BIO 102 Lecture Notes - Lecture 13: Conifer Cone, Gymnosperm, Antheridium
8 Nov 2016
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Document Summary
Gymnosperms: seeds totally exposed or borne on scales of cone: no ovary wall surrounds the ovules, ex. Angiosperms: flowering plants that produce seeds with in mature ovary. Gymnosperms conifers: reproductive parts are borne in male and female strobili (cones) Woody trees/shrubs that produce annual additions of secondary tissues (wood or bark) Many have long, narrow, tough, needles or small scale like leaves. Most are evergreen, few are deciduous (seasonal) Embryophytes: the zygote and is produced and divides by mitosis to produce the sporophyte. Layered with different parts of the life cycle that is released all together. Consists of leaf like scales that bear sporangia on the underside. Microsporangia contain microsporocytes which undergo meiosis to form four haploid microspores. Microspores develop into immature male gametophytes (pollen grain) with 4 cells: 2 of which (a generative cell and tube cell) are involved in reproduction. Each scale bears 2 ovules, or megasporangia, on its upper surface.
