How do Organisms Reproduce Class 10 Notes

These Notes for Class 10 Science Chapter 7 How do Organisms Reproduce? give you a fast, concept-first revision of the whole chapter, built on the latest 2026-27 CBSE syllabus. They cover why organisms reproduce and the role of DNA copying, the modes of asexual reproduction, the meaning of sexual reproduction and variation, reproduction in flowering plants through pollination and fertilisation, and reproduction in human beings with the male and female systems, the menstrual cycle and reproductive health.

• Every idea explained with a one-line meaning, a simple diagram, and the everyday example CBSE keeps repeating in the board exam.
• Full coverage of fission, budding, fragmentation, regeneration, spore formation, vegetative propagation, pollination, fertilisation, the placenta and menstruation.
• Notes aligned with the 2026-27 CBSE Class 10 Science syllabus and written for the board exam; no NEET or JEE references because this is a Class 10 board chapter.

These Collegedunia revision notes are curated by Science subject experts, mapped to the 2026-27 NCERT textbook, and refined against the last five years of CBSE Class 10 Science board papers.

What the Notes for Class 10 Science Chapter 7 How do Organisms Reproduce? Cover

Reproduction is the one life process an individual can live without, yet it keeps a species going. This chapter answers one question: how do living things make more of their own kind? These notes follow the NCERT order in exam-ready blocks:

• Why reproduce: DNA copying, why offspring look like parents, and how variation keeps a species alive.
• Asexual reproduction: fission, fragmentation, regeneration, budding, spores and vegetative propagation.
• Sexual reproduction: gametes, meiosis, pollination and fertilisation; and human reproduction with the placenta and menstrual cycle.

Why and How Do Organisms Reproduce in Class 10 Science

Organisms of the same kind look alike because their body designs are written in DNA (Deoxyribo Nucleic Acid) inside the chromosomes of every cell. DNA decides which proteins a cell makes, and proteins decide the body design. So the first event in any reproduction is the making of a fresh copy of the DNA, after which the cell divides into two.

No copying is perfect. Every time DNA is copied, tiny differences called variations creep in. These are the raw material for evolution and help the species survive.

• Each population fills a well-defined place, or niche, in its ecosystem.
• Accurate DNA copying keeps the body design suited to that niche, giving stability.
• If the niche changes suddenly, built-in variation gives a few members a chance to survive.

Asexual Reproduction in Class 10 Science: Fission, Budding and More

In asexual reproduction a single parent produces new individuals without joining germ-cells, so the offspring are almost exact copies, called a clone. Single-celled organisms just split, while organisms with tissues use more organised methods.

Spore Formation and Vegetative Propagation in Plants

In spore formation, used by simple multi-cellular organisms, the bread mould Rhizopus grows thread-like hyphae bearing sporangia, each holding hundreds of spores. Spores have thick protective walls, so they survive harsh conditions and grow into new moulds on a moist surface.

In vegetative propagation, a part of the parent plant grows into a whole new plant. It is natural (shoots from a potato's "eyes", buds on a Bryophyllum leaf) or artificial (cutting, layering, grafting and tissue culture).

Farmers like it because plants flower and fruit earlier, seedless plants (banana, orange) can still be grown, and every new plant is genetically identical to the parent.

Sexual Reproduction and Variation in Class 10 Science

Sexual reproduction needs two parents. Each makes a gamete, and the two fuse to start a new individual. Its big advantage is that it mixes the variations of two individuals, producing far more variation than asexual modes.

If each generation simply added the full DNA of two parents, it would double each time. Meiosis, a special cell division, makes germ-cells with half the usual chromosomes, so when two gametes fuse the full number is restored.

The male gamete is small and motile; the female gamete is large, non-motile and carries food for the early embryo. The table compares the two types.

Sexual Reproduction in Flowering Plants: Pollination and Fertilisation

In flowering plants the reproductive parts sit inside the flower: sepals (protective), petals (attract pollinators), stamens (male) and the pistil or carpel (female). A flower with both stamens and pistil is bisexual (Hibiscus); one with only one is unisexual (papaya).

The anther makes pollen grains holding the male gametes; the stigma catches pollen, the style is the tube the pollen tube grows down, and the ovary holds the ovules, each with one egg.

Pollination is the transfer of pollen from an anther to a stigma, the step before fertilisation. It is self-pollination (same flower) or cross-pollination, where wind, water or insects carry pollen to another flower of the same kind. A pollen tube then grows down the style to the ovary, where the male gamete fuses with the egg. This fusion is fertilisation, producing the zygote.

After fertilisation, the flower parts change in a fixed, often-tested way:

Reproduction in Human Beings: Male and Female Reproductive Systems

Humans reproduce sexually, and the body matures for this at puberty. In girls the breasts develop and menstruation begins; in boys facial hair grows and the voice deepens. Puberty marks physical maturity, not readiness for sexual activity or raising children.

The male reproductive system makes and delivers the sperms. The testes make sperms and testosterone, and lie in the scrotum outside the body, because sperm formation needs a temperature below body temperature. The vas deferens carries sperms to the urethra, which carries both sperm and urine. The seminal vesicles and prostate gland add fluids; sperms plus these fluids make semen.

The female reproductive system makes the eggs, receives the sperm, and nurtures the baby until birth.

• Ovaries make eggs and female hormones; from puberty, one egg matures roughly each month.
• The egg travels to the uterus through a thin oviduct (fallopian tube).
• The uterus (womb) is where the baby develops; it opens into the vagina through the cervix.

Fertilisation, the Placenta and the Menstrual Cycle

During intercourse, sperms enter through the vagina, swim up, and meet the egg in the oviduct. If a sperm fuses with the egg, fertilisation occurs and a zygote forms. The zygote divides into the embryo, which embeds in the uterus lining and grows organs to become a foetus over about nine months.

The embryo is fed through the placenta, a disc in the uterine wall. On the embryo's side are finger-like villi giving a large surface area; on the mother's side are blood spaces around them. Glucose and oxygen pass from mother to embryo, and the embryo's waste passes back into the mother's blood. The baby is born by rhythmic contractions of the uterus.

Each month the uterus prepares a thick, blood-rich lining for a possible embryo. If the egg is not fertilised, no embryo arrives, so this lining breaks down and leaves the body as blood and mucus. This is menstruation, lasting two to eight days.

Reproductive Health, Contraception and the Sex Ratio

Good reproductive health means staying free of disease and making safe choices. Sexually transmitted diseases (STDs) spread through the sexual act and include bacterial ones (gonorrhoea, syphilis) and viral ones (warts, HIV-AIDS). A condom helps prevent many of these infections.

To plan family size and protect health, several contraceptive methods are used, grouped by how they work:

• Barrier (condom): stops sperm reaching the egg, and also blocks STDs.
• Hormonal (oral pills): change hormones so no egg is released.
• Intra-uterine device (loop, copper-T): placed inside the uterus.
• Surgical: vasectomy (vas deferens) and tubectomy (oviduct) block the gamete path.

A healthy society also needs a balanced female-to-male sex ratio. Female foeticide, the illegal sex-selective abortion of female foetuses, has pushed the child sex ratio down, so the law prohibits prenatal sex determination.

Also Check: The full set of CBSE board paper questions for this chapter, with step-by-step answers, is included in the downloadable PDF above, updated for the 2026-27 cycle.

Other Resources for Class 10 Science Chapter 7 How do Organisms Reproduce?

Pair these revision notes with the matching NCERT Solutions, the formula sheet, handwritten notes and the official NCERT book chapter. All resources for Class 10 Science Chapter 7 How do Organisms Reproduce? are linked below.

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