Unit 7 plants
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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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Unit 7 plants

Unit 7 Plants

Part 2:

Tissues, Roots, Stems & Leaves


Plant tissues 1 dermal tissue

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)


Plant tissues 2 vascular tissue

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


Plant tissues 3 ground tissue

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


Plant growth

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


Plant roots 1 types

Plant Roots: 1. Types

  • Taproots Long, thick primary root; mainly in dicots

  • Fibrous roots  Branching system, no primary; mainly in monocots


Plant roots 2 structure growth

Plant Roots: 2. Structure/Growth


Plant roots 3 functions

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


Stems 1 structure function

Stems: 1. Structure/Function

  • Three functions:

    • Produce leaves/branches/flowers

    • Hold leaves up to sun

    • Transport substances between roots + leaves


Stems 2 primary growth

Stems: 2. Primary Growth

  • Primary growth: New cells only produced at root + shoot tips (ends)

  • Cell division in apical meristem


Stems 3 secondary growth

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


Stems 3 secondary growth1

Stems: 3. Secondary Growth

  • Leads to formation of wood

  • Wood = layers of xylem

  • Center = oldest, eventually non-functional xylem (heartwood)

  • Exterior layer = sapwood (active)


Leaves 1 structure

Leaves: 1. Structure

  • Blades: flattened; collect sunlight

  • Petiole: stem


Leaves 2 function

Leaves: 2. Function

  • A. Photosynthesis

    • Special ground tissue: mesophyll palisade + spongy)

    • Stomata (pores; gas movement)

    • Guard cells (regulation)


Leaves 2 function1

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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