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By Ankit Gupta
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Updated on 26 Jun 2026, 15:27 IST
How Do Organisms Reproduce? is Chapter 7 of NCERT Class 10 Science and an important Biology chapter for CBSE board exam preparation. This chapter explains why reproduction is necessary, how organisms reproduce asexually and sexually, how flowering plants form seeds, and how the human reproductive system works.
These How Do Organisms Reproduce Class 10 Notes are written in a simple and exam-focused way to help students revise the chapter quickly. The notes cover DNA copying, variation, binary fission, budding, fragmentation, regeneration, spore formation, vegetative propagation, sexual reproduction in flowering plants, puberty, male and female reproductive systems, fertilisation, placenta, menstruation, reproductive health, contraception, and sexually transmitted diseases.
Students can use these notes for school exams, pre-board exams, CBSE board revision, MCQs, assertion-reason questions, previous year questions, case-based questions, and long-answer questions.
The CBSE Class 10 Science Notes Chapter 7 - How Do Organisms Reproduce also emphasize the importance of reproductive health, especially in humans. It discusses topics like contraception, fertilization, menstrual cycle, and the development of the embryo. Understanding reproduction helps learners appreciate how life continues, adapts, and evolves.
| Topic | What You Will Learn |
| Reproduction | Process by which organisms produce new individuals |
| DNA Copying | Transfer of hereditary information from parents to offspring |
| Variation | Small differences that help species survive changing conditions |
| Asexual Reproduction | Reproduction involving a single parent |
| Sexual Reproduction | Reproduction involving male and female gametes |
| Flowering Plants | Pollination, fertilisation, seed formation, and germination |
| Human Reproduction | Puberty, reproductive organs, fertilisation, pregnancy, and menstruation |
| Reproductive Health | STDs, contraception, and responsible health awareness |
Reproduction is the biological process by which living organisms produce new individuals of their own kind. It helps in the continuation of a species from one generation to the next.
Reproduction is not necessary for the survival of an individual organism, but it is necessary for the survival of the species. If organisms do not reproduce, their species will slowly disappear after the death of existing individuals.
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Do Check: CBSE Class 10 Science Notes
Reproduction is important because it:
DNA contains the genetic information that controls the body design and functions of an organism. During reproduction, DNA is copied and passed from the parent to the offspring.
DNA copying is important because the new organism must receive genetic instructions from the parent. However, DNA copying is not always perfectly accurate. Small changes may occur during copying, and these changes produce variations.
DNA copying is not the only step in reproduction. A new cell also needs cellular structures such as cytoplasm and cell organelles. If only DNA is copied but no cell structure is formed around it, the copied DNA cannot survive as a new individual.
Variation means small differences among individuals of the same species. These differences may help organisms survive when the environment changes.
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Example:
If a population of bacteria lives in normal water and the water temperature suddenly rises, most bacteria may die. But a few bacteria with heat-resistant variation may survive and multiply. This shows why variation is important for the survival of a species.
Do Check: CBSE Class 10 Science Syllabus
There are two main types of reproduction:
| Basis | Asexual Reproduction | Sexual Reproduction |
| Parents involved | One parent | Usually two parents |
| Gametes | Not formed | Male and female gametes are formed |
| Fertilisation | Does not occur | Occurs |
| Variation | Less variation | More variation |
| Offspring | Usually identical to parent | Similar but not identical to parents |
| Examples | Amoeba, Hydra, yeast, Rhizopus | Humans, flowering plants |
Asexual reproduction is a type of reproduction in which a single parent produces new individuals. Gametes are not formed, and fertilisation does not occur. The offspring are usually similar to the parent.
| Method | Example |
| Binary fission | Amoeba, Leishmania |
| Multiple fission | Plasmodium |
| Budding | Hydra, yeast |
| Fragmentation | Spirogyra |
| Regeneration | Planaria |
| Spore formation | Rhizopus |
| Vegetative propagation | Potato, ginger, Bryophyllum |
Binary fission is a method of asexual reproduction in which one parent cell divides into two daughter cells.
In Amoeba, the nucleus divides first. Then the cytoplasm divides, forming two daughter Amoebae.
Process:
Parent Amoeba → Nucleus divides → Cytoplasm divides → Two daughter Amoebae are formed
Leishmania is a unicellular parasite that causes kala-azar. It has a whip-like structure called a flagellum at one end. In Leishmania, binary fission occurs in a definite longitudinal orientation because of this flagellum.
Exam Tip:
Leishmania is an important example because its binary fission occurs in a definite orientation.
Multiple fission is a method of asexual reproduction in which one parent cell divides into many daughter cells at the same time.
Plasmodium, the malarial parasite, reproduces by multiple fission. Its nucleus divides many times, and each nucleus gets surrounded by cytoplasm to form many new individuals.
| Basis | Binary Fission | Multiple Fission |
| Meaning | One cell divides into two daughter cells | One cell divides into many daughter cells |
| Number of offspring | Two | Many |
| Example | Amoeba, Leishmania | Plasmodium |
| Condition | Usually favourable conditions | Often unfavourable conditions |
Budding is a method of asexual reproduction in which a small outgrowth called a bud develops on the parent body. The bud grows and separates to form a new individual.
In Hydra, repeated cell division at one specific site forms a bud. The bud grows into a small Hydra and later separates from the parent.
In yeast, a small bud grows on the parent cell. It increases in size and finally detaches to form a new yeast cell.
Fragmentation is a method of asexual reproduction in which the body of an organism breaks into smaller pieces, and each piece grows into a new organism.
Spirogyra is a filamentous algae. When its filament breaks into smaller fragments, each fragment can grow into a new Spirogyra under favourable conditions.
Regeneration is the ability of an organism to regrow lost body parts. In some simple organisms, small body pieces can grow into complete individuals.
If the body of Planaria is cut into pieces, each piece can grow into a complete Planaria.
Regeneration is not considered normal reproduction in complex organisms because their bodies are highly organised into tissues, organs, and organ systems. Complex organisms cannot grow into complete individuals from cut pieces. Also, organisms do not normally depend on being cut into pieces to reproduce.
Spore formation is a method of asexual reproduction in which tiny reproductive bodies called spores are formed inside sporangia.
Rhizopus is commonly seen as bread mould. The thread-like structures on bread are called hyphae. These are not reproductive parts. The small blob-like structures at the tips of hyphae are called sporangia. Sporangia contain spores.
When spores are released and fall on a suitable surface, they germinate and form new Rhizopus.
| Term | Meaning |
| Hyphae | Thread-like structures of Rhizopus |
| Sporangia | Structures that contain spores |
| Spores | Reproductive bodies that grow into new organisms |
Vegetative propagation is a type of asexual reproduction in plants. In this method, new plants are produced from vegetative parts such as roots, stems, leaves, or buds.
| Plant Part | Example |
| Root | Sweet potato |
| Stem | Potato, ginger |
| Leaf | Bryophyllum |
| Bud | Potato eyes |
Vegetative propagation is useful because:
Tissue culture is an artificial method of vegetative propagation. In this method, a small piece of plant tissue or cells is taken from the growing tip of a plant and placed in a nutrient medium.
The cells divide rapidly and form a mass of cells called a callus. The callus is transferred to another medium containing hormones, where it develops into small plantlets. These plantlets can then be grown into complete plants.
Sexual reproduction is a type of reproduction in which male and female gametes fuse to form a zygote. The zygote develops into a new individual.
Sexual reproduction produces more variation than asexual reproduction because the offspring receive genetic material from two parents.
Flowers are the reproductive parts of flowering plants. A flower may contain male parts, female parts, or both.
| Part | Function |
| Sepals | Protect the flower in bud stage |
| Petals | Attract pollinators |
| Stamen | Male reproductive part |
| Anther | Produces pollen grains |
| Filament | Supports the anther |
| Pistil / Carpel | Female reproductive part |
| Stigma | Receives pollen grains |
| Style | Provides path for pollen tube |
| Ovary | Contains ovules |
| Ovule | Contains female germ cell |
| Type of Flower | Meaning | Examples |
| Unisexual flower | Has either male or female reproductive part | Papaya, watermelon |
| Bisexual flower | Has both male and female reproductive parts | Hibiscus, mustard |
Pollination is the transfer of pollen grains from the anther to the stigma of a flower.
| Type | Meaning |
| Self-pollination | Pollen is transferred to the stigma of the same flower or another flower on the same plant |
| Cross-pollination | Pollen is transferred to the stigma of a flower on another plant of the same species |
After pollination, the pollen grain lands on the stigma and germinates. It forms a pollen tube that grows through the style and reaches the ovary. The pollen tube enters the ovule, where the male germ cell fuses with the female egg cell to form a zygote.
Pollen grain lands on stigma → Pollen tube forms → Pollen tube grows through style → Pollen tube reaches ovary → Pollen tube enters ovule → Male germ cell fuses with egg cell → Zygote is formed
| Before Fertilisation | After Fertilisation |
| Zygote | Embryo |
| Ovule | Seed |
| Ovary | Fruit |
| Ovary wall | Fruit wall |
A seed contains the embryo of a future plant. Under suitable conditions, the seed grows into a seedling. This process is called germination.
| Part | Function |
| Seed coat | Protects the seed |
| Cotyledons | Store food for the embryo |
| Plumule | Develops into the future shoot |
| Radicle | Develops into the future root |
Seeds need:
Human beings reproduce sexually. The male reproductive system produces sperms, and the female reproductive system produces eggs. Fertilisation occurs when a sperm fuses with an egg to form a zygote.
Do Check: CBSE Class 10 Science Sample Papers
Puberty is the stage at which the reproductive system becomes mature. During this stage, the body undergoes several physical and hormonal changes.
Remember:
Puberty changes happen gradually and may occur at different ages for different individuals.
The male reproductive system produces sperms and transfers them to the female reproductive tract.
| Part | Function |
| Testes | Produce sperms and testosterone |
| Scrotum | Holds testes outside the abdominal cavity |
| Vas deferens | Carries sperms from testes |
| Seminal vesicles | Add fluid and nutrients to sperms |
| Prostate gland | Adds fluid that helps sperm movement |
| Urethra | Common passage for urine and semen |
| Penis | Transfers semen into the female reproductive tract |
Testes are located outside the abdominal cavity in the scrotum because sperm formation requires a temperature about 2–3°C lower than normal body temperature. The scrotum helps maintain this lower temperature for proper sperm production.
The seminal vesicles and prostate gland add secretions to sperms. These secretions provide a fluid medium for sperm transport and also supply nutrition to the sperms.
The female reproductive system produces eggs, supports fertilisation, and provides a suitable place for embryo development.
| Part | Function |
| Ovaries | Produce eggs and female hormones |
| Fallopian tubes / Oviducts | Carry egg from ovary to uterus; usual site of fertilisation |
| Uterus | Site where embryo develops |
| Cervix | Lower narrow part of uterus |
| Vagina | Receives sperms and acts as birth canal |
Fertilisation is the fusion of sperm and egg to form a zygote. In humans, fertilisation usually takes place in the fallopian tube.
After fertilisation, the zygote divides repeatedly to form an embryo. The embryo moves to the uterus and attaches to the uterine lining. This attachment is called implantation.
Sperm reaches fallopian tube → Sperm fuses with egg → Zygote is formed → Zygote divides to form embryo → Embryo implants in uterus
The placenta is a special tissue that helps the embryo receive nutrition from the mother’s blood. It is a disc-like tissue embedded in the uterine wall.
The placenta has villi on the embryo’s side and blood spaces on the mother’s side. This provides a large surface area for the exchange of materials.
| Function | Explanation |
| Nutrient supply | Transfers glucose and nutrients from mother to embryo |
| Oxygen supply | Transfers oxygen from mother’s blood to embryo |
| Waste removal | Transfers waste materials from embryo to mother’s blood |
| Exchange surface | Villi provide large surface area for exchange |
The uterus prepares itself every month to receive a fertilised egg. Its lining becomes thick and spongy so that it can support the embryo if fertilisation occurs.
If the egg is not fertilised, it survives for about one day. The thick uterine lining is no longer needed and slowly breaks down. It comes out through the vagina as blood and mucus. This process is called menstruation.
Menstruation usually occurs once every month and may last for about 2 to 8 days.
Reproductive health means physical, mental, and social well-being related to the reproductive system. It includes awareness about puberty, personal hygiene, prevention of diseases, and responsible decision-making.
Sexually transmitted diseases, or STDs, are infections that may spread through sexual contact. Some STDs are caused by bacteria, while others are caused by viruses.
| Type of STD | Examples |
| Bacterial STDs | Gonorrhoea, syphilis |
| Viral STDs | Warts, HIV-AIDS |
Awareness, medical guidance, and safe health practices help in prevention and treatment.
Contraceptive methods are used to prevent unwanted pregnancy. Different methods work in different ways.
| Method | Examples | How It Works |
| Barrier method | Condoms, diaphragms | Prevents sperm from meeting the egg |
| Hormonal method | Pills | Changes hormonal balance and may prevent egg release |
| Intrauterine device | Copper-T | Placed in the uterus to prevent implantation |
| Surgical method | Vasectomy, tubectomy | Blocks transport of gametes |
Note:
This topic should be studied as part of reproductive health education. For health-related decisions, medical guidance is important.
Students should practise neat and labelled diagrams because diagram-based questions are common in exams.
| Diagram | Why It Is Important |
| Binary fission in Amoeba | Shows cell division in unicellular organisms |
| Budding in Hydra | Common example of budding |
| Spore formation in Rhizopus | Shows hyphae, sporangia, and spores |
| Vegetative propagation in Bryophyllum | Shows plant reproduction from leaves |
| Structure of flower | Important for plant reproduction |
| Pollen germination on stigma | Shows pollen tube pathway |
| Seed structure | Shows seed coat, cotyledon, plumule, and radicle |
| Male reproductive system | Important labelled diagram |
| Female reproductive system | Important labelled diagram |
| Common Mistake | Correct Concept |
| Writing reproduction is needed for individual survival | Reproduction is needed for continuity of species |
| Ignoring DNA copying | DNA copying transfers hereditary information |
| Confusing binary and multiple fission | Binary fission forms two cells; multiple fission forms many cells |
| Forgetting Leishmania example | Leishmania shows binary fission in a definite orientation |
| Calling regeneration normal reproduction in complex organisms | Regeneration is not normal reproduction in complex organisms |
| Confusing pollination and fertilisation | Pollination is pollen transfer; fertilisation is fusion of gametes |
| Not defining plumule and radicle | Plumule forms shoot; radicle forms root |
| Not explaining placenta properly | Placenta helps exchange nutrients, oxygen, and wastes |
| Mixing bacterial and viral STDs | Gonorrhoea and syphilis are bacterial; warts and HIV-AIDS are viral |
Using CBSE Class 10 Science notes for Chapter 7 helps students study faster and understand better.
These notes are perfect for quick study before exams. You don’t need to read the whole textbook again. The notes give short summaries, key points, and diagrams for a fast review. They save time and help you cover all topics like asexual and sexual reproduction, pollination, fertilization, and reproductive health.
DNA copying and variation are big ideas in this chapter. The notes explain how DNA passes traits from parents to offspring and how small changes during copying create variation. These changes help living things adapt and survive. The notes keep this topic short and simple for easy understanding.
The notes include clear meanings of important science words like:
Knowing these terms helps you write better answers in exams.
Do Check: NCERT Solutions for Class 10 Science
The notes explain hard topics in small, easy steps.
For example:
Charts and labeled diagrams make it easier to remember how each process works.
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DNA copying is essential because DNA carries genetic information from parents to offspring. It helps maintain the basic body design of the species. Small changes during DNA copying create variations, which may help organisms survive changing environmental conditions.
In binary fission, one parent cell divides into two daughter cells. In multiple fission, one parent cell divides into many daughter cells at the same time. Amoeba and Leishmania show binary fission, while Plasmodium shows multiple fission.
Regeneration is not considered normal reproduction in complex organisms because complex bodies are organised into tissues, organs, and organ systems. Such organisms cannot grow into complete individuals from cut pieces and do not normally depend on being cut to reproduce.
The placenta helps the embryo receive glucose, oxygen, and nutrients from the mother’s blood. It also transfers waste materials from the embryo to the mother’s blood. Its villi provide a large surface area for exchange of materials.
Testes are located outside the abdominal cavity in the scrotum because sperm production requires a temperature about 2–3°C lower than normal body temperature. The scrotum helps maintain this lower temperature for proper sperm formation.
If the egg is not fertilised, the thick and spongy lining of the uterus is no longer needed. It slowly breaks down and comes out through the vagina as blood and mucus. This process is called menstruation.
Pollen germination begins when a pollen grain lands on the stigma. It forms a pollen tube that grows through the style and reaches the ovule. The male germ cell travels through the tube and fuses with the egg cell to form a zygote.
Plumule and radicle are parts of the embryo inside a seed. The plumule develops into the future shoot, while the radicle develops into the future root during germination.
Bacterial STDs include gonorrhoea and syphilis. Viral STDs include warts and HIV-AIDS. These diseases may spread through sexual contact and require awareness, prevention, and proper medical guidance.
Important diagrams include binary fission in Amoeba, budding in Hydra, spore formation in Rhizopus, flower structure, pollen germination on stigma, seed structure, male reproductive system, and female reproductive system.