BI111 Study Guide - Pollen Tube, Sporangium, Gymnosperm

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12 Apr 2013
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Gymnosperms (gymnos- naked, sperma- seed) - naked seeds. Major changes in plants structures related to reproduction. 4 types of gymnosperms: conifers, cycads, ginkgoes cool cats get girls, gnetophytes. 24. 5a major reproductive adaptations occurred as gymnosperms evolved. Ovules: increased protection for female gametophyte and egg. Two steps that would lead to the formation of a seed step 1. Spores are retained inside sporangia on the sporophyte step2. Megaspores = one per sporangium (4 produced by meiosis- 1 survies) heterosporous plant = gametophyte develops inside the megaspore wall and inside the megasporangium. The egg developing inside the gametophyte = ovule [when fertilized= seed] Fertilized egg = embryo -> surrounded by protective layer = seed coat how can the sperm go through the layer of megasporangium? a male structure will penetrate through the tissue and release sperm inside the female gametophyte. Pollen: eliminating the need for water in reproduction. Heterosporous plants -> microspore produces a male gametophyte ( in a microspore wall)

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