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Transcript of Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Evolution of...
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Evolution of Plants
Chapter 16
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Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Outline
• 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
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
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Generalized Plant Life Cycle
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Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Moss Life Cycle
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Leaf Vascular System
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Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Fern Life Cycle
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Seed Plants
• 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.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Seed Structure
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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)
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Conifer Life Cycle
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Angiosperm Flower
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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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Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Angiosperm Life Cycle
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Dicots and Monocots
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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)
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
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
Copyright © McGraw-Hill Companies Permission required for reproduction or display