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Spores and seeds (Biology notes) exam 2

Spores and seeds (Biology notes) exam 2 - Exam 2 Wed 30...

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Exam 2 Wed. 30 september-Tuesday 6 october Kingdom plantae Spores and seeds They are not the same, in plants, spores are single celled haploid structures that develop into gametophytes, seeds are multicellular structures that develop into sporophytes. The Bryophytes Hornworts, Liverworts, and mosses 3 Phyla of non-vascular plants Anthocerophyta- the hornworts Hepatophyta- the liver worts Bryophyta- The mosses (relationships amont these three phyla not well understood)~25,000 species (most are mosses) Adaptations to life on land Waxy cuticle, sporopollenin, apical meristems, Cecondary products Multicellular gametangia- structures that procude gamates Antheridia- sperm Archegonia- eggs Zygote develops into a multicellular embryo inside the archegonium Bryophyte Habitats Generally found in damp, shady environments A few aquatic species Some species live in very dry habitats (surfaces of rocks) Not because they are efficient at transporting water- because they can tolerate desiccation Live cycle Oogamous(large non motal egg and motal sperm) , heteromorphic alteration of generations As in all lants gametes are produced by mitosis not meiosis Gametophyte (1n) phase of the life cycle predominant phase- Longer lived, larger, nutritionally independent. Phylum anthocerophyta The hornworts not very common diverse or large Phylum Hepatophyta Thalloid and leafy liverworts Sporophytes quite small and in some species non photosynthetic (completely dependent on the gametophyte for nutrition) Tend to live in damp and shady habitats Male Gametophyte of Marchantia Antheridiophore (male) produce antheridium with many sperm Female gametophyte of marchantia Archegoniphores (female) archegonium produces eggLiverwort embryo (Multicellular embryo developing in an archegonium) Leafy Liverwort Produce sporophytes Many are able to reproduce asexually Mosses The mosses- sporophytes realitively large (compared to liverworts) and carry out some photosynthesis, but gametophyte generation is predominant Some species have water conducting cells called hydroids (even thought bryophytes are called non vascular some species do have simple vascular systems)
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Moss Diversity World’s largest moss- dawsonia superba (native to australia) Moss life cycle Protonemata is produced from spores, Produce into bud like structures and grow into male and femal gametophytes. Male gametophyte- many sperm produced in each antheridium Female gametophyte- one egg produced in archegoinia Fertilization Sperm must move from antheridium to the egg in the archegonium Requires external water- the sperm are flagellated and swim to the egg Produces a 2N zygote (sperm gets to egg because of the rain) embryo develops inside th archegonium. Grows as a long narrow stalk emerging from the archegonium
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Spores and seeds (Biology notes) exam 2 - Exam 2 Wed 30...

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