Chapter: How Do Organisms Reproduce?
Class 10 – Science (Biology)
1. Introduction to Reproduction
What is Reproduction?
Reproduction is the biological process by which living organisms produce offspring similar to themselves, ensuring the continuity of species.
2. Importance of Reproduction
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Maintains the existence of species.
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Transfers genetic information from one generation to the next.
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Leads to evolution through variations.
3. Types of Reproduction
There are two main types of reproduction:
A. Asexual Reproduction
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Involves a single parent.
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No formation of gametes.
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Offspring are genetically identical (clones).
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Common in unicellular and some multicellular organisms.
Types of Asexual Reproduction:
| Type | Description | Examples |
|---|---|---|
| Binary Fission | One cell divides into two identical cells. | Amoeba, Bacteria |
| Multiple Fission | One cell divides into many daughter cells. | Plasmodium |
| Budding | A new organism grows as a bud on the parent. | Hydra, Yeast |
| Spore Formation | Spores are produced which germinate into new organisms. | Rhizopus (bread mould) |
| Fragmentation | Body breaks into parts, each grows into a new organism. | Spirogyra |
| Regeneration | Lost body part grows into a new organism. | Planaria, Hydra |
| Vegetative Propagation | New plants grow from parts like roots, stems, leaves. | Potato (tuber), Bryophyllum (leaf), Ginger (rhizome) |
B. Sexual Reproduction
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Involves two parents (male and female).
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Formation and fusion of gametes (sperm and egg).
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Results in genetic variation.
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Occurs in most plants and animals.
4. Sexual Reproduction in Plants
Parts of a Flower (Reproductive Organ):
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Stamen (Male part):
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Anther: Produces pollen grains (male gametes).
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Filament: Supports the anther.
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Carpel / Pistil (Female part):
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Stigma: Receives pollen.
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Style: Tube that connects stigma to ovary.
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Ovary: Contains ovules (female gametes).
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Steps in Sexual Reproduction in Plants:
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Pollination – Transfer of pollen from anther to stigma.
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Self-pollination: Same flower or same plant.
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Cross-pollination: Different plants.
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Fertilization – Fusion of male and female gametes in the ovary.
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Zygote formation – Fertilized egg that grows into an embryo.
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Seed and fruit formation – Ovule becomes seed, ovary becomes fruit.
5. Sexual Reproduction in Humans
Male Reproductive System:
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Testes: Produce sperm and hormone testosterone.
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Scrotum: Sac holding testes outside the body.
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Vas deferens: Carries sperm from testes.
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Urethra: Common duct for sperm and urine.
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Penis: Organ for sperm transfer.
Female Reproductive System:
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Ovaries: Produce eggs (ova) and hormones estrogen and progesterone.
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Fallopian Tubes: Site of fertilization.
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Uterus: Where embryo implants and develops.
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Vagina: Birth canal and receives sperm.
Process of Human Reproduction:
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Fertilization – Fusion of sperm and egg in the fallopian tube.
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Zygote formation → Embryo → Fetus
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Gestation period: ~9 months in humans.
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Birth: Delivery of the baby through the vagina.
6. Puberty
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The age at which reproductive organs become functional.
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Controlled by hormones.
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Males: Testosterone
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Females: Estrogen, Progesterone
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7. Reproductive Health
A. Birth Control Methods (Contraception):
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Barrier methods: Condoms
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Oral contraceptives: Pills
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Surgical methods: Vasectomy (male), Tubectomy (female)
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IUCD: Copper-T
B. Sexually Transmitted Infections (STIs):
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Examples: HIV-AIDS, Gonorrhea, Syphilis
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Prevention: Safe sex practices, awareness, hygiene
8. Differences Between Asexual and Sexual Reproduction
| Feature | Asexual | Sexual |
|---|---|---|
| Parents | One | Two |
| Gametes | Not involved | Involved |
| Offspring | Identical | Variation present |
| Speed | Fast | Slower |
| Examples | Amoeba, Hydra | Humans, Plants, Animals |
9. Variation
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Result of sexual reproduction.
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Important for evolution and adaptability.
10. Summary
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Reproduction ensures continuity of life.
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Asexual reproduction: Simple, no variation.
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Sexual reproduction: Complex, brings variation.
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Plants and animals have specialized organs for reproduction.
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Reproductive health is essential for well-being and population control.
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