Human reproduction is the sexual and viviparous process by which humans produce offspring through gamete formation and internal fertilisation. Important Questions Class 12 Biology Chapter 2 focus on reproductive organs, gametogenesis, fertilisation, pregnancy, and birth.
Human reproduction becomes easier when students see it as one connected sequence, not separate diagrams. Important Questions Class 12 Biology Chapter 2 help revise male and female reproductive systems, spermatogenesis, oogenesis, menstrual cycle, fertilisation, implantation, pregnancy, parturition, and lactation. The NCERT 2026-27 chapter explains humans as sexually reproducing and viviparous organisms, where fertilisation is internal and development occurs inside the female body.
Key Takeaways
- Human reproduction: Humans reproduce sexually and give birth to young ones, so they are viviparous.
- Gametogenesis: Testes produce sperms through spermatogenesis, while ovaries produce ova through oogenesis.
- Menstrual cycle: Ovulation usually occurs around the middle of a 28/29-day cycle.
- Pregnancy: Implantation of the blastocyst in the uterus leads to pregnancy.
Important Questions Class 12 Biology Chapter 2 Structure 2026
| Key Area |
What To Revise |
Exam Use |
| Reproductive systems |
Testes, ovaries, ducts, glands, uterus, mammary glands |
Diagram and function questions |
| Gametogenesis and cycle |
Spermatogenesis, oogenesis, hormones, menstrual phases |
Process and comparison answers |
| Development events |
Fertilisation, implantation, placenta, parturition, lactation |
Long answers and NCERT questions |
Human Reproduction Class 12 Chapter Overview
Human reproduction includes gamete formation, transfer of sperms, fertilisation, zygote formation, implantation, gestation, and childbirth. The male and female systems perform different but connected roles.
The male system produces and transfers sperms. The female system produces ova, supports fertilisation, allows pregnancy, and helps nourish the newborn through lactation.
The NCERT 2026 chapter also explains hormonal control. GnRH, LH, FSH, estrogen, progesterone, oxytocin, hCG, hPL, and relaxin appear in key reproductive events.
Human Reproduction Class 12 Important Questions
Human reproduction starts with the formation of gametes after puberty. The complete process includes fertilisation, embryo development, pregnancy, birth, and lactation.
These human reproduction class 12 important questions build the base before system-wise details.
Q1. What Is Human Reproduction Class 12?
Human reproduction is sexual and viviparous reproduction in which humans produce offspring through gametes and internal fertilisation.
Male gametes are sperms. Female gametes are ova.
Fertilisation forms a diploid zygote. The embryo develops inside the uterus.
Q2. Why Are Humans Called Viviparous?
Humans are called viviparous because they give birth to young ones.
The embryo develops inside the uterus. The placenta supports exchange between mother and foetus.
This differs from oviparous animals that lay eggs.
Q3. What Are The Main Events In Human Reproduction?
The main events are gametogenesis, insemination, fertilisation, implantation, gestation, parturition, and lactation.
Gametogenesis forms sperms and ova. Insemination transfers sperms into the female reproductive tract.
Fertilisation forms a zygote. Gestation ends with childbirth.
Q4. Why Are Important Questions Class 12 Biology Chapter 2 Useful For Board Preparation?
Important Questions Class 12 Biology Chapter 2 are useful because the chapter has many process, diagram, and hormone-based questions.
Students must connect organs with functions. They must also explain fertilisation, implantation, pregnancy, and birth in sequence.
NCERT diagrams are important for labelled-answer practice.
Male Reproductive System Class 12 Important Questions
The male reproductive system produces sperms and transfers them into the female reproductive tract. It includes testes, accessory ducts, glands, and external genitalia.
Students should understand the path of sperm movement from seminiferous tubules to urethra.
Q5. Describe The Male Reproductive System Class 12.
The male reproductive system has a pair of testes, accessory ducts, accessory glands, and penis.
The testes lie in the scrotum. They produce sperms and androgens.
Accessory ducts transport sperms. Accessory glands add seminal plasma.
Q6. Why Are Testes Located In The Scrotum?
Testes are located in the scrotum to maintain a lower temperature for spermatogenesis.
The scrotum keeps testes about 2 to 2.5°C below internal body temperature. This temperature supports sperm formation.
High temperature can reduce sperm production.
Q7. What Is The Structure Of A Testis?
Each adult testis is oval and contains about 250 testicular lobules.
Each lobule has one to three highly coiled seminiferous tubules. Sperms form inside these tubules.
The testis also contains interstitial spaces with Leydig cells.
Q8. Describe The Structure Of Seminiferous Tubules Class 12.
Seminiferous tubules are highly coiled tubules where sperms are produced.
Their inner lining has male germ cells and Sertoli cells. Male germ cells undergo meiosis to form sperms.
Sertoli cells nourish developing germ cells.
Q9. What Is The Function Of Leydig Cells?
Leydig cells synthesise and secrete androgens.
They lie in the interstitial spaces outside seminiferous tubules. Testosterone is the main androgen.
Androgens support spermatogenesis and male reproductive functions.
Q10. Name The Male Accessory Ducts.
The male accessory ducts are rete testis, vasa efferentia, epididymis, and vas deferens.
Seminiferous tubules open into rete testis. Rete testis connects to vasa efferentia.
The sperm pathway continues through epididymis, vas deferens, ejaculatory duct, and urethra.
Q11. What Are The Male Accessory Glands?
The male accessory glands are paired seminal vesicles, one prostate gland, and paired bulbourethral glands.
Their secretions form seminal plasma. Seminal plasma contains fructose, calcium, and enzymes.
Bulbourethral glands also lubricate the penis.
Female Reproductive System Class 12 Important Questions
The female reproductive system produces ova, receives sperms, supports fertilisation, and carries pregnancy. It also supports birth and lactation.
The main organs are ovaries, oviducts, uterus, cervix, vagina, external genitalia, and mammary glands.
Q12. Describe The Female Reproductive System Class 12.
The female reproductive system has ovaries, oviducts, uterus, cervix, vagina, external genitalia, and mammary glands.
Ovaries produce ova and ovarian hormones. Oviducts transport ova and support fertilisation.
The uterus supports implantation and pregnancy.
Q13. What Are The Functions Of Ovaries?
Ovaries produce ova and ovarian hormones.
They are the primary female sex organs. They secrete estrogen and progesterone.
Each ovary contains follicles at different stages of development.
Q14. Describe The Parts Of The Fallopian Tube.
The fallopian tube has infundibulum, ampulla, and isthmus.
The infundibulum lies near the ovary and has fimbriae. Fimbriae collect the ovum after ovulation.
The ampulla is the usual site of fertilisation. The isthmus joins the uterus.
Q15. What Is The Structure Of The Uterus?
The uterus is a single, inverted pear-shaped organ also called the womb.
It has three layers: perimetrium, myometrium, and endometrium. Endometrium undergoes cyclical changes.
Myometrium contracts strongly during delivery.
Q16. What Is The Function Of Mammary Glands?
Mammary glands produce milk for the newborn.
Each breast has 15 to 20 mammary lobes. The alveoli secrete milk.
Milk passes through mammary ducts, mammary ampulla, lactiferous duct, and nipple.
Q17. Why Is Hymen Not A Reliable Indicator Of Virginity?
Hymen is not a reliable indicator of virginity because it can break for reasons other than coitus.
It may break due to sports, sudden fall, cycling, or tampon use. In some women, it may persist after coitus.
NCERT clearly states that hymen presence or absence cannot prove sexual experience.
Gametogenesis Class 12 Questions With Answers
Gametogenesis forms haploid gametes from diploid germ cells. In males it forms sperms, and in females it forms ova.
Spermatogenesis starts at puberty, while oogenesis begins during embryonic development.
Q18. What Is Gametogenesis Class 12?
Gametogenesis is the process of formation of male and female gametes.
In males, it forms sperms through spermatogenesis. In females, it forms ova through oogenesis.
Both processes include meiotic division.
Q19. What Is Spermatogenesis Class 12?
Spermatogenesis is the process by which spermatogonia form sperms inside seminiferous tubules.
It begins at puberty. Spermatogonia divide and form primary spermatocytes.
Each primary spermatocyte undergoes meiosis and produces four haploid spermatids.
Q20. Explain The Steps Of Spermatogenesis.
Spermatogenesis converts diploid spermatogonia into haploid sperms.
- Spermatogonia multiply by mitosis.
- Some become primary spermatocytes.
- Primary spermatocytes undergo meiosis I and form two secondary spermatocytes.
- Secondary spermatocytes undergo meiosis II and form four spermatids.
- Spermatids transform into spermatozoa through spermiogenesis.
Q21. Which Hormones Regulate Spermatogenesis?
GnRH, LH, FSH, and androgens regulate spermatogenesis.
GnRH stimulates the anterior pituitary. The pituitary releases LH and FSH.
LH acts on Leydig cells. FSH acts on Sertoli cells and supports spermiogenesis.
Q22. What Is The Difference Between Spermiogenesis And Spermiation?
Spermiogenesis converts spermatids into spermatozoa, while spermiation releases sperms from seminiferous tubules.
During spermiogenesis, spermatids develop head, neck, middle piece, and tail. Their heads become embedded in Sertoli cells.
During spermiation, mature sperms leave the seminiferous epithelium.
Q23. Describe The Structure Of A Human Sperm.
A human sperm has head, neck, middle piece, and tail.
The head contains a haploid nucleus and acrosome. Acrosome has enzymes that help fertilisation.
The middle piece contains mitochondria. The tail helps sperm movement.
Q24. What Is Oogenesis Class 12?
Oogenesis is the formation of a mature female gamete from oogonia.
It begins during embryonic development. Oogonia form primary oocytes before birth.
Primary oocytes remain arrested in prophase I until puberty.
Q25. Explain The Steps Of Oogenesis.
Oogenesis forms one functional ovum and polar bodies through unequal meiotic divisions.
- Oogonia form primary oocytes before birth.
- Primary oocytes enter prophase I and remain arrested.
- A primary follicle develops around each primary oocyte.
- At puberty, follicles grow into secondary and tertiary follicles.
- The primary oocyte completes meiosis I and forms a secondary oocyte and first polar body.
- The Graafian follicle ruptures and releases the secondary oocyte.
Q26. Differentiate Between Spermatogenesis And Oogenesis.
Spermatogenesis forms four sperms, while oogenesis forms one ovum and polar bodies.
| Basis |
Spermatogenesis |
Oogenesis |
| Site |
Seminiferous tubules of testes |
Ovaries |
| Starts |
At puberty |
During embryonic development |
| Gametes formed |
Four functional sperms |
One functional ovum |
| Division type |
Equal meiotic divisions |
Unequal meiotic divisions |
| Continuity |
Continues in adult males |
Cyclic after puberty and stops at menopause |
This difference is repeatedly asked because it tests timing, site, and product.
Menstrual Cycle Class 12 Important Questions
The menstrual cycle is the reproductive cycle of female primates. In humans, it repeats at an average interval of 28/29 days.
Hormones from the pituitary and ovary control ovarian and uterine changes.
Q27. What Is Menstrual Cycle Class 12?
Menstrual cycle is the cyclic reproductive change in human females from one menstruation to the next.
It begins at puberty with menarche. It stops around 50 years of age at menopause.
A typical cycle lasts about 28/29 days.
Q28. What Are Menarche And Menopause?
Menarche is the first menstruation, and menopause is the permanent stopping of menstrual cycles.
Menarche begins at puberty. Menopause usually occurs around 50 years of age.
The reproductive phase extends between menarche and menopause.
Q29. Explain The Phases Of Menstrual Cycle.
The menstrual cycle has menstrual, follicular, ovulatory, and luteal phases.
| Phase |
Main Event |
Hormonal Feature |
| Menstrual Phase |
Breakdown of endometrium causes menstrual flow |
Low ovarian hormones |
| Follicular Phase |
Follicles mature and endometrium regenerates |
FSH and estrogen rise |
| Ovulatory Phase |
Graafian follicle ruptures and releases ovum |
LH surge |
| Luteal Phase |
Corpus luteum forms and secretes progesterone |
Progesterone maintains endometrium |
Ovulation occurs around the middle of the cycle.
Q30. What Is LH Surge And Why Is It Important?
LH surge is the rapid rise of luteinising hormone around mid-cycle.
It causes rupture of the Graafian follicle. This releases the secondary oocyte from the ovary.
LH surge induces ovulation.
Q31. What Is The Function Of Corpus Luteum?
Corpus luteum secretes progesterone after ovulation.
Progesterone maintains the endometrium. This prepares the uterus for implantation.
If fertilisation does not occur, corpus luteum degenerates.
Q32. Why Does Menstruation Occur?
Menstruation occurs because the endometrial lining breaks down when fertilisation does not occur.
The corpus luteum degenerates in the absence of pregnancy. Progesterone levels fall.
This causes disintegration of the endometrium and menstrual flow.
Fertilisation And Implantation Class 12 Questions
Fertilisation occurs only when sperm and ovum reach the ampullary region together. This is why every coitus does not lead to pregnancy.
Implantation begins after the blastocyst reaches and embeds in the uterus.
Q33. What Is Fertilisation And Implantation Class 12?
Fertilisation is fusion of sperm and ovum, while implantation is attachment of blastocyst to the uterine endometrium.
Fertilisation forms a diploid zygote. Implantation leads to pregnancy.
Both events occur before embryonic development inside the uterus.
Q34. Where Does Fertilisation Occur In Humans?
Fertilisation occurs in the ampullary region of the fallopian tube.
Sperms reach this region after insemination. The ovum also reaches the ampulla after ovulation.
Fertilisation occurs only when both gametes reach the ampulla together.
Q35. How Does A Sperm Fertilise The Ovum?
A sperm fertilises the ovum by entering through the zona pellucida and fusing with the ovum.
The acrosome releases enzymes that help sperm entry. The ovum membrane then blocks entry of additional sperms.
This prevents polyspermy and ensures one sperm fertilises one ovum.
Q36. Who Determines The Sex Of The Baby?
The father determines the sex of the baby.
The ovum always carries an X chromosome. Sperms carry either X or Y chromosome.
An X-bearing sperm forms XX female zygote. A Y-bearing sperm forms XY male zygote.
Q37. What Is Cleavage In Human Reproduction?
Cleavage is repeated mitotic division of the zygote during its movement through the oviduct.
It forms 2, 4, 8, and 16 blastomeres. The 8 to 16-celled embryo is called morula.
Morula later forms the blastocyst.
Q38. What Is Implantation?
Implantation is embedding of the blastocyst into the endometrium of the uterus.
The trophoblast attaches to the endometrium. Uterine cells divide rapidly and cover the blastocyst.
Implantation marks the beginning of pregnancy.
Pregnancy And Embryonic Development Class 12 Questions
Pregnancy begins after implantation. The placenta forms between maternal tissue and the developing embryo.
This section links embryonic layers, placental function, and month-wise development.
Q39. What Is Placenta Class 12?
Placenta is the structural and functional connection between the foetus and maternal body.
It forms from chorionic villi and uterine tissue. It helps exchange nutrients, oxygen, carbon dioxide, and wastes.
The placenta also acts as an endocrine tissue.
Q40. What Are The Functions Of Placenta?
Placenta supports exchange, transport, protection, and hormone secretion during pregnancy.
It supplies oxygen and nutrients to the embryo. It removes carbon dioxide and wastes.
It secretes hCG, hPL, estrogens, and progestogens.
Q41. What Is The Function Of Umbilical Cord?
Umbilical cord connects the foetus with the placenta.
It transports substances between mother and foetus. It supports nutrient and waste exchange through placental circulation.
The foetus depends on it during pregnancy.
Q42. What Are The Three Germ Layers In Embryonic Development?
The three germ layers are ectoderm, mesoderm, and endoderm.
They arise from the inner cell mass after implantation. These layers form all tissues and organs.
Stem cells in the inner cell mass can give rise to different tissues.
Q43. Describe Major Events In Human Embryonic Development.
Human embryonic development follows a month-wise pattern during pregnancy.
- After one month, the embryo’s heart forms.
- By the end of the second month, limbs and digits develop.
- By 12 weeks, most major organ systems form.
- During the fifth month, foetal movements and hair appear.
- By 24 weeks, eyelids separate and eyelashes form.
- By nine months, the foetus becomes fully developed.
Parturition And Lactation Class 12 Questions
Parturition is childbirth at the end of gestation. Lactation supports newborn nutrition after birth.
Both processes depend on hormonal and maternal body changes.
Q44. What Is Parturition Class 12?
Parturition is the process of childbirth or delivery of the foetus.
It occurs at the end of the gestation period. Human pregnancy lasts about nine months.
Strong uterine contractions expel the baby through the birth canal.
Q45. Explain The Hormonal Control Of Parturition.
Parturition occurs through a neuroendocrine mechanism involving foetal signals and oxytocin.
Signals from the foetus and placenta cause mild uterine contractions. This is called foetal ejection reflex.
The maternal pituitary releases oxytocin. Oxytocin increases uterine contractions until delivery occurs.
Q46. What Is Lactation Class 12?
Lactation is the production and release of milk by mammary glands.
Mammary glands differentiate during pregnancy. They produce milk towards the end of pregnancy.
Lactation helps feed the newborn after birth.
Q47. What Is Colostrum And Why Is It Important?
Colostrum is the milk produced during the first few days after childbirth.
It contains several antibodies. These antibodies help develop resistance in the newborn.
Doctors recommend breastfeeding during early infant growth.
NCERT Class 12 Biology Chapter 2 Questions
NCERT questions often test exact terms, diagrams, true-false correction, and process order. Students should answer with direct biological language.
These NCERT Class 12 Biology Chapter 2 questions follow the 2026 textbook scope.
Q48. Fill In The Blanks From Human Reproduction.
The correct answers are sexually, viviparous, internal, haploid, diploid, ovulation, LH, fertilisation, fallopian tube, blastocyst, and placenta.
- Humans reproduce sexually.
- Humans are viviparous.
- Fertilisation is internal in humans.
- Male and female gametes are haploid.
- Zygote is diploid.
- Release of ovum is called ovulation.
- Ovulation is induced by LH.
- Fusion of gametes is called fertilisation.
- Fertilisation occurs in the fallopian tube.
- Zygote divides to form blastocyst.
- Placenta provides vascular connection between foetus and uterus.
Q49. Correct The False Statements From NCERT Human Reproduction.
The corrected statements replace wrong organ or cell names with accurate terms.
- Androgens are produced by Leydig cells.
- Spermatozoa get nutrition from Sertoli cells.
- Leydig cells are found in testes.
- Oogenesis takes place in ovaries.
- Menstrual cycle ceases during pregnancy.
- Hymen is not a reliable indicator of virginity.
Q50. How Many Eggs Are Released In Identical And Fraternal Twins?
Identical twins usually develop from one fertilised egg, while fraternal twins develop from two eggs.
One ovum is released and fertilised in identical twins. The zygote splits into two embryos.
Two ova are released and fertilised by two sperms in fraternal twins.
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