NEET Human Reproduction Previous Year Questions with Solutions

The male sex accessory ducts include the rete testis, vasa efferentia, epididymis, and vas deferens. Sperm generated in seminiferous tubules pass sequentially through these ducts to mature and undergo transport.

• • Options (1), (2), and (3) belong to the male reproductive system.

Each Fallopian tube is 10–12 cm long and consists of three distinct segments: (1) Infundibulum (the funnel-shaped opening closest to the ovary, featuring finger-like fimbriae that collect the ovum after ovulation), (2) Ampulla (the wider middle region where fertilization occurs), and (3) Isthmus (the narrow terminal lumen joining the uterus).

• • Infundibulum is exclusively a female reproductive structure.

Infundibulum is part of the female reproductive system, and therefore not part of the male reproductive system.

• • Matches official NTA final answer key Option D / (4).

Both LH and FSH attain a peak level in the middle of the menstrual cycle (around day 14). Rapid secretion of LH leading to its maximum concentration (termed the LH surge) induces rupture of the mature tertiary Graafian follicle and release of the secondary oocyte into the peritoneal cavity.

• • Statement I is factually and physiologically accurate.

Following ovulation, the remaining granulosa and theca cells of the ruptured Graafian follicle undergo luteinization under LH stimulation to form a yellow endocrine body, the corpus luteum. The corpus luteum secretes large quantities of PROGESTERONE, which maintains the secretory endometrium for implantation.

• • While a minor amount of estrogen is produced, progesterone is the primary, defining hormone.
• • Stating that it "secretes large amount of estrogen" is a classic NTA trap and is incorrect.

Statement I is correct, but Statement II is incorrect. This corresponds to Option (3).

• • Matches official NTA final answer key Option C / (3).

Placenta acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progestogens, and in the later phase of pregnancy, a hormone called relaxin is also secreted by the ovary/placenta.

• • Hormones like hCG, hPL and relaxin are produced in women only during pregnancy.

Luteinizing hormone (LH) is a pituitary gonadotropin secreted by gonadotroph cells of the anterior pituitary gland under the stimulation of hypothalamic GnRH. It is never synthesized or secreted by placental trophoblasts.

• • hCG shares structural homology with LH and binds LH receptors to maintain the corpus luteum, but LH itself is strictly of pituitary origin.

During oogenesis, the primary oocyte completes its first meiotic division within the tertiary follicle to form a secondary oocyte and a tiny first polar body. The secondary oocyte forms a new acellular glycoprotein membrane around itself called zona pellucida.

• • Zona pellucida contains sperm-binding glycoproteins ZP1, ZP2, and ZP3.

Outside the zona pellucida lies the corona radiata, formed of radially elongated follicle/granulosa cells. During fertilization, sperm acrosomal enzymes (hyaluronidase and acrosin) penetrate the corona radiata and digest the zona pellucida. Contact of one sperm induces a cortical reaction in the zona pellucida, blocking polyspermy.

• • Prevents polyspermy and ectopic implantation in the fallopian tube.

A human sperm is a microscopic structure composed of four distinct anatomical regions enclosed by a plasma membrane:

• • Head: Contains an elongated haploid nucleus holding the paternal Genetic material (DNA/chromosomes). Hence, A matches IV.
• • Middle piece: Possesses numerous spirally arranged mitochondria (nebenkern) that produce ATP/Energy for the movement of the tail. Hence, B matches III.
• • Acrosome: An anterior cap-like structure derived from the Golgi apparatus, filled with hydrolytic Enzymes (hyaluronidase, corona penetrating enzyme, acrosin) that facilitate penetration of the zona pellucida of the ovum. Hence, C matches I.
• • Tail: A long flagellum consisting of an axial filament that facilitates vigorous Sperm motility, essential for traveling through the female reproductive tract to reach the ampullary region. Hence, D matches II.

Assembling the individual pairings:

• • A -> IV (Head - Genetic material)
• • B -> III (Middle piece - Energy)
• • C -> I (Acrosome - Enzymes)
• • D -> II (Tail - Sperm motility)

The unambiguous combination is A-IV, B-III, C-I, D-II, corresponding to Option (1).

Human gestation lasts 9 months (3 trimesters / ~38 weeks). NCERT documents the following precise developmental milestones:

• • After 1 month of pregnancy: The embryo's heart is formed. The first sign of growing foetus may be noticed by listening to the heart sound carefully through the stethoscope. Hence, Statement C is correct.
• • By the end of the second month of pregnancy (8 weeks): The foetus develops limbs and digits. Hence, Statement D is correct.
• • By the end of 12 weeks (first trimester): Most of the major organ systems are formed, for example, the limbs and external genital organs are well-developed. Hence, Statement A is correct, and Statement B (which claims 8 weeks) is incorrect.
• • During the fifth month: The first movements of the foetus and appearance of hair on the head are usually observed. Hence, Statement E is correct.
• • By the end of 24 weeks (second trimester): The body is covered with fine hair, eye-lids separate, and eyelashes are formed.
• • By the end of 9 months: The foetus is fully developed and is ready for delivery.

Evaluating all five candidate statements:

• • A: Correct (12 weeks = major organ systems).
• • B: Incorrect (contradicts 12 weeks milestone).
• • C: Correct (1 month = heart formed).
• • D: Correct (end of 2nd month = limbs and digits).
• • E: Correct (5th month = hair on head observed).

Statements A, C, D, and E Only are correct. This corresponds unambiguously to Option (4).

Spermatogenesis and oogenesis exhibit profound temporal differences:

• • Initiation: Oogenesis is initiated during the embryonic development stage when a couple of million gamete mother cells (oogonia) are formed within each foetal ovary; no more oogonia are formed and added after birth. Primary oocytes enter prophase-I of meiosis-I and get temporarily arrested. In contrast, spermatogenesis starts only at puberty due to the significant increase in the secretion of GnRH. Therefore, reductive division begins much earlier in females. Statement A is TRUE.
• • Inter-meiotic Interval (Gap): In males, primary spermatocytes complete Meiosis I to form secondary spermatocytes, which immediately undergo Meiosis II to form spermatids (duration is just hours to days). In females, Meiosis I completes only at puberty inside the tertiary follicle (a gap of 12 to 50 years!), and Meiosis II is arrested at Metaphase II until sperm entry at fertilization. Hence, the gap between meiosis I and II is vastly shorter in males. Statement B is TRUE.

Cytoplasmic division during female meiosis:

• • Oogonia divide mitotically to form primary oocytes (which are diploid and arrested in prophase I).
• • The first meiotic division of the primary oocyte is unequal, resulting in the formation of a large haploid secondary oocyte and a tiny first polar body.
• • Thus, the first polar body is associated with the formation of the secondary oocyte, NOT the primary oocyte. Statement C is FALSE.

Hormonal events of the menstrual cycle:

• • Both LH and FSH attain a peak level in the middle of the cycle (about 14th day). Rapid secretion of LH leading to its maximum level during the mid-cycle called LH surge induces rupture of Graafian follicle and thereby the release of ovum (ovulation).
• • Menstrual flow and endometrial sloughing result from the degeneration of the corpus luteum and subsequent precipitous drop in progesterone levels, not from the LH surge. Statement D is FALSE.

Statements A and B are true, while C and D are false. This matches Option (1).

The reproductive life of human females is demarcated by two canonical physiological milestones:

• • Menarche: The very first menstrual bleeding marking the onset of puberty (typically between ages 11–14). It signifies the activation of the hypothalamic-pituitary-ovarian axis.
• • Menopause: The permanent cessation of menstrual cycles and ovarian follicular activity, occurring naturally around 45–50 years of age.

Distinguishing unrelated biological phenomena:

• • Diapause: A stage of suspended physiological development or metabolic dormancy exhibited by many zooplankton species in lakes and ponds to avoid unfavorable conditions.
• • Ovulation: The mid-cycle process occurring under the influence of the LH surge where the mature Graafian follicle ruptures to release the secondary oocyte into the peritoneal cavity.

The first menstruation is scientifically designated as Menarche, matching Option (2).

Multiple gestations in humans occur via two distinct physiological mechanisms:

• • Monozygotic (Identical) Twins: Arise from the cleavage and separation of a single blastocyst derived from a single fertilization event (one sperm + one ovum). Because they inherit identical nuclear genomes, monozygotic twins are invariably concordant for chromosomal sex (strictly both XX or both XY).
• • Dizygotic (Fraternal) Twins: Arise when two separate primary follicles mature and ovulate simultaneously (polyovulation). Each ovum is fertilized by an independent sperm cell, producing two genetically distinct zygotes.

Analyzing the sex chromosomes of the newborn twins:

• • The boy twin possesses an $XY$ chromosomal constitution (formed by union of an $X$-bearing ovum and a $Y$-bearing sperm).
• • The girl twin possesses an $XX$ chromosomal constitution (formed by union of an $X$-bearing ovum and an $X$-bearing sperm).
• • Because they have different sex chromosome karyotypes, they could not have arisen from the cleavage of a single zygote.
• • They must have developed from two distinct zygotes produced by two separate fertilization events. Thus, they are fraternal twins.

Why the remaining options are incorrect:

• • Option (1): They are monozygotic twins -> Impossible for opposite-sex twins.
• • Option (3): Conceived through IVF -> Fraternal twins occur frequently through natural polyovulation; IVF is not mandatory.
• • Option (4): Have 75% identical genetic content -> Fraternal twins share, on average, 50% of their segregating genetic material, identical to ordinary siblings.

The deduction that must be true is that they are fraternal twins, matching Option (2).

In males, Luteinizing Hormone (LH) acts at the Leydig cells (interstitial cells) and stimulates synthesis and secretion of androgens. Follicle Stimulating Hormone (FSH) acts on the Sertoli cells and stimulates secretion of some factors which help in the process of spermiogenesis. Claiming FSH acts upon Leydig cells is factually false. Thus, Assertion A is false.

Growing ovarian follicles actively synthesize and secrete estrogens in females under FSH stimulation. In males, the interstitial cells of Leydig secrete androgens (principally testosterone). Thus, Reason R is a true statement.

Assertion A is false but Reason R is true, matching Option (2).

The mammary glands of the female undergo differentiation during pregnancy and start producing milk towards the end of pregnancy by the process called lactation. Breast-feeding during the initial period of infant growth is strongly recommended by physicians for bringing up a healthy baby. Assertion A is true.

The milk produced during the initial few days of lactation is called colostrum. It contains several antibodies (particularly secretory $IgA$) absolutely essential to develop passive immunity and systemic resistance in the newborn baby whose immune system is still immature. Reason R is true.

The protective immunological defense conferred by colostrum antibodies is the exact physiological rationale why breast-feeding is recommended. Thus, Reason R is the correct explanation of Assertion A.

Each fallopian tube (oviduct) is about 10-12 cm long and extends from the periphery of each ovary to the uterus. The part closer to the ovary is the funnel-shaped infundibulum. The edges of the infundibulum possess finger-like projections called fimbriae. The infundibulum leads to a wider part of the oviduct called ampulla. The last part of the oviduct, isthmus, has a narrow lumen and it joins the uterus.

The uterus is hollow, pear-shaped and consists of three anatomical regions: fundus (upper dome-shaped region), body/corpus (main central portion), and cervix (lower narrow canal opening into vagina).

Uterine fundus belongs to the uterus, not the fallopian tube.

NCERT states: "The presence or absence of hymen is not a reliable indicator of virginity or sexual experience." Statement I is true.

The hymen is often torn during the first coitus (intercourse). However, it can also be broken by a sudden fall or jolt, insertion of a vaginal tampon, active participation in some sports like horseback riding, cycling, etc. In some women the hymen persists even after coitus. Therefore, asserting it is torn during the first coitus "only" is medically and factually incorrect. Statement II is false.

Statement I is true but Statement II is false, matching Option (1).

Spermatogenesis starts at the age of puberty due to significant increase in the secretion of gonadotropin releasing hormone (GnRH). GnRH acts at the anterior pituitary gland and stimulates secretion of two gonadotropins: luteinizing hormone (LH) and follicle stimulating hormone (FSH, Label A).

LH acts at the Leydig cells (interstitial cells, Label B) and stimulates synthesis and secretion of androgens. Androgens, in turn, stimulate the process of spermatogenesis. FSH acts on the Sertoli cells (Label C) and stimulates secretion of some factors.

The factors secreted by Sertoli cells under FSH influence are required specifically for the transformation of non-motile spermatids into functional spermatozoa, a process termed spermiogenesis (Label D).

Cyclical reproductive changes in placental mammals are categorized into two major patterns based on taxonomic orders: - In non-primate mammals (cows, sheep, rats, deers, dogs, tiger): oestrus cycle. - In primates (monkeys, apes, humans): menstrual cycle. Statement A is TRUE.

The onset of menstruation at puberty in human females is termed menarche, whereas the permanent cessation of reproductive cycling around age 50 is termed menopause: Statement B claims the first menstrual cycle is called menopause, which is blatantly FALSE.

NCERT states verbatim: - "Lack of menstruation may be indicative of pregnancy." (Statement C is TRUE) - "Cyclic menstruation is an indicator of normal reproductive phase and extends between menarche and menopause." (Statement D is TRUE) Therefore, Statements A, C, and D are correct.

The vas deferens ascends from the scrotum, enters the pelvic cavity through the inguinal canal, loops over the urinary bladder, and unites with the duct of the seminal vesicle to form the common ejaculatory duct:

In the human female reproductive tract, the narrow spindle-shaped lumen traversing the cervix connects the uterine body to the vagina:

NCERT states verbatim: - "It [vas deferens] receives a duct from seminal vesicle and opens into urethra as the ejaculatory duct." (Statement I is TRUE) - "The cavity of the cervix is called cervical canal which along with vagina forms the birth canal." (Statement II is TRUE)

Following fertilization and cleavage in the fallopian tube, the blastocyst reaches the uterine cavity. The trophoblast layer attaches to the glandular, highly vascularized uterine endometrium, embedding the embryo in the process known as implantation:

In an unfertilized ovarian cycle, declining LH levels lead to the regression of the corpus luteum into a fibrotic scar (corpus albicans). The subsequent collapse of circulating progesterone withdraws hormonal support, causing spiral arteriolar spasm, necrosis, and menstrual disintegration of the stratum functionale:

Assertion states that the endometrium is necessary for implantation. The biological explanation for this is that the endometrium provides the rich vascular supply, decidual reaction, and placental anchorage required to sustain fetal development. Reason explains why menstruation occurs in the *absence* of pregnancy. Thus, R does NOT explain A.

At the time of ovulation and subsequent fertilization in the ampulla of the fallopian tube, the secondary oocyte is surrounded by three structural barriers: 1. Corona radiata: An outer cellular coat composed of follicular granulosa cells cemented by hyaluronic acid. 2. Zona pellucida: A thick, non-cellular, transparent glycoprotein coat secreted by the oocyte and surrounding follicle cells. 3. Perivitelline space: Fluid-filled space separating the zona pellucida from the underlying vitelline membrane (plasma membrane/oolemma).

The zona pellucida is composed of four primary glycoproteins: ZP1, ZP2, ZP3, and ZP4. ZP3 functions as the primary sperm receptor: - Proteins on the sperm head plasma membrane specifically bind ZP3. - This binding triggers an influx of $Ca^{2+}$ into the sperm, initiating the acrosome reaction. - Hydrolytic enzymes (acrosin, hyaluronidase) digest a path through the zona pellucida. - Upon entry of the first sperm, cortical granules release enzymes into the perivitelline space that alter the zona pellucida (zona reaction or cortical reaction), destroying remaining ZP3 receptors to permanently block polyspermy.

Parturition (the process of delivering the foetus through labor) is governed by an integrated neuroendocrine mechanism known as the foetal ejection reflex: - Signals for parturition originate from the fully developed foetus and placenta, inducing mild uterine contractions. - (1) Estrogen-to-Progesterone Ratio: In late pregnancy, placental estrogen synthesis rises while local progesterone dominance declines. This high estrogen/progesterone ratio upregulates oxytocin receptors on myometrial smooth muscle cells and promotes gap junction formation between myocytes. - (3) Oxytocin Release: Maternal posterior pituitary secretes oxytocin, which acts directly on the myometrium to cause vigorous contractions. - (2) Prostaglandin Synthesis: Uterine decidua and fetal membranes synthesize prostaglandins ($PGF_{2\alpha}$ and $PGE_2$), which further amplify uterine contractions and soften/dilate the cervix in a positive feedback loop (Ferguson reflex).

Prolactin (PRL) is an anterior pituitary peptide hormone that stimulates the differentiation of mammary alveolar epithelium and drives milk synthesis during the puerperium (lactation). During pregnancy, high circulating levels of placental steroids (estrogen and progesterone) block the lactogenic action of prolactin on the breasts. Following parturition and placental expulsion, steroid levels plummet, disinhibiting prolactin to initiate copious milk production. Prolactin has zero stimulatory effect on myometrial contraction or labor initiation.

During human pregnancy, the placenta acts as a temporary endocrine gland producing hormones essential for fetal maintenance: human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, and progesterone. - In the later phase of pregnancy, a peptide hormone called relaxin is secreted by the maternal ovary, specifically by the corpus luteum (and in minor amounts by the placenta/decidua). - Physiological Action: Relaxin loosens and relaxes the fibrous pubic symphysis (interpubic fibrocartilage) and softens the cervix, expanding the pelvic outlet to facilitate unimpeded passage of the foetus during parturition.

- Graafian follicle: Matures during the follicular phase of the non-pregnant menstrual cycle and ruptures at ovulation; it does not exist in late pregnancy. - Foetus: Does not secrete maternal relaxin to prepare maternal pelvic ligaments. - Uterus (Myometrium/Endometrium): Acts as the target organ responding to oxytocin, prostaglandins, and relaxin, not the source designated in NCERT.

Human female gametogenesis exhibits two prolonged developmental arrests: 1. First Meiotic Arrest: Primary oocytes enter meiosis I during fetal gestation and remain arrested at the diplotene stage of prophase I until puberty. 2. Resumption at Puberty: Each menstrual cycle, the pre-ovulatory LH surge triggers completion of meiosis I, producing a large haploid secondary oocyte ($n$) and a small first polar body. 3. Second Meiotic Arrest (Metaphase II): The secondary oocyte promptly enters meiosis II, but arrest occurs at metaphase II mediated by cytostatic factor (CSF) and maturation-promoting factor (MPF). 4. Ovulation: The secondary oocyte is ovulated into the fallopian tube in this arrested metaphase II condition.

When the fertilizing spermatozoon binds to the oolemma and fuses with the egg plasma membrane, a wave of intracellular calcium ($Ca^{2+}$) release activates the anaphase-promoting complex/cyclosome (APC/C). This degrades cyclin B, breaking the metaphase II arrest. Meiosis II is completed, extruding the second polar body and forming the mature haploid female pronucleus.

During the follicular phase of the menstrual cycle, primary follicles grow into mature Graafian follicles under the stimulation of gonadotropins (LH and FSH). The growing follicles secrete increasing levels of Estrogen.

Around day 12-14, the concentration of Estrogen reaches a critical peak (high concentration of Estrogen). Unlike low estrogen which exerts negative feedback, this sustained high level of estrogen switches to POSITIVE feedback on the anterior pituitary and hypothalamus.

The positive feedback of high estrogen induces rapid secretion of LH leading to its maximum level during mid-cycle (LH surge). LH surge induces rupture of the mature Graafian follicle and release of the ovum (ovulation).

Option (2) proposes high progesterone: Progesterone is very low prior to ovulation and rises only during the luteal phase. Options (3) and (4) state low LH and low FSH, whereas LH is at its highest peak. Thus, Option (1) is the only physiologically sound answer among the choices.

Placenta acts as an endocrine tissue producing hormones essential for maintaining pregnancy, including human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, and progestogens. Thus, (a) matches (ii).

Zona pellucida is a non-cellular, translucent glycoprotein layer surrounding the mammalian ovum/secondary oocyte, which induces the acrosome reaction upon sperm contact and blocks polyspermy. Thus, (b) matches (iii).

Bulbo-urethral (Cowper's) glands are paired male accessory sex glands whose secretions help in the lubrication of the penis during copulation. Thus, (c) matches (iv).

Leydig cells (interstitial cells) are located in the interstitial spaces between seminiferous tubules in the testes; they synthesize and secrete testicular hormones called androgens (primarily testosterone). Thus, (d) matches (i).