BharatNotes Why this chapter matters for UPSC: This is Chapter 7 of NCERT's Class X Science (Reprint 2026-27). It opens with a question few textbooks ask, why living things reproduce at all when an individual can live without doing so, and answers it with DNA copying and variation. It then covers the ways single organisms reproduce, sexual reproduction in flowering plants and in humans, and reproductive health: sexually transmitted diseases, contraception, sex-selective abortion and population. Prelims general science draws on its matched pairs (organism and mode of reproduction, flower parts, organs and their work); Mains questions on sex ratio, population and women's health rest on its last section.
Contemporary hook: On 28 February 2026 the Prime Minister launched a nationwide HPV vaccination drive for 14-year-old girls from Ajmer, Rajasthan. The Health Ministry's release calls cervical cancer "the second most common cancer among women in India" and names persistent infection with high-risk human papillomavirus types, "particularly types 16 and 18", as its primary cause. This chapter's last section, on keeping reproduction safe for health, is where such public-health measures belong.
🧠 First Principles — Read This First
Reproduction serves the species, not the individual. NCERT starts from a plain observation: "reproduction is not necessary to maintain the life of an individual organism". An organism that never reproduces can still live out its life. What reproduction does is make new bodies, so that a species continues after its individuals die. To make a new body, the organism must copy its DNA, the blueprint for the body, and build the cell apparatus around the copy.
Copying is never perfect, and that is useful. NCERT puts it in one line: "No bio-chemical reaction is absolutely reliable." Each copy of DNA differs slightly from the original. Most changes are harmful or neutral, but over generations they give a population a store of variation. If the surroundings change, a few variants may survive where the rest die. In NCERT's words, "Variation is thus useful for the survival of species over time."
Two strategies, one trade-off. In asexual reproduction a single parent makes copies of itself: fast, simple and with little variation. In sexual reproduction two parents each give a germ cell, and the offspring carries a new combination of DNA, so variation is larger. But combining two cells would double the DNA every generation, so sexual reproduction needs a special cell division, meiosis, that halves the DNA in the germ cells first.
PART 1 — Quick Reference
Table 1: How single organisms reproduce
| Mode | What happens | NCERT examples | Page |
|---|---|---|---|
| Binary fission | The cell splits into two equal halves | Many bacteria and protozoa; Amoeba splits in any plane; Leishmania (kala-azar) splits in a definite orientation, set by the whip-like structure at one end | pp. 115-116 |
| Multiple fission | One cell divides into many daughter cells at the same time | Plasmodium (malarial parasite) | p. 116 |
| Budding | A small bud grows out and separates | Yeast (Activity 7.1); Hydra, from regenerative cells dividing repeatedly at one site | pp. 115-117 |
| Fragmentation | The mature body breaks into pieces, each of which grows into a new individual | Spirogyra (Activity 7.4) | p. 116 |
| Regeneration | A cut piece grows into a complete organism, using specialised cells | Hydra, Planaria | pp. 116-117 |
| Vegetative propagation | New plants from roots, stems or leaves | Sugarcane, roses and grapes by layering or grafting; Bryophyllum from buds in the notches of the leaf margin; potato and money-plant (Activities 7.5-7.6) | pp. 117-118 |
| Spore formation | Spores formed in sporangia, protected by thick walls, grow when they land on a moist surface | Rhizopus (bread mould, Activity 7.2) | p. 118 |
Source: NCERT, Science Class X, ch. 7, Reprint 2026-27, sections 7.2.1-7.2.6 (pp. 115-118).
Table 2: The parts of a flower
| Part | What it is | NCERT line |
|---|---|---|
| Sepals and petals | Outer parts of the flower | NCERT asks what they might do; they are not reproductive parts |
| Stamen | Male reproductive part | Produces pollen grains, "yellowish in colour" |
| Pistil | Female reproductive part, in the centre of the flower | Made of three parts: ovary, style, stigma |
| Ovary | Swollen bottom part of the pistil | Holds ovules; each ovule has an egg cell |
| Style | Middle, elongated part | The pollen tube grows through it |
| Stigma | Terminal part | "may be sticky"; receives pollen |
| Unisexual flower | Has either stamens or pistil | Papaya, watermelon |
| Bisexual flower | Has both stamens and pistil | Hibiscus, mustard |
Source: NCERT, Science Class X, ch. 7, Reprint 2026-27, section 7.3.2 (pp. 120-121).
Table 3: From pollen to seed
| Step | What happens |
|---|---|
| Pollination | Pollen is carried from the stamen to the stigma: to the same flower (self-pollination) or another flower (cross-pollination), by wind, water or animals |
| Pollen tube | A tube grows out of the pollen grain, through the style, to the ovary |
| Fertilisation | The male germ cell fuses with the female gamete in the ovule; the product is the zygote |
| Embryo and seed | The zygote divides to form an embryo within the ovule; the ovule develops a tough coat and becomes a seed |
| Fruit | The ovary grows and ripens into a fruit |
| Germination | The seed's embryo develops into a seedling under suitable conditions (Activity 7.7: soaked Bengal gram) |
Source: NCERT, Science Class X, ch. 7, Reprint 2026-27, section 7.3.2 (p. 121).
Table 4: The human male reproductive system
| Organ | Work | NCERT detail |
|---|---|---|
| Testes | Make sperms and the hormone testosterone | Lie outside the abdominal cavity, in the scrotum, because sperm formation needs a temperature lower than normal body temperature |
| Vas deferens | Carries sperms | Joins a tube from the urinary bladder |
| Urethra | Common passage for sperms and urine | |
| Prostate and seminal vesicles | Add their secretions | The fluid makes transport easier and provides nutrition |
| Sperm | Tiny body | Mainly genetic material, with a long tail to move towards the female germ cell |
Source: NCERT, Science Class X, ch. 7, Reprint 2026-27, section 7.3.3(a) (p. 123).
Table 5: The human female reproductive system
| Organ | Work | NCERT detail |
|---|---|---|
| Ovaries | Make eggs and some hormones | A girl is born with thousands of immature eggs; from puberty, one egg is produced every month by one of the ovaries |
| Oviduct (fallopian tube) | Carries the egg to the uterus | Fertilisation takes place here |
| Uterus | Holds and nourishes the embryo | An elastic, bag-like structure; it opens into the vagina through the cervix |
| Placenta | Links embryo and mother | A disc in the uterine wall: villi on the embryo's side, blood spaces on the mother's; passes glucose and oxygen to the embryo and takes away its wastes |
| Pregnancy and birth | About nine months; the child is born through rhythmic contractions of the muscles of the uterus |
Source: NCERT, Science Class X, ch. 7, Reprint 2026-27, section 7.3.3(b) (pp. 123-124) and summary (p. 126).
Table 6: When the egg is not fertilised
| Event | NCERT detail |
|---|---|
| Uterus prepares every month | Its lining becomes thick and spongy, ready to nourish an embryo |
| Egg not fertilised | It lives for about one day |
| Lining not needed | It breaks down and is passed out: this is menstruation |
| Duration | Usually about two to eight days, in a cycle of roughly every month |
Source: NCERT, Science Class X, ch. 7, Reprint 2026-27, section 7.3.3(c) (p. 124).
Table 7: Sexually transmitted diseases and contraception
| Item | NCERT classification | What it does |
|---|---|---|
| Gonorrhoea, syphilis | Bacterial infections | Spread by sexual contact |
| Warts, HIV-AIDS | Viral infections | Spread by sexual contact |
| Condom (mechanical barrier) | Barrier | Stops sperm reaching the egg; helps prevent transmission of infections to some extent |
| Oral pills | Hormonal | Change the body's hormonal balance so that eggs are not released; can have side effects |
| Loop or copper-T | Placed in the uterus | Prevents pregnancy; can cause side effects due to irritation of the uterus |
| Surgery | Blocks the vas deferens (male) or the fallopian tube (female) | Stops sperm or egg from travelling |
Source: NCERT, Science Class X, ch. 7, Reprint 2026-27, section 7.3.3(d) (p. 125).
Table 8: NCERT lines to read with care
| NCERT says | The record |
|---|---|
| The body of 7.3.2 says the stamen produces pollen grains; the word "anther" first appears in the summary ("anther to the stigma", p. 126) and in Exercise 3 ("The anther contains", p. 127) | Not wrong, but the term is never defined in the chapter. Class XII names the parts of a stamen: "the long and slender stalk called the filament, and the terminal generally bilobed structure called the anther." Pollen grains are made in the anther. |
| Summary: "In fission, many bacteria and protozoa simply divide into two or more daughter cells" (p. 126) | The body keeps two cases apart: binary fission into "two equal halves" (p. 115) and multiple fission, as in Plasmodium, into "many daughter cells simultaneously" (p. 116). The summary line joins them. |
| "prenatal sex determination has been prohibited by law" (p. 125) | Correct, but unnamed. The law is the Pre-Conception and Pre-Natal Diagnostic Techniques (Prohibition of Sex Selection) Act, 1994 (Act 57 of 1994): see the box in PART 2. |
| Activity 7.6 (money-plant) is printed before Activity 7.5 (potato) on p. 118 | A layout slip only; do both. |
Source: NCERT, Science Class X, ch. 7, Reprint 2026-27 (pp. 115-127); NCERT, Biology Class XII, ch. 1 "Sexual Reproduction in Flowering Plants", section 1.2.1; Act 57 of 1994 (text as amended).
PART 2 — Concepts & Narrative
Do organisms create exact copies of themselves? (7.1)
We notice a species because there are many of its members, and the members look alike because they came from similar parents. NCERT traces that likeness to DNA. Reproduction copies the DNA, and "DNA copying is accompanied by the creation of an additional cellular apparatus", so that a cell can divide into two cells, each with a copy of the blueprint.
The copies are close but not exact. The copying machinery makes small errors, and NCERT calls this "inbuilt tendency for variation during reproduction" "the basis for evolution". Too much change and the new cell cannot work; a little change is the raw material that lets a population meet a changing world.
The importance of variation (7.1.1)
Niche. NCERT: "Populations of organisms fill well-defined places, or niches, in the ecosystem, using their ability to reproduce." The body design of a species fits its niche. If the niche changes, for example if the water warms, a population with some variation has a chance that a few of its members will survive the new conditions.
NCERT's example is a population of bacteria living in temperate waters. If the water were heated by global warming, "most of these bacteria would die, but the few variants resistant to heat would survive and grow further." Without variation, no one would survive. This is why NCERT treats variation as useful for a species, even though it is an accident of copying for the individual.
Modes of reproduction used by single organisms (7.2)
Fission. For unicellular organisms, cell division itself is reproduction. Many bacteria and protozoa simply split into two equal halves. Amoeba can split in any plane. Leishmania, which causes kala-azar, has a whip-like structure at one end, and its binary fission occurs in a definite orientation in relation to that structure. Plasmodium, the malarial parasite, divides into many daughter cells at once: multiple fission.
Fragmentation. In multicellular organisms with a simple body, such as Spirogyra, the filament simply breaks up into smaller pieces upon maturation, and each piece grows into a new individual (Activity 7.4, with a slide of Spirogyra).
Why complex bodies cannot just split. For organisms with many cell types, organised into tissues and organs, "cell-by-cell division would be impractical". They need a single cell type that is "capable of growing, proliferating and making other cell types under the right circumstances". Reproduction in such organisms depends on these cells.
Regeneration. Hydra and Planaria can be cut into any number of pieces, and each piece grows into a complete organism. Regeneration is carried out by specialised cells, which divide and then change into the various cell types and tissues; this change is called development. NCERT adds a caution: "regeneration is not the same as reproduction, since most organisms would not normally depend on being cut up to be able to reproduce."
Budding. Hydra uses its regenerative cells for reproduction in the process of budding: an outgrowth forms from repeated cell division at one specific site, grows into a tiny individual and detaches when mature. Yeast reproduces by small buds (Activity 7.1: yeast in sugar solution, seen under a microscope).
Vegetative propagation. Roots, stems and leaves can give rise to new plants. Gardeners use layering or grafting to grow sugarcane, roses and grapes. NCERT lists three advantages: plants raised this way bear flowers and fruits earlier than those grown from seeds; the method propagates plants such as banana, orange, rose and jasmine "that have lost the capacity to produce seeds"; and all the plants produced are "genetically similar enough to the parent plant to have all its characteristics". In Bryophyllum, buds produced in the notches along the leaf margin fall on the soil and grow into new plants.
Tissue culture (NCERT box, p. 118). Cells or tissue are taken from the growing tip of a plant and placed in an artificial medium, where they divide rapidly to form a small group of cells called callus. The callus is moved to another medium containing hormones for growth and differentiation, and the plantlets are then placed in soil. Many plants can be raised from one parent in disease-free conditions; NCERT notes that the method is commonly used for ornamental plants.
Spore formation. On moist bread, Rhizopus grows thread-like structures, the hyphae, which NCERT says "are not reproductive parts". The reproductive parts are tiny blob-on-a-stick structures, sporangia, holding cells, the spores, that can grow into new Rhizopus. Spores are covered by thick walls that protect them until they reach a moist surface.
Sexual reproduction (7.3)
NCERT starts with an everyday observation: "Bulls alone cannot produce new calves, nor can hens alone produce new chicks." In such cases both sexes, males and females, are needed to produce a new generation.
Why the sexual mode? (7.3.1). Copying errors give variation slowly. Combining the DNA of two individuals gives far more new combinations. But the problem is arithmetic: if two whole cells fused, the new cell would have twice the amount of DNA, and every generation would double it again. The answer is a special lineage of cells in specialised organs that have "half the number of chromosomes and half the amount of DNA", made by a process called meiosis. When two such germ cells combine, the normal amount is restored.
Germ cells and meiosis. Germ cells (gametes) carry half the DNA of a body cell; meiosis is the division that makes them. In many organisms the two germ cells differ: "One germ-cell is large and contains the food-stores while the other is smaller and likely to be motile." The motile germ cell is called male, the one with the food store female. In humans these are the sperm and the egg.
Sexual reproduction in flowering plants (7.3.2)
The reproductive parts of angiosperms are in the flower: "Stamens and pistil are the reproductive parts of a flower which contain the germ-cells." NCERT asks the student to think about what petals and sepals might do. The stamen produces pollen grains; the pistil, in the centre, has a swollen ovary, a long style and a stigma that may be sticky. The ovary contains ovules, and each ovule has an egg cell.
Pollen must reach the stigma. If it goes to the stigma of the same flower, that is self-pollination; to another flower, cross-pollination, achieved by agents like wind, water or animals. After the pollen lands on a suitable stigma, a tube grows out of the pollen grain and travels through the style to reach the ovary, where the male germ cell fuses with the female gamete. The zygote divides several times to form an embryo within the ovule; the ovule develops a tough coat and becomes a seed, and the ovary ripens into a fruit. The seed holds the future plant, which develops into a seedling under suitable conditions: germination. Activity 7.7 asks students to soak Bengal gram (chana) seeds and observe their parts.
Reproduction in human beings (7.3.3)
Human beings use sexual reproduction. NCERT describes the changes of the teenage years (thick hair in new parts of the body, oily skin and pimples; in girls, breast growth and the start of menstruation; in boys, facial hair and a cracking voice) and explains them in one sentence: "as the rate of general body growth begins to slow down, reproductive tissues begin to mature. This period during adolescence is called puberty."
The male reproductive system (a). The testes lie outside the abdominal cavity, in the scrotum, "because sperm formation requires a lower temperature than the normal body temperature." Besides making sperms, the testes secrete testosterone, which regulates sperm formation and brings about the changes of puberty in boys. The sperms travel through the vas deferens, which unites with a tube from the urinary bladder; "The urethra thus forms a common passage for both the sperms and urine." The prostate and seminal vesicles add their secretions, which make transport easier and provide nutrition. Sperms are tiny bodies consisting mainly of genetic material and a long tail.
The female reproductive system (b). The ovaries make eggs and some hormones. A girl is born with thousands of immature eggs; at puberty some start maturing, and one egg is produced every month by one of the ovaries. The egg is carried to the uterus through the oviduct, or fallopian tube; the two oviducts unite into the uterus, an elastic bag-like structure, which opens into the vagina through the cervix. Fertilisation occurs in the oviduct. The fertilised egg, the zygote, gets implanted in the lining of the uterus and divides; the uterus lining thickens and is richly supplied with blood to nourish the growing embryo.
The placenta. NCERT describes it as "a disc which is embedded in the uterine wall. It contains villi on the embryo's side of the tissue. On the mother's side are blood spaces, which surround the villi." The villi give a large surface for exchange: glucose and oxygen pass from mother to embryo, and the embryo's wastes go the other way into the mother's blood. The child develops inside the mother's body for approximately nine months and is born as a result of rhythmic contractions of the muscles in the uterus.
When the egg is not fertilised (c). The ovary releases one egg every month, and every month the uterus prepares by making its lining thick and spongy. If the egg is not fertilised, "it lives for about one day". The lining is then not needed; it slowly breaks down and comes out through the vagina. This is menstruation, which "usually lasts for about two to eight days".
Reproductive health (d). NCERT notes that sexual maturation is gradual and that the body may be ready before the mind; it names the pressures: from friends to take part in activities, from families to marry and have children, and from government agencies to avoid having children. Because sexual contact is intimate, diseases can pass between partners: "bacterial infections such as gonorrhoea and syphilis, and viral infections such as warts and HIV-AIDS." A condom on the penis can help prevent transmission of many of these to some extent.
Pregnancy makes major demands on the body and the mind of the woman, and if she is not ready for it her health suffers; that is the purpose of contraception. NCERT groups the methods: mechanical barriers, which stop the sperm reaching the egg; drugs, usually pills, which change the hormonal balance so that eggs are not released; devices such as the loop or the copper-T placed in the uterus; and surgery, which blocks the vas deferens in males or the fallopian tube in females. NCERT also warns that surgery has been misused: "illegal sex-selective abortion of female foetuses" has led to a situation in which the "child sex ratio is declining at an alarming rate in some sections of our society, although prenatal sex determination has been prohibited by law".
NCERT closes with population. A large population makes it hard to raise living standards for everyone, but it adds a qualifier that is useful for any Mains answer: "if inequality in society is the main reason for poor standards of living for many people, the size of the population is relatively unimportant."
Did the 2020-21 edition differ?
No. In the 2020-21 edition this was Chapter 8 (pp. 127-141); in Reprint 2026-27 it is Chapter 7 (pp. 113-127). Its sections, boxes, activities and exercises read the same; only the numbering of the chapter, its sections and its activities has moved by one.
Source: NCERT, Science Class X, 2020-21 edition (whole-book zip, Wayback Machine capture of 9 October 2021), compared with Reprint 2026-27.
Beyond the textbook: the HPV vaccination drive (February 2026)
On 28 February 2026 the Prime Minister launched a nationwide HPV vaccination drive for 14-year-old girls from Ajmer, Rajasthan. The Health Ministry's release sets out the programme:
- Why. Cervical cancer "is the second most common cancer among women in India" (as the release puts it, citing the WHO GLOBOCAN report 2022), and persistent infection with high-risk HPV types, "particularly types 16 and 18", is its primary cause.
- Vaccine. "India's national programme uses Gardasil-4 (Quadrivalent: HPV types 6, 11, 16, 18) in a single-dose schedule": one 0.5 ml intramuscular injection.
- Who. Girls aged 14, defined as "those who have completed 14 years but have not yet completed 15 years".
- How. Vaccination is voluntary and free of cost, given at government health facilities only after parental or guardian consent, which is recorded on the U-WIN digital platform.
A vaccine works before infection, by preparing the immune system; it is a different kind of protection from the barrier methods in NCERT's list.
Source: PIB (Ministry of Health and Family Welfare), "Prime Minister Shri Narendra Modi Launches Nationwide HPV Vaccination Drive for 14-Year-Old Girls from Ajmer, Rajasthan", 28 February 2026.
Beyond the textbook: surrogacy and assisted reproduction law
Two Acts of 2021 regulate how medical technology is used for the fertilisation and pregnancy this chapter describes.
The Surrogacy (Regulation) Act, 2021 (No. 47 of 2021) came into force on 25 January 2022, as the Supreme Court recorded in a judgment of 9 October 2025. Section 4(iii)(b) sets who may be a surrogate mother:
- only "an ever married woman having a child of her own and between the age of 25 to 35 years on the day of implantation";
- "a willing woman shall act as a surrogate mother";
- "no woman shall act as a surrogate mother by providing her own gametes";
- "no woman shall act as a surrogate mother more than once in her lifetime".
The Act, as enacted, does not require the surrogate to be a close relative of the intending couple; that is a common error in notes. The Surrogacy (Regulation) Amendment Rules, 2024 (notified 21 February 2024) allow a donor gamete "when the District Medical Board certifies that either husband or wife constituting the intending couple suffers from medical condition necessitating use of donor gamete", and a single woman (widow or divorcee) using surrogacy "must use self eggs and donor sperms".
The Assisted Reproductive Technology (Regulation) Act, 2021 (No. 42 of 2021, published 18 December 2021) lets clinics offer these services to a woman "above the age of twenty-one years and below the age of fifty years" and a man above twenty-one and below fifty-five (section 21). Banks may obtain oocytes only from women "between twenty-three years of age and thirty-five years of age", and under section 27(4) an oocyte donor may donate only once in her life, with no more than seven oocytes retrieved from her.
Source: The Surrogacy (Regulation) Act, 2021, s. 4; Surrogacy (Regulation) Amendment Rules, 2024 (Gazette of India, 21 February 2024); Supreme Court of India, judgment of 9 October 2025; The Assisted Reproductive Technology (Regulation) Act, 2021, ss. 21 and 27.
Beyond the textbook: the law behind "prohibited by law", and the latest survey
The law NCERT refers to is the Pre-Conception and Pre-Natal Diagnostic Techniques (Prohibition of Sex Selection) Act, 1994 (Act 57 of 1994). In its amended text:
- section 3A prohibits sex selection: no person, "including a specialist or a team of specialists in the field of infertility", shall conduct or aid in conducting "sex selection on a woman or a man or on both";
- section 5(2) bars anyone, including the person conducting the test, from telling the pregnant woman, her relatives or anyone else "the sex of the foetus by words, signs, or in any other manner";
- section 6 says no person shall conduct "any pre-natal diagnostic techniques including ultrasonography for the purpose of determining the sex of a foetus."
On population, the Health Ministry's release of the sixth National Family Health Survey (NFHS-6, conducted 2023-24, released 29 May 2026) states: "India's Total Fertility Rate (TFR) remains at 2.0. The Contraceptive Prevalence Rate (CPR) increased from 66.7% to 69.1%". A TFR of 2.0 means that, at current rates, a woman would have two children on average over her life.
Source: The Pre-Conception and Pre-Natal Diagnostic Techniques (Prohibition of Sex Selection) Act, 1994, ss. 3A, 5 and 6 (amended text, as reproduced by Indian Kanoon); PIB (Ministry of Health and Family Welfare), release on NFHS-6, 29 May 2026.
PART 3 — UPSC Integration
Cross-paper relevance
- Prelims (general science) — modes of asexual reproduction and their examples, flower parts, unisexual and bisexual flowers, pollination and fertilisation, human reproductive organs and their work, the placenta, sexually transmitted diseases and contraception.
- GS1 (Society: population, women) — sex-selective abortion and the child sex ratio; population and inequality; contraception and women's choices.
- GS2 (Health; laws) — reproductive health, the HPV vaccination drive, the Surrogacy and ART Acts, the law against sex selection, NFHS-6.
- GS3 (Science and technology; agriculture) — tissue culture and vegetative propagation in horticulture; variation as the basis of adaptation.
Past questions on these themes: "Why do some of the most prosperous regions of India have an adverse sex ratio for women? Give your arguments." (Mains 2014 GS1); "'Empowering women is the key to control population growth.' Discuss." (Mains 2019 GS1).
Frames for Mains Answers
1. Why variation matters. Copying of DNA is never exact; the small differences let a few members of a population survive when the niche changes (NCERT's heat-resistant bacteria). Sexual reproduction adds variation by combining two parents' DNA, with meiosis keeping the amount constant.
2. Sex ratio: technology and law. NCERT names the mechanism: tests that reveal the sex of a foetus, misused for illegal sex-selective abortion, while the law prohibits prenatal sex determination. Cite the PCPNDT Act's sections 3A, 5(2) and 6 and argue that the law alone has not been enough "in some sections of our society", NCERT's own qualifier.
3. Population and women. Use NCERT's line that if inequality is the main cause of poverty, population size is "relatively unimportant"; add NFHS-6 (TFR 2.0, contraceptive prevalence up from 66.7 % to 69.1 %) to show that fertility has fallen with wider choice, which is the case for empowering women.
4. Reproductive health as public health. Barrier methods and condoms prevent some infections only to some extent; a vaccine protects before infection, as in the HPV drive for 14-year-old girls (28 February 2026). Regulation of surrogacy and ART protects women from exploitation (one surrogacy per lifetime; one oocyte donation per lifetime).
Exam Strategy
Prelims fact-traps:
- Amoeba splits in any plane; Leishmania in a definite orientation.
- Plasmodium = multiple fission; yeast = budding (NCERT's Exercise 1); Spirogyra = fragmentation; Rhizopus = spores; Planaria = regeneration; Hydra = regeneration and budding.
- Regeneration is not reproduction in NCERT's view.
- Bryophyllum buds form in the notches of the leaf margin.
- Papaya and watermelon have unisexual flowers; Hibiscus and mustard bisexual.
- Fertilisation in humans takes place in the oviduct (fallopian tube), not the uterus.
- Testes lie outside the abdomen because sperm formation needs a lower temperature.
- Placenta: villi on the embryo's side, blood spaces on the mother's.
- Unfertilised egg: about one day; menstruation: about two to eight days.
- Gonorrhoea and syphilis are bacterial; warts and HIV-AIDS viral (NCERT).
- Surrogacy Act: no close-relative condition; ever-married, own child, 25-35, once in a lifetime.
- HPV drive: girls aged 14, single dose, Gardasil-4 (types 6, 11, 16, 18), launched 28 February 2026 from Ajmer.
Mains: Use NCERT's own lines on variation, sex-selective abortion and population as the base, then add the law and the survey with their dates.
Practice Questions
Questions 1-3 are the NCERT exercise MCQs. Practice (UPSC-pattern, not past papers): questions 4-10.
1. Asexual reproduction takes place through budding in
(a) Amoeba.
(b) Yeast.
(c) Plasmodium.
(d) Leishmania.
Answer: (b). Amoeba and Leishmania divide by binary fission, Plasmodium by multiple fission (NCERT Answers, p. 218).
2. Which of the following is not a part of the female reproductive system in human beings?
(a) Ovary
(b) Uterus
(c) Vas deferens
(d) Fallopian tube
Answer: (c). The vas deferens carries sperms in the male (NCERT Answers, p. 218).
3. The anther contains
(a) sepals.
(b) ovules.
(c) pistil.
(d) pollen grains.
Answer: (d) (NCERT Answers, p. 218).
4. Consider the following pairs of organism and mode of reproduction:
1. Plasmodium — multiple fission
2. Planaria — regeneration
3. Rhizopus — budding
4. Bryophyllum — buds on the leaf margin
How many of the pairs are correctly matched?
(a) Only one
(b) Only two
(c) Only three
(d) All four
Answer: (c). Rhizopus reproduces by spores formed in sporangia.
5. Which of the following plants bear unisexual flowers, according to NCERT?
1. Papaya
2. Mustard
3. Watermelon
4. Hibiscus
Select the correct answer:
(a) 1 and 2 only
(b) 1 and 3 only
(c) 2 and 4 only
(d) 3 and 4 only
Answer: (b). Mustard and Hibiscus flowers have both stamens and pistil.
6. Consider the following statements:
1. The testes lie outside the abdominal cavity because sperm formation needs a temperature lower than normal body temperature.
2. In human beings, fertilisation normally takes place in the uterus.
3. In the placenta, the villi lie on the mother's side and the blood spaces on the embryo's side.
Which of the statements given above is/are correct?
(a) 1 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2 and 3
Answer: (a). Fertilisation occurs in the oviduct; the villi are on the embryo's side.
7. With reference to the Surrogacy (Regulation) Act, 2021, consider the following statements:
1. A surrogate mother must be a close relative of the intending couple.
2. A surrogate mother must be an ever-married woman having a child of her own.
3. A woman may act as a surrogate mother only once in her lifetime.
Which of the statements given above are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer: (b). Section 4(iii)(b) sets no close-relative condition.
8. With reference to the nationwide HPV vaccination drive launched in February 2026, consider the following statements:
1. It covers girls aged 14 years.
2. It uses a quadrivalent vaccine covering HPV types 6, 11, 16 and 18.
3. It follows a two-dose schedule.
Which of the statements given above are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer: (a). The programme uses a single-dose schedule.
9. According to NCERT, which of the following sexually transmitted diseases are caused by viruses?
1. Gonorrhoea
2. Syphilis
3. Warts
4. HIV-AIDS
Select the correct answer:
(a) 1 and 2 only
(b) 2 and 3 only
(c) 3 and 4 only
(d) 1 and 4 only
Answer: (c). Gonorrhoea and syphilis are bacterial infections.
10. NCERT calls variation "useful for the survival of species over time". Explain this with examples from asexual and sexual reproduction, and say why sexual reproduction needs meiosis. (150 words)
NCERT exercises (where the answers are on this page): 4 the section on the sexual mode; 5 Table 4; 6 Table 6; 7 Table 2; 8 Table 7; 9 Table 1 and the section on complex bodies; 10 the variation section; 11 the section on reproductive health.
📦 Revision Capsule
Hard Facts
- Binary fission: bacteria, protozoa, Amoeba (any plane), Leishmania (definite orientation); multiple fission: Plasmodium.
- Budding: yeast, Hydra; fragmentation: Spirogyra; regeneration: Hydra, Planaria; spores: Rhizopus; leaf buds: Bryophyllum.
- Vegetative propagation: layering or grafting (sugarcane, roses, grapes); seedless banana, orange, rose, jasmine.
- Flower: stamen (pollen) + pistil (ovary, style, stigma); unisexual papaya, watermelon; bisexual Hibiscus, mustard.
- Male: testes (sperms, testosterone) in the scrotum; vas deferens; urethra; prostate and seminal vesicles.
- Female: ovaries; oviduct (site of fertilisation); uterus; cervix; placenta (villi and blood spaces).
- Egg lives about one day; menstruation about two to eight days; pregnancy about nine months.
Core Concepts
- Reproduction copies DNA; imperfect copying gives variation; variation lets a species survive change.
- Complex bodies cannot reproduce cell by cell; they rely on specialised cells.
- Sexual reproduction combines two parents' DNA; meiosis halves the DNA in germ cells first.
- Reproductive health covers infections, contraception, sex-selective abortion and population.
Confused Pairs
- Binary fission (two cells) vs multiple fission (many cells at once).
- Regeneration (from a cut piece) vs budding (from a site of repeated division).
- Hyphae (not reproductive) vs sporangia (hold spores).
- Self-pollination vs cross-pollination.
- Oviduct = fallopian tube (one organ, two names) vs vas deferens (male).
- Class X's single account of fertilisation vs Class XII's double fertilisation in flowering plants.
- Barrier contraception vs vaccination: one blocks contact, the other prepares immunity.
- Surrogacy Act (who may be a surrogate) vs ART Act (clinics, banks and donors).
Data Points
- HPV drive: launched 28 February 2026 from Ajmer; girls aged 14; Gardasil-4, single 0.5 ml dose.
- Surrogacy Act 2021: in force 25 January 2022; surrogate 25-35, ever-married with own child, once in a lifetime.
- ART Act 2021: women 21-50, men 21-55; oocyte donors 23-35, once, at most seven oocytes.
- NFHS-6 (released 29 May 2026): TFR remains 2.0; contraceptive prevalence 66.7 % → 69.1 %.
PYQ Pattern
- Mains 2014 GS1: why some of India's most prosperous regions have an adverse sex ratio for women.
- Mains 2019 GS1: "Empowering women is the key to control population growth".
Sources
- NCERT, Science, Textbook for Class X, ch. 7 "How do Organisms Reproduce?", Reprint 2026-27 — ncert.nic.in PDF.
- NCERT, Science, Class X, Answers, Reprint 2026-27 — ncert.nic.in PDF.
- NCERT, Science, Class X, 2020-21 edition (whole-book zip), as archived on 9 October 2021 — Wayback Machine.
- NCERT, Biology, Textbook for Class XII, ch. 1 "Sexual Reproduction in Flowering Plants" — ncert.nic.in PDF.
- PIB (Ministry of Health and Family Welfare), "Prime Minister Shri Narendra Modi Launches Nationwide HPV Vaccination Drive for 14-Year-Old Girls from Ajmer, Rajasthan", 28 February 2026 — pib.gov.in.
- The Surrogacy (Regulation) Act, 2021 (No. 47 of 2021) — PRS Legislative Research PDF.
- Surrogacy (Regulation) Amendment Rules, 2024, Gazette of India, 21 February 2024 — egazette.gov.in PDF.
- Supreme Court of India, judgment of 9 October 2025 on age limits under the Surrogacy Act — sci.gov.in PDF.
- The Assisted Reproductive Technology (Regulation) Act, 2021 (No. 42 of 2021), Gazette of India, 18 December 2021 — egazette.gov.in PDF.
- The Pre-Conception and Pre-Natal Diagnostic Techniques (Prohibition of Sex Selection) Act, 1994 (Act 57 of 1994), amended text as reproduced by Indian Kanoon.
- PIB (Ministry of Health and Family Welfare), release on the National Family Health Survey-6, 29 May 2026 — pib.gov.in.
