Biology 1030 [7] - Plant Diversity 09 W LIVE...
Transcript of Biology 1030 [7] - Plant Diversity 09 W LIVE...
Biology 1030 Winter 2009
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Plant DiversityChapter 29 (573-588)Chapter 30 (591-606)
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What is a Plant?• Plants are characterized by multiple traits:
– AutotrophicAutotrophic
– Cell walls
– Storage material is starch
– Bodies made of three organ types
– Haplodiplontic life cycle
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• Two multicellular stages
– They have tissues which develop from apical meristems
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Plant Phyla• ~300,000 species
• 10 phyla exist
• Three major groups– Bryophytes
• Bryophyta – mosses
– Seedless vascular plants• Pterophyta ferns
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• Pterophyta – ferns
– Seed plants• Coniferophyta – conifers
• Anthophyta – flowering plants
Phyla You Don’t Need to Know• You are not responsible to know these phyla
– Hepatophytap p y
– Anthocerophyta
– Lycophyta
– Cycadophyta
– Ginkophyta
– Gnetophyta
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Alternation of Generations• Two multicellular stages
– Gametes (n)
Gametophyte
nMitosisMitosis
– Zygote• Mitosis
– Sporophyte• Meiosis
– Spores• Mitosis
n
n
Gamete
FERTILIZATIONMEIOSIS
n
n
Spore
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Mitosis
– Gametophyte
– Gametes
2n Zygote
Mitosis
Sporophyte
Sporophytes• Multicellular, diploid
– Grow from zygote
May have vascular tissue– May have vascular tissue
• Function– Sporangia (sporangium)
Spores
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– Sporocytes Spores
Sporangium
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Gametophytes• Multicellular, haploid
– Grow from spores
Never have vascular tissue– Never have vascular tissue
• Function– Gametangia
• Archegonia (female) • Antheridia (male)
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Eggs Sperm(inside)
Basic Plant Body• Three organs
• Below ground
Apical bud
g1. Roots
• Above ground2. Stems (shoots)
3. Leaves
Shootsystem
Vegetativeshoot
Leaf
St
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• Vascular tissue
• Waxy cuticle
Stem
Rootsystem
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Evolution of Land Plants1. Green algae ancestor
2. Non-vascular plants– Bryophytes
3 V l l t
• Apparent trends– True organs
– Dominant generation3. Vascular plants
– Non-seed plants
– Seed plants
– Dependency on water
– Size and complexity
1GREENALGA
Liverworts
Hornworts
Mosses
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Lycophytes (club mosses,spike mosses, quillworts)
Pterophytes (ferns,horsetails, whisk ferns)
Gymnosperms
Angiosperms
Millions of years ago (mya)500 450 400 350 300 50 0
Phylum Bryophyta• Perennial gametophyte
– Protonema(ta)
Gametophores– Gametophores
– Apical meristem
• Dioecious gametophytes– Male & female
– Gametangia on mature plants
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Bryophyta Body Plans• Gametophyte
– No xylem or phloem• Non-vascular• Non-vascular
• Impact on size
– No true organs• Thin ‘leaves’
• Simple ‘stems’
• Small ‘rhizoids’
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– No cuticle• Impact on environment
= A thallus
Bryophyta Body Plans• Sporophyte
– Dependent on the gametophyte• Grows onGrows on
• Fed by
– Foot– Seta– Sporangium
• Homosporous
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Moss Water Loss• All habitats
• Desiccation can occur in many
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Life on Dry Land
• Evolution of specific structures: – Transport tissue
• Xylem & Phloem– Epidermal secretions
• Cuticle
• Xylem & Phloem
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Vasculartissue
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Vascular Plants• Sporophyte
dominantLong lived– Long-lived
– Most are perennial
• Three true organs– Roots
– Shoots
Leaves
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– Leaves
• Three tissue types– Ground
– Dermal
– Vascular
• Three cell types– Parenchyma
– Collenchyma
– Sclerenchyma
Phylum Pterophyta• The ferns
– Seedless vascular plants
• Sporophyte dominant– Perennial
– Independent gamteophyte
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Pterophyta Body Plans• Short-lived gametophyte
– Thallus• Prothallium emerges• Prothallium emerges
– Small, photosynthetic
• Hormonal sex determination– Hermaphroditic gametophyte
• Antheridiogen
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– Male gametophyte
Pterophyta Body Plans• Long-lived sporophyte
– True organs
– Underground stem (= rhizome)
– Compound leaves (fronds)• Fiddlehead
– RootsLeaves
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• Shoot apical meristem
• Root apical meristems Rhizome
Roots
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Pterophyta Body Plans• Sporangia on leaves
– Sporophylls
Annulus– Annulus
– Sporocytes • Homospores
• Clustered in sori (sorus)– Indusium
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The Seed Plants• Heterosporous spore production
– Megaspores
Microspores– Microspores
• Dioecious gametophytes– Very small
– Dependent
• Ovule develops into the seed
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Ovule develops into the seed– Fertilization
• Pollen grain– Carries sperm
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Reduced Gametophytes• Trend
–
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• Retention in megasporangium– Protection
• Gymnosperms
• Sporophyte tissueI t t
Ovules & Seeds
– Integument
– Megasporangium
• One megaspore
• Megagametophyte– Microscopic
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– Archegonia
• Fertilization– Nutritive tissue
• Angiosperms
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Pollen Grains• Sporophytes house gametophytes
– Cross fertilization
• Sperm transfer vessels– Not dependent on water
• Male gametophytes
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– Incredibly reduced
Pollen Grains• Dispersal
– Wind
Wind & animals– Wind & animals
• Pollination– Direct
– Indirect
• Pollen tube forms
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• Pollen tube forms– Sperm transfer
– Fertilization IN ovule
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Phylum Coniferophyta• Gymnosperms (naked seeds)
• Sporophyte dominant
• Cones– Pollen cone – microsporangia
• Microsporophylls
– Ovulate cone – megasporangia • Megasprorphylls
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Coniferophyta Body Plans• Sporophytes
• Most are evergreensL i l dl– Leaves are simple needles
– Thick cuticle
• Very long lived
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Coniferophyta Body Plans• Megagametophyte
• Microscopic – 1000s of cells2 6 h i– 2-6 archegonia
• Fully dependent
• Nutrition source
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Coniferophyta Body Plans• Microgametophyte
• Microscopic – 4 cells1 t b ll– 1 tube cell
– 2 prothallial cells
– 1 generative cell
• Exine – coat
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• Generative cell division– Produces 2 sperm
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Coniferophyta Pollination• Sperm transfer
– Advantages
• Direct pollination– Can be a long process
• Ovule forms a naked seed
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Anthophyta• Angiosperms (enclosed seeds)
• Sporophyte dominant
• The flowering plants– Very successful group
• Sporangia contained in a flower
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– Stamen – microsporangia
– Carpel – megasporangia
• Can be found in every environment
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Anthophyta Body Plans• Sporophytes
• Two major groupsM t– Monocots
– (Eu)dicots
– Seed leaves
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Sporophyte Body Plans• Embryos
– Seed leaves
• Leaf venation
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• Stem vascular tissue
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Sporophyte Body Plans• Roots
• Pollen grains
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• Flowers
Anthophyta Body Plans• Megagametophyte
• Microscopic – 7 cells (8 nuclei)P th lli l ( ti d l)– Prothallial (antipodal)
– Syngergids
– Egg
– Polar nuclei
N h i
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• No archegonia
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Anthophyta Body Plans• Microgametophyte
• Microscopic – only 2 cells!T b ll– Tube cell
– Generative cell
• Exine – coat
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• 2 sperm cells– Double fertilization
Anthophyta Pollination
• Sperm transfer– Advantages
Pollen grain
Stigma
• Indirect pollination– Double fertilization
• Seeds are enclosed
Pollen tube
Style
2 sperm
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in a fruit Ovary
Ovule
Micropyle