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Unit 2 Plants

Unit 2 Plants. Plant Structure Roots Absorb water and dissolved nutrients from soil Anchor Plant Stems Support system Must be strong to hold up leaves and branches To get sunlight Transport Water and Carry food to and from roots. 3. Leaves Main photosynthetic system

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Unit 2 Plants

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  1. Unit 2 Plants

  2. Plant Structure • Roots • Absorb water and dissolved nutrients from soil • Anchor Plant • Stems • Support system • Must be strong to hold up leaves and branches • To get sunlight • Transport Water and Carry food to and from roots

  3. 3. Leaves • Main photosynthetic system • Increase sunlight absorption • Take in carbon dioxide and water • Release oxygen and water

  4. 3 main types of tissues • Dermal Tissue • Outer covering • Consists of a single layer of epidermal cells • Thick waxy coating

  5. 2. Vascular Tissue • Transport system that moves water and nutrients throughout the plant • Contains specialized cells 1. Xylem – transporter of water up the plant a. Like tin cans stacked up b. Ends of cells die and result is a tube c. Tracheid – pointed and overlapping d. Vessel members – large rounded

  6. Phloem – Carries food down from leaves • Cells have holes that allow things to pass through • Sieve tube elements – main tube • Sieve Plate – Plate with holes in between sieve tube elements • Companion cells – support the phloem cells and aid in movement of substances

  7. 3. Ground tissue • Tissue between dermal and vascular tissue • Consists of 3 types of cells • Parenchyma – thin cell walls with large central vacuoles surrounded by a thin layer of cytoplasm • Collenchyma – have strong, flexible cell walls that help support larger plants • Sclerenchyma – extremely thick and rigid cell wall that makes tissue tough and strong

  8. Plant Growth and Meristimatic Tissue • Plants grow terminally (ends) • Grow and produce new cells at the tips of roots and stems as long as they live • Cells are produced in meristems a. Meristems – tissue that continue to grow throughout the plants lives 1. Meristematic tissue – tissue where cells are rapidly dividing

  9. Meristems –Continued • Apical Meristem – a group of cells that divide to produce new cells for increase in length of stems and roots • Only tissue that makes new cells by mitosis • In meristems cells are almost exactly the same • Eventually they develop into mature cells with specialized structures and functions • Differentiation – changing of cells in order to do a specialized job a. All cells develop the same and change to form all the diff. types of cells in a plant

  10. Roots Roots Section of notes

  11. 2 Main Types of Roots • Tap Root – • One primary root • Found mostly in dicots (organized plants) • Ex: Carrot • Fibrous Root – • Many branches of smaller roots • Helps to increase surface area • Also aids in anchoring of taller plants and for shallow soil

  12. Structure • Root hair – • Increase surface area • Cortex – • Ground tissue (paren, sclaren, collen ) • Endodermis – • encases vascular tissue • Epidermis – • Outer covering • Vascular cylinder – a. Contains all xylem and Phloem

  13. Root cap – • Protect tip of root and apical meristem • Zones of root • Zone of cell division • Cells rapidly divide • Apical meristem in this region • Zone of elongation • Cells elongate and are becoming differentiated • Zone of maturation/differentiation 1. Cells mature to specialized cells

  14. Root Functions • Anchor Plant • Absorb nutrients and water from soil • Nutrients • Main nutrients – ESSENTIAL Nutrients • Nitrogen – proper leaf growth • Phosphorus – synthesis of DNA and development • Potassium – synthesis of protein and carbohydrates • Magnesium – synthesis of chlorophyll • Calcium – cell growth and division • Trace Nutrients – only small quantities, too much = poison a. Zinc, copper, boron, chlorine, sulfur

  15. Root functions (Cont) • Active Transport • Uses ATP to transport minerals from soil • Movement into vascular cylinder • Water needs to get into vascular tissue • All V. tissue is surrounded by endodermis that has water proof system trapping everything in • Plant allows water into cylinder at root tips • Storage • Plants store energy and food in some roots 1. Ex: carrot

  16. Stems

  17. Structure and Function • Function • Produce leaves, branches, flowers • Hold leaves for sunlight • Transport between roots and leaves • Storage

  18. Structure • Node – where leaves are attached • Internode – region between nodes • Buds – undeveloped tissue that can produce new stems and leaves • Bud scales – protect bud and fall off for growing • Bud Scale Scars – scars left when bud scales fall off each growing season • Terminal Bud – apical meristem of stem that is protected by bud scales. 1. Only place stems grow longer

  19. Monocot vs. Dicot • Vascular Bundle – a group of xylem and phloem bunched together • Monocot • Vascular bundles scatter through out the stem • No real pattern • Separated by ground tissue • Dicot • Vascular bundles are arranged in a cylindrical like pattern forming a ring • Pith – parenchyma cells inside the ring of vascular bundles

  20. Primary and Secondary growth of stems • Primary Growth – only growth at the ends of plants • Happens in apical meristem of terminal bud • Secondary Growth – an increase in width • Mostly occurs in Dicots • Dicots grow in width • Happens in other meristems • Lateral meristems - where cell division occurs to increase width

  21. 3. Lateral meristems • Cork cambium - produces the outer covering of stems • Vascular cambium – lateral meristimatic tissue that produces vascular tissue and increases width

  22. Formation of vascular cambium • Thin layer between xylem and phloem bundles • Produces more Xylem and Phloem • Result is a thicker stem • Cortex – spongy storage layer of ground tissue inside the epidermis • Cork – thick outer coving of stems

  23. Formation of Wood • Comes from layers of Xylem • Wood is Xylem • Older xylem stops transporting water • Heartwood – older xylem that stops transporting water completely • Older = darker • Sap wood – older xylem that still functions a little • Lighter than heartwood

  24. b. Spring wood • Lighter wood (xylem) with thin cell walls • Forms during beginning of growth season • During rapid cell division • Late wood • Darker wood (xylem) with thick cell walls • Thicker walls from longer growth season • Cell division happens slower so thicker cell walls • Result of these 2 woods is a Tree ring • Thick ring – good growing season • Thin ring – bad growing season

  25. Formation of Bark • Bark – includes all tissue from Vascular cambium outward • Layers • Phloem – transports food • Cork cambium – makes cork (protective layer) • Cork – made from old nonfunctioning phloem

  26. Leaves

  27. Leaf Structure • Parts • Blade – flattened section for increased surface area • Petiole – thin stalk that attaches blade to stems • Veins – xylem and phloem bundles in leaves • Kinds • Compound – many leaves on same petiole • Simple – one leaf per petiole

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