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Download 3.2 The Plants - Hutchison
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3.2 The Plants Pages 86-87 Importance • Supply food through photosynthesis • Provide shelter and nesting sites • Products include paper, medicines, wood, clothing Challenges • • • • Habitat destruction Pollution Invasive species Climate change 4 types • • • • Bryophytes-non vascular plants Pteridophytes-seedless vascular plants Gymosperms-cone bearing Angiosperms-flowering plants Characteristics • • • • • • Multicellular Eukaryotic cells Photosynthetic Cell walls contain cellulose Sessile Incredible diversity Alternation of generations • Diploid (2n) produces spores, Haploid (n) produces gametes. Adaptions for life on land • waxy cuticle (prevents water loss) • stomata (tiny pores for air and water vapour exchange) Bryophytes • Mosses, liverworts and hornworts Bryophytes • Example: sphagnum moss • cuticle and stomata • no vascular tissue or true leaves, roots or seeds • Wet conditions for reproduction • Antheridia (sperm), Archegonia (eggs) • Sporangium produce haploid spores • Gemmae (n) for asexual reproduction Lycophytes and Pterophytes: The ferns Lycophytes and Pterophytes • Lycophytes-club mosses • Pterophytes-ferns Lycophytes and Pterophytes • • • • • • Vascular tissue (xylem and phloem) Lignin in cell walls (rigidity) Seedless Example: horsetails Rhizomes (stems) Fronds (leaves) Angiosperms and Gymnosperms • Pollen- waterproof capsules, male gametophyte • Ovule-female gametophyte • Fertilization produces a seed (2n) • 70% of all human food comes from the seeds of corn, rice and wheat Gymnosperms • Conifers • Cones • Examples: pine, spruce, cedar, juniper Angiosperms • • • • Flowering plants Flowers (reproductive organs) Fruit (ovary and outer tissues) Cotyledon (store foods)
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