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CHP.-1.REPRODUCION IN ORGANISMS

CHP.-1.REPRODUCION IN ORGANISMS. CLASS- XII. Life span – The period from birth to natural death of an organism. Reproduction – a biological process in which an organism gives rise to young ones similar to itself. Types of reproduction –

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CHP.-1.REPRODUCION IN ORGANISMS

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  1. CHP.-1.REPRODUCION IN ORGANISMS CLASS- XII

  2. Life span– The period from birth to natural death of an organism. • Reproduction– a biological process in which an organism gives rise to young ones similar to itself. • Types of reproduction– • Asexual reproduction– offspring is produced by a single parent with or without formation of gametes. • Sexual reproduction– When two parents participate in reproductive process & also involve fusion of male & female gametes.

  3. Asexual reproduction • Budding in Yeast

  4. Binary fission - Amoeba

  5. Zoospores of Chlamydomonas

  6. Conidia of Penicillium

  7. Buds in Hydra

  8. Gemmules in sponge

  9. Vegetative propagation in plants (Eyes of potato)

  10. Rhizome of ginger

  11. Bulbil of Agave

  12. Leaf buds of Bryophyllum

  13. Offset of Water hyacinth

  14. Sexual reproduction • Events in sexual reproduction – 1.Pre-fertilisation events– (i) Gametogenesis (ii) Gamete transfer 2. Fertilisation 3.Post-fertilisation events– (i) Zygote (ii) Embryogenesis

  15. Pre-fertilisation events • 1.Gametogenesis • It is the process of formation of male & female gametes. • Homogametes– morphologically similar. • Heterogametes– morphologically different.

  16. Bisexual– male & female reproductive structures in the same plant.(Homothallic & Monoecious ). • Unisexual– male & female reproductive structures on different plants. (Heterothllic & Dioecious). • Gametes are haploid. • In diploid organisms specialised cells called meiocytes ( gamete mother cell ) undergo meiosis.

  17. 2.Gamete transfer– • In most of the organisms male gamete is motile & the female gamete is stationary. • In aquatic plants gamete transfer takes place through Water. • Male gametes are produced in very large number because a large number of male gametes are lost during transport.

  18. 3. Fertilisation– • Fusion of gametes is known as syngamy which results in the formation of Zygote. • External fertilisation– syngamy occurs outside the body of the organism. Eg. Algae, Fishes, Amphibians. • Internal fertilisation– syngamy occurs inside the body of organism. Eg. Reptiles, Birds, Mammals, most of the plants.

  19. Post-fertilisation events • 1. The Zygote • 2. Embryogenesis • It is the process of development of embryo from the Zygote. • Zygote undergo cell division (Mitosis) & cell differentiation. Oviparous animals–lay eggs Eg. Reptiles, birds. Viviparous animals- zygote develop into a young one inside the body of female organism.

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