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Sexual Life cycles Plant structure and Phylogeny

Sexual Life cycles Plant structure and Phylogeny. The Angiosperms. Outline. Brief review 9. ALTERNATION OF GENERATIONS 8. PLANT EVOLUTION 7. ANGIOSPERM LIFE HIST. Define sex cell. All life is organized into 3 domains. 2 Domains of prokaryotes, 1 of all eukaryotes

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Sexual Life cycles Plant structure and Phylogeny

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  1. Sexual Life cyclesPlant structure and Phylogeny The Angiosperms

  2. Outline • Brief review • 9. ALTERNATION OF GENERATIONS • 8. PLANT EVOLUTION • 7. ANGIOSPERM LIFE HIST.

  3. Define sex cell.

  4. All life is organized into 3 domains • 2 Domains of prokaryotes, 1 of all eukaryotes • Bacteria & Archaea- prokaryotic • Eukaryota- Includes all 4 eukaryotic kingdoms: protista, animalia, plantae, fungi

  5. Most of the many Eukaryotic species reproduce sexually

  6. Despite an inherent twofold cost, higher species reproduce sexually • Sexually reproducing species must have 2 offspring to “break even” • 2 offspring from an asexually reproducing species doubles the population

  7. Animal species alternate between diploid (mitotic) and haploid (meiotic) In animals, only the diploid stage is multicellular

  8. Sexual life cycle of Animals gametic or diplontic - meiosis forms gametes, no spores - mainly like a sporophyte (2n) - produce gametes (1n) via meiosis - fertilization results in zygote (2n) - sporophyte grows via mitosis 

  9. Schematic gametic life cycle Sporophyte

  10. Many fungi work the opposite way zygotic or haplontic - zygote undergoes meiosis - mainly like a gametophyte (1n) - produce gametes (1n) via mitosis - fertiliz. results in zygote (2n) - produce spores (1n) via meiosis - gametophyte grows via mitosis 

  11. Most plants have two multicellular life cycle stages- gametophyte and sporophyte plants - sporic or diplohaplontic - alternate sporo- & gametophyte - meiosis forms spores - sporophytes (2n) dominate - produce spores (1n) via meiosis - gametophyte (1n) develops inside cone/flower via mitosis - prod. gametes (1n) via mitosis - fertiliz. results in zygote (2n) - sporophyte grows via mitosis

  12. 8. PLANT EVOLUTION

  13. Plant phylogeny

  14. The PhylumBryophytaincludes liverworts and mosses Simplest terrestrial plants- avascular evolve multicell. & terrestrial - adapt to gravity, so small/low - no roots, rhizoids only anchor • sperm needs H2O to fertilize ova

  15. In mosses, the sporophyte and gametophyte are similar in size

  16. Ferns are vascular plants ferns (Phylum Pterophyta) evolve vasculature (vessels), allows fronds to grow large - true roots absorb H2O, minerals - no seeds, sperm still needs H2O

  17. The gametophyte is smaller in the fern life cycle

  18. The gametophyte nurtures the young sporophyte

  19. Conifers are the prototypical gymnosperm gymnosperms (Phy. Coniferophyta) - evergreen needles reduce evap. • ova in larger female cones • sperm in pollengrains from male cones, dispersed by wind • no fruit, naked seeds protect + provide nutrients to embryo 

  20. Gymnosperms include cycads & ginkoes

  21. Gymnosperms have no flowers or fruits • Mostly wind-pollinated • The most massive indiviual living things- Giant sequoia

  22. The tallest and most massive- here in CA

  23. Male & Female Gametophytes are greatly reduced in gymnosperms

  24. Angiosperms are flowering plants angiosperms (Phylum Anthophyta) - deciduous leaves drop off in winter, surv. low temp/H2O • flowers attract animal pollinators with color-smell-nectar, • more efficient for fertilization • endosperm in seeds stores nutrients, esp. in grains/nuts • fruit attracts animals to disperse & fertilize seeds, reduces comp.

  25. Basic (monoecious) Flower structure

  26. The male angiosperm gametophyte is even smaller inside anthers - meiosis prod. microspore (1n) - becomes the pollen grain = malegametophyte (1n) - with 2 sperm cells + tube cell

  27. The female gametophyte houses the seed • inside carpels - meiosis prod. megaspore (1n) becomes the ovary = female gametophyte (1n) • = ovum + central cell (n+n)

  28. Pollination • pollination - pollen grain to stigma - tube cell grows pollen tube to reach ovary • double fertilization • - 1st sperm cell (1n) + ovum (1n) • = zygote (2n sporophyte)

  29. The seed is a capsule containing a plant embryo • - 2nd sperm cell + central cell (n+n) = endosperm (3n, food in seed) • seed - seed coat around endosperm - zygote grows into embryo via mitosis - ovary around seed becomes fruit

  30. The plant embryo is already formed • embryo - epicotyl becomes shoot • - hypocotyl becomes root • - cotyledons becomes leaves

  31. Plant phylogeny

  32. 6. MONOCOTS VS. DICOTS • angiosperms - flowering plants • - divided into 2 major groups • monocots - corn, grasses • - 1 cotyledon (embryonic leaf) • - narrow leaves with parallel veins • - flower parts in 3’s, fibrous roots • - vascular bundles scattered, • primary growth only • dicots - most other angiosperms • - 2 cotyledons absorb endosperm • - broad leaves with network veins • - flower parts in 4 or 5’s, taproot • - vasc. bundles arranged in ring, • secondary growth possible

  33. Monocots vs. Dicots

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