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Unit 7 Plants

Unit 7 Plants. Part 2: Tissues, Roots, Stems & Leaves. Plant Tissues – 1. Dermal Tissue. Outer covering Made of epidermal cells Waxy coating: cuticle Accessories: Trichomes (“fuzz”) Root hairs (absorption) Guard cells (regulate water/gas movement at surface).

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Unit 7 Plants

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  1. Unit 7 Plants Part 2: Tissues, Roots, Stems & Leaves

  2. Plant Tissues – 1. Dermal Tissue • Outer covering • Made of epidermal cells • Waxy coating: cuticle • Accessories: • Trichomes (“fuzz”) • Root hairs (absorption) • Guard cells (regulate water/gas movement at surface)

  3. Plant Tissues – 2. Vascular Tissue • Transport system – Moves water/nutrients • Xylem: water-conducting tissue • Tracheids • Vessel elements • Phloem: food-conducting tissue • Sieve tube elements • Companion cells

  4. Plant Tissues – 3. Ground Tissue • Everything else • Three types • Parenchyma (majority)  Thin cell walls; functions include storage & photosynthesis • Collenchyma Strong, flexible cell walls; functions include support • Sclerenchyma  Extremely thick/rigid; extra support/toughness

  5. Plant Growth • Indeterminate (never stop) • Meristem Tissue clusters where new growth occurs via mitosis • Cells produced in meristem = undifferentiated (not yet specialized) • Apical meristem = at end of root or stem; responsible for increased length • Cells gradually differentiate

  6. Plant Roots: 1. Types • Taproots Long, thick primary root; mainly in dicots • Fibrous roots  Branching system, no primary; mainly in monocots

  7. Plant Roots: 2. Structure/Growth

  8. Plant Roots: 3. Functions • Anchor • Uptake nutrients from soil (N, P, K, Mg, Ca) • Active transport of mineral ions  Leads to osmosis of water • One-way movement into vascular cylinder and up (capillary action) • Generates root pressure to move water/nutrients from roots all the way up plant

  9. Stems: 1. Structure/Function • Three functions: • Produce leaves/branches/flowers • Hold leaves up to sun • Transport substances between roots + leaves

  10. Stems: 2. Primary Growth • Primary growth: New cells only produced at root + shoot tips (ends) • Cell division in apical meristem

  11. Stems: 3. Secondary Growth • Stems grow thicker/wider • Dicots and conifers • Division of the vascular cambium (a different kind of meristem) • Produces more xylem + phloem • Grows from inside - outward • Protected by cork cambium

  12. Stems: 3. Secondary Growth • Leads to formation of wood • Wood = layers of xylem • Center = oldest, eventually non-functional xylem (heartwood) • Exterior layer = sapwood (active)

  13. Leaves: 1. Structure • Blades: flattened; collect sunlight • Petiole: stem

  14. Leaves: 2. Function • A. Photosynthesis • Special ground tissue: mesophyll palisade + spongy) • Stomata (pores; gas movement) • Guard cells (regulation)

  15. Leaves: 2. Function • B. Transpiration • Loss of water • Replaced by water drawn up from roots • C. Gas exchange • Take in CO2, give off O2 • Guard cells regulate movementin response to environment

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