Q40. Which organ sheds its inner lining during menstruation?
[RRB Technician Grade III — 9 October 2026]
(A) Fallopian tube
(B) Uterus
(C) Liver
(D) Ovary
Answer: (B) Uterus
Explanation: Menstrual bleeding occurs when the functional layer of the uterine endometrium breaks down and is expelled. Falling ovarian hormone levels trigger this process if implantation has not occurred. The ovaries regulate the cycle, but the lining being shed belongs to the uterus.
Q39. Which event is counted as Day 1 of the human menstrual cycle?
[RRB Technician Grade III — 8 October 2026, Shift 2]
(A) Beginning of menstrual bleeding
(B) Release of the secondary oocyte
(C) Union of sperm and ovum
(D) Embedding of the blastocyst
Answer: (A) Beginning of menstrual bleeding
Explanation: The menstrual cycle is conventionally counted from the first day of menstrual flow. At this time, the uterine lining is being shed. Ovulation generally occurs later during the cycle; fertilisation and implantation occur only when conception takes place.
Q38. What is the commonly cited average duration of a human menstrual cycle?
[RRB Technician Grade III — 8 October 2026, Shift 1]
(A) 60 days
(B) 7 days
(C) 14 days
(D) 28 days
Answer: (D) 28 days
Explanation: NCERT uses approximately 28 or 29 days as the typical menstrual cycle length. Actual cycles vary among individuals and can fluctuate over time. The duration is measured from the start of one menstrual period to the start of the next.
Q37. From where does a developing embryo of a placental mammal principally obtain nourishment?
[RRB Technician Grade III — 8 October 2026, Shift 1]
(A) Eggshell
(B) Maternal body
(C) Surrounding pond water
(D) An external yolk sac alone
Answer: (B) Maternal body
Explanation: In placental mammals, nutrients and oxygen reach the developing conceptus from maternal circulation through the placenta. Maternal and fetal blood generally remain separated by placental tissue. This arrangement supports sustained embryonic and fetal growth within the uterus.
Q36. Why is feeding colostrum to a newborn especially beneficial?
[RRB Technician Grade III — 6 October 2026, Shift 3]
(A) It changes the newborn’s blood group
(B) It guarantees early tooth eruption
(C) It replaces all vaccinations
(D) It supplies antibodies and nutrients
Answer: (D) It supplies antibodies and nutrients
Explanation: Colostrum is the first milk produced around childbirth. It is rich in protective immunoglobulins, especially secretory IgA, and provides concentrated nutrients. Early breastfeeding helps protect the infant against infection while feeding and bonding are established after delivery.
Q35. In spermatogenesis, which cell undergoes the first meiotic division?
[UPSC NDA — 12 April 2026]
(A) Spermatogonium
(B) Primary spermatocyte
(C) Secondary spermatocyte
(D) Sertoli cell
Answer: (B) Primary spermatocyte
Explanation: A diploid primary spermatocyte enters meiosis I and produces two haploid secondary spermatocytes. Each secondary spermatocyte then undergoes meiosis II, forming spermatids. Spermatogonia multiply mitotically, while Sertoli cells support the differentiating germ cells inside seminiferous tubules.
Q34. Which structure is absent from the normal male reproductive system?
[UPSC CDS II (General Knowledge) — 14 September 2025]
(A) Prostate gland
(B) Testis
(C) Cervix
(D) Scrotum
Answer: (C) Cervix
Explanation: The cervix is the narrow lower part of the uterus that opens into the vagina and belongs to female reproductive anatomy. The testes produce sperm, the scrotum houses the testes, and the prostate contributes secretions to semen.
Q33. Which pair consists entirely of structures of the male reproductive system?
[RRB NTPC Graduate Level, Stage II — 13 October 2025]
(A) Vas deferens and oviduct
(B) Uterus and vagina
(C) Oviduct and penis
(D) Vas deferens and scrotum
Answer: (D) Vas deferens and scrotum
Explanation: The vas deferens transports sperm from the epididymis toward the ejaculatory duct, while the scrotum contains the testes. An oviduct, uterus and vagina belong to the female reproductive tract. Therefore, only the final pair contains two male structures.
Q32. The uterus communicates with the vagina through which structure?
[RRB Paramedical — 28 April 2025]
(A) Oviduct
(B) Vas deferens
(C) Ovary
(D) Cervix
Answer: (D) Cervix
Explanation: The cervix is the lower cylindrical part of the uterus. Its cervical canal connects the uterine cavity with the vagina, allowing menstrual flow outward and sperm passage inward. During childbirth, the cervix dilates to permit delivery of the baby.
Q31. What is the biological term for the first menstrual period?
[NEET UG — 2025]
(A) Menopause
(B) Menarche
(C) Ovulation
(D) Implantation
Answer: (B) Menarche
Explanation: Menarche marks the first menstrual bleeding and generally occurs during puberty as ovarian and uterine cycles mature. Menopause denotes the permanent cessation of menstrual cycles later in life. Ovulation means oocyte release, whereas implantation occurs after fertilisation.
Q30. Which tube serves as the common outlet for urine and semen in human males?
[RRB Technician Grade III — 30 December 2024]
(A) Urethra
(B) Urinary bladder
(C) Scrotum
(D) Vas deferens
Answer: (A) Urethra
Explanation: The male urethra carries urine from the bladder and semen during ejaculation, although these functions are regulated separately. The vas deferens carries sperm toward the ejaculatory duct. The bladder stores urine, and the scrotum contains the testes.
Q29. Through which organ are oxygen and nutrients transferred to a growing fetus?
[RRB Technician Grade III — 28 December 2024]
(A) Scrotum
(B) Placenta
(C) Oviduct
(D) Ovary
Answer: (B) Placenta
Explanation: The placenta is the exchange organ joining maternal supply with fetal needs. Nutrients and oxygen cross its barrier into fetal circulation, while carbon dioxide and wastes move in the opposite direction. It also produces hormones important for sustaining pregnancy.
Q28. Why are human testes located in the scrotum outside the abdominal cavity?
[RRB Technician Grade III — 28 December 2024]
(A) To keep them much hotter than the body
(B) To maintain a temperature below core body temperature
(C) To ensure they remain at exactly core temperature
(D) To store urine temporarily
Answer: (B) To maintain a temperature below core body temperature
Explanation: Sperm production functions optimally at a temperature roughly 2–2.5°C below core body temperature. The scrotum, with muscular and vascular temperature-regulating mechanisms, helps maintain this cooler environment. Excessive sustained heat may impair normal spermatogenesis.
Q27. Which structure transports the ovulated oocyte toward the uterus?
[RRB Technician Grade III — 24 December 2024]
(A) Fallopian tube
(B) Vagina
(C) Cervix
(D) Placenta
Answer: (A) Fallopian tube
Explanation: Fimbriae near the infundibulum help collect the released secondary oocyte. Ciliary movement and muscular contractions move it through the oviduct toward the uterus. Fertilisation usually occurs in the ampullary–isthmic region of the fallopian tube.
Q26. Which human reproductive cell is motile by means of a flagellum?
[RRB Junior Engineer, Stage I — 16 December 2024]
(A) Embryo
(B) Ovum
(C) Spermatozoon
(D) Zygote
Answer: (C) Spermatozoon
Explanation: A mature spermatozoon possesses a flagellar tail whose movement provides propulsion through fluid. Mitochondria in its middle piece supply energy. The human secondary oocyte is not independently motile, and neither the zygote nor the embryo is a flagellated gamete.
Q25. Which combination chiefly generates genetic variation during sexual reproduction?
[UPSC NDA — 3 September 2023]
(A) Mitosis and budding
(B) Meiosis and fertilisation
(C) Binary fission and mitosis
(D) Vegetative propagation and fragmentation
Answer: (B) Meiosis and fertilisation
Explanation: During meiosis, crossing over and independent assortment create genetically varied haploid gametes. Random fertilisation then combines genetic information from two parents in new ways. Mitosis and asexual reproductive processes generally preserve parental genetic combinations more closely.
Q24. Which kind of cell division is called reduction division?
[SSC CHSL Tier I — 8 August 2023]
(A) Telophase
(B) Meiosis
(C) Prophase
(D) Mitosis
Answer: (B) Meiosis
Explanation: Meiosis I reduces chromosome number from diploid to haploid by separating homologous chromosome pairs. This allows fertilisation to restore diploidy without doubling the chromosome count every generation. Mitosis maintains chromosome number, while prophase and telophase are division stages.
Q23. What does IVF stand for in reproductive biology?
[SSC MTS, 2022 Cycle (exam held 2 May 2023)]
(A) In vitro fragmentation
(B) In vitro fertilisation
(C) Internal vascular fusion
(D) In vivo fission
Answer: (B) In vitro fertilisation
Explanation: In vitro fertilisation involves bringing sperm and oocytes together under laboratory conditions. Following fertilisation and early embryo culture, an embryo can be transferred to the uterus. It is an assisted reproductive technique and differs from normal internal fertilisation.
Q22. What process occurs when the endometrium breaks down in the absence of pregnancy?
[RRB Group D — 29 September 2022]
(A) Menopause
(B) Menstruation
(C) Spermiation
(D) Implantation
Answer: (B) Menstruation
Explanation: When fertilisation and implantation do not occur, the corpus luteum degenerates and progesterone and oestrogen levels fall. This causes the functional uterine lining to disintegrate, producing menstrual flow. Menopause, by contrast, represents permanent cessation of ovarian cycles.
Q21. In which part of the female reproductive tract does human fertilisation normally occur?
[RRB Group D — 28 September 2022]
(A) Vagina
(B) Uterine cavity
(C) Cervix
(D) Ampullary–isthmic region of the oviduct
Answer: (D) Ampullary–isthmic region of the oviduct
Explanation: Human sperm generally meet the secondary oocyte in the ampullary–isthmic region of the fallopian tube. Fusion initiates development of a diploid zygote, which undergoes cleavage during passage toward the uterus. Implantation subsequently takes place in the endometrium.
Q20. Which sperm part contains the X or Y chromosome involved in determining chromosomal sex?
[RRB Group D — 30 September 2022]
(A) Middle piece
(B) Head
(C) Tail
(D) Neck only
Answer: (B) Head
Explanation: The sperm head contains the haploid nucleus bearing either an X or a Y chromosome. The oocyte ordinarily provides an X chromosome. Combining these at fertilisation establishes the typical XX or XY chromosomal complement of the resulting zygote.
Q19. Which embryological process produces the three primary germ layers?
[DSSSB PGT Biology (Female) — 16 July 2021]
(A) Fertilisation
(B) Cleavage
(C) Gastrulation
(D) Spermiogenesis
Answer: (C) Gastrulation
Explanation: Gastrulation reorganises early embryonic cells into ectoderm, mesoderm and endoderm. These layers give rise to different tissues and organ systems during later differentiation. Fertilisation forms the zygote, cleavage increases blastomere number, and spermiogenesis produces mature sperm morphology.
Q18. When does a human secondary oocyte complete its second meiotic division?
[NEET UG — 2020]
(A) Before entering the fallopian tube
(B) After the entry of a sperm
(C) During fetal ovarian development
(D) Only after implantation
Answer: (B) After the entry of a sperm
Explanation: The secondary oocyte remains arrested in metaphase II after ovulation. Sperm entry triggers completion of meiosis II, generating the mature ovum and second polar body. This is followed by formation and fusion of pronuclei to establish the zygote.
Q17. Which description correctly explains the expression “test-tube baby”?
[RRB Junior Engineer — 31 May 2019]
(A) Both fertilisation and development occur in a tube
(B) Fertilisation occurs outside the body and further development occurs in the uterus
(C) Fertilisation occurs only in the uterus but birth is in a laboratory
(D) The embryo develops entirely outside the maternal body
Answer: (B) Fertilisation occurs outside the body and further development occurs in the uterus
Explanation: The popular expression refers to in vitro fertilisation followed by embryo transfer. Gametes are brought together under controlled laboratory conditions; after initial development, an embryo is placed in the uterus, where implantation and subsequent fetal development can occur.
Q16. Fertilisation in humans is normally classified as which type?
[SSC MTS — 14 August 2019]
(A) Internal fertilisation
(B) External fertilisation
(C) External budding
(D) Vegetative fertilisation
Answer: (A) Internal fertilisation
Explanation: In humans, sperm and secondary oocyte ordinarily unite within the female reproductive tract, specifically the oviduct. This is internal fertilisation. External fertilisation takes place outside the body, such as in many aquatic animals, and is not the normal human mechanism.
Q15. Which is the correct route followed by sperm from the seminiferous tubules?
[NEET UG — 2019]
(A) Seminiferous tubules → epididymis → rete testis → vas deferens
(B) Seminiferous tubules → rete testis → vasa efferentia → epididymis → vas deferens
(C) Seminiferous tubules → vas deferens → rete testis → epididymis
(D) Seminiferous tubules → ureter → bladder → urethra
Answer: (B) Seminiferous tubules → rete testis → vasa efferentia → epididymis → vas deferens
Explanation: Sperm leave seminiferous tubules through the rete testis, then pass into the vasa efferentia and epididymis. Following maturation and storage, they travel along the vas deferens toward the ejaculatory duct. The ureter belongs to the urinary system.
Q14. Which early milk contains important maternal antibodies for the newborn?
[UPSC CDS — 18 November 2018]
(A) Ordinary milk secreted months after birth
(B) Transitional milk alone
(C) Colostrum
(D) Artificially fortified water
Answer: (C) Colostrum
Explanation: Colostrum is the yellowish first milk produced immediately after childbirth. It contains high concentrations of protective antibodies and useful proteins. Its immunological benefits are particularly valuable before the infant’s own immune defences become fully mature, making early feeding important.
Q13. Arrange these reproductive events in order:
1. Implantation;
2. Ovulation;
3. Sex determination;
4. Fertilisation.
[UPPSC LT Grade Assistant Teacher (Home Science) — 29 July 2018]
(A) 4, 3, 1, 2
(B) 2, 4, 3, 1
(C) 2, 3, 1, 4
(D) 1, 3, 4, 2
Answer: (B) 2, 4, 3, 1
Explanation: Ovulation releases the secondary oocyte; fertilisation follows if sperm reaches it. Chromosomal sex is fixed at fertilisation by the sperm’s X or Y chromosome, so these events are essentially simultaneous biologically. Cleavage precedes later implantation of the blastocyst.
Q12. The release of mature spermatozoa from Sertoli cells into seminiferous tubule lumens is called what?
[UPPSC GIC Lecturer (Zoology) — 2017]
(A) Spermiation
(B) Azoospermia
(C) Spermiogenesis
(D) Oogenesis
Answer: (A) Spermiation
Explanation: Spermiation is the detachment and release of differentiated spermatozoa from Sertoli cells into the seminiferous tubule lumen. Spermiogenesis is the preceding transformation of spermatids into spermatozoa. Azoospermia is the absence of sperm in ejaculated semen.
Q11. Where does sperm formation occur inside the testes?
[RPSC Second Grade Teacher (Science) — 1 July 2017]
(A) Epididymis
(B) Vas deferens
(C) Prostate gland
(D) Seminiferous tubules
Answer: (D) Seminiferous tubules
Explanation: Spermatogenesis takes place in the germinal epithelium of seminiferous tubules, supported by Sertoli cells. The epididymis is important for later sperm maturation and storage. The vas deferens transports sperm, while the prostate adds secretions to semen.
Q10. What is introduced into the female reproductive tract during artificial insemination?
[UPSC CDS — 14 February 2016]
(A) An unfertilised egg alone
(B) A fully developed fetus
(C) Semen containing sperm
(D) A blastocyst and an egg together
Answer: (C) Semen containing sperm
Explanation: Artificial insemination introduces semen containing sperm into the female reproductive tract, commonly the cervix or uterus, without normal intercourse. Fertilisation may then occur inside the oviduct. It differs from in vitro fertilisation, where gamete fusion occurs in a laboratory.
Q9. Select the correct sequence of cell types during spermatogenesis.
[RPSC Second Grade Teacher (Science) — 2015]
(A) Spermatogonia → spermatocytes → spermatids → spermatozoa
(B) Spermatogonia → spermatids → spermatocytes → spermatozoa
(C) Spermatocytes → spermatogonia → spermatids → spermatozoa
(D) Spermatids → spermatogonia → spermatocytes → spermatozoa
Answer: (A) Spermatogonia → spermatocytes → spermatids → spermatozoa
Explanation: Diploid spermatogonia give rise to primary spermatocytes, which undergo meiosis to produce haploid spermatids through a secondary spermatocyte stage. Spermiogenesis then remodels spermatids into spermatozoa. The progression represents multiplication, maturation and differentiation within seminiferous tubules.
Q8. Which region of the human oviduct lies nearest the ovary?
[AIPMT Preliminary Examination — 2010]
(A) Infundibulum
(B) Isthmus
(C) Ampulla
(D) Uterine part
Answer: (A) Infundibulum
Explanation: The infundibulum is the funnel-shaped ovarian end of the fallopian tube, bearing fingerlike fimbriae that help collect the released oocyte. The wider ampulla follows, while the narrower isthmus approaches the uterus. Fertilisation commonly occurs near their junction.
Q7. What principally initiates the fetal ejection reflex at the end of pregnancy?
[AIPMT — 2009]
(A) A sudden fall in maternal blood glucose
(B) Signals from the fully developed fetus and placenta, together with cervical stretching
(C) Increased secretion of melatonin
(D) Disappearance of all placental hormones
Answer: (B) Signals from the fully developed fetus and placenta, together with cervical stretching
Explanation: Signals associated with the mature fetus and placenta initiate mild uterine contractions and cervical stretching. Neural feedback promotes maternal oxytocin release, which intensifies contractions through a positive-feedback mechanism. This cycle facilitates expulsion of the fetus during parturition.
Q6. Which extraembryonic membrane protects the developing human embryo within an enclosing fluid?
[AIPMT — 2008]
(A) Amnion
(B) Chorion
(C) Yolk sac
(D) Allantois
Answer: (A) Amnion
Explanation: The amnion forms an enclosing sac containing amniotic fluid. This fluid cushions the developing embryo and fetus, protects against mechanical shocks and helps prevent drying. The chorion contributes to placental structures; the other membranes perform different developmental roles.
Q5. Which ovarian structure functions as an endocrine gland after ovulation?
[AIPMT — 2007]
(A) Primary follicle
(B) Corpus luteum
(C) Zona pellucida
(D) Oogonium
Answer: (B) Corpus luteum
Explanation: After ovulation, cells of the ruptured Graafian follicle reorganise into the corpus luteum. This temporary endocrine structure secretes progesterone and some oestrogen, helping maintain the endometrium. Without pregnancy, it normally regresses and hormone concentrations fall.
Q4. Which anterior pituitary hormone chiefly acts on Sertoli cells?
[AIPMT — 2006]
(A) LH
(B) TSH
(C) FSH
(D) ACTH
Answer: (C) FSH
Explanation: Follicle-stimulating hormone acts on Sertoli cells to support spermatogenesis, including production of androgen-binding protein and inhibin. Luteinising hormone acts mainly on Leydig cells, stimulating testosterone secretion. Thyroid-stimulating hormone and ACTH target different endocrine glands.
Q3. Which hormone is NOT secreted by the human placenta?
[AIPMT — 2004]
(A) Oestrogens
(B) Progesterone
(C) Prolactin
(D) Human chorionic gonadotropin
Answer: (C) Prolactin
Explanation: Human placenta releases hCG, human placental lactogen, progesterone and oestrogens during pregnancy. Prolactin, which supports milk synthesis in mammary glands, is primarily secreted by the maternal anterior pituitary. Therefore, prolactin is not regarded as a placental secretion.
Q2. The establishment of anterior–posterior and dorsal–ventral polarity in an embryo is termed what?
[AIPMT — 2003]
(A) Organizer phenomenon
(B) Pattern formation
(C) Binary fission
(D) Spermiation
Answer: (B) Pattern formation
Explanation: Pattern formation establishes spatial identities and body axes in the developing embryo, enabling cells to adopt region-specific fates. Signalling gradients and regulatory genes coordinate this organisation. It differs from cleavage, which increases cell number, and from spermiation, which releases sperm.
Q1. What happens to individual cell size during early cleavage of a mammalian zygote?
[AIPMT — 2002]
(A) The whole embryo shrinks continuously
(B) The embryo greatly increases in total size
(C) Individual blastomeres increase steadily in size
(D) Individual blastomeres become progressively smaller
Answer: (D) Individual blastomeres become progressively smaller
Explanation: Cleavage consists of rapid mitotic divisions without substantial growth between divisions. Consequently, the original zygotic cytoplasm becomes distributed among increasingly numerous, smaller blastomeres. The embryo generally remains enclosed by the zona pellucida during these initial developmental stages.