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Chapter 38

Chapter 38. Angiosperm Reproduction. Angiosperm Reproduction. Angiosperms have 3 unique features: Flowers, Fruits, & Double Fertilization Microsporangia Pollen sacs in the anther Diploid cells = meiosis  male gametophyte (pollen) Pollen has 2 haploid nuclei

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Chapter 38

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  1. Chapter 38 Angiosperm Reproduction

  2. Angiosperm Reproduction • Angiosperms have 3 unique features: • Flowers, Fruits, & Double Fertilization • Microsporangia • Pollen sacs in the anther • Diploid cells = meiosis  male gametophyte (pollen) • Pollen has 2 haploid nuclei • Tube nucleus – 1 sperm develops into a pollen tube • Generative nucleus – divides into 2 sperm cells which remain inside the pollen tube

  3. Ovary • Ovules form with a diploid cell • Soon 4 haploid megapsores form • Eventually get 8 haploid nuclei, but only 3 are most important • 1 haploid nucleus = egg • Will combine with sperm nucleus to form the zygote • 2 other nuclei are called polar nuclei • Polar nuclei will fuse with sperm nucleus to make 3n endosperm

  4. Watch Animation • 38-01.swf

  5. Pollination • Pollen lands on stigma • Pollen tube made from pollen grain • Pollen tube grows down into the ovary • When pollen tube reaches ovule, double fertilization occurs

  6. Double Fertilization • Double fertilization is the union of 2 sperm cells forming zygote & endosperm • Unique to angiosperms • 1 sperm fertilizes the egg  zygote • Zygote develops into the embryo  sporophyte • Other sperm combines with both polar nuclei = 3n nucleus • This 3n tissue  endosperm • Endosperm – food storing tissue in the seed

  7. After double fertilization • Ovule develops into a seed • Ovary develops into fruit which encloses the seed • Fruit protects the enclosed seed • Fruit aids in dispersal by wind or animales • Seed coat – protects embryo & its food supply • Radicle – embryonic root • Epicotyl – shoot tip with pair of miniature leaves

  8. Seed • As the seed matures, It goes dormant • Low metabolic rate, growth and development are suspended • Seed resumes growth given suitable environmental conditions for germination

  9. Asexual Reproduction in Plants • Asexual reproduction in plants is called vegetative reproduction • Fragmentation • Type of vegetative reproductive • When a part of the parent plant is separated and then generates into a new plant, genetically identical to parent plant • Self-fertilization is another means of asexual reproduction

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