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Chpt. 29 Plant Diversity Colonization of Land
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Plant Classification:
PHYLUM
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Division Plant Classification: Phyta = suffix for division name
ex. Bryophyta = moss Pterophyta = fern
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Plant Evolution: from where did they come??
Green algae mm Common ancestor
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The first plants For more than 3 billion years, Earth’s terrestrial surface was lifeless life evolved in the seas 1st photosynthetic organisms were aquatic green algae - the PROTIST kingdom
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Plant Evolution: Diverged from green algae called Charophytes.
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Present day relatives to ancient plants:
Chara Coleochaete Protists Volvox
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Evidence: 1. Homologous chloroplasts 2. Biochemical similarity
3. Cell wall similarity (cellulose) 4. Sperm similarity (flagellated) 5. Genetic relationship (similar a.a. sequences and rRNA)
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Evidence: Modern Charophytes grow in shallow water, NOT ALWAYS UNDERWATER. This may have allowed them to be pre-adapted to move to land.
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WOW!!! It is hard to live on the land… what adaptations would be necessary for a successful move from water algae to land plants??
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Adaptations for Land Colonization:
Specialization: need to capture light & CO2 above ground (shoots) need to capture water & minerals below ground (roots)
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Perpetual embryonic region
Did you ever consider: plants just can’t get up and move to the water, CO2 etc.??? shoots Perpetual embryonic region
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Perpetual embryonic region
Did you ever consider: plants just can’t get up and move to the water, CO2 etc.??? Perpetual embryonic region roots
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Adaptations for Land Colonization: 2. Cuticle
= waxy layer keeps from drying out in the air - H2O conservation
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Adaptations for Land Colonization:
2. Cuticle = waxy layer keeps from drying out in the air - H2O conservation
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Problem Cuticle blocks CO2 and O2 gas exchanges between the cells and the environment.
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Adaptations for Land Colonization:
3. Stomata = gas exchange on leaf / prevents water loss
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Adaptations for Land Colonization:
4. Sporopollenin = polymer on spores and pollen. Makes walls of spores tough… Assists reproduction in the harsh land environment
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Adaptations for Land Colonization: 5. Gametangia (multicellular)
= multicellular, protective area for gametes organ that produces gametes keeps gametes from drying out
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Adaptations for Land Colonization:
5. a) Archegonia (female) produces eggs keeps from drying out = protective area for gametes
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Adaptations for Land Colonization:
5. a)Archegonia (female) produces eggs keeps from drying = protective area for gametes
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Adaptations for Land Colonization:
5. b)Antheridia (male) produces sperm keeps from drying out = protective area for gametes
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Two multicellular body forms:
6) Alternation of Generations Two multicellular body forms: SPOROPHYTE - (2N) GAMETOPHYTE - (N)
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Two multicellular body forms:
6) Alternation of Generations Two multicellular body forms: SPOROPHYTE - (2N) GAMETOPHYTE - (N)
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6) Alternation of Generations
multicellular / haploid produces the gametes
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6) Alternation of Generations
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6) Alternation of Generations
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6) Alternation of Generations
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6) Alternation of Generations
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6) Alternation of Generations
multicellular diploid produces haploid spores
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6) Alternation of Generations
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6) Alternation of Generations
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6) Alternation of Generations
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Plants: Evolutionary Trends
____________ non-vascular land plants ____________ seedless vascular plants ____________ pollen & “naked” seeds ____________ flowers & fruit seed plants vascular plants Plants: Evolutionary Trends colonization of land
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Plants: Evolutionary Trends
1. Reduction of Gametophyte. 2. Change from flagellated sperm to pollen. 3. Development of seeds, flowers, and fruits. 4. Development of vascular tissues. Plants: Evolutionary Trends
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Plant Evolution: bryophytes
Mosses Liverworts Hornworts for at least 50 million years these were the only plants! mm
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Plant Evolution: bryophytes
mm
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Plant Evolution: bryophytes
°Gametophyte = DOMINANT generation mm
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this is the dominant stage
GAMETOPHYTE
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Plant Evolution: bryophytes
° nonvascular mm -“rootless” - thallus -no wter transport -“leaves”, one cell thick -close to ground -WHY?
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How do they get water?
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Where must mosses live?
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“Peat Moss” Peat Bog
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Produces gametes this is dominant stage
Plant Evolution: bryophytes °Gametangia mm Produces gametes this is dominant stage eggs in archegonia sperm in antheridia
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antheridia archegonia
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Plant Evolution: bryophytes
°Gametangia - why is this is a HUGE evolutionary deal!!! mm
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Plant Evolution: bryophytes
°Gametangia - Protects of zygote from the elements! mm
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Plant Evolution: bryophytes
°Sporophyte = NOT DOMINANT generation mm
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Plant Evolution:bryophytes
°often found in wet habitats… WHY? mm
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Plant Evolution:bryophytes
°are never taller than 10cm tall… WHY? mm
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Sporophyte Produces spores (n) in a sporangium or capsule.
Parasitic on the gametophyte.
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Sporophyte Sporangium Spores (n)
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Plant Evolution:bryophytes
° Sporopollenin -spores w/ protective coating mm
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Plant Evolution:bryophytes
° Sporopollenin -spores w/ protective coating. protection of spore for harsh environment mm
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Plant Evolution:bryophytes
° Sporopollenin -spores w/ protective coating. protection of spore for harsh environment mm
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Bryophytes -Importances
Peat Moss (many uses). Soil Formation. First plants in primary Succession
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And then....
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(we are still w/o seeds)
Vascular Plants (we are still w/o seeds)
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Seedless Vascular Plants
The ferns and fern allies. A collection of several different plant divisions.
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STEMS & LEAVES SHOOTS ROOTS
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Characteristics True vascular tissue. Xylem –> water/minerals.
Phloem –> food.
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PHLOEM ANATOMY:
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XYLEM ANATOMY:
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Plant Evolution: Evolutionary significance of vascular tissue? - mm
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Plant Evolution: Evolutionary significance of vascular tissue allows the organism to achieve a larger size mm
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Plant Evolution: Evolutionary significance of vascular tissue allows the organism to achieve a larger size this allows for more spores!! mm
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Plant Evolution: No seed, flower, or fruit.
Green algae mm No seed, flower, or fruit. Still we have flagellated sperm (no pollen)
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diploid haploid
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Plant Evolution: SPOROPHYTE - becomes the DOMINANT stage over gametophyte what is the evolutionary significance? mm
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Plant Evolution: pterophyte
More complex (remember, mosses spend more time in the gametophyte stage.) mm
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Plant Evolution: pterophyte
Branched - what is the evolutionary significance? mm
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Plant Evolution: pterophyte
Branched - what is the evolutionary significance? more opportunity for more sporangia (area where spores develop) .. More reproduction!!! mm
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Spore Type Homosporous - one kind of spore.
produces bisexual gametophyte both archegonia and antheridia on one structure)
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SORUS - on leaf… holds sporangia
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Spore Type Homosporous - one kind of spore
produces bisexual gametophyte both archegonia and antheridia on one structure)
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SPORANGIA - holds spores
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Spores mitose -> gametophyte (n)
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prothallium
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GAMETOPHYTE archegonia antheridia
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gametophyte matures and produces GAMETAMGIA
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H2O HANDY evolutionary trick… sperm and egg DO NOT the same time!!!
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Sporophyte grows out of the gametophyte
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SPOROPHYTE grows out of gametophyte
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Bush = sporophyte generation Iraq = gametophyte generation
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Ferns Often have underground stems called rhizome.
Leaf called a frond. ‘baby leaf’ a fiddlehead.
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fronds fiddleheads
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Fern – Life cycle Sporophyte Sori on fronds
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Fern – Life cycle Sorus Sporangium
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Fern – Life cycle Germinating Spore Gametophytes
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Fern – Life cycle Young Sporophytes
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Fern – Life cycle Young Sporophytes
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SIGNIFICANCE Formed the first forests!!
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SIGNIFICANCE Accelerated rate of photosynthesis (increased rate of CO2 removal from the atmosphere)
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Global cooling / widespread glacial formation
SIGNIFICANCE Global cooling / widespread glacial formation
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SIGNIFICANCE COAL
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SIGNIFICANCE COAL
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Early Pteridophytes: Tree Ferns
Fossil fuels… I get it! Carboniferous forest – mya Forests of seedless plants decayed into deposits of coal & oil
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Summary ģ Know the general characteristics of plants (what makes them successful on land). ģ Know the alternation of generations for plants. ģ What are the evolutionary trends in plants?
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Summary For each plant division, know: Examples Characteristics
Life Cycle Economic/Ecological Importance
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