Chapter 38 - Angiosperm Reproduction and Biotechnology

Chapter 38 - Angiosperm Reproduction and Biotechnology -...

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Chapter 38 Class Notes – Angiosperm Reproduction and Biotechnology – Page 1 Max Sauberman AP Biology – Mr. Schilp Chapter 38 Angiosperm Reproduction and Biotechnology Seeds: A parasitic plant produces huge flowers that produce up to 4 million seeds. Many angiosperms reproduce sexually and asexually. Since the beginning of agriculture, plant breeders have genetically manipulated traits of wild angiosperm species by artificial selection. Angiosperms: Pollination enables gametes to come together within a flower. In angiosperms, the sporophyte is the dominant generation, the large plant that we see. The gametophytes are reduced in size and depend on the sporophyte for nutrients. Male gametophytes (pollen grains) and female gametophytes (embryo sacs) develop within flowers. Flowers contain stamens (anthers and filaments) and carpels (stigma, style, and ovary). Flower Structure: Flowers are the reproductive shoots of the angiosperm sporophyte. They consist of four floral organs: sepals, petals, stamens, and carpels. Many flower variations have evolved during the 140 million years of angiosperm history. Flowers can have bilateral symmetry or radial symmetry (daffodil). A superior ovary lies above the sepal. An inferior ovary lies below the sepal. A semi-inferior ovary lies right around the sepal. Monoecious vs. Dioecious: A plant is monoecious if it contains stamens and carpels on different flowers (flowers are unisexual). A plant is dioecious if stamens and carpels are on the same flower (flowers are bisexual). Gametophyte Development and Pollination: In angiosperms, pollination is the transfer of pollen from an anther to a stigma.
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Chapter 38 Class Notes – Angiosperm Reproduction and Biotechnology – Page 2 If pollination succeeds, a pollen grain produces a pollen tube that grows down into the ovary and discharges sperm near the embryo sac. Pollen develops from microspores within the sporangia of anthers. Development of a Male Gametophyte: Pollen grains develop within the microsporangia (pollen sacs) of anthers at the tips of the stamens. Each microsporangium contains diploid microsporocytes. Each microsporocyte divides by meiosis, producing haploid microspores, each of which becomes a pollen grain. Within a pollen grain, the male gametophyte becomes mature when its generative nucleus divides, forming two
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This note was uploaded on 03/17/2011 for the course BIO 101 taught by Professor Sullivan during the Spring '08 term at Harvard.

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Chapter 38 - Angiosperm Reproduction and Biotechnology -...

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