CBSE Class 10 Science Revision Notes Chapter 7 How do Organisms Reproduce 2026–27

Reproduction is the process by which organisms produce new individuals of their own kind. In CBSE Class 10 Science Chapter 7, students study DNA copying, variation, asexual reproduction, sexual reproduction and reproductive health.

How do Organisms Reproduce? explains how living organisms continue their species. Reproduction is not needed for the survival of one individual, but it is needed for the survival of a species.

Use these CBSE Class 10 Science Revision Notes Chapter 7 for the 2026–27 academic year to revise DNA copying, variation, fission, budding, flowering plant reproduction and the human reproductive system. Focus on process flow, differences and important terms from the NCERT chapter.

Key Takeaways

• DNA copying: Reproduction begins with copying DNA, which carries body design information.
• Variation: Small differences during DNA copying help species survive changing conditions.
• Asexual reproduction: One parent produces new individuals through fission, budding, fragmentation or spores.
• Sexual reproduction: Two germ-cells combine to form a zygote with new combinations of variation.

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CBSE Class 10 Science Revision Notes Chapter 7 on How do Organisms Reproduce: Chapter Overview

Reproduction creates new individuals that look similar to their parents. This happens because organisms pass body design information from one generation to the next.

Reproduction keeps populations stable over time. It also creates variation, which helps species survive when surroundings change.

Important Topics in CBSE Notes Class 10 Science Chapter 7

Class 10 Science Chapter 7 Notes include asexual and sexual modes of reproduction. The chapter also explains why DNA copying and variation are linked with evolution.

The chapter has several diagram-based topics. Revise the flower, male reproductive system and female reproductive system with labelled parts.

How do Organisms Reproduce Class 10 Notes: DNA Copying and Variation

DNA is the information source for making proteins. Proteins control body design, so DNA copying is a basic event in reproduction.

DNA Copying in Class 10 Science Chapter 7 Notes

DNA is present in chromosomes inside the nucleus. During reproduction, the cell makes a copy of its DNA before division.

The two new cells are similar, but they may not be exactly identical. Small copying changes can create variation.

Importance of Variation in Reproduction Notes

Variation means differences between individuals of the same species. It appears because DNA copying is not always perfectly exact.

If water temperature rises, most bacteria may die. A few heat-resistant bacteria may survive and multiply.

Variation may not always benefit one individual. It is useful for the survival of a species over time.

Asexual Reproduction in CBSE Class 10 Science Revision Notes Chapter 7

Asexual reproduction involves only one parent. New individuals are produced without the fusion of male and female gametes.

Asexual reproduction can happen through fission, fragmentation, regeneration, budding, vegetative propagation and spore formation.

Fission in How do Organisms Reproduce Class 10 Notes

Fission is a mode of asexual reproduction in unicellular organisms. One organism divides to form new individuals.

In Amoeba, binary fission can occur in any plane. In Leishmania, binary fission occurs in a definite orientation because of its body structure.

Plasmodium divides into many daughter cells at the same time. This process is called multiple fission.

Fragmentation and Regeneration in Class 10 Science Chapter 7 Notes

Fragmentation occurs when a simple multicellular organism breaks into pieces. Each fragment grows into a new individual.

Regeneration is carried out by specialised cells. These cells divide, form many cells and develop into different tissues.

Regeneration is not the same as reproduction in all organisms. Most organisms do not normally reproduce by being cut into pieces.

Budding, Vegetative Propagation and Spore Formation

Budding, vegetative propagation and spore formation are common asexual methods. They use different body parts or specialised structures.

In Hydra, a bud develops due to repeated cell division at one site. The bud matures, detaches and becomes a new individual.

In Bryophyllum, buds grow in the notches of leaves. These buds fall on the soil and develop into new plants.

In Rhizopus, spores are present inside sporangia. Thick walls protect spores until they reach a moist surface.

Sexual Reproduction in How do Organisms Reproduce Class 10 Notes

Sexual reproduction involves two individuals. Male and female gametes combine to form a new individual.

Why Sexual Reproduction Creates Variation

Sexual reproduction combines DNA from two different individuals. This creates new combinations of variations.

Sexual reproduction helps generate more variation. Variation supports the survival of species in changing environments.

Male and Female Gametes in Class 10 Science Chapter 7 Notes

Gametes are reproductive cells. Male and female gametes have half the number of chromosomes.

When male and female gametes fuse, the normal chromosome number is restored. The zygote then develops into a new individual.

Sexual Reproduction in Flowering Plants Class 10 Notes

Flowers are the reproductive parts of angiosperms. Stamens and pistil contain the germ-cells.

Parts of a Flower and Their Functions

A flower may be unisexual or bisexual. A unisexual flower has either stamen or pistil, while a bisexual flower has both.

The stamen produces pollen grains. The pistil contains stigma, style and ovary.

Each ovule has an egg cell. The male germ-cell from pollen fuses with the female gamete present in the ovule.

Pollination, Fertilisation, Seed Formation and Germination

Pollination is the transfer of pollen from anther to stigma. Fertilisation is the fusion of male and female germ-cells.

After pollen lands on a suitable stigma, a pollen tube grows through the style. It carries the male germ-cell to the ovary.

After fertilisation, the zygote divides many times and forms an embryo inside the ovule. The ovule becomes a seed and the ovary becomes a fruit.

Human Reproduction in CBSE Notes Class 10 Science Chapter 7

Humans reproduce by sexual reproduction. Male and female reproductive systems produce gametes and support fertilisation.

Puberty is the period when reproductive tissues begin to mature. It brings physical changes in boys and girls.

Male Reproductive System in Class 10 Science Chapter 7 Notes

The male reproductive system produces sperms and transfers them to the female reproductive tract.

Sperm formation needs a lower temperature than normal body temperature. This is why testes are present in the scrotum.

Testosterone regulates sperm formation. It also brings changes seen in boys during puberty.

Female Reproductive System in Class 10 Science Chapter 7 Notes

The female reproductive system produces eggs and supports embryo development.

One egg is produced every month by one of the ovaries after puberty. The egg travels through the fallopian tube.

The uterus has a thick lining with blood supply. This prepares it to receive and nourish an embryo.

Fertilisation, Implantation and Placenta

Fertilisation occurs when sperm fuses with the egg. In humans, this usually happens in the fallopian tube.

The placenta helps in exchange between mother and embryo. It provides a large surface area for glucose and oxygen transfer.

Wastes from the developing embryo also pass into the mother’s blood through the placenta.

Menstruation and Reproductive Health in Class 10 Science Chapter 7 Notes

Menstruation occurs when the egg is not fertilised. The thick lining of the uterus breaks down and comes out through the vagina.

Menstruation usually lasts for about two to eight days. It takes place roughly every month.

Reproductive health includes physical and mental readiness for reproduction. It also includes protection from infections and unwanted pregnancy.

Contraceptive Methods in How do Organisms Reproduce Class 10 Notes

Contraception helps avoid pregnancy. Different methods act in different ways.

Condoms can help reduce transmission of many sexually transmitted infections. Oral pills and copper-T do not protect from such infections.

Prenatal sex determination is prohibited by law. A healthy society needs a balanced female-male sex ratio.

Important Points of How do Organisms Reproduce Class 10 Notes

These quick points cover the main facts from Science Notes for Chapter 7 How do Organisms Reproduce Class 10.

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