Reproductive System Class 10 ICSE — Selina Chapter 11
The reproductive system class 10 ICSE chapter in Selina Biology explains how humans produce new individuals, from gamete formation to birth. It covers the male and female reproductive organs, the menstrual cycle, fertilisation, implantation, the placenta, and parturition. Each section builds on the last, so reading in order helps. This page explains every section with the key terms and functions you need, alongside the chapter PDF for reference.
The chapter also draws on the Class 10 Biology series, where earlier chapters set up the hormones that drive these processes.
Download The Reproductive System Class 10 ICSE Biology Chapter 11 PDF
Download the The Reproductive System Class 10 ICSE Biology chapter PDF from the Selina Concise textbook to revise offline or print for practice. It is the full chapter as printed in the book — 18 pages, 9 sections, 47 questions.
What is inside Chapter 11
18 pages · 9 sections · 47 exercise questions
| Section | Title |
|---|---|
| 11.1 | REPRODUCTION IN GENERAL |
| 11.2 | REPRODUCTION IN HUMANS |
| 11.1 | Male Reproductive System |
| 11.2.2 | Female Reproductive System |
| 11.3 | MENSTRUAL CYCLE |
| 11.4 | FERTILISATION (Union of egg nucleus and sperm nucleus) |
| 11.5 | IMPLANTATION (CONCEPTION) AND PREGNANCY |
| 11.6 | PLACENTA |
| 11.7 | PARTURITION (BIRTH) |
- PROGRESS CHECK: 0 questions
- REVIEW QUESTIONS: 21 questions
- PROGRESS CHECK: 7 questions
- REVIEW QUESTIONS: 19 questions
11.1 REPRODUCTION IN GENERAL
Reproduction is the formation of new individuals by sexual or asexual means. Each new individual can, in turn, repeat the process. Many simple organisms reproduce asexually, while humans reproduce only sexually.
In asexual reproduction, the reproductive unit is any portion of the parent body. The unit can range from the whole body to a small fragment. In hydra, a bud grows out of the body, separates, and develops into a full hydra. No gametes form, and only one parent is involved.
Sexual reproduction needs two gametes — the egg and the sperm. These fuse during fertilisation to form a zygote, which develops into the offspring. Table 11.1 lists the differences between the two patterns. Asexual reproduction shows no genetic mixing and little variation. Sexual reproduction mixes genetic material and increases variation. Asexual reproduction produces more offspring quickly. Sexual reproduction is slower and produces fewer offspring.
Secondary sexual characters are the outward features that distinguish the sexes. In this Class 10 ICSE chapter, these include body and facial hair, breasts in females, muscularity, skeletal structure, behaviour, and a deeper voice in males. Across the animal world, such features help individuals identify and attract mates.
11.2 REPRODUCTION IN HUMANS
The human reproductive organs divide into primary and accessory parts. The primary parts are the gonads. In males, the testes produce sperms. In females, the ovaries produce eggs. These organs make the sex cells.
The accessory parts help transfer and meet the two kinds of gametes. They also support the egg’s growth and development up to the birth of the baby. The sperm ducts, accessory glands, oviducts, and uterus all fall into this group.
Are secondary sexual characters reproductive parts? The chapter answers clearly: no. These features do not participate in reproduction. They signal maturity and attract partners, but they never carry gametes or support development. The distinction matters because it defines which organs belong to the reproductive system and which do not.
In the Class 10 ICSE syllabus, the gonads are the only primary parts. Everything else that aids reproduction is accessory. The next two sections describe the male and female organs in detail.
11.1 Male Reproductive System
The male reproductive system has four main organs. The testes produce sperms. The sperm ducts carry them. The accessory glands add seminal fluid. The penis transfers the sperms into the female. The urethra, inside the penis, conveys the sperms from the sperm ducts.
The two testes lie in the scrotum, a thin-walled sac of skin. In the embryo, the testes descend from the abdomen into the scrotum shortly before birth. They sit outside the body because sperms mature only at a temperature 2 to 3°C lower than body heat. The scrotum regulates this. In heat, its skin loosens so the testes hang away. In cold, it contracts and draws them closer.
Edge case: if the testes do not descend, the condition leads to sterility — the inability to produce sperms. The body’s high temperature prevents sperm maturation in an undescended testis.
Each testis is encased in a capsule partitioned into 15-20 lobules. Each lobule contains seminiferous tubules, where spermatogenesis produces the sperms, and interstitial or Leydig cells, which secrete testosterone. Mature sperms pass through 12-14 efferent ducts into the epididymis, a coiled tube about 6 metres long that stores sperms until they mature and become motile.
From each testis, the sperm duct or vas deferens travels upward through the inguinal canal into the abdomen. Sometimes the intestine bulges through this canal into the scrotum, causing the common inguinal hernia. The two sperm ducts loop over the ureters and join the urethra at the back of the urinary bladder.
Three accessory glands contribute to the semen. The seminal vesicles produce a secretion that activates the sluggish sperms. The prostate gland pours an alkaline secretion that neutralises acid in the vagina. The bulbo-urethral or Cowper’s glands produce a lubricant.
The penis is a highly vascular organ with erectile tissue and vascular spaces. Under stimulation, blood fills these spaces and compresses the veins, producing erection. The sperm course runs from the seminiferous tubules to the epididymis, then through the sperm duct and urethra to the urethral opening. A common mistake is reversing the first two steps — the epididymis comes before the sperm duct. Semen is the milky mixture of sperms and gland secretions.
A single ejaculation averages 2 to 3 ml and contains 200 to 400 million sperms.
11.2.2 Female Reproductive System
The female reproductive system has five parts. A pair of ovaries produces the eggs. A pair of oviducts conveys them. The pear-shaped uterus houses the growing embryo. The vagina and vulva form the lower passage and external genitalia.
The ovaries are small ovoid bodies. Normally, only one egg matures in each ovary every alternate month. A maturing egg sits in a cellular sac called a follicle. As the egg grows, the follicle enlarges, fills with fluid, and becomes the Graafian follicle. Oogenesis is the process by which ova-producing cells give rise to the mature ovum. Ovulation is the rupture of the follicle, releasing the egg. The fimbrae, cilia at the oviducal funnel, pick up the released egg.
After ovulation, the empty follicle becomes the corpus luteum, a yellow mass. It secretes oestrogen and progesterone. Progesterone prepares the uterus to receive the embryo.
A common mistake is treating ovum and egg as identical. An ovum is just the female gamete. A hen’s egg is the ovum plus albumen and shell added as it passes down the oviduct. All ova are eggs, but not all eggs are ova.
The oviducts, or Fallopian tubes, are about 12 cm long. Cilia push the ovum in, and muscular peristalsis moves it toward the uterus. The uterus is a hollow, pear-shaped organ about 7 cm by 5 cm, with an upper wider portion and a lower cervix. The vagina is a muscular tube 10 to 15 cm long, elastic enough for childbirth. In young females, the hymen partially closes its opening.
The vulva contains the labia minora, labia majora, and the clitoris, which is the equivalent of the male penis.
Puberty is the period when the immature reproductive system matures. In girls, the first sign at about age 10 is breast enlargement. In boys, testis enlargement appears at about 11 years.
11.3 MENSTRUAL CYCLE
The menstrual cycle repeats about every 28 days during a woman’s reproductive years. Menarche is the onset of menstruation, around age 13. Menopause is its permanent stoppage, around age 45. Pregnancy temporarily stops the flow.
The cycle has four phases. The menstrual phase lasts 3 to 5 days, when the uterine lining sheds and blood is discharged. The follicular phase follows, as follicle hormones thicken the uterine wall and supply it with blood. The ovulatory phase occurs on about day 13 or 14, when the follicle ruptures and releases the egg. The luteal phase runs from day 15 to 28, when the corpus luteum secretes progesterone and the lining thickens further.
If no fertilisation occurs, the egg disintegrates and the lining sheds on day 28. If the egg is fertilised and implanted, progesterone from the persistent corpus luteum prevents another follicle from maturing, so there is no discharge. A common mistake: without pregnancy, the corpus luteum degenerates and the uterine wall cannot stay thickened. Its functional life is about 14 days.
Worked example: a woman’s reproductive period runs from about 13 to 45 years, which is 32 years. At one egg every 28 days, she releases about 13 eggs per year. Over 32 years, that comes to roughly 417 eggs in her lifetime. The chapter’s long-answer question asks for exactly this calculation, using the one egg per 28 days rate and the 13-45 year span.
11.4 FERTILISATION (Union of egg nucleus and sperm nucleus)
Fertilisation is the fusion of the male gamete (sperm) and the female gamete (ovum) to form a zygote. During copulation, sperms are released in the vagina near the cervix. A single ejaculation contains about 400 million sperms. They swim at about 1.5 mm per minute, pass through the cervix and uterus, and reach the oviducts. If an ovum is present, one sperm fertilises it.
The days soon after ovulation — day 12 or 13 after the onset of menstruation — are most favourable for conception. Many sperms die on the way and are absorbed.
Each sperm part has a function. The acrosome at the head secretes hyaluronidase, an enzyme that dissolves the wall of the ovum. The nucleus carries 22 + X or 22 + Y chromosomes, which combine with the egg’s 22 + X chromosomes to restore 23 pairs. The middle piece contains mitochondria that provide ATP energy for swimming. The tail makes lashing movements for propulsion.
Sperms may survive in the female passage for a few days, but their fertilising power lasts only one or two days. When one sperm enters the egg, a chemical barrier prevents the entry of others. The tail is left behind; only the head containing the nucleus penetrates. The sperm nucleus then fuses with the egg nucleus.
11.5 IMPLANTATION (CONCEPTION) AND PREGNANCY
The zygote soon starts dividing by cleavage into 2, 4, 8, 16 cells and so on. By the time it reaches the uterus, it has formed a hollow ball of numerous cells called the blastocyst. This embryo forms a pit in the endometrium and fixes there about 5 to 7 days after ovulation. This process is implantation, and it produces the state of pregnancy.
By the end of five weeks of pregnancy, the embryo is quite advanced. The heart and circulatory system have formed. After two months, the limbs have also formed.
Four terms matter here. An embryo is a growing egg after fertilisation until the main body parts and internal organs take shape. A foetus is the embryo once it starts to look like a baby, from about 7 weeks of gestation onward. Pregnancy is the state of carrying the unborn young one inside the body. Gestation is the full term of embryonic development in the uterus, about 280 days in humans.
11.6 PLACENTA
The placenta is a disc-like structure attached to the uterine wall. The umbilical cord, a cord containing blood vessels, connects it to the foetus. The placenta is formed of two sets of minute finger-like processes, the villi. One set comes from the uterine wall, the other from the embryo’s allantois. The two sets interlock but never open into each other. Maternal and foetal blood come close but never mingle.
The placenta allows diffusion in two directions. From mother to foetus pass oxygen, glucose, amino acids, lipids, vitamins, mineral ions, certain drugs, alcohol, nicotine, antibodies, and viruses. From foetus to mother pass carbon dioxide, urea, and other wastes. The placenta does not allow germs through, but the HIV virus can cross if the mother is infected.
The placenta also acts as an endocrine gland. It produces oestrogen and progesterone. The presence of progesterone in urine provides the basis for certain pregnancy tests. The hormones here connect to the endocrine glands chapter, which covers the same hormones in more detail.
The amnion is a sac that develops around the embryo, filled with amniotic fluid. The fluid protects the embryo from physical shocks, keeps even pressure all around, allows the foetus restricted movement, and prevents the foetus from sticking to the amnion.
11.7 PARTURITION (BIRTH)
Parturition is birth. Gestation lasts about 280 days in humans. At birth, powerful uterine contractions push the baby out head first. Within minutes, the blood vessels in the umbilical cord shrink and can be tied and cut. About 15 minutes later, the placenta breaks from the uterus and is expelled as the after-birth. The uterus contracts and returns to normal over a few days.
Gestation periods vary across mammals. The rabbit carries for 32 days, the cat and dog for 65, swine for 114, humans for 280, cows for 290, horses for 340, and elephants for 600 days.
Fraternal twins come from two eggs fertilised at the same time. They may be both boys, both girls, or one of each, and are otherwise like ordinary siblings of the same age. About 75 per cent of twins are fraternal, also called diovular or dizygotic. Identical twins come from a single fertilised egg that splits early in cell division. They are always the same sex and very similar, yet fingerprints, birth marks, and handwriting differ.
| Feature | Fraternal twins | Identical twins |
|---|---|---|
| Origin | Two eggs fertilised separately | One egg splits during early division |
| Sex | Both boys, both girls, or one of each | Always the same sex |
| Similarity | Like ordinary siblings | Very similar; fingerprints and birth marks differ |
| Share of twins | About 75 per cent | About 25 per cent |
Triplets and quadruplets arise from various combinations of splitting zygotes and multiple eggs. Test-tube babies are produced by in vitro fertilisation, where a mature ovum is fertilised in a glass container and then placed in the uterus. Siamese or conjoined twins are identical twins that failed to separate completely. Uterine contractions during birth are a rare example of positive feedback — each contraction signals the uterus to contract further until delivery is complete.
The Class 10 ICSE chapter closes with birth and the after-birth, completing the arc from reproduction in general to a new individual.
What to practise from the Reproductive System Class 10 ICSE
The chapter has four exercise blocks. Work through them in order after reading each section.
- Progress Check — true or false statements on the oviducts, ovulation, clitoris, and vagina
- Review Questions — 21 questions covering multiple choice, very short, short, and long answer types, plus structured diagram-based questions
- Progress Check — 7 questions on the sperm parts, implantation, placenta, and gestation
- Review Questions — 19 questions including multiple choice, matching, table completion, and structured diagram-based types
The structured, diagram-based questions ask you to label the male and female reproductive systems, trace the sperm route, and identify stages of fertilisation and the developing foetus. Practising these with the figures in the book helps you recall the parts by their positions. For the full set of subjects, browse the other Class 10 books. You can also cross-check the chapter scope against the syllabus published on the official CISCE website.
Reproductive System Class 10 ICSE frequently asked questions
What is the reproductive system class 10 ICSE chapter about?
This chapter explains how humans reproduce, from gamete formation to birth. It covers the male and female reproductive organs, the menstrual cycle, fertilisation, implantation, the placenta, and parturition. It also defines reproduction and separates asexual from sexual reproduction.
What is the difference between an embryo and a foetus in the Class 10 ICSE syllabus?
An embryo is the growing egg after fertilisation until the main body parts and internal organs begin to take shape. Once the embryo starts to look like a baby, from about 7 weeks of gestation, it is called a foetus.
Which route does a sperm follow in the Class 10 ICSE male reproductive system?
Sperms travel from the seminiferous tubules to the epididymis, where they are stored and mature. They then pass through the sperm duct or vas deferens and enter the urethra, which carries them to the urethral opening. The order is epididymis, then sperm duct, then urethra.
How many eggs does a woman produce in her lifetime according to this ICSE chapter?
At one egg every 28 days over a reproductive period of about 32 years, a woman releases roughly 417 eggs. The calculation divides the total days of the reproductive period by 28. This is the pattern used in the chapter’s long-answer question.
Where does fertilisation take place in the female reproductive system, as explained in this ICSE chapter?
Fertilisation occurs in the oviduct or Fallopian tube, not in the uterus. Sperms swim up through the cervix and uterus to reach the ovum in the oviduct, where one sperm enters the egg.
Reference: ICSE Class 10 Biology textbook material, chapter 11: The Reproductive System — CISCE-aligned.