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Chapters 22 - 24

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Chapters 22 - 24 Plants I. Introduction to Plants What is a plant? - a multicellular eukaryote that has a cell wall made of cellulose; they carry out photosynthesis ... – PowerPoint PPT presentation

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Title: Chapters 22 - 24


1
Chapters 22 - 24
  • Plants

2
I. Introduction to Plants
  • What is a plant?
  • - a multicellular eukaryote that has a cell
    wall made of cellulose they carry out
    photosynthesis using chlorophyll

3
  • What do plants need to survive?
  • 1. Sunlight to carry out
    photosynthesis
  • 2. Water Minerals for growth and
    photosynthesis

4
  • 3. Gas exchange CO2 needed for
    photosynthesis, O2 needed for
    respiration
  • 4. Movement of water and nutrients to
    distribute the products of photosynthesis
    throughout the plant body

5
II. Plant Groups
  • Bryophytes (nonvascular plants)
  • 1. Depend on standing water for reproduction
  • 2. Lack vascular tissue
    (specialized tissue that moves water and
    nutrients throughout the plant),
    so only grow to a few centimeters tall

6
  • 3. No true roots, stems, or leaves
  • 4. Groups of bryophytes
  • a. Mosses
  • b. Liverworts
  • c. Hornworts

7
  • Seedless vascular plants
  • 1. Contain vascular tissue xylem
    (conducts water) and phloem (conducts
    nutrients)
  • 2. Produce lignin makes cell walls
    rigid
  • 3. True roots, stems, and leaves

8
  • 3. Groups of seedless vascular plants
  • a. Club mosses
  • b. Horsetails
  • c. Ferns

9
  • Seed plants
  • 1. contain vascular tissue and lignin
  • 2. true roots, stems, and leaves

10
  • 3. Seed plant reproduction
  • a. Pollination occurs when a male
    gametophyte (pollen grain) is
    transferred to a female gametophyte
    water is NOT required
  • b. Pollination leads to a seed (a plant
    embryo food supply) surrounded by a
    protective seed coat

11
  • Groups of seed plants
  • a. Gymnosperms bear seeds on cones
  • - gnetophytes, cycads, ginkgoes, and
    conifers

12
  • b. Angiosperms (flowering plants) bear seeds
    in protective layers of tissue
  • 1. flowers contain ovaries, which
    surround and protect the seeds
  • 2. after pollination, the ovary develops
    into a fruit, which protects the seed an
    aids in dispersal

13
  • 3. monocots and dicots
  • - named for of cotyledons (seed leaves)
    monocots have 1, dicots have 2
  • 4. woody and herbaceous plants
  • - woody plants produce wood as they grow
    trees, shrubs, vines
  • - herbaceous plants do not produce wood
    dandelions, sunflowers, petunias

14
  • 5. annuals, biennials, perenials
  • - annuals complete a life cycle in one
    growing season (1 year)
  • - biennials 2 years
  • - perennials more than 2 years

15
III. Specialized Tissues in Plants
  • Meristematic tissue
  • 1. found in tips of roots and shoots
  • 2. only plant tissue that produces new cells
    by mitosis

16
  • Dermal tissue
  • 1. outer covering of plant
  • 2. consists of epidermal cells covered with
    a thick, waxy layer (cuticle) that prevents
    water loss
  • Vascular tissue
  • - xylem and phloem
  • Ground tissue
  • - lies between dermal and vascular tissue

17
IV. Roots
  • Types of roots
  • 1. taproots
  • - one primary root
  • - found mainly in dicots
  • 2. fibrous roots
  • - many branched roots
  • - found mainly in monocots

18
  • B. Root structure and growth
  • - a mature root has an outside layer
    (epidermis), a central cylinder of vascular
    tissue, ground tissue between the two tissues
  • C. Root functions
  • 1. anchor plant in ground
  • 2. absorb water and nutrients from soil

19
V. Stems
  • Functions of stems
  • 1. produce leaves, branches, and flowers
  • 2. hold up leaves in sunlight
  • 3. transport substances between roots and
    leaves

20
  • Composed of dermal, vascular, and ground tissue
  • 1. monocot stems scattered bundles of
    vascular tissue
  • 2. dicot stems vascular tissue arranged
    in a ring

21
VI. Leaves
  • Leaf structure
  • 1. Most leaves have thin flattened sections
    called blades
  • 2. The blade is attached to the stem by a
    stalk called the petiole

22
Petiole
Blade
23
  • Leaf functions
  • 1. photosynthesis sunlight collection
  • 2. transpiration evaporation of water from
    leaves
  • 3. gas exchange stomata (pores) are
    opened and closed by guard cells to regulate
    CO2, O2, and water vapor

24
VII. Structure of flowers
  • Sepals usually green, enclose the bud before it
    opens
  • Petals used to attract pollinators

25
  • Stamens male reproductive parts composed of
  • 1. anther produces pollen
  • 2. filament long, thin stalk that supports
    the anther

26
  • Carpels (pistils) female reproductive parts
    composed of
  • 1. ovary contains ovules where female
    gametes are produced
  • 2. stigma sticky part at top where pollen
    grains land
  • 3. style stalk connecting ovary to stigma

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VII. Pollination and fertilization in angiosperms
  1. Pollen can be carried from one flower to another
    by wind or animals
  2. Pollen lands on the stigma and begins to grow a
    pollen tube

29
  1. Pollen tube grows into the style and eventually
    reaches the ovary
  2. Sperm nucleus fuses with the egg to form an
    embryo
  3. Food rich tissue called endosperm is formed to
    nourish the seedling as it grows

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IX. Seed development and germination
  • As angiosperm seeds mature, the ovary walls
    thicken to form a fruit that encloses the
    developing seeds
  • - Fruit a ripened ovary that contains seeds
  • - examples grapes, peaches, beans, peanuts,
    cucumbers

32
  • Seeds are dispersed by
  • 1. animals enclosed in fleshy,
    nutritious fruits
  • 2. wind or water enclosed in lightweight
    fruits
  • C. Germination is the early growth stage of plant
    embryos
  • - seeds absorb water, endosperm swells, seed
    coat cracks open
  • - young root emerges from cracked seed coat

33
X. Vegetative reproduction and plant propagation
  • Some plants can reproduce asexually through
    vegetative reproduction
  • - new plants can grow from horizontal stems,
    plantlets, and underground roots

34
  • Plant propagation the use of cuttings,
    grafting, or budding to make identical copies of
    a plant, or to produce offspring from seedless
    plants
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