Lab9_Gymnosperms_Angiosperms

Lab9_Gymnosperms_Angiosperms - Seed Plants Seed plants have...

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1 Seed Plants • Gymnosperms – plants with exposed seeds borne on cones. (Exercise 30) – Phylum Cycadophyta (Cycads have flagellated sperm) – Phylum Ginkgophyta (Gingko do not bear cone; leaves shape) – Phylum Coniferophyta (Conifers are cone-bearing plants) – Phylum Gnetophyta (Gnetophytes with a few rare genera, see Fig. 30.11) Seed plants have vascular tissue and make seeds. • Angiosperms –flowering plants, seeds develop inside a protective structure called a carpel . (Exercise 31) – Phylum Anthophyta Molecular Phylogenies of Plants
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2 All Land Plants Undergo Alternation of Generations Gametophyte: a multicellular haploid phase; Sporophyte: a multicellular diploid phase. • Alternation of generations: – Gametophytes are microscopic; – Sporophytes are large and free-living. Heterospory • Seed plants can produce two distinct types of spores and spore-producing structures—a development known as heterospory .
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3 Gymnosperms: Conifer • Sporophylls are modified leaves specialized for reproduction . – Also found in ferns • Microsporophyll – in male cones (staminate cones) – Layer of microsporangium that produces spores. – Male cones are relatively small and similar in all conifers. – Male cones form on the lower branch of pine trees. • Megasporophyll – in female cones (ovulate cones) – Two spore-producing megasporangia on upper surface. – Female cones are variable. – Female cones form on the upper branches. • Cones are reproductive structure of sporophyte generation that consist of several scale-like sporophylls arranged about a central axis.
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4 Sporangium in pine (male) • Male microsporangium microspore mother cells (2n) meiosis microspores (n) mitosis pollen grains (male gametophyte with four nuclei and a pair of bladderlike wings). microsporophyll microsporangium microgametophytes (pollen grains) from microspores wings Sporangium in pine (female) • Female megasporangia megaspore mother cells (2n) meiosis megaspore (n) mitosis megagametophyte (female gametophyte surrounded by nucellus and integuments)
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This note was uploaded on 02/25/2011 for the course BIO 138 taught by Professor Wu during the Summer '08 term at Staten Island.

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Lab9_Gymnosperms_Angiosperms - Seed Plants Seed plants have...

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