# Human Reproduction Notes, Class 12 Biology | SwaVid Human Reproduction, NCERT Class 12 Biology: notes with key ideas, key terms, common mistakes and 3 quick checks with worked answers. Canonical: https://www.swavid.com/cbse/class-12/biology/chapter/human-reproduction Source: https://www.swavid.com/cbse/class-12/biology/chapter/human-reproduction # Human Reproduction ## Key terms ## Key ideas ## Common mistakes ## Quick checks ## Keep going ## Questions parents ask ## Class 12 Biology on SwaVid ### Male reproductive system ### Female reproductive system ### Gametogenesis ### Menstrual cycle ### Fertilisation and implantation ### Pregnancy and embryonic development ### Parturition and lactation ### Next chapter ### Related chapter ### Related chapter ### All chapters SwaVid › CBSE › Class 12 › Biology › Human Reproduction Notes written by SwaVid from the NCERT textbook. Class 12 Biology, Chapter 2. Key ideas, formulas and common mistakes. CBSE prints 16 marks for Unit VI, not for this chapter alone. Short answer. This chapter describes the anatomy and physiology of the male and female reproductive systems in humans. It covers gametogenesis, the hormonal control of the menstrual cycle, fertilisation, embryonic development, and parturition. Source: NCERT Biology (Reprint 2026-27) , Chapter 2, Human Reproduction The male system includes paired testes located inside the scrotum, accessory ducts, accessory glands, and external genitalia. Testes contain seminiferous tubules lined by male germ cells and Sertoli cells, while interstitial Leydig cells secrete androgens. The female system consists of ovaries, oviducts, uterus, cervix, vagina, and external genitalia, along with mammary glands. Ovaries produce the female gamete and steroid hormones, while the fallopian tube provides the site for fertilisation. Spermatogenesis transforms spermatogonia into mature spermatozoa in seminiferous tubules under the control of LH and FSH. Oogenesis begins during embryonic development and pauses at prophase I, resuming only at puberty to yield one mature ovum and polar bodies per primary oocyte. The reproductive cycle in human females repeats roughly every 28 to 29 days and consists of menstrual, follicular, ovulatory, and luteal phases. A surge of LH around day 14 induces the rupture of the Graafian follicle and release of the secondary oocyte. A sperm penetrates the corona radiata and zona pellucida of the secondary oocyte at the ampullary region of the fallopian tube. The resulting diploid zygote undergoes cleavage to form a blastocyst, which embeds into the endometrium. Chorionic villi and uterine tissue interlock to form the placenta, which provides nutrition, oxygen, and hormones like hCG, hPL, and relaxin. The inner cell mass differentiates into three germ layers that give rise to all adult tissues. Signals from the fully developed fetus and placenta trigger the fetal ejection reflex, stimulating oxytocin release from the maternal pituitary. Oxytocin causes stronger uterine contractions to expel the baby, while mammary glands differentiate to produce milk towards the end of pregnancy. Try each question first. Then tap it to see the answer. Each primary spermatocyte undergoes meiosis to produce 4 functional spermatozoa: 100 × 4 = 400 spermatozoa. Each primary oocyte undergoes meiosis to produce 1 functional ovum and polar bodies: 100 × 1 = 100 ova. 400 spermatozoa and 100 ova The corpus luteum secretes large amounts of progesterone, which is essential for the maintenance of the endometrium. In the absence of fertilisation, the corpus luteum degenerates, leading to the disintegration of the endometrium and menstruation. The corpus luteum secretes progesterone; it degenerates if fertilisation does not occur Primary oocytes enter meiosis I during fetal life and get temporarily arrested at prophase I (diplotene stage). This first arrest is lifted only upon reaching puberty when the primary follicle resumes development within each cycle. Arrested at prophase I of meiosis I; resumed at puberty Reproductive Health . Sexual Reproduction in Flowering Plants . Principles of Inheritance and Variation . The 13 chapters of Class 12 Biology . CBSE does not give marks to one chapter. It prints 16 marks for Unit VI, Reproduction, which includes Human Reproduction. No. They are written by SwaVid from the NCERT textbook. The CBSE curriculum is the reference for what is assessed. Reproductive Health. SwaVid is an AI tutor for Indian students in Classes 6 to 12. It finds the earlier ideas a child missed, then teaches today’s chapter. Start free to see how it works. - Ch 2 NCERT book - 16 marks, Unit VI - 3 quick checks - Confusing spermiogenesis with spermiation . Remember that spermiogenesis converts spermatids into spermatozoa, whereas spermiation is the subsequent detachment and release of spermatozoa from Sertoli cells. - Assuming oogenesis produces four functional haploid ova from one primary oocyte . Recall that oogenesis involves unequal cytoplasmic divisions, yielding only one mature ovum and two or three tiny polar bodies that degenerate. - Stating that fertilisation occurs in the uterus . Fertilisation takes place specifically in the ampullary region of the fallopian tube, after which the dividing embryo moves into the uterus. - Writing that relaxin is secreted only by the placenta . According to NCERT, relaxin is secreted by the ovary in the later stages of pregnancy. ## Key Links - [CBSE](https://www.swavid.com/cbse) - [Class 12](https://www.swavid.com/cbse/class-12) - [Biology](https://www.swavid.com/cbse/class-12/biology/chapters) - [Start free →](https://www.swavid.com/signup) - [All 13 chapters](https://www.swavid.com/cbse/class-12/biology/chapters) - [NCERT Biology (Reprint 2026-27)](https://ncert.nic.in/textbook.php) - [Open notes](https://www.swavid.com/cbse/class-12/biology/chapter/reproductive-health) - [Open notes](https://www.swavid.com/cbse/class-12/biology/chapter/sexual-reproduction-in-flowering-plants) - [Open notes](https://www.swavid.com/cbse/class-12/biology/chapter/principles-of-inheritance-and-variation) - [Class 12 Biology](https://www.swavid.com/cbse/class-12/biology/chapters) - [Start free →](https://www.swavid.com/signup)