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Plant Classification

Plant Classification

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Plant Classification

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  1. Plant Classification

  2. Alternation of generations • Sporophyte (diploid) • Begins when sperm fertilizes egg (zygote) • Diploid zygote divides by mitosis to create a mature sporophyte • Meiosis produces haploid cells called spores • Haploid spores released

  3. Alternation of generations • Gametophyte (haploid) • Begins with spores created by meiosis • Spore grows into gametophyte • Male gametophyte creates sperms • Female gametophyte creates eggs • Sperm & egg create diploid zygote (process repeats)

  4. Group 1: Seedless, Nonvascular Plants • Live in moist environments • Liverworts • Hornworts • Mosses

  5. Mosses • Nonvascular, seedless • Grow low to ground to retain moisture • Lack true leaves • Leaf-like structures only 1 cell thick • Rhizoids anchor into soil • Early inhabitant of new ecosystems (succession)

  6. Moss Life Cycle • Gametophyte phase • Dominant stage • Carpet of moss growing near ground • Archegonium: produces female egg • Antheridium: produces male sperm • Sperm swims through water to fertilize egg • Sporophyte phase • Stalk grows up from the gametophyte • Sporangia houses haploid spores • Spores land and new gametophyte grows See appendix B in your text book

  7. 1) Moss gametophytes grow near the ground (haploid stage) 2) Through water, sperm from the male gametophyte will swim to the female gametophyte to create a diploid zygote 3) Diploid sporophyte will grow from the gametophyte where the zygote is located 4) Sporophyte will create and release haploid spores . . . . . sporophyte gametophyte

  8. 5) Spores land and grow into new gametophytes 6) The process repeats . . . . . ground gametophyte

  9. Group 2: Seedless, Vascular Plants • Vascular system allows nutrient transport to greater heights • Club mosses • Horsetails • Ferns

  10. Ferns • Seedless, vascular plants • Vascular: allows taller growth • Rhizoids: underground stems draw nutrients • Fronds: leaves uncurl • sporangia on underside • Sori: clusters of sporangia

  11. Fern Life Cycle • Sporophyte phase • Dominant stage • Sporangia produces haploid spores • Spores released into air • Gametophyte phase • Spore grows into prothallus • Archegonium: produces female egg • Antheridium: produces male sperm • Sperm swims to egg • Zygote begins sporophyte stage See appendix B in your text book

  12. 1) Sporophyte creates and releases haploid spores . . . . Adult Sporophyte (diploid) ground

  13. 2) Spores land in the soil . . . . ground

  14. 3) From the haploid spores, a prothallus (haploid gametophyte) grows in the soil -- Rhizoids anchor Let’s zoom in ground

  15. 4) Sperm swim through water from the antheridium to the archegonia Let’s zoom back out

  16. 5) Diploid sporophyte (fiddlehead) grows from the prothallus -- prothallus eventually dies ground

  17. 6) Fiddlehead uncurls into fronds of ferns. 7) Cycle repeats -- Sporangia creates spores to be released . . . . ground

  18. Group 3: Seed producing, Vascular Plants • Gymnosperms • Cycads • Ginko • Conifers • Angiosperms

  19. Group 3: Seed producing, Vascular Plants • 1) Seed plants don’t depend on water to reproduce • Pollen (contains sperm) combines with egg • Egg hardens into a seed • 2) Nourishment and protection • Nourish: Nutrients inside seed for the embryo • Protection: Hard shell • 3) Allow dispersal • Carried by wind, water, animals

  20. Type 1: Gymnosperms Seeds not enclosed in a fruit produced inside cones Cone = reproductive structure Male cones: produce pollen Female cones: produce eggs and seeds Group 3: Seed producing, Vascular Plants

  21. Gymnosperm example: Conifers Cone plants Needle-like leaves Common to lumber industry Evergreen, Pine, Redwood, Cedar Group 3: Seed producing, Vascular Plants

  22. Conifers • Seed advantages • Don’t depend on water • Protects & nourishes embryo • Allow plants to grow in new locations • Conifers: woody cone houses seeds • Male cones: produce pollen • Female cones: produce egg • Pines, redwoods, spruce, cedar

  23. Conifer Life Cycle • Sporophyte phase (dominant) • Cones grow on tree • Female cones • Megaspores inside archegonia (gametophyte) • Male cones • Microspores (gametophyte) released from antheridia • sticks to archegonium • Pollen tube grows from pollen • Sperm travels down pollen tube (zygote/seed created) • Sporophyte stage restarts

  24. 1) Male and female seed cones grow in adult sporophytes

  25. 2) Pollen grains released from the male seed cones -- Pollen is the male gametophyte Let’s zoom into the female seed cone

  26. 3) Pollen grain sticks to the female ovule 4) Pollen tube grows from the male spore 5) Two nuclei transfer into female spore - one fertilizes the egg 6) Diploid embryo develops (sporophyte stage restarts)

  27. 7) After seeds harden, the cone reopens and the seeds are released

  28. 8) Seed will land ground

  29. 9) Seedling grows into (sporophyte)…the cycle repeats ground

  30. female male

  31. Group 3: Seed producing, Vascular Plants • Type 2: Angiosperms (flowering plants) • Flower = reproductive structure • Protects gamete and fertilized eggs • Seeds enclosed in a fruit • Fruit: Plant ovary • Often attract animals to disperse the seeds inside

  32. Angiosperm types(flowering plants) • 2 groups: Monocots and Dicots (based on seed type) • Cotyledon: embryonic leaf • Monocots: embryo with 1 seed leaf • Dicots: embryo with 2 seed leaves

  33. Monocots vs. Dicots

  34. Angiosperm Life Spans • Three Life Span Types: • Annuals • 1 year: Mature…produce seeds…die • Biennials • 1st year: produces short stem, low growth leaves, food reserves • 2nd year: taller stem, leaves, flowers, seeds • Perennials • Live for more than 2 years

  35. Flowers • Reproductive structure of flowering plants • Sepals • outer ring of leaves • protection • Petals • Inner ring of leaves • Brightly colored to attract pollinators • Open petals & sepals reveal male and female structures

  36. Flowers • Female Carpel • Inner most part • Ovary: within the base (female gametophyte) • Style: long stalk • Stigma: sticky tip, collects pollen • Male Stamen • Surrounds carpel • Filaments: long stalks • Anther: produces pollen (male gametophyte)

  37. 1) Flower matures and opens

  38. 2) Microspores (male gametophytes) created in the anthers

  39. In the Anthers • Meiosis makes 4 microspores • In each microspore • Nucleus splits in two • 1 nucleus: forms pollen tube • 1 nucleus: splits again to make 2 more nuclei • 1 nucleus: fertilizes the egg • 1 nucleus: fuses to make endosperm

  40. 3) Microspores continue to develop

  41. 4) Ovaries divide by meiosis to create megaspore

  42. In the Ovules • Meiosis makes 4 megaspores (only 1 survives) • In megaspore • Mitosis creates 8 nuclei • 1 nucleus: egg cell • 2 nuclei: form embryo sac • 5 nuclei: disintegrate

  43. Microspore lands on stigma

  44. Microspores (pollen) released

  45. Microspores (pollen) land on the stigma

  46. Pollen tube and 2 nuclei transfer into the ovule . .

  47. 5 & 6) Pollen tube grows from pollen • Two sperm nuclei follow down the pollen tube

  48. 7) Double fertilization: • 1 sperm nuclei fuses w/ egg (zygote created) • 1 sperm nuclei fuses w/ the embryo sac (endosperm created)