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Plants

Plants. An Overview. What are plants?. Plants are Multicellular : made of more than 1 cell Photosynthetic: make food and energy from sun Eukaryotes: cells have membrane bound organelles Their cells are surrounded by a cell wall made of cellulose.

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Plants

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  1. Plants An Overview

  2. What are plants? • Plants are • Multicellular: made of more than 1 cell • Photosynthetic: make food and energy from sun • Eukaryotes: cells have membrane bound organelles • Their cells are surrounded by a cell wall made of cellulose. • Most reproduce sexually (pollen), but some can reproduce asexually (spores).

  3. Evolution:Where do today’s plants come from? • Ancestors of today’s plants date back 450 million years ago: ALGAE • Plants evolved from living in an underwater environment to living on dry land. • They still required lots of water to survive so retaining water was very important.

  4. Bryophytes • Bryophytes (mosses): • NO vascular tissue. Must live in very wet areas and need a lot of water to survive . They stop growing during dry spells. • No seeds

  5. Lycophytes (Ferns) • Vascular plants • Usespores • No Seeds

  6. Tracheophytes • Tracheophytes: • The first true land plants • Vascular tissues that transport water and nutrients • Ferns • Gymnosperms: plants with cones: conifers, evergreens • Angiosperms: flowering plants

  7. Adaptations for land • Roots: They anchor the plant into the ground and absorb nutrients and water from the soil. • Leaves: Broad and flat leaves allow more surface area to take in sunlight for photosynthesis and little openings in the leaf called stomata for gas exchange and preventing water loss • Vascular Tissue: Xylem and phloem carry nutrients and products of photosynthesis through the plant to where they need to go.

  8. Adaptations for land • Stems: Hold up leaves to capture as much light as possible. • Spores: can survive for long times • Gametes: (Pollen and Ovule) • Pollen : Pollination through pollen grains that are carried by insects or the wind. • pollination • Fertilization: sperm used to need film of water to swim to egg

  9. Water potential • Osmosis • Diffusion • Water potential: • solute concentration + pressure

  10. Bulk Flow • Long distance transport • Bulk flow = movement of fluid driven by pressure. • In Phloem, loading of sugar makes pressure at one end of a tube, forcing sap to the opposite end. • In Xylem, it is tension (negative pressure) that drives transport • Transpiration • Cohesion • Absorption at root

  11. Roots • Root hairs • Extensions of epidermis • Increase surface area • Where most absorption occurs • Symbiosis of roots and fungi • Increase surface area (a lot) for absorption

  12. Gymnosperms and Angiosperms • Gymnosperms (evergreens, conifers) • Vascular Tissue • Seeds: cone-shaped structures that hung on the outside of the plant. • Angiosperms (flowering plants): • Vascular Tissue • Seeds • Flowers.

  13. Alternation of Generation

  14. Ferns Mosses

  15. Spore survival • Prior to seeds: spore was the only protected stage for plants. • Spore is single cell • Could survive: cold hot dry • Could be dispersed to another environment

  16. Spore Release

  17. Evolution of SEEDS • Seeds are multicellular • Has protective integument coat from ovule • Can be dormant for days months years

  18. Seed Release

  19. Seed • Seed : • Embryo: immature plant • Endosperm:food supply • Seed coat of integument • Ovule develops into seed

  20. Seed parts • Embryo • Endosperm • Seed coat

  21. Ovule • Ovary produces the ovule • Ovule parts: • INTEGUMENT • FEMALE GAMETOPHYTE (egg)

  22. Gymnosperms

  23. Angiosperms

  24. Seed Release

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