1. Evolution of Plants Chapter 16
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2. Adapting to Terrestrial Life Vascular Plants Seedless Vascular Plants
Outline
Adapting to Terrestrial Life
Vascular Plants
Seedless Vascular Plants
Seed Plants
Gymnosperms
Angiosperms
Flowers
Dicots and Monocots
Seed Dispersal
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3. Adapting to Terrestrial Living
Green algae that were probably the ancestors of today’s plants are aquatic organisms not well-adapted to living on land.
Had to overcome three challenges:
Minerals absorption from rocky surfaces
Water conservation
Reproduction on land
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4. Adapting to Terrestrial Living
Mineral Absorption
Plants require relatively large amounts of six inorganic minerals:
Nitrogen, potassium, calcium, phosphorus, magnesium, and sulfur.
Mycorrhizae
Water Conservation
Cuticle - watertight outer covering.
Stomata - gas and vapor exchange.
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5. Adapting to Terrestrial Living
Reproduction on Land
Due to immobility, gametes must avoid drying while they are transferred by wind or insects.
Spore Development
Generation alteration
Sporophytes - diploid generation
Gametophyte - hapolid generation
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6. Generalized Plant Life Cycle
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7. Evolution of Vascular System
Terrestrial plants are required to carry water up from roots to leaves, and carbohydrates down from leaves to roots.
Vascular System
Specialized strands of connected hollow cells.
Nine of Twelve living plant phyla are vascular.
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8. Only two phyla of living plants lack a vascular system:
Nonvascular Plants
Only two phyla of living plants lack a vascular system:
Liverworts (Hepaticophyta)
Hornworts (Anthocerophyta)
Simple Vascular Systems
Mosses were first plants to evolve strands of specialized conduction cells.
No specialized wall thickening.
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9. Moss Life Cycle
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10. Evolution of Vascular Tissue
Appeared approximately 430 mya.
Grew by cell division at the tips of stem and roots (Primary Growth).
About 380 mya vascular plants developed a growth in which a cylinder of cells beneath the bark divides, producing new cells around plant’s periphery (Secondary Growth).
Necessary for tall trees with thick trunks.
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11. Leaf Vascular System
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12. Seedless Vascular Plants
Most abundant of the four phyla of seedless vascular plants contain ferns with about 12,000 living species.
Have both gametophyte and sporophyte individuals, each independent and self-sufficient.
Gametophyte produces eggs and sperm.
Sporophyte bears and releases hapolid spores.
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13. Fern Life Cycle
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14. Male and Female gametophytes
Seed Plants
Seed - Embryo cover that offers protection of embryonic plant at its most vulnerable stage.
Male and Female gametophytes
Male - microgametophytes (pollen grains) arise from microspores.
Female - megametophytes contain eggs and develop from megaspores produced within ovule.
Pollination - transfer of pollen.
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15. Five living phyla of seed plants:
Four are gymnosperms - ovules not completely enclosed by sporophyte tissue at time of pollination.
Fifth is angiosperms - ovules completely enclosed by vessel of sporophyte tissue (carpel) at time of pollination.
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16. Seed Structure
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17. Adaptive value of seeds: Dispersal Facilitate migration and dispersal
Seed Plants
Adaptive value of seeds:
Dispersal
Facilitate migration and dispersal
Dormancy
Wait for favorable conditions
Germination
Synchronization with environment
Nourishment
Energy source for young plants
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18. Coniferophyta (Conifers) Trees that produce seeds in cones.
Gymnosperm Phyla
Coniferophyta (Conifers)
Trees that produce seeds in cones.
Most familiar of four gymnosperm phyla.
Seeds develop on scales within cones and are exposed at time of pollination.
Cycadophyta (Cycads)
Ginkgophyta (Ginkos)
Gnetophyta (Gneetophytes)
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19. Conifer Life Cycle
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20. Comprise 90% of all living plants.
Rise of Angiosperms
Comprise 90% of all living plants.
Use roots to anchor plants in one place to obtain nutrients.
Produce tiny male gametes that are easily transported.
Flower - reproductive organs that employ bright colors to attract pollinators and nectar to induce entrance into the flower to contact pollen grains.
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21. Structure consists of four distinct whorls:
Flowers
Structure consists of four distinct whorls:
Outermost - Protects flower from physical damage (sepals).
Second - Attracts pollinators (petals).
Third - Produces pollen grains (stamens and anther).
Fourth - Produces Eggs (Carpel)
Ovary
Style
Stigma
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22. Angiosperm Flower
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23. Why Different Kinds of Flowers
Different pollinators are attracted to specific types of flowers.
Bees most numerous insect pollinators.
Becomes coated with pollen while inside the flower.
Butterflies
Moths
Hummingbirds
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24. Male gametophyte contains two sperm.
Double Fertilization
Angiosperms produce a highly nutritious tissue (endosperm) within their seeds.
Male gametophyte contains two sperm.
Second fuses to form endosperm cell (double fertilization).
Dicotyledons - Embryos with two seed leaves.
Monocotyledons - Embryos with one seed leaf.
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25. Angiosperm Life Cycle
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26. Dicots and Monocots
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27. Seed Dispersal - Fruits
Fruit - mature, ripened ovary containing fertilized seeds, surrounded by a carpel.
Fleshy fruits encourage predation.
Berries - Many seeded forms on inner carpel wall. (Grapes, Tomatoes)
Drupes - Stony inner layer adhering to single seed. (Peaches, Olives)
Pomes - Fleshy portion comes from petals and sepals. (Apples, Pears)
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28. Adapting to Terrestrial Life Vascular Plants Seedless Vascular Plants
Review
Adapting to Terrestrial Life
Vascular Plants
Seedless Vascular Plants
Seed Plants
Gymnosperms
Angiosperms
Flowers
Dicots and Monocots
Seed Dispersal
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

29. Copyright © McGraw-Hill Companies
Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies