The trap that costs marks: confusing spermatogenesis output with oogenesis output, and misremembering how long spermatogenesis actually takes. One primary spermatocyte yields four functional spermatozoa — not one, not two. And the entire cycle takes approximately 64 days, not hours or a few days.
Male reproductive anatomy — the functional chain:
The testes are located in the scrotum (2–2.5°C below core body temperature — essential for spermatogenesis). Each testis contains 250 lobules, each lobule contains 1–3 seminiferous tubules. The seminiferous tubules are the site of sperm production. Between the tubules, Leydig cells (interstitial cells) secrete testosterone.
Inside each seminiferous tubule: spermatogonia (diploid, 2n) line the basement membrane. Sertoli cells provide nutrition, support, and secrete inhibin (feedback to FSH).
Spermatogenesis — the sequence:
Spermatogonium (2n) → primary spermatocyte (2n, after mitosis) → two secondary spermatocytes (n, after meiosis I) → four spermatids (n, after meiosis II) → four spermatozoa (after spermiogenesis).
Key facts: all four products are functional gametes. The process takes ~64 days. Spermiogenesis (spermatid → spermatozoon) involves acrosome formation, tail development, and mitochondrial sheath arrangement. Spermiation is the release of mature sperm from Sertoli cells into the lumen.
Accessory glands: Seminal vesicles (fructose for energy), prostate (alkaline fluid to neutralise vaginal acidity), bulbourethral/Cowper's glands (lubrication).
Hormonal control: GnRH → FSH (acts on Sertoli cells → spermatogenesis support) + LH (acts on Leydig cells → testosterone). Testosterone is essential for spermatogenesis and secondary sexual characteristics.
Watch out: NEET frequently tests the 64-day duration, the four-functional-sperm output, and the distinction between spermiogenesis (morphological maturation) and spermiation (release).
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
Which cells in the testis secrete testosterone?
Answer: D. Leydig cells (interstitial cells) located between seminiferous tubules secrete testosterone under LH stimulation (NCERT Class 12 Biology Chapter 2, page 28).
Why A is wrong: A is wrong because Sertoli cells provide nutritional support and secrete inhibin, not testosterone. (trap: similar-term confusion between the two testicular support cell types)
Why B is wrong: B is wrong because spermatogonia are germ cells that undergo division to form sperm — they do not have endocrine function.
Why C is wrong: C is wrong because spermatids are immature post-meiotic cells undergoing morphological transformation; they have no secretory role.
How many functional spermatozoa are produced from one primary spermatocyte?
Answer: B. One primary spermatocyte undergoes meiosis I (→ 2 secondary spermatocytes) then meiosis II (→ 4 spermatids), all four becoming functional spermatozoa (NCERT Class 12 Biology Chapter 2, page 28).
Why A is wrong: A is wrong because 1 functional gamete per primary cell is the oogenesis pattern, not spermatogenesis. (trap: spermatogenesis vs oogenesis product confusion)
Why C is wrong: C is wrong because 2 would be the count after only meiosis I; meiosis II still doubles the number.
Why D is wrong: D is wrong because 8 would require an extra division beyond the two meiotic divisions — that does not occur in gametogenesis.
The approximate duration of spermatogenesis in human males is:
Answer: C. The complete spermatogenic cycle — from spermatogonium to mature spermatozoon — takes approximately 64 days in humans. This is the classic physiology-text estimate; later measurements put it nearer 74 days, and NCERT itself gives no duration. Either way, 64 days is the only option of the right size.
Why A is wrong: A is wrong because 7 days is far too short; even meiosis alone takes ~24 days within the cycle. (trap: underestimating spermatogenesis duration)
Why B is wrong: B is wrong because 24 hours confuses the timeline with a single cell-division event — the entire differentiation sequence spans weeks. (trap: spermatogenesis timing confusion)
Why D is wrong: D is wrong because 120 days exceeds the documented cycle length; the measured cycle is about 64–74 days.
Spermiogenesis refers to:
Answer: C. Spermiogenesis is the post-meiotic morphological transformation of round spermatids into mature spermatozoa (acrosome, tail, mitochondrial sheath formation) — distinct from spermiation which is the release step (NCERT Class 12 Biology Chapter 2, page 28).
Why A is wrong: A is wrong because the formation of spermatogonia from primordial germ cells occurs during embryonic development, well before spermiogenesis begins at puberty.
Why B is wrong: B is wrong because release of spermatozoa from Sertoli cells is called spermiation, not spermiogenesis. (trap: similar-term confusion between spermiogenesis and spermiation)
Why D is wrong: D is wrong because division of secondary spermatocytes is meiosis II — a division event, not the morphological differentiation that defines spermiogenesis.
Which statement best describes how testicular hormones (androgens) relate to the male accessory ducts and glands (epididymis, vas deferens, seminal vesicle, prostate)?
Answer: B. The functions of the male sex accessory ducts and glands are maintained by testicular hormones (androgens), and the secretions of the epididymis, vas deferens, seminal vesicle, and prostate are in turn essential for the maturation and motility of sperms — a two-way dependency between hormonal control and accessory-gland output (NCERT Class 12 Biology, Chapter 2, page 32).
Why A is wrong: A reverses the relationship: androgens (testosterone) are produced by the Leydig cells of the testis, not the seminal vesicles, and it is androgens that maintain the accessory ducts and glands — the glands do not act back on the testis to regulate spermatogenesis (trap: reversing hormone source and target).
Why C is wrong: C is wrong because accessory-duct and gland function is explicitly hormone-dependent — their secretory activity is maintained by testicular androgens, not constant or hormone-independent.
Why D is wrong: D is wrong because it is androgens (not FSH) that maintain the accessory ducts and glands; FSH acts on Sertoli cells within the seminiferous tubules, a separate target from the accessory gland pathway.
Inhibin is secreted by which of the following cells and acts on which pituitary hormone?
Answer: A. Sertoli cells secrete inhibin, which provides negative feedback specifically on FSH secretion from the anterior pituitary (NCERT Class 12 Biology Chapter 2, page 28).
Why B is wrong: B is wrong because Leydig cells secrete testosterone (not inhibin), and testosterone feeds back on LH — but that is a different feedback loop. (trap: confusing which testicular cell targets which pituitary hormone)
Why C is wrong: C is wrong because spermatogonia are germ cells with no known endocrine secretory function, and GnRH is hypothalamic, not pituitary.
Why D is wrong: D is wrong because while Sertoli cells do secrete inhibin, its target is FSH, not LH. LH is regulated by testosterone from Leydig cells.
A seminiferous tubule is lined by two types of cells. The germ cells and the non-dividing cells that nourish developing sperm are called:
Answer: B. Sertoli cells are the non-dividing somatic cells within seminiferous tubules that provide structural support, nutrition, and a blood-testis barrier for developing germ cells (NCERT Class 12 Biology Chapter 2, page 28).
Why A is wrong: A is wrong because Leydig cells are located BETWEEN seminiferous tubules (interstitial space), not lining them. They are endocrine, not nutritive. (trap: confusing location — interstitial vs intratubular)
Why C is wrong: C is wrong because spermatocytes are germ cells themselves (the dividing cells in the tubule), not the supportive non-dividing cells.
Why D is wrong: D is wrong because epididymal cells line the epididymis (a separate structure for sperm storage and maturation), not the seminiferous tubules.
During spermatogenesis, a secondary spermatocyte has which chromosome complement and ploidy?
Answer: D. After meiosis I, secondary spermatocytes are haploid (n = 23). However, since meiosis II has not yet occurred, each chromosome still consists of two sister chromatids joined at the centromere (NCERT Class 12 Biology Chapter 2, page 28).
Why A is wrong: A is wrong because 2n/46 is the ploidy of the primary spermatocyte BEFORE meiosis I. After reductional division, chromosome number halves. (trap: confusing primary vs secondary spermatocyte ploidy)
Why B is wrong: B is wrong because 4n/92 does not occur in any stage of normal human spermatogenesis; it would imply failed separation beyond diploidy.
Why C is wrong: C is wrong because single-chromatid chromosomes (n, 23 with 1 chromatid each) describe spermatids AFTER meiosis II — secondary spermatocytes still retain sister chromatids.
Get a structured 30-day study plan and a complete formula booklet — delivered to your inbox instantly.
Pattern: Spermatogenesis output and comparison questions (anchored to NEET pattern: unit bundle — recall and direct_application on gametogenesis)
Given
A human male has 100 primary spermatocytes that enter meiosis in the seminiferous tubules.
Required
How many functional spermatozoa will be produced? How does this compare to the output if 100 primary oocytes completed oogenesis?
Concept
Spermatogenesis: each primary spermatocyte → 4 functional spermatozoa (symmetric division).
Oogenesis: each primary oocyte → 1 functional ovum + 3 polar bodies (asymmetric division).
Formula/Rule
• Sperm count = number of primary spermatocytes × 4• Ova count = number of primary oocytes × 1
Substitution
• Sperm = 100 × 4• Ova = 100 × 1
Calculation
• Sperm = 400• Ova = 100
Note: The multipliers (4, 1) are exact counting integers and do not involve sig-fig considerations.
Final answer
400 functional spermatozoa from 100 primary spermatocytes.
100 functional ova (with 300 polar bodies) from 100 primary oocytes.
Common trap
Confusing the two: saying oogenesis also produces 4 functional gametes (it does not — asymmetric cytokinesis ensures only 1 ovum retains the bulk cytoplasm). This is trap trap: spermatogenesis vs oogenesis — the similar-term confusion between the two gametogenic pathways.
Similar NEET-style question
"If 50 spermatogonia each undergo one round of mitotic division to become primary spermatocytes, how many spermatozoa are ultimately produced?" Answer: 400 spermatozoa. One mitotic division of 50 spermatogonia gives 50 × 2 = 100 cells, each of which becomes a primary spermatocyte; meiosis then turns each primary spermatocyte into 4 spermatozoa, so 100 × 4 = 400. The stem specifies a mitotic division, and a mitosis that produced no extra cell would not be one — do not let the phrase “become primary spermatocytes” absorb the doubling.
---
Testes (in scrotum, ~2-3 °C cooler) — seminiferous tubules with Sertoli cells (nurse) + Leydig cells (testosterone). Epididymis → vas deferens → ejaculatory duct → urethra. Spermatogenesis: spermatogonia → primary spermatocyte → meiosis → spermatozoa. ~60-65 days.
-- NCERT Class 12 Biology, Ch. 2, p. 27These are the exact patterns that cause wrong answers in NEET. Each trap includes when it triggers and how to avoid it.
Category: Similar Terms
Spermatogenesis: 1 spermatogonium → 4 sperm (all functional). Oogenesis: 1 oogonium → 1 functional ovum + 3 polar bodies.
Question on number of functional gametes per primary cell.
Sperm: 4. Ovum: 1 (with 3 polar bodies discarded).
Root cause: term confusion
Spermatogenesis cycle = ~64 days in humans. Spermatozoa storage in epididymis ~20-30 days more. Meiosis itself takes ~24 days.
More in Reproduction: 8 exam traps and mistakes · 1 question pattern from its other lessons.
8 questions from NEET 2022, 2023, 2024, 2025, 2026. Answers verified against NTA official keys.
Sperm motility is due to ______.
Which of the following structure is not a part of the male reproductive system ?
Identify the correct option (A), (B), (C), (D) with respect to spermatogenesis.
Page numbers are the ones printed in the current NCERT textbook (2023 rationalised edition), unless marked pre-2023. The books are free at ncert.nic.in.
Test yourself on this topic with real past-paper questions:
Practice this topic →