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THE PLANT KINGDOM
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All Plants Evolved from Common Ancestor: Ancient Green Algae
Cell walls made of cellulose Store excess carbohydrates as starch Form a cell plate during cytokinesis Have same photosynthetic pigments: Chlorophyll a and b Carotenoid – carotene and xanthophyll
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Adaptations to life on land:
Cuticle Waxy layer on aerial portion that prevents dessication Thickness depends on how dry the environment is
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Adaptations to life on land:
Cuticle Stomata: Pores on the surface of leaves and stems Allows for gas exchange
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Adaptations to life on land:
Cuticle Stomata Gametangia Multicellular sex organs Covered by a layer of sterile cells – protection Embryo develops inside gametangia
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Plant Life Cycle Alternation of generations Gametophyte
Multicellular haploid stage Produces gametes Sporophyte Multicellular diploid stage Produces spores
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Gametophyte generation
Gives rise to haploid gametes by mitosis Sperm cells form in antheridia Egg cells form in archegonia Once sperm cell fertilizes an egg cell, a zygote is formed
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Sporophyte generation
Begins with diploid zygote Zygote divides by mitosis and develops into embryo Grows into mature sporophyte plant Specialized cells called sporogenous cells divide by meiosis into haploid spores
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Four Main Groups of Plants
Bryophytes Seedless vascular plants Gymnosperms Angiosperms
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Bryophytes Nonvascular plants Rely on diffusion and osmosis
Restricted in size Generally require moist environment MOSSES, LIVERWORTS, HORNWORTS
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Moss Life Cycle
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Vascular Plants Ferns, Gymnosperms, Angiosperms
Contain xylem and phloem Cell walls contain lignin Strengthening polymer Support Conduction Allows plants to grow tall
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Seedless Vascular Plants
Ferns & club mosses Most important adaptation: Xylem – transports water Phloem – transports food Transport allows plants to grow larger
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Club Mosses Only group of vascular plants with microphyll True Roots
Leaf with single vascular strand True Roots Rhizome & aerial stems Reproductive leaves with sporangia
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Ferns Rhizome w/ roots Fronds Sori found on fronds
Clusters of sporangia Sporagenous cells undergo meiosis spores
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Fern Life Cycle Prothallus
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Homospory vs. Heterospory
Homospory – sporophyte produces 1 kind of spore Heterospory – microspores & megaspores
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Dominant Stages Bryophyte – Gametophyte Seedless Vascular – Sporophyte
Gymnosperms – Sporophyte Angiosperms - Sporophyte
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