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Unformatted text preview: • • Homospory vs. Heterospory Gymnosperms • • • • Phylum Cycadophyta Phylum Ginkgophyta Phylum Coniferophyta Phylum Gnetophyta Lab 4: Plants II – Lab 4: Plants II – The Evolution of Seed Plants • • • • (gymnosperm) fossils Pine Life Cycle / Seed Development Tree Identification Activity Initiation of Seed Germination Experiment Homospory vs. Heterospory Homospory vs. Heterospory • homospory ­ “same spore” • sporophyte makes one type of spore • thus, only one type of gametophyte • gametophyte makes both antheridia and archegonia, and thus both sperm and eggs Alternation of Generations (Sporic Meiosis) Alternation of Generations (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 Homospory vs. Heterospory Homospory vs. Heterospory • heterospory – “different spore” • sporophyte makes two types of spores (megaspores and microspores) • two gametophyte sexes: microspore male gametophyte sperm megaspo...
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