart despite their unusual oxygen content" ], "answer": 0, "explanation": "The corpus luteum persists and continues progesterone secretion. hCG acts like LH and prevents luteal degeneration in early pregnancy." }, { "id": "reproduction-hcg-integrated", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: early trophoblast cells secrete human chorionic gonadotropin?", "options": [ "The endometrium stays thick and uterine contractions are restrained — The steroid maintains secretory uterine tissue suitable for implantation", "The corpus luteum persists and continues progesterone secretion — hCG acts like LH and prevents luteal degeneration in early pregnancy", "Gases, nutrients and wastes exchange efficiently without normal direct blood mixing — Large area, short distance and maintained concentration gradients favour diffusion and transport", "Relatively deoxygenated blood and wastes reach the exchange surface — The arteries carry blood away from the fetal heart despite their unusual oxygen content" ], "answer": 1, "explanation": "The corpus luteum persists and continues progesterone secretion. hCG acts like LH and prevents luteal degeneration in early pregnancy." }, { "id": "reproduction-progesterone-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: Progesterone remains high after ovulation?", "options": [ "Gases, nutrients and wastes exchange efficiently without normal direct blood mixing", "Relatively deoxygenated blood and wastes reach the exchange surface", "The endometrium stays thick and uterine contractions are restrained", "Oxytocin release and uterine contractions intensify" ], "answer": 2, "explanation": "The endometrium stays thick and uterine contractions are restrained. The steroid maintains secretory uterine tissue suitable for implantation." }, { "id": "reproduction-progesterone-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: the endometrium stays thick and uterine contractions are restrained?", "options": [ "The fetal head stretches the cervix during labour", "Maternal and fetal blood flow closely on opposite sides of thin placental villi", "Fetal blood travels through umbilical arteries toward the placenta", "Progesterone remains high after ovulation" ], "answer": 3, "explanation": "The endometrium stays thick and uterine contractions are restrained. The steroid maintains secretory uterine tissue suitable for implantation." }, { "id": "reproduction-progesterone-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After progesterone remains high after ovulation, which explanation best links the change to its outcome?", "options": [ "The steroid maintains secretory uterine tissue suitable for implantation", "Large area, short distance and maintained concentration gradients favour diffusion and transport", "The arteries carry blood away from the fetal heart despite their unusual oxygen content", "A positive-feedback loop increases cervical stretch until delivery" ], "answer": 0, "explanation": "The endometrium stays thick and uterine contractions are restrained. The steroid maintains secretory uterine tissue suitable for implantation." }, { "id": "reproduction-progesterone-integrated", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: progesterone remains high after ovulation?", "options": [ "Gases, nutrients and wastes exchange efficiently without normal direct blood mixing — Large area, short distance and maintained concentration gradients favour diffusion and transport", "The endometrium stays thick and uterine contractions are restrained — The steroid maintains secretory uterine tissue suitable for implantation", "Relatively deoxygenated blood and wastes reach the exchange surface — The arteries carry blood away from the fetal heart despite their unusual oxygen content", "Oxytocin release and uterine contractions intensify — A positive-feedback loop increases cervical stretch until delivery" ], "answer": 1, "explanation": "The endometrium stays thick and uterine contractions are restrained. The steroid maintains secretory uterine tissue suitable for implantation." }, { "id": "reproduction-placenta-exchange-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Maternal and fetal blood flow closely on opposite sides of thin placental villi. Which outcome follows most directly?", "options": [ "Oxytocin release and uterine contractions intensify", "Relatively deoxygenated blood and wastes reach the exchange surface", "Gases, nutrients and wastes exchange efficiently without normal direct blood mixing", "Prolactin secretion supports milk production" ], "answer": 2, "explanation": "Gases, nutrients and wastes exchange efficiently without normal direct blood mixing. Large area, short distance and maintained concentration gradients favour diffusion and transport." }, { "id": "reproduction-placenta-exchange-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which change most directly explains this observation: gases, nutrients and wastes exchange efficiently without normal direct blood mixing?", "options": [ "Fetal blood travels through umbilical arteries toward the placenta", "Suckling stimulates sensory pathways after birth", "The fetal head stretches the cervix during labour", "Maternal and fetal blood flow closely on opposite sides of thin placental villi" ], "answer": 3, "explanation": "Gases, nutrients and wastes exchange efficiently without normal direct blood mixing. Large area, short distance and maintained concentration gradients favour diffusion and transport." }, { "id": "reproduction-placenta-exchange-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After maternal and fetal blood flow closely on opposite sides of thin placental villi, which explanation best links the change to its outcome?", "options": [ "Large area, short distance and maintained concentration gradients favour diffusion and transport", "A positive-feedback loop increases cervical stretch until delivery", "The arteries carry blood away from the fetal heart despite their unusual oxygen content", "Reduced hypothalamic dopamine permits anterior-pituitary prolactin release" ], "answer": 0, "explanation": "Gases, nutrients and wastes exchange efficiently without normal direct blood mixing. Large area, short distance and maintained concentration gradients favour diffusion and transport." }, { "id": "reproduction-umbilical-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After fetal blood travels through umbilical arteries toward the placenta, which observation is most likely?", "options": [ "Oxytocin release and uterine contractions intensify", "Relatively deoxygenated blood and wastes reach the exchange surface", "Prolactin secretion supports milk production", "FSH and LH peaks are suppressed and ovulation is unlikely" ], "answer": 1, "explanation": "Relatively deoxygenated blood and wastes reach the exchange surface. The arteries carry blood away from the fetal heart despite their unusual oxygen content." }, { "id": "reproduction-umbilical-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "A learner records that relatively deoxygenated blood and wastes reach the exchange surface. Which preceding event best accounts for it?", "options": [ "The fetal head stretches the cervix during labour", "Suckling stimulates sensory pathways after birth", "Fetal blood travels through umbilical arteries toward the placenta", "Steady synthetic oestrogen and progestogen provide negative feedback" ], "answer": 2, "explanation": "Relatively deoxygenated blood and wastes reach the exchange surface. The arteries carry blood away from the fetal heart despite their unusual oxygen content." }, { "id": "reproduction-umbilical-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After fetal blood travels through umbilical arteries toward the placenta, which explanation best links the change to its outcome?", "options": [ "A positive-feedback loop increases cervical stretch until delivery", "Reduced hypothalamic dopamine permits anterior-pituitary prolactin release", "Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge", "The arteries carry blood away from the fetal heart despite their unusual oxygen content" ], "answer": 3, "explanation": "Relatively deoxygenated blood and wastes reach the exchange surface. The arteries carry blood away from the fetal heart despite their unusual oxygen content." }, { "id": "reproduction-umbilical-integrated", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: fetal blood travels through umbilical arteries toward the placenta?", "options": [ "Relatively deoxygenated blood and wastes reach the exchange surface — The arteries carry blood away from the fetal heart despite their unusual oxygen content", "Oxytocin release and uterine contractions intensify — A positive-feedback loop increases cervical stretch until delivery", "Prolactin secretion supports milk production — Reduced hypothalamic dopamine permits anterior-pituitary prolactin release", "FSH and LH peaks are suppressed and ovulation is unlikely — Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge" ], "answer": 0, "explanation": "Relatively deoxygenated blood and wastes reach the exchange surface. The arteries carry blood away from the fetal heart despite their unusual oxygen content." }, { "id": "reproduction-oxytocin-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "A student models this change: The fetal head stretches the cervix during labour. What should the model predict first?", "options": [ "Prolactin secretion supports milk production", "Oxytocin release and uterine contractions intensify", "FSH and LH peaks are suppressed and ovulation is unlikely", "Semen contains almost no sperm but testosterone production continues" ], "answer": 1, "explanation": "Oxytocin release and uterine contractions intensify. A positive-feedback loop increases cervical stretch until delivery." }, { "id": "reproduction-oxytocin-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "What is the most likely cause when oxytocin release and uterine contractions intensify?", "options": [ "Suckling stimulates sensory pathways after birth", "Steady synthetic oestrogen and progestogen provide negative feedback", "The fetal head stretches the cervix during labour", "Both vas deferens are cut and sealed" ], "answer": 2, "explanation": "Oxytocin release and uterine contractions intensify. A positive-feedback loop increases cervical stretch until delivery." }, { "id": "reproduction-oxytocin-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After the fetal head stretches the cervix during labour, which explanation best links the change to its outcome?", "options": [ "Sperm transport is interrupted without removing endocrine tissue in the testes", "Reduced hypothalamic dopamine permits anterior-pituitary prolactin release", "Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge", "A positive-feedback loop increases cervical stretch until delivery" ], "answer": 3, "explanation": "Oxytocin release and uterine contractions intensify. A positive-feedback loop increases cervical stretch until delivery." }, { "id": "reproduction-oxytocin-integrated", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: the fetal head stretches the cervix during labour?", "options": [ "Oxytocin release and uterine contractions intensify — A positive-feedback loop increases cervical stretch until delivery", "Prolactin secretion supports milk production — Reduced hypothalamic dopamine permits anterior-pituitary prolactin release", "FSH and LH peaks are suppressed and ovulation is unlikely — Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge", "Semen contains almost no sperm but testosterone production continues — Sperm transport is interrupted without removing endocrine tissue in the testes" ], "answer": 0, "explanation": "Oxytocin release and uterine contractions intensify. A positive-feedback loop increases cervical stretch until delivery." }, { "id": "reproduction-prolactin-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: Suckling stimulates sensory pathways after birth?", "options": [ "FSH and LH peaks are suppressed and ovulation is unlikely", "Prolactin secretion supports milk production", "A dangerous ectopic pregnancy may rupture maternal tissue", "Semen contains almost no sperm but testosterone production continues" ], "answer": 1, "explanation": "Prolactin secretion supports milk production. Reduced hypothalamic dopamine permits anterior-pituitary prolactin release." }, { "id": "reproduction-prolactin-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: prolactin secretion supports milk production?", "options": [ "Both vas deferens are cut and sealed", "Steady synthetic oestrogen and progestogen provide negative feedback", "Suckling stimulates sensory pathways after birth", "An embryo implants in an oviduct rather than the uterus" ], "answer": 2, "explanation": "Prolactin secretion supports milk production. Reduced hypothalamic dopamine permits anterior-pituitary prolactin release." }, { "id": "reproduction-prolactin-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After suckling stimulates sensory pathways after birth, which explanation best links the change to its outcome?", "options": [ "Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge", "The narrow tube cannot safely support placental invasion and fetal growth", "Sperm transport is interrupted without removing endocrine tissue in the testes", "Reduced hypothalamic dopamine permits anterior-pituitary prolactin release" ], "answer": 3, "explanation": "Prolactin secretion supports milk production. Reduced hypothalamic dopamine permits anterior-pituitary prolactin release." }, { "id": "reproduction-prolactin-integrated", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: suckling stimulates sensory pathways after birth?", "options": [ "Prolactin secretion supports milk production — Reduced hypothalamic dopamine permits anterior-pituitary prolactin release", "Semen contains almost no sperm but testosterone production continues — Sperm transport is interrupted without removing endocrine tissue in the testes", "FSH and LH peaks are suppressed and ovulation is unlikely — Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge", "A dangerous ectopic pregnancy may rupture maternal tissue — The narrow tube cannot safely support placental invasion and fetal growth" ], "answer": 0, "explanation": "Prolactin secretion supports milk production. Reduced hypothalamic dopamine permits anterior-pituitary prolactin release." }, { "id": "reproduction-contraceptive-pill-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Steady synthetic oestrogen and progestogen provide negative feedback. Which outcome follows most directly?", "options": [ "Semen contains almost no sperm but testosterone production continues", "FSH and LH peaks are suppressed and ovulation is unlikely", "A dangerous ectopic pregnancy may rupture maternal tissue", "All resulting gametes have an abnormal chromosome number" ], "answer": 1, "explanation": "FSH and LH peaks are suppressed and ovulation is unlikely. Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge." }, { "id": "reproduction-contraceptive-pill-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which change most directly explains this observation: FSH and LH peaks are suppressed and ovulation is unlikely?", "options": [ "Both vas deferens are cut and sealed", "An embryo implants in an oviduct rather than the uterus", "Steady synthetic oestrogen and progestogen provide negative feedback", "Homologous chromosomes fail to separate during meiosis I" ], "answer": 2, "explanation": "FSH and LH peaks are suppressed and ovulation is unlikely. Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge." }, { "id": "reproduction-contraceptive-pill-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After steady synthetic oestrogen and progestogen provide negative feedback, which explanation best links the change to its outcome?", "options": [ "Sperm transport is interrupted without removing endocrine tissue in the testes", "The narrow tube cannot safely support placental invasion and fetal growth", "Both homologues enter one daughter cell and neither enters the other", "Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge" ], "answer": 3, "explanation": "FSH and LH peaks are suppressed and ovulation is unlikely. Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge." }, { "id": "reproduction-contraceptive-pill-integrated", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: steady synthetic oestrogen and progestogen provide negative feedback?", "options": [ "FSH and LH peaks are suppressed and ovulation is unlikely — Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge", "A dangerous ectopic pregnancy may rupture maternal tissue — The narrow tube cannot safely support placental invasion and fetal growth", "All resulting gametes have an abnormal chromosome number — Both homologues enter one daughter cell and neither enters the other", "Semen contains almost no sperm but testosterone production continues — Sperm transport is interrupted without removing endocrine tissue in the testes" ], "answer": 0, "explanation": "FSH and LH peaks are suppressed and ovulation is unlikely. Pituitary gonadotropin release remains too low for dominant-follicle maturation and an LH surge." }, { "id": "reproduction-vasectomy-outcome", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After both vas deferens are cut and sealed, which observation is most likely?", "options": [ "A dangerous ectopic pregnancy may rupture maternal tissue", "Semen contains almost no sperm but testosterone production continues", "All resulting gametes have an abnormal chromosome number", "Maternal IgG may destroy fetal red blood cells" ], "answer": 1, "explanation": "Semen contains almost no sperm but testosterone production continues. Sperm transport is interrupted without removing endocrine tissue in the testes." }, { "id": "reproduction-vasectomy-cause", "chapter": "Reproduction", "difficulty": "Standard", "stem": "A learner records that semen contains almost no sperm but testosterone production continues. Which preceding event best accounts for it?", "options": [ "An embryo implants in an oviduct rather than the uterus", "Homologous chromosomes fail to separate during meiosis I", "Both vas deferens are cut and sealed", "An Rh-negative sensitized mother carries an Rh-positive fetus" ], "answer": 2, "explanation": "Semen contains almost no sperm but testosterone production continues. Sperm transport is interrupted without removing endocrine tissue in the testes." }, { "id": "reproduction-vasectomy-mechanism", "chapter": "Reproduction", "difficulty": "Standard", "stem": "After both vas deferens are cut and sealed, which explanation best links the change to its outcome?", "options": [ "The narrow tube cannot safely support placental invasion and fetal growth", "Both homologues enter one daughter cell and neither enters the other", "Memory cells rapidly produce placental-crossing anti-Rh antibodies", "Sperm transport is interrupted without removing endocrine tissue in the testes" ], "answer": 3, "explanation": "Semen contains almost no sperm but testosterone production continues. Sperm transport is interrupted without removing endocrine tissue in the testes." }, { "id": "reproduction-vasectomy-integrated", "chapter": "Reproduction", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: both vas deferens are cut and sealed?", "options": [ "Semen contains almost no sperm but testosterone production continues — Sperm transport is interrupted without removing endocrine tissue in the testes", "A dangerous ectopic pregnancy may rupture maternal tissue — The narrow tube cannot safely support placental invasion and fetal growth", "All resulting gametes have an abnormal chromosome number — Both homologues enter one daughter cell and neither enters the other", "Maternal IgG may destroy fetal red blood cells — Memory cells rapidly produce placental-crossing anti-Rh antibodies" ], "answer": 0, "explanation": "Semen contains almost no sperm but testosterone production continues. Sperm transport is interrupted without removing endocrine tissue in the testes." }, { "id": "reproduction-ectopic-outcome", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "A student models this change: An embryo implants in an oviduct rather than the uterus. What should the model predict first?", "options": [ "All resulting gametes have an abnormal chromosome number", "A dangerous ectopic pregnancy may rupture maternal tissue", "Maternal IgG may destroy fetal red blood cells", "Fertilization can bypass some causes of tubal or male-factor infertility" ], "answer": 1, "explanation": "A dangerous ectopic pregnancy may rupture maternal tissue. The narrow tube cannot safely support placental invasion and fetal growth." }, { "id": "reproduction-ectopic-cause", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "What is the most likely cause when a dangerous ectopic pregnancy may rupture maternal tissue?", "options": [ "Homologous chromosomes fail to separate during meiosis I", "An Rh-negative sensitized mother carries an Rh-positive fetus", "An embryo implants in an oviduct rather than the uterus", "Eggs are fertilized with sperm in a laboratory and an embryo is transferred" ], "answer": 2, "explanation": "A dangerous ectopic pregnancy may rupture maternal tissue. The narrow tube cannot safely support placental invasion and fetal growth." }, { "id": "reproduction-ectopic-mechanism", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "After an embryo implants in an oviduct rather than the uterus, which explanation best links the change to its outcome?", "options": [ "Gametes are brought together under controlled conditions before uterine placement", "Both homologues enter one daughter cell and neither enters the other", "Memory cells rapidly produce placental-crossing anti-Rh antibodies", "The narrow tube cannot safely support placental invasion and fetal growth" ], "answer": 3, "explanation": "A dangerous ectopic pregnancy may rupture maternal tissue. The narrow tube cannot safely support placental invasion and fetal growth." }, { "id": "reproduction-nondisjunction-outcome", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Which immediate result is most consistent with this condition: Homologous chromosomes fail to separate during meiosis I?", "options": [ "All resulting gametes have an abnormal chromosome number", "Fertilization can bypass some causes of tubal or male-factor infertility", "Oestrogen falls while FSH and LH become persistently high", "Maternal IgG may destroy fetal red blood cells" ], "answer": 0, "explanation": "All resulting gametes have an abnormal chromosome number. Both homologues enter one daughter cell and neither enters the other." }, { "id": "reproduction-nondisjunction-cause", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Which condition would most specifically produce this result: all resulting gametes have an abnormal chromosome number?", "options": [ "An Rh-negative sensitized mother carries an Rh-positive fetus", "Homologous chromosomes fail to separate during meiosis I", "Eggs are fertilized with sperm in a laboratory and an embryo is transferred", "Ovarian follicles are largely depleted" ], "answer": 1, "explanation": "All resulting gametes have an abnormal chromosome number. Both homologues enter one daughter cell and neither enters the other." }, { "id": "reproduction-nondisjunction-mechanism", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "After homologous chromosomes fail to separate during meiosis I, which explanation best links the change to its outcome?", "options": [ "Memory cells rapidly produce placental-crossing anti-Rh antibodies", "Gametes are brought together under controlled conditions before uterine placement", "Both homologues enter one daughter cell and neither enters the other", "Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary" ], "answer": 2, "explanation": "All resulting gametes have an abnormal chromosome number. Both homologues enter one daughter cell and neither enters the other." }, { "id": "reproduction-nondisjunction-integrated", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: homologous chromosomes fail to separate during meiosis I?", "options": [ "Maternal IgG may destroy fetal red blood cells — Memory cells rapidly produce placental-crossing anti-Rh antibodies", "Fertilization can bypass some causes of tubal or male-factor infertility — Gametes are brought together under controlled conditions before uterine placement", "Oestrogen falls while FSH and LH become persistently high — Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary", "All resulting gametes have an abnormal chromosome number — Both homologues enter one daughter cell and neither enters the other" ], "answer": 3, "explanation": "All resulting gametes have an abnormal chromosome number. Both homologues enter one daughter cell and neither enters the other." }, { "id": "reproduction-rh-disease-outcome", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "An Rh-negative sensitized mother carries an Rh-positive fetus. Which outcome follows most directly?", "options": [ "Maternal IgG may destroy fetal red blood cells", "Fertilization can bypass some causes of tubal or male-factor infertility", "Oestrogen falls while FSH and LH become persistently high", "Monozygotic twins with nearly identical nuclear genotypes form" ], "answer": 0, "explanation": "Maternal IgG may destroy fetal red blood cells. Memory cells rapidly produce placental-crossing anti-Rh antibodies." }, { "id": "reproduction-rh-disease-cause", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Which change most directly explains this observation: maternal IgG may destroy fetal red blood cells?", "options": [ "Eggs are fertilized with sperm in a laboratory and an embryo is transferred", "An Rh-negative sensitized mother carries an Rh-positive fetus", "Ovarian follicles are largely depleted", "One early embryo splits into two developing individuals" ], "answer": 1, "explanation": "Maternal IgG may destroy fetal red blood cells. Memory cells rapidly produce placental-crossing anti-Rh antibodies." }, { "id": "reproduction-rh-disease-mechanism", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "After an Rh-negative sensitized mother carries an Rh-positive fetus, which explanation best links the change to its outcome?", "options": [ "Gametes are brought together under controlled conditions before uterine placement", "Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary", "Memory cells rapidly produce placental-crossing anti-Rh antibodies", "Both individuals originate from the same fertilized egg rather than two separate eggs" ], "answer": 2, "explanation": "Maternal IgG may destroy fetal red blood cells. Memory cells rapidly produce placental-crossing anti-Rh antibodies." }, { "id": "reproduction-rh-disease-integrated", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: an Rh-negative sensitized mother carries an Rh-positive fetus?", "options": [ "Fertilization can bypass some causes of tubal or male-factor infertility — Gametes are brought together under controlled conditions before uterine placement", "Oestrogen falls while FSH and LH become persistently high — Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary", "Monozygotic twins with nearly identical nuclear genotypes form — Both individuals originate from the same fertilized egg rather than two separate eggs", "Maternal IgG may destroy fetal red blood cells — Memory cells rapidly produce placental-crossing anti-Rh antibodies" ], "answer": 3, "explanation": "Maternal IgG may destroy fetal red blood cells. Memory cells rapidly produce placental-crossing anti-Rh antibodies." }, { "id": "reproduction-ivf-outcome", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "After eggs are fertilized with sperm in a laboratory and an embryo is transferred, which observation is most likely?", "options": [ "Fertilization can bypass some causes of tubal or male-factor infertility", "Oestrogen falls while FSH and LH become persistently high", "Monozygotic twins with nearly identical nuclear genotypes form", "Haploid cells with varied allele combinations are produced" ], "answer": 0, "explanation": "Fertilization can bypass some causes of tubal or male-factor infertility. Gametes are brought together under controlled conditions before uterine placement." }, { "id": "reproduction-ivf-cause", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "A learner records that fertilization can bypass some causes of tubal or male-factor infertility. Which preceding event best accounts for it?", "options": [ "Ovarian follicles are largely depleted", "Eggs are fertilized with sperm in a laboratory and an embryo is transferred", "One early embryo splits into two developing individuals", "A diploid germ cell completes meiosis" ], "answer": 1, "explanation": "Fertilization can bypass some causes of tubal or male-factor infertility. Gametes are brought together under controlled conditions before uterine placement." }, { "id": "reproduction-ivf-mechanism", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "After eggs are fertilized with sperm in a laboratory and an embryo is transferred, which explanation best links the change to its outcome?", "options": [ "Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary", "Both individuals originate from the same fertilized egg rather than two separate eggs", "Gametes are brought together under controlled conditions before uterine placement", "Two divisions follow one DNA replication, with crossing over and independent assortment" ], "answer": 2, "explanation": "Fertilization can bypass some causes of tubal or male-factor infertility. Gametes are brought together under controlled conditions before uterine placement." }, { "id": "reproduction-ivf-integrated", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: eggs are fertilized with sperm in a laboratory and an embryo is transferred?", "options": [ "Haploid cells with varied allele combinations are produced — Two divisions follow one DNA replication, with crossing over and independent assortment", "Oestrogen falls while FSH and LH become persistently high — Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary", "Monozygotic twins with nearly identical nuclear genotypes form — Both individuals originate from the same fertilized egg rather than two separate eggs", "Fertilization can bypass some causes of tubal or male-factor infertility — Gametes are brought together under controlled conditions before uterine placement" ], "answer": 3, "explanation": "Fertilization can bypass some causes of tubal or male-factor infertility. Gametes are brought together under controlled conditions before uterine placement." }, { "id": "reproduction-menopause-outcome", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "A student models this change: Ovarian follicles are largely depleted. What should the model predict first?", "options": [ "Oestrogen falls while FSH and LH become persistently high", "Haploid cells with varied allele combinations are produced", "Monozygotic twins with nearly identical nuclear genotypes form", "Testosterone secretion increases" ], "answer": 0, "explanation": "Oestrogen falls while FSH and LH become persistently high. Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary." }, { "id": "reproduction-menopause-cause", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "What is the most likely cause when oestrogen falls while FSH and LH become persistently high?", "options": [ "One early embryo splits into two developing individuals", "Ovarian follicles are largely depleted", "LH stimulates interstitial cells in the testes", "A diploid germ cell completes meiosis" ], "answer": 1, "explanation": "Oestrogen falls while FSH and LH become persistently high. Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary." }, { "id": "reproduction-menopause-mechanism", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "After ovarian follicles are largely depleted, which explanation best links the change to its outcome?", "options": [ "Two divisions follow one DNA replication, with crossing over and independent assortment", "Both individuals originate from the same fertilized egg rather than two separate eggs", "Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary", "LH receptor signalling promotes steroid synthesis in Leydig cells" ], "answer": 2, "explanation": "Oestrogen falls while FSH and LH become persistently high. Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary." }, { "id": "reproduction-menopause-integrated", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: ovarian follicles are largely depleted?", "options": [ "Monozygotic twins with nearly identical nuclear genotypes form — Both individuals originate from the same fertilized egg rather than two separate eggs", "Testosterone secretion increases — LH receptor signalling promotes steroid synthesis in Leydig cells", "Haploid cells with varied allele combinations are produced — Two divisions follow one DNA replication, with crossing over and independent assortment", "Oestrogen falls while FSH and LH become persistently high — Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary" ], "answer": 3, "explanation": "Oestrogen falls while FSH and LH become persistently high. Loss of ovarian hormones removes negative feedback from hypothalamus and pituitary." }, { "id": "reproduction-twin-types-outcome", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Which immediate result is most consistent with this condition: One early embryo splits into two developing individuals?", "options": [ "Monozygotic twins with nearly identical nuclear genotypes form", "Testosterone secretion increases", "Sperm development is supported", "Haploid cells with varied allele combinations are produced" ], "answer": 0, "explanation": "Monozygotic twins with nearly identical nuclear genotypes form. Both individuals originate from the same fertilized egg rather than two separate eggs." }, { "id": "reproduction-twin-types-cause", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Which condition would most specifically produce this result: monozygotic twins with nearly identical nuclear genotypes form?", "options": [ "A diploid germ cell completes meiosis", "One early embryo splits into two developing individuals", "LH stimulates interstitial cells in the testes", "FSH and testosterone act on seminiferous tubules" ], "answer": 1, "explanation": "Monozygotic twins with nearly identical nuclear genotypes form. Both individuals originate from the same fertilized egg rather than two separate eggs." }, { "id": "reproduction-twin-types-mechanism", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "After one early embryo splits into two developing individuals, which explanation best links the change to its outcome?", "options": [ "Two divisions follow one DNA replication, with crossing over and independent assortment", "LH receptor signalling promotes steroid synthesis in Leydig cells", "Both individuals originate from the same fertilized egg rather than two separate eggs", "Sertoli cells respond by nurturing germ cells and regulating spermatogenesis" ], "answer": 2, "explanation": "Monozygotic twins with nearly identical nuclear genotypes form. Both individuals originate from the same fertilized egg rather than two separate eggs." }, { "id": "reproduction-twin-types-integrated", "chapter": "Reproduction", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: one early embryo splits into two developing individuals?", "options": [ "Haploid cells with varied allele combinations are produced — Two divisions follow one DNA replication, with crossing over and independent assortment", "Testosterone secretion increases — LH receptor signalling promotes steroid synthesis in Leydig cells", "Sperm development is supported — Sertoli cells respond by nurturing germ cells and regulating spermatogenesis", "Monozygotic twins with nearly identical nuclear genotypes form — Both individuals originate from the same fertilized egg rather than two separate eggs" ], "answer": 3, "explanation": "Monozygotic twins with nearly identical nuclear genotypes form. Both individuals originate from the same fertilized egg rather than two separate eggs." }, { "chapter": "Reproduction", "id": "applied-meiosis-number", "difficulty": "Standard", "stem": "An organism has 2n = 16 chromosomes. How many chromosomes are normally present in a gamete and in a zygote after fertilisation?", "options": [ "8 and 16", "16 and 32", "8 and 8", "4 and 16" ], "answer": 0, "explanation": "Meiosis halves the chromosome number to n = 8 in each gamete. Fusion of two haploid gametes restores 2n = 16." }, { "chapter": "Reproduction", "id": "applied-fertilisation-path", "difficulty": "Foundation", "stem": "Which location normally hosts fertilisation in humans?", "options": [ "Uterine cavity", "Uterine tube, usually its ampulla", "Cervix", "Vagina" ], "answer": 1, "explanation": "Fertilisation normally occurs in the uterine tube, usually the ampulla. The developing embryo subsequently travels to the uterus, where implantation normally occurs." }, { "chapter": "Reproduction", "id": "applied-hormone-pattern", "difficulty": "Challenge", "stem": "Which event is most closely associated with the sharp mid-cycle rise shown?", "options": [ "Sperm maturation", "Menstruation on that same day in every cycle", "Ovulation", "Implantation before fertilisation" ], "answer": 2, "explanation": "A mid-cycle LH surge triggers the events leading to ovulation. The values are illustrative; timing and hormone levels vary among individuals.", "visual": { "kind": "table", "caption": "Illustrative relative LH concentration during one cycle", "headers": [ "Cycle day", "Relative LH" ], "rows": [ [ "8", "5" ], [ "12", "7" ], [ "14", "45" ], [ "18", "6" ] ] } }, { "chapter": "Reproduction", "id": "applied-placental-exchange", "difficulty": "Standard", "stem": "Why can oxygen move from maternal blood to fetal blood without the two blood supplies normally mixing directly?", "options": [ "Maternal and fetal blood are the same continuous vessel system", "Fetal red cells routinely enter maternal arteries", "The placenta pumps atmospheric air into fetal lungs", "A thin exchange barrier allows diffusion down a partial-pressure gradient" ], "answer": 3, "explanation": "The placental exchange surface separates the blood supplies while allowing gases to diffuse across it. Exchange does not require unrestricted direct mixing of maternal and fetal blood." } ] }