Forms strands that conduct water, minerals, and organic compounds. Much of the inside of nonwoody parts of plants. Includes roots, stems, and leaves

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Lydia Lawrence
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1 Biology II

2 Vascular plants have 3 tissue systems: Dermal Protective outer layer of plant Vascular Forms strands that conduct water, minerals, and organic compounds Ground Much of the inside of nonwoody parts of plants Includes roots, stems, and leaves

3 Green Ground Purple Vascular Tan - Dermal

4 Covers outside of plant s body Forms skin called epidermis Made up of single layer of flat cells in most plants Often have hair-like extensions to slow water loss by trapping moisture Called root hairs help increase water absorption

6 Waxy cuticle protects epidermis of stems and leaves Also prevents water loss Made it possible for plants to live in drier environments Water lilies also have cuticle protects leaves and repel water Cork on woody stems and roots Several layers of dead cells Contains a waterproof material not covered by cuticle Functions in gas exchange and absorption of mineral nutrients in addition to protection

8 Stomata, singular stoma permits plants to exchange oxygen and carbon dioxide (since the cuticle does not) Extend through cuticle and outer layer of cells Found on at least some parts of most plants Guard cells border each stoma Stomata open to gain CO 2 from air also loses water this way When closed, plant conserves water, but photosynthesis slows (shortage of CO 2 )

9 Why does photosynthesis slow down when stomata are closed?

10 Two kinds of vascular tissue Xylem Phloem Composed of cells that are stacked end to end like sections of pipe Allow most vascular plants to grow much larger than nonvascular plants

Composed of thick-walled cells that conduct water and mineral nutrients from a plant s roots through its stems to its leaves At maturity, cells are dead still has strong cell walls Conducting cells

11 Composed of thick-walled cells that conduct water and mineral nutrients from a plant s roots through its stems to its leaves At maturity, cells are dead still has strong cell walls Conducting cells Tracheids Water flows from one to the next through pits, or thin areas in cell walls Vessel elements Link to form vessels Have large perforation in ends that allow water to flow quickly between elements

Made up of cells that conduct sugars and nutrients throughout a plant s body Cells have cell wall, cell membrane, and cytoplasm Lack organelles or have modified organelles Conducting cells Sieve-tube

13 Made up of cells that conduct sugars and nutrients throughout a plant s body Cells have cell wall, cell membrane, and cytoplasm Lack organelles or have modified organelles Conducting cells Sieve-tube members Link to form sieve tubes Pores in walls connect the cytoplasms and allow substances to pass from cell to cell Companion cells Contain organelles Carry out cellular respiration, protein synthesis, and other metabolic functions

15 Makes up much of the inside of nonwoody plants Surrounds and supports vascular tissue Most consists of thin-walled cells that remain alive and keep their nucleus after maturity Also contains some that do the opposite (die, thick-walled cells) Contain many specialized structures In leaves packed with chloroplasts In stems and roots vacuoles (water storage) In angiosperms, makes up flesh of fruits Largely absent in woody parts of plants

17 Roots, stems, and leaves contain all three tissue types

18 Anchor plants Absorb water and nutrient minerals Can function in storage of sugar and starch (organic) Monocots highly branched, fibrous roots Dicots central root, called taproot system

19 Has central core of vascular tissue surrounded by ground tissue Ground tissue surrounding vascular tissue called cortex Roots covered by dermal tissue Epidermis covers all of root except root tip Epidermal cells behind root tip often produce root hairs Increase surface area Roots hairs = extensions of epidermal cells Mass of calls called root cap covers and protects root tip

21 Stems support leaves and house vascular tissue Can be specialized for other functions Stems of cacti store water Potatoes stores nutrients Leaves attach to stems at nodes Internode space between two nodes

22 Herbaceous plants have stems that are flexible and usually green Vascular bundles bundles of xylem and phloem Surrounded by ground tissue In dicots, bundles are in a ring Ground tissue outside of bundles is called cortex Pith = ground tissue inside bundles Covered by epidermis

Stiff and nongreen Buds produce new growth, are found at the tips of nodes Young has central core of pith and a ring of vascular bundles Fuse into solid cylinders as stem matures Layers of xylem form

23 Stiff and nongreen Buds produce new growth, are found at the tips of nodes Young has central core of pith and a ring of vascular bundles Fuse into solid cylinders as stem matures Layers of xylem form innermost cylinder major component of wood Phloem lies outside cylinder of xylem Covered by cork protect from damage and water loss Cork and phloem make of layers(bark) of woody stem Wood in center is called heartwood Provides support but no longer conducts water Sapwood outside heartwood Contain vessel elements that can conduct water

24 Primary photosynthetic organs of plants Most have flattened portion called blade Attached to stem by a stalk, called petiole can be divided into 2+ sections called leaflets Undivided leaves are simple leaves 2+ leaflets are compound leaves

Leaf is mass of ground tissue covered by epidermis Cuticle coats upper and lower Xylem and phloem found in veins of leaves Veins are extensions of vascular bundles that run from tips of roots to

25 Leaf is mass of ground tissue covered by epidermis Cuticle coats upper and lower Xylem and phloem found in veins of leaves Veins are extensions of vascular bundles that run from tips of roots to edges of leaves In leaves, ground tissue is called mesophyll Packed with chloroplasts Most plants have 2 layers of mesophyll Palisade layer closely packed, columnar cells Spongy layer loosely packed cells Stomata usually located in lower epidermis of leaf

27 Water lily specialized for floating Stomata on upper surface Cactus modified as spines Protect plant from herbivores Garden pea form tendrils that climb Venus flytrap can catch insects

28 Seed develops from ovule and contains a plant embryo Embryo contains embryonic root and embryonic shoot Cotyledons, or seed leaves are attached to embryonic shoot Gymnosperm embryos =2+ cotyledons Angiosperms = monocot 1, dicot 2

29 Embryo within seed is in dormancy Can remain in dormancy for thousands of years Germination process of plant embryo resuming growth 1 st sign emergence of root

30 Sprout in response to certain changes in environment Rising temp, soil moisture, sometimes cold, fire, passing through digestive system of animal, falling onto a rock Must have water and oxygen penetrate seed coat Allows seed to swell and breaks seed coat

specialized tissues Primary growth increases length of height Result in primary

31 Part of plant s body that grows mostly upward is shoot Part that grows down = root Meristems active regions of growth Made of undifferentiated cells, develop into specialized tissues Primary growth increases length of height Result in primary tissues Secondary growth increases width of stems and roots Result in secondary tissues

32 Apical meristems located at the tips of stems and roots Produce primary growth via cell division Differentiate into roots, stems, and leaves Each plant has 2 one at the tip of the embryonic root, and one at tip of embryonic shoot Makes stems and roots get longer, not wider Primary growth would end if all cells in apical meristem differentiated Undifferentiated cells are left behind to produce new meristems New meristems found at buds at base of leaves and within roots

33 Some undifferentiated cells left behind as stems and roots lengthen to produce lateral meristems Responsible for increase in width of stems and roots Called secondary growth Most dramatic in woody plants Produced by cell division in two lateral meristems Form thin cylinders near outside of woody stems and roots Cork cambium lies within the bark and produces cork cells Vascular cambium Lies just under bark and produces secondary xylem and secondary phloem

Chapter 23 Notes Roots Stems Leaves

Chapter 23 Notes Roots Stems Leaves I. Specialized tissue in plants - effective way to ensure the plant s survival A. Seed plant structure 1. Roots - a. Absorbs water and dissolves nutrients b. anchors