Plants - PowerPoint PPT Presentation

Loading...

PPT – Plants PowerPoint presentation | free to view - id: 7417dc-ZDcwN



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Plants

Description:

Plants - Cardinal Spellman High School ... AP Biology – PowerPoint PPT presentation

Number of Views:85
Avg rating:3.0/5.0
Slides: 82
Provided by: cardin5
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Plants


1
Plants
  • AP Biology

2
Quick Facts About Plants
  • Multicelled, eukaryotic, photosynthetic
    autotrophs
  • Life cycle characterized by alternation of
    generations
  • Ancestral plants lived in aquatic areas but are
    now mostly on land

3
Bryophytes
  • Non-vascular lack xylem and phloem
  • Absorb water through diffusion
  • Contain flagellated sperm that swim through water
    to fertilize an egg
  • Lack lignin, tissue that supports tall plants
  • restricted to moist habitats and are tiny

4
Bryophytes
  • Grow on rocks, soil and trees
  • Can be used as fuel (sphagnum, peat moss)
  • Examples mosses, liverworts, hornworts

5
Tracheophytes
  • Plants with vascular tissue
  • Xylem and phloem for transport
  • Lignified transport vessels to support plant
  • Roots to absorb, anchor and support
  • Leaves, increasing surface for photosynthesis
  • Dominant sporophyte generation during developmen

6
Two Types of Tracheophytes
  • Seed plants
  • More advanced and far more numerous
  • Gymnosperms (bearing cones)
  • Angiosperms (bearing flowers and fruits)
  • Seedless plants
  • Ferns

7
Ferns
  • Seedless tracheophytes
  • Primitive plants reproducing with spores
  • Homosporous, producing only one type of spore
    which develops into a bisexual gametophyte
  • Restricted to moist habitats
  • Sperm are flagellated and must swim to fertilize
    an egg

8
Seed Plants
  • Heterosporous, producing megaspores and
    microspores
  • Megaspores female gametophytes
  • Microspores male gametophytes
  • Sperm are not flagellated, and therefore are not
    restricted to moist environments

9
Gymnosperms (Conifers)
  • First seed plants on earth
  • Seeds are naked, as they are not enclosed
    inside a fruit, like angiosperms
  • Seeds are exposed on modified leaves that form
    cones (dry environments)
  • Modifications include needle-shaped eaves
  • Depend on wind for pollination

10
Gymnosperms (Conifers)
  • Pines, firs, redwoods, junipers and sequoia

11
Angiosperms (Flowering Plants)
  • Seed plants whose reproductive structures are
    flowers and fruits
  • 90 of all plants
  • Color and scent of flowers attracts animals that
    will carry pollen from one plant to another
  • After pollination and fertilization, ovary
    becomes fruit and ovule becomes seed

12
Angiosperms (Flowering Plants)
  • Fruit protects seeds and aids in their dispersal
  • Examples
  • Maple trees have seeds with wings helping them
    travel greater distances
  • Some plants have burrs on their fruits that cling
    to fur or clothing
  • Animals eat and digest fruit while tough seeds
    pass through digestive tract, eventually being
    deposited with feces as fertilizer

13
Monocots vs. Dicots
Characteristic Monocot Dicot
Cotyledons (seed leaves) One Two
Vascular bundles in stem Scattered In a ring
Leaf venation Parallel Netlike
Floral parts Usually in 3s Usually in 4s or 5s
Roots Fibrous roots Taproots
14
Plants Move Towards Land
  • Plants moved to land as competition for resources
    increased
  • Problems supporting plant body while absorbing
    and conserving water

15
Modifications
  • Cell wall made of cellulose to give support and
    maintain shape
  • Roots and root hairs absorb water and nutrients
    from soil
  • Stomates open to exchange gas and close to
    prevent water loss
  • Cutin, waxy coating on leaf, prevents excess
    water loss from leaves

16
Modifications
  • Some plants have protective jacket of cells
    called gametangia, protecting gametes and zygotes
    as well as preventing drying out
  • Sporopollenin, a tough polymer, is resistant to
    environmental damage and protects plants
  • Found in walls of spores and pollen

17
Modifications
  • Seeds and pollen have a protective coat
    preventing desiccation
  • Xylem and phloem vessels enable plants to grow
    tall
  • Lignin embedded in xylem and other plant cells
    provide support

18
Primary Growth
  • Meristem
  • Enables plants to grow as long as they live
  • Continually divides and generates new cells
  • Apical meristem
  • In tips of roots and buds of shoots is the source
    of primary growth, the elongation of the plant
    down into the soil and up into the air

19
Secondary Growth
  • Lateral meristem
  • Provides secondary growth, or increase in girth
  • Herbaceous (nonwoody) plants
  • Only primary growth
  • Woody plants
  • Secondary growth responsible for thickening of
    roots and shoots

20
Plant Tissue
  • Dermal tissue
  • Covers and protects plant
  • Includes epidermis, guard cells, root hairs,
    cuticle cells
  • Vascular tissue
  • Xylem and phloem, transporting water and
    nutrients
  • Ground tissue
  • Support, storage, photosynthesis

21
Vascular Tissue Xylem
  • Water and mineral-conducting tissue
  • Consists of two types of elongated cells
  • Tracheids and vessel elements
  • Both dead at functional maturity
  • Tracheids
  • Long, thin cells that overlap and taper at the
    ends
  • Water passes from one cell to another through
    pits, with no secondary cell wall
  • Areas with secondary cell wall are hardened with
    lignin providing support and transport

22
Vascular Tissue Xylem
  • Vessel elements
  • Wider, shorter, thinner walled, less tapered
  • Align end to end
  • Ends are perforated to allow free flow through
    vessel tubes
  • Seedless vascular plants and gymnosperms have
    only tracheids most angiosperms have both
    tracheids and vessel elements
  • Xylem makes up wood of plants

23
(No Transcript)
24
Vascular Tissue Phloem
  • Carries sugars from photosynthetic leaves to rest
    of plant by active transport
  • Consist of chains of sieve tube members or
    elements whose end walls contain sieve plates
  • Facilitate flow of fluid from one cell to the
    next
  • Alive at maturity
  • Lack nuclei, ribosomes and vacuoles

25
Vascular Tissue Phloem
  • Connected to each sieve tube member is at least
    one companion cell
  • Contains a full set of organelles
  • Nurtures sieve tube elements

26
(No Transcript)
27
Vascular Tissue Ground Tissue
  • Support, storage, photosynthesis
  • Three cell types
  • Parenchyma, scelernchma, collenchyma
  • KEEP IN MIND THAT FORM RELATES TO FUNCTION

28
Vascular Tissue Ground Tissue
  • Parenchymal cells
  • Primary cell walls that are thin and flexible
  • Lack secondary cell walls
  • Contain one large vacuole
  • Some contain chloroplasts and carry out
    photosynthesis
  • Parenchymal cells in roots contain plastids and
    store starch
  • When turgid, give support and shape

29
Vascular Tissue Ground Tissue
  • Parenchymal cells
  • After a plant is injured, parenchymal cells
    retain ability to divide and differentiate into
    other cell types
  • An entire plant can be regenerated or cloned from
    one parenchymal cell (in a lab)

30
Vascular Tissue Ground Tissue
  • Collenchymal cells
  • Unevenly thickened primary cell walls but lack
    secondary cell walls
  • Mature cells are alive
  • Support growing stem
  • Strings of a stalk of celery are collenchymal
    cells

31
Vascular Tissue Ground Tissue
  • Sclerenchymal cells
  • Thick primary and secondary cell walls fortified
    with lignin
  • Support plant
  • Two forms are fiber and sclereids
  • Fibers are long thin and occur in bundles make
    rope and linen
  • Sclereids are short and irregularly shaped make
    up tough seed coats and pits

32
Roots
  • Absorb nutrients from soil, anchor plant and
    store food
  • Made of specialized tissues and structures

33
Roots
  • Epidermis covers surface of roots modified for
    absorption
  • Root hairs extend out from each cell and increase
    surface area
  • Cortex consists of parenchymal cells that contain
    plastids to store starch and organic substances

34
Roots
  • Vascular cylinder or stele of root consists of
    xylem and phloem surrounded by tissue called
    pericycle, from which lateral roots arise
  • Endodermis surrounds vascular cylinder each
    endoderm cell is wrapped with the Casparian
    strip, a continuous band of suberin, waxy
    material impervious to water

35
Roots
  • Endoderm selects which minerals can enter
  • Apical meristem which provides primary growth (up
    and down)
  • Three zones of cells during primary growth
  • Zone of cell division (bottom)
  • Zone of elongation (middle)
  • Zone of differentiation (top)

36
Roots
  • Root tip is protected by a root cap, which
    secretes a substance that digests the earth
  • Zone of cell division
  • Meristem cells actively divide
  • Zone of elongation
  • Cells elongate and push root cap deeper into soil
  • Zone of differentiation
  • Protoderm becomes epidermis, ground meristem
    becomes cortex, procambium becomes xylem and
    phloem

37
Types of Roots
  • Taproot
  • Single large root that gives rise to branch roots
  • Common in dicots
  • Fibrous root system
  • Holds plant firmly in place
  • Common in monocots

38
Types of Roots
  • Adventitious roots
  • Roots that arise above ground
  • Aerial roots
  • Found in marshes
  • Stick out of water and give air to root cells
  • Prop roots
  • Grow above ground out from base of stem
  • Support plant

39
Stems
  • Primary stem tissue
  • Vascular tissue exists as vascular bundles
  • Xylem inside, phloem outside, meristem tissue in
    between
  • Monocots
  • Vascular bundles scattered throughout stem
  • Dicots
  • Vascular bundles arranged in a ring

40
(No Transcript)
41
Stems
  • Ground tissue
  • Consists of cortex and pith
  • Used for storage

42
Secondary Growth in Stems
  • Produced by lateral meristem
  • Replaces dermal tissue with bark
  • Second lateral meristem adds vascular tissue
  • Wood is secondary xylem accumulation

43
The Leaf
  • Epidermis upper and lower protection for leaf
  • Cuticle waxy coating minimizing water loss
  • Guard cells contain chloroplasts control
    opening of stomates
  • Stomates tiny openings allowing for gas exchange

44
The Leaf
  • Mesophyll
  • Palisade layer cells packed tightly contain
    many chloroplasts
  • Spongy layer cells packed loosely, allowing for
    diffusion of gases less chloroplasts
  • Vascular bundles (veins) found in mesophyll
    carry water and nutrients
  • Specialized bundle sheath cells surround veins

45
Stomates
  • Accounts for majority of water loss
  • Opened and closed by guard cells
  • If guard cells absorb water by osmosis and become
    turgid, they curve and open stomates
  • If guard cells lose water and become flaccid,
    stomate closes

46
Stomates
47
Why Stomates Open
  • Loss of CO2 within air spaces of leaf
  • Occurs when photosynthesis begins
  • Increase in potassium ions
  • Lowers water potential, causing water to diffuse
    into them
  • Stimulation of blue light in a guard cell
  • Stimulates proton pumps which promote uptake of
    potassium ions
  • Active transport of H out of guard cells

48
Why Stomates Close
  • Lack of water
  • Guard cells become flaccid and close
  • High temperatures
  • Increases cellular respiration which increases
    concentration of carbon dioxide
  • Abscisic acid
  • Produced in response to dehydration

49
Transport in Plants
  • Xylem rises against gravity without using energy
  • Transpirational pull pulls water up
  • Root pressure pushes xylem upward a few yards
  • Water droplets on leaves in the morning result
    from root pressure, a process called guttation

50
Root Pressure
51
Transpirational Pull
  • Transpiration is the evaporation of water from
    leaves
  • This causes negative pressure to develop in xylem
  • Cohesion of water helps pull a column of water
    upward
  • Absorption of sunlight causes water to evaporate

52
Transpirational Pull
53
Transpirational Pull-Cohesion Tension Theory
  • For each molecule of water that evaporates,
    another molecule of water is drawn from the root
    to replace it
  • Factors affecting transpiration
  • Humidity increased slows, decreased speeds
  • Wind reduces humidity, speeding up transpiration
  • Increased light increased photosynthesis,
    increased water vapor, increased transpiration
  • Stomates if closed, stops transpiration

54
Absorption of Nutrients and Water
  • Apoplast and symplast
  • Performs lateral movement of water and solutes
  • Symplast
  • continuous cytoplasmic system interconnected by
    plasmodesmata
  • Long-distance transport
  • Apoplast
  • Network of cell walls and intercellular spaces
  • Short-distance, extracellular transport

55
Absorption of Water and Nutrients
  • Mycorrhizae
  • Symbiotic structures consisting of the plants
    roots intermingled with hyphae (filaments) of
    fungus
  • Increase amount of nutrients to be absorbed

56
Absorption of Water and Nutrients
  • Rhizobium
  • Symbiotic bacterium living in nodules on roots of
    specific legumes
  • Fix nitrogen gas from air into a form that plants
    can use
  • Nitrogen-fixing bacteria

57
Absorption of Nutrients and Water
  • Bulk flow
  • Movement of fluids across great distances within
    a plant

58
Translocation of Phloem Sap
  • Phloem sap travels through plant from sugar
    source to sugar sink
  • This is called translocation
  • Source is where sugar is being produced (leaves)
  • Sink is where sugar is stored or consumed (roots
    and fruit)

59
Plant Reproduction
  • Asexual
  • Accomplished through vegetative propagation
  • A piece of the vegetative part of the plant
    (root, stem or leaf) can produce a new plant
    genetically identical to the parent
  • Grafting (plant parts are fused together)
  • Cuttings (taking plant stem cells and placing
    them in soil)
  • Bulbs (underground buds)
  • Runners (stem grown underground)

60
Sexual Reproduction in Flowering Plants
  • Flower is the sexual organ
  • Process begins with pollination
  • One pollen grain contains three haploid nuclei
    (one tube nucleus, two sperm nuclei)
  • Grain lands on the sticky stigma of the flower
  • Pollen grain absorbs moisture and sprouts,
    forming a pollen tube that burrows down the style
    into the ovary

61
Sexual Reproduction in Flowering Plants
  • Two sperm nuclei travel down the pollen tube into
    the ovary
  • Once inside, two remaining sperm nuclei enter the
    ovule through the micropyle
  • One sperm nucleus (haploid) fertilizes the egg
    (haploid) and becomes the embryo (2n)
  • The other sperm nucleus fertilizes the two polar
    bodies and becomes the triploid (3n) endosperm,
    food for the embryo

62
Sexual Reproduction in Flowering Plants
  • This process is double fertilization
  • After fertilization, ovule becomes the seed and
    ripened ovary becomes the fruit
  • Monocots food reserves remain in endosperm in
    coconuts, endosperm is the liquid
  • Dicots mature seed lacks endosperm since they
    are transported

63
(No Transcript)
64
The Seed
  • Protective coat, embryo and cotyledon or
    endosperm
  • Embryo
  • Hypotcotyl becomes lower part of stem
  • Epicotyl becomes upper part of stem
  • Radicle (embryonic root) first organ to emerge
    from the germinating seed

65
Alternation of Generations
  • Haploid (n) and diploid (2n) generations
    alternate
  • Gametophyte (n) produces gametes by mitosis
  • Fuse during fertilization to form 2n zygotes
  • Each zygote develops into a sporophyte (2n),
    which produces haploid spores (n) by meiosis
  • Each haploid spore forms a new gametophyte

66
Mosses and Bryophytes
  • Alternation of generations
  • Haploid generation is dominant diploid
    generation lives a short time and depends on the
    gametophyte for food

67
Mosses and Bryophytes
  • Overview
  • Gametophyte dominates
  • Archegonia and antheridia develop on tips of
    gametophyte
  • Sporophyte grows out of the top of the
    gametophyte and obtains nutrients from it
  • Haploid spores are formed in mature sporangia

68
Ferns
  • Sporophyte generation is larger than and
    independent from gametophyte
  • Archegonia and antheridia both develop underneath
    heart-shaped haploid gametophyte
  • Sperm swim from antheridia to archegonia (of
    different plants) to form a diploid zygote
  • Zygote grows into a large diploid sporophyte
    plant
  • Haploid spores emerge and land on the ground to
    sprout into gametophytes

69
Seed Plants
  • Flowering plants
  • Gametophyte generation exists inside the
    sporophyte generation and depends totally on it
  • Meiosis occurs inside anthers and pistils
  • Anthers produce microspores, forming male
    gametophytes
  • Ovules produce megaspores, forming female
    gametophytes

70
Fertilization of Seed Plants
  • Occurs in ovary, forming zygotes that develop
    into sporophyte embryos in the ovule
  • Ovule becomes the seed, carrying embryo and food
    for it

71
Seed Plants
  • Gymnosperms (conifers)
  • Sporophytes whose sporangia are packed inside
    cones
  • Gametophyte generation develops from haploid
    spores
  • Small pollen cones produce microspores, which
    become male gametophytes
  • Larger ovulate cones produce megaspores, which
    become female gametophytes

72
Plant Responses to Stimuli
  • Hormones
  • Coordinate growth, development and environmental
    responses
  • Signal transduction pathways amplify hormone
    signals and connect them to specific cell
    responses

73
Auxin
  • Responsible for phototropisms
  • Enhances apical dominance (upward growth)
  • Stimulates stem elongation and growth
  • Indoleacetic acid
  • Spraying synthetic auxin on tomato plants induces
    fruit production without pollination (seedless
    tomatoes)

74
Cytokinins
  • Stimulate cytokinesis and cell division
  • Delay senescence (aging) by inhibiting protein
    breakdown
  • Produced in roots and travel upward

75
Gibberellins
  • Promote stem and leaf elongation
  • Work with auxins to promote cell growth
  • Induce bolting, the rapid growth of a floral stalk

76
Abscisic Acid
  • Inhibits growth
  • Enables plants to withstand drought
  • Closes stomates during stress
  • Promotes seed dormancy, keeping seeds from
    sprouting until spring

77
Ethylene
  • Gas hormone
  • Promotes fruit ripening (positive feedback)
  • Produced during stressful times
  • Facilitates apoptosis, or cell death
  • Promotes leaf abcission
  • If a leaf falls from the plant, a scar forms to
    prevent pathogens from entering

78
Tropisms
  • Growth of a plant toward or away from a stimulus
  • Thigmotropism (touch)
  • Geotropism (gravity)
  • Phototropism (light)
  • Growth toward a stimulus is positive tropism
    while away from it is negative tropism

79
Signal Transduction Pathway
  • Reception, transduction and response
  • Receptor is stimulated and activates a second
    messenger
  • Secondary messengers are cyclic nucleotides (AMP
    and GMP) that transfer and amplify signals
  • This messenger leads to a response by altering
    factors and targeting specific cells

80
Photoperiodism
  • Physiological response to the photoperiod
  • Relative lengths of day and night
  • Biological clock set to 24 hour day (circadian
    rhythm)
  • Long-day plants (short night plants)flower when
    light period is longer than a certain number of
    hours
  • Short-day plants and day-neutral plants flower
    regardless of length of day

81
Photoperiodism
  • Phytochrome is the pigment responsible for
    keeping track of the length of days and nights
  • Pr (red light absorbing)
  • Phytochrome is synthesized in this manner
  • When the plant is exposed to light, it convers
    to
  • Pfr (infrared light absorbing)
  • In the dark, Pfr reverts back to Pr
  • Enables plant to keep track of time
About PowerShow.com