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Reproduction in Angiosperms

Reproduction in Angiosperms . IB Topic 9.3.1-9.3.3. Reproduction in flowering plants . Flowering plants contain their reproductive organs in the flower Flowers are often hermaphrodite structures  both male and female parts . Draw and Label … .

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Reproduction in Angiosperms

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  1. Reproduction in Angiosperms IB Topic 9.3.1-9.3.3

  2. Reproduction in flowering plants • Flowering plants contain their reproductive organs in the flower • Flowers are often hermaphrodite structures  both male and female parts

  3. Draw and Label … • A diagram showing the structure of a dicotyledonous animal pollinated flower • Sepal, petal, anther, filament, stigma, and ovary • See Figure 10.27 (Clegg)

  4. The Buttercup Flower

  5. Parts of the flower • Sepals: • Collectively called the calyx • Enclose the flower in the bud and are usually small, green, and leaf like • Petals: • Collectively called the corolla • Often colored and conspicuous (may attract insects and other animals) • Stamens: • The male part of the flower • Consist of anthers (housing pollen grains) and the filament (stalk) • Carpels: • The female part of the flower • There may be one or many & they may be fused together or free standing • Each carpel consists of an ovary and a stigma (which receives pollen)

  6. Addressing some vocabulary … • Pollination: is the transfer of pollen from a mature anther to a receptive stigma • The pollen may come from the anthers of the same flower or flowers of the same plant • Self pollination • Or, the pollen may come from flowers on a different plant of the same species • Cross pollination

  7. So, how is that pollen transferred? • Typically by insects and wind • Insect pollinated plants typically produce nectar which attracts insects to the flower • Although in some species, pollen can be transferred by: • Birds • Bats • Running water

  8. What comes after pollen transfer … ? • FERTILIZATION!!! • Can only occur after pollen has landed on the stigma and has germinated there • Fertilization is the fusion of male and female gametes to form a zygote

  9. What’s double fertilization? • The pollen grain produces a pollen tube, which grows down between the cells of the style and into the ovule • The pollen tube delivers two male nuclei • One fuses with the egg • The other fuses with another nucleus  triggers the formation of the food store for the developing embryo

  10. Fertilization in a flowering plant

  11. How are seeds formed and dispersed? • Seeds develop from the fertilized ovule • After fertilization: • The zygote grows by mitotic division (embryonic root, stem, and cotyledon) • As the seed matures, the outer layers become the protective seed coat (testa) and the whole ovary develops into the fruit. • The water content of the seed decreases • The seed moves into a dormancy period

  12. The Seed • The seed is a form in which the flowering plant may be dispersed • Seed dispersal is the carrying of the seed away from the vicinity of the parenting plant • Wind, animals, water, and explosive mechanisms help disperse seeds

  13. The structure of a dicotyledonous seed (broad bean seed)

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