01:119:116 Lecture Notes - Lecture 8: Microphyte, Decongestant, Black Pepper

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Gametophyte: microscopic, develop spores internally, dependent on sporophyte, protects gametophyte from environment, ensures nutrients for gametophyte. Production: megaspore - grows into female gametophyte, microspore - grows into male gametophyte, ovule: megasporangium (2n) + megaspore (n) + Integuments: protective sporophyte tissue around megasporangium, form seed coat: gymnosperms - 1 integument, angiosperms - 2 integuments. Gymnosperms - naked seeds (most are conifers: seeds exposed on modified leaves cones (strobili, pine life cycle (sporophyte dominant) In most conifer species, each tree has both ovulate and pollen cones. Microsporocytes divide by meiosis haploid microspores pollen grain (male gametophyte enclosed within pollen wall) Ovulate cone scale has two ovules, each containing megasporangium. Pollination occurs when pollen grain reaches ovule pollen grain germinates form pollen tube pollen tube digests its way to megasporangium. While pollen tube develops, megasporangium undergoes meiosis 4 haploid cells one cell survives and becomes megaspore. Megaspore develops into female gametophyte with 2-3 archegonia, each will form an egg.

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