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Producers II

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  • "naked" seeds because they are not enclosed in a protective covering (such as a nut or fruit). <br /> Cycad - sago palm, found when dinosaurs lived <br /> Gnetophyta (nee-tuh-fyts): Welwitschia (top), Ephedra (bottom right), <br />
  • Top right is dandelion pollen <br />
  • Germination is the start of growth in the seed. Three factors are required for successful germination: <br /> Water - allows the seed to swell up and the embryo to start growing <br /> Oxygen - so that energy can be released for germination <br /> Warmth - germination improves as temperature rises (up to a maximum) <br />
  • About less than 105 are woody and the rest of the 30,000 species are herbaceous. <br /> Stems have vascular bundles scattered throughout. <br /> Roots are adventitious (branching) <br />
  • About half of the 200,000 species are woody and the other half herbaceous. <br /> Stems have vascular bundles in a ring around outer edge. <br /> Roots are primary (taproot) and adventitious (branching) <br />
  • Why would a seed NOT germinate if lacking these conditions? <br />
  • 3 groups of seeds are grown in a cardboard box. <br /> A - when the tips are removed, no auxin is made so the stems do not grow <br /> B – when the tips are covered, auxin moves to all parts of the stem causing all parts to grow <br /> C - when the tips are lit from one side only auxin accumulates on the shaded side causing it to grow more than the illuminated side <br />

Producers II Producers II Presentation Transcript

  • Plants - Earth's Producers Gymnosperms & Angiosperms
  • Gymnosperms Most gymnosperms have – literally: "naked seeds" • (no protective fruit/nut) – needles or scales rather than leaves – deep-growing root systems • Cycads (Cycadophyta) – palm-like trees of tropics/subtropics • Ginkoes (Ginkgophyta) – only one species: Ginkgo biloba • Gnetophytes (Gnetophyta) – Over 70 species in 3 genera – trees, shrubs & vines – found in arid deserts or rain forest • Conifers (Coniferophyta) – cone bearing trees, evergreens – pine, fir, spruce, cedar, juniper, etc.
  • Gymnosperms - Conifers • Vascular – deep roots – woody stems (can be tall) – waxy scales or needleshaped leaves • Evergreen (usually) • Grow in dry, cool climates • Produce seeds in cones – male cones produce pollen – pollen transported by wind – female cones, once fertilized, produce seeds
  • Angiosperms - Flowering Plants • Literaly "seed in a vessel" – Produce seeds in "fruits" – fruit, nut, veggie, etc. – flowers containing ovaries produce seeds • Vascular – roots, stems & leaves – amazing variety
  • Flower Anatomy • Flowers are the reproductive organs (gametophyte stage) of angiosperms – Stamen • holds pollen (male sex cells) – Carpel • holds ovule (female sex cell) – Petals • attract insects for pollination • Pollination occurs when pollen is transferred to stigma – 1st step to fertilization
  • Methods of Pollination • Bees, flies, butterflies, hummingbirds – Feed on nectar & pollen – Attracted by color & smell • Wind – Huge amounts of pollen form clouds
  • Form & Function of Pollen • The shape and form of pollen is related to its method of pollination… • Insect-pollinated species have sticky or barbed pollen grains • Wind-pollinated species is lightweight, small and smooth (corn pollen)
  • Fertilization • Pollen sends “tubes” down style to join with ovule(s) • Fertilized ovule(s) becomes seed (embryo) • Ovary becomes fruit – food source for embryo • Seeds remain dormant until germination (when seeds sprout) – sprout is sporophyte stage of plant
  • Seed Dispersal
  • Two Types of Angiosperm Seeds
  • Monocots • • • • • One seed-leaf Parallel veins Mostly herbaceous stems Petals in multiples of 3 i.e. grass, bamboo
  • Dicots • Two seed-leaves • Branching veins • Woody or herbaceous stems • Petals in 4’s or 5’s • i.e. trees, roses
  • Germination • Environmental conditions required before a seed will sprout: – Temperature • for adequate metabolism & growth – Moisture • seed will swell & soften when water is present – Oxygen • required for cellular respiration – Other factors: • passage of time, chilling, light exposure
  • Tropisms • Tropisms describe any plant growth toward or away from an external stimulus – phototropism • toward light • into soil (away from light) – gravitropism • downward (roots) • upward - stems – negative, against gravity – thigmotropism • response to touch – hydrotropism • movement in response to a concentration gradient • Plant movement & growth is controlled by hormones Tropisms Video
  • Plant Hormones • Hormones are chemicals in plants that affect: – – – – – growth of roots, stems, leaves seed germination ripening of fruit formation of flowers shedding of leaves • The hormone auxin influences the rate division meiosis) of cell (mitosis & Hormone Video
  • Vegetative Reproduction • Asexual reproduction = cloning – Offspring are genetically identical to parent • Examples: – – – – – Bulbs, corms Tubers, rhizomes Runners Gemmae Cuttings