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(Plants (week 9)) - Coggle Diagram

- - - - 5. Apical Meristems
        
        allow plants to grow high above ground (CO2, light) and below ground (water, mineral nutrients)
        
        specialised tissue at growing tips where rapid cell division occurs
        
        Cells produced by apical meristem then differentiate into outer epidermis or other internal tissues
      - Protection of gametes, zygotes, spores
        
        2. Embryophytes
        
        multicellular, dependent embyos
        
        grow protected inside parent plant
        
        4. Tough and protected spores
        
        sporopollenin
        
        makes walls more resistant to drying
        
        sporangium
        
        protective specialised organ where spores are produced
        
        3. Gametangia
        
        specialised organ for gamete production (sex organs)
        
        Antheridium (male)
        
        Archegonium (female)
      - 1. Alternation of generations
        
        switch between phases
        
        sporophyte
        
        multicellular diploid
        
        gametophyte
        
        multicellular haploid
    - - 1.2 BYA
        
        500 MYA
        
        Now
        
        290000 living species
        
        small plants, fungi, animals emerged on land
        
        Cyanobacteria appeared
      - Moving onto land
        
        Advantages
        
        More CO2 in air than water
        
        Soil rich in mineral nutrients
        
        bright sunlight, unfiltered by water
        
        Less competition + predators
        
        Disadvantages/Challenges
        
        Scarcity of water
        
        Lack of structural support against gravity
      - Closely related to green algae
        
        classified as embryophytes by textbook
      - Plant Phyla
        
        Non-vascular Plants (Bryophytes) (470MYA)
        
        Mosses
        
        Giant moss
        
        Hornworts
        
        Liverworts
        
        Vascular Plants (have vascular tissue) (425 MYA)
        
        Seedless vascular plants
        
        Lycophytes
        
        spike mosses
        
        quilworts
        
        club mosses
        
        Monilophytes
        
        ferns
        
        horsetails
        
        whisk ferns
        
        Seed Plants (flowering plants) (360 MYA)
        
        Gymnosperms
        
        Angiosperms
    - - Kingdom: Plantae (land plants)
      - Plant characteristics
        
        photosynthetic organisms
        
        that have adapted to life on land
        
        most live in terrestrial habitats
        
        some returned to aquatic habitats e.g. seagrass
        
        eukaryotes
        
        cell walls
        
        photosynthetic autotrophs
        
        source of energy for metabolism = sunlight
        
        fix CO2 to create organic compounds
        
        live in terrestrial habitats (except extreme/harsh environments)
    - - Nonvascular Plants (bryophytes)
        
        Characteristics
        
        primative land plants
        
        simple structure
        
        need abundance of water/moist environments
        
        lack specialised conductive tissues/no conducting system
        
        usually quite small (some big)
        
        3 Phyla
        
        liverworts (phylum Hepatophyta)
        
        9000 species
        
        usually small <2 cm
        
        found in humid envrionments
        
        hornworts (phylum Anthocerophyta)
        
        100 species
        
        most small, grow in humid places
        
        some larger, grow on trees
        
        mosses (phylum Bryophyta)
        
        *note bryophytE= ALL nonvascular, bryophytA = ONLY mosses
        
        15000 species
        
        "carpet" is mostly gametophytes (dominant life stage)
        
        Sporophytes are elongated, visible to the naked eye
        
        Life Cycle
        
        dominant gametophyte (haploid) stage
        
        Spore
        
        gametophyte
        
        1 more item...
        
        (protonema + gametophore, anchored by rhizoid)
        
        1 more item...
        
        Ecological Significance
        
        colonise bare soil and rocks
        
        help retain nitrogen
        
        important role in creating niches for other organisms to live
        
        peat bogs sore a lot of soil carbon (30%) yet only cover 3% of land surface
        
        Higher temperatures causes peat moss to dry and decompose, releasing CO2
        
        small herbaceous (nonwoody) plants
        
        Life Cycle (all 3 phyla)
        
        gametophytes
        
        larger and longer-living than sporophytes
        
        sporophytes typically present only part of time
        
        spore germinates into gametophytes
        
        composed of protonema and gamete-producing gametophore
        
        rhizoids anchor gametophytes to is constrained by lack of vascular tissues
        
        the height of gametophyte is constrained by lack of vascular tissues
        
        mature gametophytes produce flagellated sperm in antheridium and egg in archegonium
        
        sperm swims through film of water to reach and fertilise egg
        
        byophyte sporophyte
        
        grow out of archegonium
        
        smallest simplist sporophyte of all extant plant groups
        
        Consists of
        
        Seta "stalk"
        
        Sporangium "capsule"
        
        Foot
        
        Each sporophyte releases enormous number of spores
        
        1 moss capsule can generate over 5 million spores
      - Vascular Plants
        
        Seedless vascular plants
        
        2 Phyla
        
        Phylum Monilophyta (monilophytes)
        
        e.g.
        
        whisk ferns
        
        horsetails
        
        ferns
        
        2 more items...
        
        most widespread seedless vascular plants (12000 species)
        
        Phylum Lycophyta (lycophytes)
        
        e.g. (although not mosses)
        
        quillworts
        
        club mosses
        
        spike mosses
        
        most are herbaceous (small and not woody) now
        
        In Carboniferous Period (359-299) there were 40m high trees
        
        Ecological Importance
        
        ancestors of lycophytes, horsetails, ferns grew tall in Devonian (419-359 MYA) and Carboniferous (359-299 MYA), forming first forests
        
        increased growth and photosynthesis removed from CO2, may have contributed to global cooling (at end of Carboniferous period)
        
        decaying of these plants have become coal, which is being burnt and contributing to global warming
        
        Life Cycle
        
        still undergo alternation of generation
        
        sporophyte phase greatly reduced
        
        Characteristics
        
        dominant sporophyte phase
        
        transport in specialised vascular tissues
        
        xylem
        
        dead tube-shaped cells "tracheids"
        
        carries water and minerals up from roots
        
        cell wall strengthened by lignin
        
        providing support and enabling greater height
        
        phloem
        
        living cells
        
        distribute sugar, amino acids, organic products
        
        Evolutionary advantage
        
        structural support + ability to carry water and nutrients above ground
        
        allows plants to grow taller
        
        outcompete shorter plants for sunlight
        
        disperse spores further (due to height)
        
        well-developed roots and leaves
        
        Leaves
        
        primary photosynthetic organ of vascular plants
        
        greatly increases SA of vascular plants
        
        can capture more sunlight energy for photosynthesis
        
        Roots
        
        anchors plant (like rhizoids)
        
        absorbs water and nutrients form soil
        
        Seed plants
        
        Evolutionary innovation
        
        gametophytes miniaturisation
        
        dominant sporophyte phase
        
        gametophyte dependent on sporophyte tissue for nutrition
        
        heterospory
        
        produces 2 kinds of spores
        
        megaspore
        
        1 more item...
        
        microspore
        
        1 more item...
        
        Specialised structures to protect gametophyte
        
        megaspore encased in ovule (protective and food layers)
        
        megaspore gives rise to female gametophyte which stays sheltered in ovule
        
        when fertilised, ovule becomes seed
        
        microspore encased in pollen wall
        
        contains sporopollenin (resistant to drying)
        
        called "pollen grain"
        
        microspore gives rise to male gametophyte sheltered in pollen grain
        
        Seeds and pollen grains
        
        diploid sporophyte produces haploid spore (meiosis)
        
        megaspore -> egg (within ovule)
        
        microspore -> sperm (within pollen grain, generally without flagella)
        
        only pollen grain leaves parent plant
        
        pollination
        
        pollen grain reaches and enters pollen tube of ovule
        
        fertilisation
        
        pollen nucleus reaches egg and and fuses -> seed
        
        Internal fertilisation and protection of embryonic sporophyte (seed) distinguishes these plants -> adaptation to dry spells
        
        3 more items...
        
        New sporophyte grows out of the seed
        
        No independent gametophyte organism
        
        1. Unfertilised ovule
        
        2. fertilised ovule
        
        3. gymnosperm seed
        
        Phylogeny
        
        2 sister clades
        
        Gymnosperms
        
        "gymno" = bare, naked "sperm" = seed
        
        seeds exposed
        
        dominant flora in Mesozoic (245-65 MYA)
        
        4 extant phyla
        
        4 more items...
        
        3 key features
        
        3 more items...
        
        Life cycle
        
        1 more item...
        
        Diversity
        
        2 more items...
        
        Angiosperms
        
        "angeion" = vessel, container "sperm" = seed
        
        seeds contained in fruit
        
        dominant flora in Cenozioc (40 MYA) particularly since late Eocene
        
        1 phylum
        
        1 more item...
        
        account for over 99.5% of all "higher plants" (seed plants) species
        
        Key features
        
        5 more items...
        
        Life Cycle
        
        8 more items...
        
        Diversity
        
        2 more items...
        
        Success
        
        4 more items...
        
        Differences
        
        wood structure
        
        different pollen
        
        gymnosperms lack flowers
        
        number of phyla
  - - - reflects evolution
      - draw resources
        
        above ground
        
        CO2, light
        
        below ground
        
        water, minerals
      - 2 systems
        
        root system
        
        below ground
        
        shoot system
        
        above ground
        
        stems + leaves
        
        vascular system distributes all the essential materials
    - - Vascular
        
        components
        
        2 vascular tissues
        
        phloem
        
        transports sugars (products of photosynthesis) from leaves to where needed/stored (e.g. roots, site of growth, developing leaves, fruits etc.
        
        alive cells
        
        pores on sidewalls to connect cytoplasm with neighbouring cells
        
        sieve tube
        
        ends of phloem cells join to other cells
        
        sieve plate
        
        1 more item...
        
        transports sugars by active streaming of cytoplasm
        
        companion cells
        
        control activity
        
        supporting cell
        
        mature cells have no nucleus, associate with these cells
        
        xylem
        
        transports water + dissolved minerals up from roots to shoots
        
        dead (functioning) cell
        
        water conductors (inc. dissolved minerals)
        
        thick mutli-layered cell walls (strengthened with cellulose + lignin)
        
        main cell type
        
        tracheid
        
        1 more item...
        
        vessel elements
        
        2 more items...
        
        functions
        
        carries out long-distance transport of materials between roots and shoots
        
        components that conduct water, minerals, food (roots/shoots)
      - Ground
        
        anything not vascular/dermal
        
        woody part of plant
        
        bulk of plant
        
        functions
        
        filler
        
        storage
        
        photosynthesis
        
        support
        
        short-distance transport
        
        components
        
        3 types of cells
        
        Collenchyma
        
        help support young parts of plant shoot
        
        elongated cells, thicker cell wall, in strands/cylinders
        
        provide flexible support without restricting growth
        
        pliable but strong (cellulose + pectin)
        
        alive, lose strength when dead
        
        Sclerenchyma
        
        support plant
        
        thick cell wall, rich in lignin (extremely rigid like skeleton)
        
        cannot elongate, occur in plants no longer growing
        
        form sheets/strands in stems of plant, scattered amount other cells
        
        many dead, thick cell wall remains as "skeleton" to support the organ (nonedible part)
        
        Parenchyma
        
        provide main soft tissue of stems, leaves, roots, petals
        
        thin walls, massed together, perform several functions
        
        photosynthesis in leaves
        
        store starch in stem/roots
        
        form basic structure for other cells
        
        important for healing (first cells to grow during wound repair)
        
        alive, fresh, cease functioning once dead
      - Dermal
        
        components
        
        epidermis
        
        surface of plant covered in continuous layer of tightly packed cells
        
        stem and leaves
        
        protect against water loss
        
        cuticle
        
        special waxy coating (watertight surface)
        
        roots (water/mineral uptake)
        
        leaves
        
        stomata
        
        increase gas exchange
        
        composed of 2 guard cells
        
        opens to let CO2 in, O2 out, H2O out
        
        close when hot and dry to minimise H2O loss
        
        functions
        
        epidermis is barrier against disease-causing pathogens
        
        enhance water and mineral uptake
        
        prevent water loss
        
        gas exchange
        
        protective covering of plant (outside)
    - - Leaves
        
        components
        
        flattened blade
        
        stalk/petiole
        
        joins lead to node of stem
        
        Types of leaves
        
        complex
        
        divided into leaflets (each may have own stalk)
        
        simple
        
        undivided blade
        
        different
        
        e.g. spines on cacti
        
        veins arrangement
        
        eudicots
        
        branching veins
        
        monocots
        
        parallel veins
        
        functions
        
        main photosynthetic organ of most vascular plants
        
        intercept light (flat)
        
        gas exchange (thin and flat)
        
        dissipate heat by transpiration
        
        leaf droppings
        
        deciduous species
        
        drop leaves all at one time in year
        
        remain leafless for part of year
        
        evergreen species
        
        drop leaves at all times of year
        
        not all at once
        
        variations
        
        spines
        
        e.g. cacti spines
        
        storage leaves
        
        leaves store food
        
        tendrils
        
        forms coil to bring plant closer to supporter
        
        carnivorous leaves
        
        leaves produce exudate to attract and ensnare insects and dissolve insect with enzymes and absorb nutrients through leaf surface
      - Stems
        
        components
        
        plant organ bearing leaves and buds
        
        alternating system of nodes
        
        points at which leaves are attached
        
        internodes
        
        stem segments between nodes
        
        apical bud
        
        shoot tip where where most growth in young shoot occurs
        
        axiliary bud
        
        structure that has potential to form lateral shoot/branch
        
        apical dominance allows maintain dormancy in most axiliary buds
        
        sends chemicals to prevent other buds from growing too quickly
        
        functions
        
        elongate and orient shoot
        
        maximise photosynthesis in leaves
        
        allow growth/height
        
        elevate reproductive structures
        
        maximise dispersal
        
        green stems also perform limited amount of photosynthesis
        
        variations
        
        stolons
        
        horizontal shoots that grow alone surface aka "runners"
        
        tubers
        
        e.g. potatoes, enlarged ends of rhizomes/stolons specialised for food storage
        
        rhizomes
        
        horizontal shoot that grows below surface, vertical shoots emerge from axillary buds
      - Roots
        
        components
        
        most eudicots/gymnosperms
        
        taproot system
        
        taproot
        
        primary root
        
        1st root to emerge from germinating seed
        
        lateral roots
        
        branch roots
        
        arise from taproot
        
        increase SA/absorption
        
        most monocots
        
        fibrous root system
        
        primary root dies early on
        
        adventitious roots
        
        small roots arise from stems or leaves
        
        lateral roots
        
        roots arise from adventitious roots
        
        good for preventing soil erosion
        
        most plants
        
        tips of elongating roots
        
        absorption occurs
        
        many tiny root hairs (increase SA)
        
        mycorrhizal associations
        
        mutualistic relationship with fungi
        
        dramatically increases SA
        
        plant -> sugar, fungi -> nutrients
        
        some plants
        
        specialised roots
        
        prop roots
        
        "strangling" aerial roots
        
        storage roots
        
        buttress roots
        
        pneumatophores
        
        like snorkels for gas exchange
        
        functions
        
        anchors plant
        
        absorbs minerals + water
        
        stores carbohydrates + other reserves