lab_05 - Lab 5: Plants III: Angiosperms: Evolution of the...

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Unformatted text preview: Lab 5: Plants III: Angiosperms: Evolution of the Flower and Fruit Task to prep for next week • Angiosperms: Phylum Anthophyta • Flowers and Fruits • Life Cycle • Tasks • • Major taxonomic groups: monocots and eudicots Task to prep for next week… • Leaf abscission demo • TA will use a razor blade to remove a pair of leaf blades from Coleus plant (leaving petioles intact!) • use wooden applicator to put lanolin paste (A) on one petiole tip (do not label) • use wooden applicator to put lanolin paste with NAA (B) on the other petiole tip (label using white paper ring) Angiosperms: Phylum Anthophyta • Angiosperms – “seed in a vessel” • at time of pollination, ovule is enclosed in sporophyte tissue (ovary) • ovary later develops into fruit that encloses the seed • other structures may also contribute to the fruit (“accessory structures”) • flowers and fruits are unique to angiosperms Angiosperms: Phylum Anthophyta • one phylum = Anthophyta = “flowering plants” two major clades: • eudicots • monocots • most of what used to be called dicots • Angiosperms: Phylum Anthophyta • monocots – some key characteristics • one cotyledon (seed leaf) • flower parts typically multiples of 3 • leaves with parallel venation of vascular tissue • two cotyledons • flower parts typically multiples of 4 or 5 • leaves with netlike venation of vascular tissue • eudicots – some key characteristics Flowers Flowers flower parts attached to receptacle in four whorls; from outside in: – – – – calyx – sepals corolla – petals androecium – stamens gynoecium – carpels Flowers complete – calyx + corolla + androecium + gynoecium incomplete – one or more whorls absent perfect – has both androecium and gynoecium imperfect – missing either androecium or gynoecium loss of whorls is a derived characteristic Flowers – – separate floral parts is the ancestral condition; fused parts is a derived characteristic connation – fusing within a whorl adnation – fusing between whorls for example, sepals and petals fused together Flowers symmetry: ancestral form is “regular” or radial symmetry (actinomorphic) Flowers derived form is “irregular” or bilaterally symmetry (zygomorphic) Fruits • typically formed from ovary wall (pericarp); may be divided into • exocarp (outer wall) • mesocarp • endocarp (inner wall, next to seed) Fruits • if material outside of ovary is included, the fruit is an “accessory fruit” • includes material derived from receptacle and/or floral tube • example: apple Fruits • three groups: • simple (derived from one pistil) • aggregate (from separate carpels on one flower) • multiple (from multiple flowers) Fruits • also divided by: • pericarp fleshy or dry at maturity • dry subdivided based on splitting at maturity • dehiscent – splits open at maturity • indehiscent – doesn’t split Angiosperm Life Cycle • still alternation of generations… Alternation of Generation (Sporic Meiosis) gametophyte mitosis gametes 1N spores haploid (1N) haploid generation generation 1N 1N meiosis diploid (2N) diploid generation generation 2N fertilization 2N (zygote) sporophyte mitosis Angiosperm Life Cycle see Figure 5­3 (pages 5.8­5.9) • key new terms to point out (beyond flower and fruit terms already covered): • Angiosperm Life Cycle embryo sac – mature female gametophyte (7 cells, 8 nuclei) Angiosperm Life Cycle double fertilization – one sperm fertilizes egg to make zygote; other fertilizes polar bodies to make 3N endosperm (used for food) Task A­1: Flower Dissection • flower structure • examine Alstroemeria and snapdragon flowers; compare to Figures 5­1 and 5­2 dissect and examine as indicated on page 5.5 • • Attend a group talk with a TA about the flowers at the back table Complete Table 5­1 for the five flowers included in the talk 1. 2. 3. 4. 5. Alstroemeria Snapdragon Carnation Lily Rose Task A­2: Flower Diversity • Task B­1: Anthers and Pollen Development • SLIDES: examine pollen grains on slides • • • Lily anther pollen tetrads 2­nucleate (mature) pollen Mixed pollen grains • • • Lilium pollen germination (demo on TV) Examine electron micrographs Examine slides on slide box (1­8) Task B­2: Ovules and Embryo Development • SLIDES: • Lily ovary megaspore mother cell • Mature embryo sac • Examine slides on slide box (8a­13) Task C­1: Fruit Types • Read about fruit types (Table 5­2) and examine drawings of them (Figures 5­6 through 5­9) Examine the fruits on demonstration, at your table, and on posters in the room Attend a group talk with a TA about fruits and fruit types Record at least one example of each type in Table 5­3 except for “other accessory fruit” and “other” • • • TODAY YOU WILL HAVE A (minimum score is zero on each half) 4 points per half, 1 point off for each error!!! HAND­IN ...
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