Unit 5 _student fall 2008

Unit 5 _student fall 2008 - 1 Plant Evolution and Basic...

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Plant Evolution and Basic Structure I. Evolution of plants (in order of appearance) Plants evolved from green algae, as lakes dried out and only those that could survive without water could survive -whole alga performs photosynthesis, and absorbs H2O A. Bryophytes:have no vascular tissue (no xylem/phloem) No xylem=no rigid support cannot grow tall 1. Properties: a. Have a _cuticle_(waxy secretion)_______ to prevent water loss b. Jacket of cells protect _gametes_(fertilization occurs in water)_____________ c. They are ___embryophytes__(initial embryo is attached and initially nourished by the parent)______________ d. Sperm require: water for fertilization 2. Ex: mosses 3. Evolutionary advantage(over algae): do not need to be __immersed in water_________________ at all times because of the _cuticle____________ (although they require moisture for reproduction); could ensure better survival of the: ____gametes and embryo____________________ B. Seedless vascular plants 1. Additional properties (compared to bryophytes): xylem and phloem Xylem contains lignin(wood) in cell walls * Note: moisture is still required for reproduction because:sperm still needs water for dispersal 2. Ex: ferns 3. Evolutionary advantage- growing tall Herbivores(avoid predators);also access sunlight C. Gymnosperms - “naked seed” 1
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seeds a. Sperm dispersal- as pollen, dispersed by wind; dependent on the wind b. Have ___seeds_________________ (embryo packaged with nourishment and a tough protective coating) 2. Ex: pine trees ( male strobili produce pollen grains ( which give rise to male gametes) and female cones are home to ovules which house female gametes 3. Evolutionary advantages – Could colonize dry land ( not need water for sperm dispersal) -fertilization is protected ( occurs inside ovule ( female cone)) - seed provides protection and nourishment for the embryo -could survive Earth’s cold temperatures because of needles D. Angiosperms “vessel seeds” FLOWERING PLANTS 1. Additional Properties (in addition to the properties of Gymnosperms) a. Have seeds that develop in protective chambers called __fruit____ b. _flowers ( temporary reproductive structures) __produced to attract pollinators (although some dispersal may also be through wind and water). 2. Ex: majority of plants,(daffodils, fruit trees, etc) Pollination is targeted by animaks, so don’t have to produce as much pollen The structure of a fruit reflects the function in seed dispersal 4. Evolutionary advantages – a. targeted____________ pollination by animals is far more efficient than leaving pollination up to chance in the wind. 2
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This note was uploaded on 02/16/2009 for the course BIOL 101 taught by Professor Hogan during the Spring '08 term at UNC.

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Unit 5 _student fall 2008 - 1 Plant Evolution and Basic...

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