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Course MindMap - Coggle Diagram

- - - - contains the more widespread progymnopserms
      - varied from size of shrub to large tree
      - no actual leaves
    - - Archeopteris: tall trees w/ abundant wood & secondary phloem
        
        stem had siphonostele pith surrounded by primary xylem bundles
      - some organisms had complete webbing, considered megaphylls
      - reproduction heterosporous, seeds not produced
        
        mega/microspores produced in own distinctive sporangium
        
        megaspores released, not retained, from sporangia
    - - earliest known heterospory progymnosperm: Chauleria
        
        from Middle Devonian Period (approx. 390 million yrs ago)
      - in Archaeosperma arnoldii fossil only one megaspore mother cell produced
        
        megasporangium surrounded by integument
        
        integument has large hole (micropyle)
        
        permits sperm cells to swim to egg after megaspore develops into mature megagametophyte
  - - - due to earliest seed ferns having 3-ribbed protostele
    - - (similar to gymnosperms/angiosperms)
      - tracheids longer/wider
      - rays many cells wide&tall
    - - wood was softer/less dense than conifers/progymnosperms
      - (also occurs in cycads & cycadeoids
  - - - all trees of moderate to very large size
        
        all have pollen cones & seed cones #produce cones rather than flowers
        
        pollen cones can be simple cones
        
        single short unbranched axis w/ microsporophylls
        
        microspore mother cell undergoes meiosis & forms microspores
        
        each develop endosporially into small gametophyte w/ 4 cells
        
        1 more item...
        
        seed cones more complex
        
        compound cones consisting of shoot w/ axillary buds
        
        short axis bears leaves called cone bracts, not sporophylls
        
        each bract has axillary bud w/ megasporophylls
        
        modern conifers have microscopic axillary buds
        
        megasporophylls fuse laterally forming ovuliferous scale
        
        inside megasporangium single megaspore mother cell undergoes meiosis
        
        3 of resulting cells degenerate leaving 1 as megaspore
        
        1 more item...
      - never vines, herbs, or annuals
      - never have bulbs/rhizomes
      - leaves always simple needles or scales
        
        leaves of most are perennial
        
        venation simple
        
        1/2 veins running down center of needle-shaped leaves
        
        several parallel veins in scale-shaped leaves
        
        veins have endodermis & tissue (transfusion tissue)
        
        consists of transfusion parenchyma&tracheids
        
        parenchyma cuboidal w/ prominent circular bordered pits
        
        mixed with the tracheids to form complex 3D pattern
        
        facilitates transfer b/t vasc. tissue & mesophyll tissue outside endodermis
      - wood lacks vessels, phloem lacks sieve tubes
      - 2 types of shoots common
        
        long shoots w/ tiny papery leaves
        
        short shoots in axial, produce familiar needle leaf
      - pollen arrives before egg is mature
        
        more than a year can pass between pollination & fertilization
        
        massive pollen tube slowly digests way to toward megagametophyte as egg forms
        
        zygote does not immediately form embryo
        
        first cells elongate as suspensor that pushes other cells deep into megagametophyte
        
        cells pushed deeper develop into embryo (called proembryo)
  - - - trunk covered w/ bark & persistent leaf bases
      - stems similar to seed ferns internally, thick cortex w/ manoxylic wood #had manoxylic wood like seed ferns
        
        tracheids long/wide, rays massive
    - - Macrozamia can get as tall as 18 meters
      - foliage leaves do not bear ovules
        
        seed cones & pollen cones produced instead
        
        pollen cones consist of spirally arranged shield-shaped microsporophylls w/ clusters of microsporangia
        
        on separate plants, always dioecious
    - - thought to be fairly extensive due to range of current species
  - - - however, individual cones of cycadeoids contain both microsporophylls & megasporophylls
        
        each ovule had stalk, megasporangium surrounded by integument
        
        b/t ovules were thick fleshy scales
        
        microsporophylls located below cluster of megasporophylls
  - - - Ginkgo biloba
        
        have both short and long shoots
        
        reproduction dioecious & gymnospermous
      - looks like large dicot tree w/ stout trunk & many branches
      - wood similar to conifers
        
        lacks vessels and axial parenchyma
  - - - Gnetum
        
        30 species
      - Ephedra
        
        40 species
        
        tough shrubs/bushes common in desert regions
        
        leaves reduced/scale like
      - Welwitschia mirabilis
        
        only species
        
        exist only in South Africa or cultivation
        
        have short, wide stem & only 2 leaves
        
        leaves grow perennially from basal meristem, becoming increasingly longer
      - mostly vines/small shrubs w/ broad leaves (similar to dicots)
        
        unusual due to being gymnosperms w/ vessels in wood
        
        pollen cones compound & contain small bracts
        
        seed cones also compact w/ extra layers of tissue around ovules
        
        fossils of organs/tissues too recent to help with evolution of group
    - - would form “Division Anthophyta”
- - - - structure: C10H16N5O14P3
        
        also carries high-energy phosphate bonds
    - - binds two protons when picking up two electrons
        
        hydrophobic due to hydrocarbon fail, can dissolve into lipids of chloroplast membrane
        
        only transports over short distances
    - - contains cofactor, heme, which holds an iron atom
        
        iron carries electrons & cycles between +2 and +3 oxidation states
        
        only transports over short distances
    - - carries electrons on a copper atom
        
        copper reduced to +1 oxidation after picking up electron
  - - - involves light energy in photosynthesis
        
        cannot he preformed by animals/fungi/nonchlorophyllous plants
    - - compounds with high-energy phosphate groups force their phosphate into ADP
        
        can occur in any part of plant anytime
    - - happens in last stages of respiration
        
        occurs in all parts of the plant at all times
  - - - known as oxidizing agents
      - reduced to NADH and NADPH when picking up a pair of electrons and a proton
        
        NADH & NADPH known as reducing agents
  - - - Photosystem I: photosynthetic unit in which chlorophyll b is less abundant
        
        pair of chlorophylls in this system absorb red light of 700nm most effectively, called P700
        
        electron is excited by this energy and is absorbed by membrane-bound electron acceptor Fx
        
        Fx is reduced and passes on electron to ferredoxin (in thylakoid membrane)
        
        then passed to enzyme ferredoxin-NADP+ reductase, where NADP+ is reduced to NADPH, which can move away from membrane
      - Photosystem II: best described as working backwards from Photosystem I
        
        plastocyanin donates electron to chlorophyll a of photosystem I reaction center
        
        plastocyanin receives electron from cytochrome b6/f complex, which receives one from a plastoquinone molecule
        
        plastoquinone receives a electrons from Q, a quinone molecule, which gets them from phaeophytin, a chlorophyll a molecule, which then oxidizes
        
        phaetophytin gains a new electron when a chlorophyll a molecule absorbs light and is activated, named P680
    - - both abundant and can be obtained without expending much energy
      - very stable and contain little chemical energy
      - reactants, and products, of photosynthesis nontoxic
    - - carbon reduced and supplied energy, converts to carbohydrate
  - - - quality: refers to colors/wavelengths it contains
        
        sunset/sunrise blue light is deflected so ground is bathed in red light
        
        underbrush/low growing plants get lower quality light due to it being filtered by the leaves above
      - quantity: refers to light intensity or brightness
        
        more light available on sunny day than cloudy day
        
        lower branches & understory plants receive less light due to being blocked by other branches/plants
      - duration: refers to the number of hours per day sunlight is available
        
        12 hour days at equator, further north or south days are longer in summer. maximum is at the poles with 24 hour days in midsummer
    - - common structure of temperate/tropical plants is palisade parenchyma on top and mesophyll on bottom
        
        good for absorbing carbon dioxide, bad for conserving water
      - in hotter climates the leaf cells are packed together without intracellular spaces, which deters water evaporation
        
        smaller surface area makes dissolving carbon dioxide from air into cytosol difficult; slows photosynthesis
    - - water is crucial to photosynthesis
        
        normally plants leave stomata open during day, but when water is not available stomata will stay closed during the day
    - - improves on RuBP carboxylase working conditions in that is avoids contact between oxygen & RuBP to prevent photorespiration #his process avoids photorespiration efficiently
      - mechanism by which carbon dioxide is absorbed, transported through, and concentrated in a leaf while keeping oxygen away from RuBP carboxylase
      - occurs in leaves with Kranz anatomy, each vascular bundle has a chlorophyllous sheath of cells, and around those are mesophyll cells
        
        mesophyll contains PEP carboxylase, has a high affinity for carbon dioxide, which lowers the ratio of water lost to carbon dioxide absorbed
        
        carbon dioxide concentrations in leaf are kept low, carbon dioxide diffuses inward rapidly when stomata open
    - - stomata only open at night
        
        air is calmer at night so water molecules are not blown away and can be reabsorbed
        
        coolness reduces transpiration
        
        ATP & NADPH cannot be stored during day for use at night due to instability
        
        CO2 stored on acids until daytime when the stomata is closed and acids break down releasing the CO2
        
        RuBP carboxylase protected from photorespiration in morning when internal CO2 levels are high
      - almost identical to C4 metabolism, PEP carboxylated, forming oxaloacetate, which is reduced
  - - - short wavelengths: have relatively large amounts of energy per quantum (cosmic rays, gamma rays, ultraviolet rays)
        
        quanta too powerful for chlorophyll, would knock electrons away from pigment & cause molecule to break apart
      - long wavelengths: have relatively low amounts of energy per quantum (infrared, microwaves, radar, radio waves)
        
        quanta too low in energy to boost electron's energy, just warms the molecule (think microwave)
      - visible light: between 390nm and 760nm
        
        contains just the right amount of energy per quantum, when absorbed by pigment electron goes from ground state to excited state
- - - - scale matters when considering the diversity of an area
      - relationship between area & species richness called species-area relationship
        
        S=cA^z
        
        S: number of species
        
        A: area
        
        c&z: constants that must be discovered by studying individual communities
      - levels of spatial scale
        
        local: small area less than a few square kilometer
        
        region: larger than local, smaller than a continent
        
        biome: large region, characterized by plants/climate
        
        biogeographical region: LARGE region, usually coincides with continent, bordered by geographical barriers (ocean, mountains, etc)
        
        Measuring Diversity:
        
        Alpha diversity: # of species/growth forms in small local site
        
        Beta diversity: compares diff b/t several small sites within larger region
        
        Gamma diversity: # of species in a region #component of species composition
      - species abundance distribution: number of species in area
    - - higher latitude = lower diversity
        
        theories for this include more extreme conditions (freezing temp, lack of rainfall)
  - - - simplest system of pred-prey interactions
      - functional response: feeding rate & handling time
        
        aka how quickly predator finds prey/how quickly predator consumes prey
        
        response is prey-dependent
      - dN/dt=rN-aNP
        
        dN/dt = rate of change w/ time of prey pop
        
        r = intrinsic rate of increase for prey species
        
        N = # of individuals of prey species in community
        
        a = predator’s per capita attack rate
        
        number of prey eaten per prey per predator per unit time
        
        prey-dependent #metapop. consists of many local pops
        
        P = number of predator individuals present
        
        prey pop stays stable when dN/dt = 0
      - net rate of change with time of predator pop
        
        dP/dt=faNP-qP
        
        dP/dt = rate of change with time of predator pop
        
        f = a constant indicating predator’s efficiency at converting eaten prey into new predators
        
        q = predators per capita mortality rate
        
        independent of pop density
        
        prey pop stable when density of predator equals r/a
        
        predator pop stable when density of prey equals q/fa
      - line indicating population stability: zero growth isocline
    - - optimal foraging theory: study of interactions between 3 factors to understand why certain plants get eaten
        
        3 factors
        
        probability that particular prey will be encountered
        
        decision by predator to attack (worth it?)
        
        probability attacked item will be successfully eaten
        
        optimal diet model:
        
        4 predictions
        
        predators should prefer whichever prey yields most energy per unit of handling time
        
        if high-yield prey become scarce, predator should broaden diet
        
        some prey items will always be eaten if encountered, others never eaten even if easy to obtain
        
        probability that a particular plant will be eaten depends partially on abundance of other plants that are easier to handle/higher value
    - - several species often compete for same resources
      - exploitation competition: resource comp. occurs when organisms actually consume a shared resource
      - interference competition: one organism restricts another’s access to resources, even if not using it
      - apparent competition: one plant species increases, predator increases, other plant species does not increase & declines from predation
  - - - primary producers
        
        ex. plants, algae, cyanobacteria
      - primary consumers
        
        herbivores
      - secondary consumers
        
        carnivores
  - - - model makes 4 assumptions
        
        region of environment is composed of many discrete patches in which the species can live
        
        some patches occupied by the species while other suitable ones are not
        
        empty patches colonized by migration from occupied patches
        
        populations within individual patches have probability of going extinct within that patch
      - source habitat: high-quality patch the species can thrive in
      - sink habitat: low-quality patch
      - fugitive species: survives by colonizing new patches, flourishing temporarily, then colonizing another patch before dying out in old patch
- - - - glucose broken down through glycolysis
        
        forms lactate in animal tissues
        
        forms ethanol in plants & fungi
    - - energy “lost” as heat during glycolysis, citric acid cycle, & mitochondrial electron transport
        
        essential to warm-blooded mammals for body temp regulation
    - - glucose broken down through glycolysis
    - - transforms glucose into erythrose and ribose
        
        produces NADPH
    - - fatty acids broken down through beta-oxidation
        
        Products:
        
        acetyl CoA
        
        FADH2
        
        NADH
    - - only occurs when RuBP carboxylase adds oxygen to ribulose-1, 5-bisphosphate
        
        produces glycolate which is transported to peroxisomes
  - - - Increase of 10°C (in range 5°C-25°C) doubles respiration rate
      - Below 5°C respiration decreases greatly
      - Above 30°C respiration increases, but not as quickly
      - Above 40° respiration slows greatly
    - - plants can maintain full respiration with as little as 1% to 2% oxygen
      - if roots are continually flooded/lacking oxygen the plant will eventually die
        
        rice seedlings only example of plants that can grow normally w/o oxygen for prolonged time #this due to anaerobic resp.
    - - fruit maturation: respiration rate is steady until just before fruit matures, burst of respiration is them triggered by endogenous hormones
      - seed maturation: respiration deceases majorly following maturity, enters dormant period
        
        in truly dormant seeds virtually no respiration occurs
  - - - Beer:
        
        made by fermenting cereal grains (ie corn, barely, rice, wheat)
        
        grain fermentation:
        
        grain is moistened to encourage germination
        
        embryo secretes enzymes to breakdown starches
        
        the grains are then dried to prevent further germination, product is known as “malt”
        
        1 more item...
      - Wine:
        
        made by fermenting fruit juices
        
        fruit fermentation (grapes):
        
        grapes are harvested, washed, and crushed
        
        S. cerevisiae is added & mixture is cooled #both add *S. cerevisiae
        
        mixture is fermented as long as sugar is present & ethanol levels don't exceed 18-20%
        
        global climate change has devastating affects on wine production due to the highly specialized growing conditions
      - Spirits:
        
        contains 20%+ ethanol
        
        Distillation:
        
        solution is heated between 78°C and 100°C
        
        ethanol evaporates due to lower boiling temperature, vapor captured in tubes and cooled to condense
        
        ethanol is added to increase alcohol content
- - - - must be extended each year
    - - mature parenchyma cells come out of cell cycle arrest, resume mitosis
      - connects fascicular cambia
    - - cells b/t metaxylem & metaphloem never undergo cell arrest
    - - fusiform initials: long, tapered cells
        
        two elongate cells produced when longitudinal division occurs w/ periclinal wall
        
        one stays as fusiform initial, one differentiates
        
        if outer cell remains cambium, inner develops into secondary xylem
        
        xylem cells increase greatly in diameter pushing cambial cells outward
        
        if inner cell remains cambium, outer develops into secondary phloem
        
        periclinal wall: wall parallel to circumference of cambium
        
        have thin primary walls & proplastids
      - ray initials: short, slightly cuboidal
        
        also periclinal division
        
        one remains cambial cell, the other differentiates
        
        inner cell: xylem parenchyma
        
        outer cell: phloem parenchyma
        
        mostly produce storage parenchyma & albuminous cells
    - - Fusiform:
        
        can occur in storied rows, or unstoried rows
        
        storied cambium: regular horizontal arrangement
        
        unstoried cambium: irregular, no horizontal pattern
      - Ray: #2 types, upright & procumbant
        
        usually grouped in short vertical rows uniserate, biseriate, or multiseriate
        
        uniseriate: one cell wide
        
        biseriate: two cells wide
        
        multiseriate: multiple cells wide
  - - - all cells interior to vascular cambium develop into secondary xylem
        
        contain all cell types in primary xylem, no new
        
        arrangment and origin differs from primary
        
        axial system: derived from fusiform initials
        
        always contains tracheary elements
        
        hardwood: contain large amounts of fibers in axial system
        
        term now used to describe all basal angiosperms & eudicots
        
        softwood: all conifers, despite actual hardness
        
        contains fibers for strength & flexibility
        
        some immature tracheary elements & fibers undergo transverse division
        
        differentiate into columns of xylem parenchyma
        
        aka axial xylem parenchyma
        
        1 more item...
        
        radial system: develops from ray initials
        
        contain only parenchyma in uniseriate, biseriate, or multiseriate masses called rays
        
        ray parenchyma:
        
        store carbohydrates & other nutrients during dormant periods
        
        conduct material over short distances radially w/in wood
        
        2 types of cells
        
        2 more items...
        
        in conifers
        
        2 more items...
        
        Growth Rings
        
        early wood: first wood formed when quiescence ceases
        
        must have high proportion of wide vessels
        
        in conifers, wide tracheids
        
        late wood: wood produced later in season
        
        lower proportion of vessels, stronger w/ number fibers
        
        in conifers, narrow, thick-walled trachieds
        
        Heartwood: dark dry wood at center of log #heartwood/sapwood in root wood/shoot wood
        
        made of broken vessels & trachieds
        
        tylosis: plug of protoplasm pushed by adjacent parenchyma cells into vessels
        
        Sapwood: lighter moist wood at outer region of log, becomes heartwood
        
        Reaction Wood
        
        produced in branches in response to stress
        
        in angiosperms, occurs mostly on upper side of branch (known as tension wood)
        
        tension wood: contains gelatinous fibers w/ walls rich in cellulose
        
        exert tension on branch to prevent drooping
        
        in conifers, occurs on underside of branch (known as compression wood)
        
        enriched in lignin, less cellulose
      - aka wood
    - - axial system: responsible for conduction up & down stem or root #woody plants use similar conducting, except with secondary xylem/phloem
        
        contains sieve tube members & companion cells in angiosperms
        
        contains sieve cells in conifers
  - - - storage parenchyma become reactivated & undergo cell division creating cork cambium #similar to activation of parenchyma cells during formation of interfasicular cambium
        
        cork cambium: cells are cuboidal, inner cell always stays cambium, outer always differentiates into cork cell
        
        in some species, c. cambium creates layer of parenchyma cells on inside
        
        all together compose the periderm
        
        provides temporary protection due to continuous interior growth stretching it circumferentially
        
        aka phelloderm
        
        aka phellem cell
        
        outer bark: all tissue outside innermost cork cambium
        
        inner bark: all secondary phloem b/t vasc. cambium & innermost cork cambium
      - aka phellogen
    - - timing of initiation varies by species
      - origin in epidermal cells: first outer bark contains only periderm & cuticle, very smooth
      - origin in cortex: first outer bark contains periderm, cortex, & epidermis, also smooth
      - origin in phloem: later bark, contains only cork and phloem
  - - - growth of alternative types of cambium structure/activity
        
        sweet potatoes:
        
        storage parenchyma increased dramatically
        
        numerous vasc. cambium arise not around entire primary xylem but around vessels/vessel groups
        
        cambia after normally, except xylem/phloem produced almost purely parenchyma
        
        new vessels surrounded by new cambium
        
        some eudicots produce included phloem
        
        common vasc. cambium produces ordinary secondary xylem & phloem then differentiates into xylem
        
        outermost secondary phloem reactivated & become new vasc. cambium, produces secondary phloem b/t two bands of xylem
    - - palm trees: #vasc. bundles contain xylem #vasc. bundles also contain phloem
        
        trunk all primary tissue w/ vasc. bundles disturbed through ground tissue
        
        bundle contains only primary xylem & phloem
        
        vasc. cambium never develops
        
        establishment growth: increase in width & addition of adventitious roots
- - - - one strand of double helix cut, two strands separate
        
        free nucleotides diffuse to regions of single-stranded DNA & pair with base
        
        ribonucleotides polymerized into short pieces of primer RNA
        
        act as substrates for DNA polymerase
        
        enters and adds depxyribo
        
        aprox. 10 nucleotides long
      - form “bubble” called replicon
  - - - single base converted to another
    - - mutagen: something that causes mutations
        
        includes certain chemicals, ultraviolet light, x-rays, & radiation
      - deletions: can be caused by one strand of DNA w/ self-complimentary sequence forms small loop
        
        DNA polymerase passes by loop w/o reading the bases in it
      - insertions: piece of foreign DNA present after cutting may be accidentally incorporated
        
        transposable elements: pieces of DNA that readily change positions from chromosome to chromosome
        
        2 basic forms
        
        insertion sequences: contain genes that code for enzymes involved cutting insertion sequence out & splicing it elsewhere
        
        only few thousand base pairs long
        
        transposon: carries genes that code for proteins not in transposition
        
        similar to insertion seq. except may be longer
    - - effects & significance depends on nature, position, & extent
      - changes to introns: unimportant generally, will not be incorporated into final mRNA
      - changes to exons: unimportant if changed codon is similar to previous, or located in noncritical location
      - the larger the mutation, the higher chance that a critical part of DNA is affected
    - - not very important, affect small area & not passed to offspring
    - - cannot be too efficient or too inefficient
        
        too efficient: all cells of individual would be completely identical, making sexual reproduction useless
        
        too inefficient: cells become not functional due to lack of repair
  - - - offspring of cross resembles each parent somewhat
    - - plant’s own pollen used to fertilize it’s own eggs
        
        can also be selfed by being crossed w/ another plant w/ same genotype
      - called selfing
    - - F1: offspring of cross, first filial generation
        
        F2: offspring of F1 generation
    - - all types of one gamete arranged on top, all types of the other gamete arranged on the left side #punnett can be used on dihybrid cross as well
    - - cross involving plant in question & homozygous recessive for the trait
  - - - maternal inheritance: zygote obtains all plastid & mitochondrial genomes from maternal parent
      - aka uniparental inheritance
    - - genetically inherited lethals most often recessive, must be homozygous to affect plant #homozygous means it has 2 of same alleles
  - - - if the 2 genes are on separate chromosomes, the alleles of one move independently of the other
    - - 9/16 of plants dominant for both traits
      - 3/16 of plants dominant first trait recessive second
      - 3/16 of plants recessive first trait dominant second
      - 1/16 of plants recessive for both
    - - exchange of genetic mat. by nonsister chromatids of homologous chromosomes
        
        recombinant chromosomes: formed from crossing-over of homologous chromosomes & recombination alleles
      - rate of crossing-over directly proportional to physical space b/t genes on chromosome
    - - when two genes occur close together on a chromosome, considered linked
      - most prominent exception to Mendel’s Law of Independent Assortment
- - - - have multicellular sporangia & gametangia
      - 3 types
        
        moss
        
        liverworts
        
        hornworts
  - - - they also differ in significant ways
  - - - Morphology:
        
        gametophytes: leafy stems of moss plants
        
        all moss stems have leaves, but not homologous with vasc. plant leaves
        
        grow from apical meristem w/ prominent apical cell
        
        leaves of almost all only one cell thick, except midrib/along margin
        
        cuticle occurs only on upper surface of most moss leaves
        
        underside uncutinized & capable of absorbing water directly
        
        stems always slender w/ little tissue differentiation
        
        surface layer only slightly different from underlying layers
        
        not called epidermis
        
        stem tissue maybe be uniform in all parts
        
        (called cortex)
        
        outer cells may be slightly narrower w/ thicker walls
        
        inner cells larger, more parenchyma, chlorophyllous
        
        in some types they grow close together & form mounds
        
        in cool/wet areas plants are more open & loose
      - Water Transport:
        
        hydroids: innermost cortex in some mosses
        
        conduct water & dissolved minerals
        
        elongated cells that lose cytoplasm when mature
        
        end walls partially digested
        
        leptoids: cells that resemble sieve cells
        
        elongated, prominent interconnections w/ adjacent cells
        
        lack nuclei at maturity, retain cytoplasm
        
        majority of mosses lack hydroids & leptoids
        
        water conducted along exterior of stems by capillary action
        
        leaves & stems so small they form spaces narrow enough to be capillary channels
        
        rhizoids: small multicellular trichome-like structures at base of stem
        
        only anchor stem, do not absorb water or minerals
        
        lack chloroplasts
      - Development
        
        growth of gametophyte begins when spore germinates/sends out long, slender chlorophyllous cell
        
        cell undergoes mitosis & produces branched system of similar cells
        
        entire network is a protonema
        
        superficially resembles filamentous green alga
        
        perennial & can grow extensively
      - Reproduction
        
        gametophore at some point produced gametangia
        
        all mosses oogamous
        
        every species has small biflagellate sperm cells & large nonmotile egg cells
        
        sperm cells produced in micorgametangia called antheridia
        
        consist of short stalk, outermost layer of sterile cell, inner mass of cells
        
        when sperm cells mature, antheridium breaks open liberating sperm
        
        1 more item...
        
        eggs occur in megagametangia called archegonia
        
        egg shaped like vase w/ long neck
        
        1 more item...
        
        antheridia & archegonia occur in same gametophore in bisexual species
        
        others have both male & female gametophores
    - - zygote undergoes transverse division
        
        basal cell located at bottom of archegonium develops into small bulbous tissue
        
        (called the foot)
        
        interface w/ gametophore
        
        absorbs sugars, minerals, and water
        
        cells are transfer cells in many species
        
        upper cell grows by cell division & expansion into simple apical sporangium
        
        (called the capsule)
        
        consists of outer layer of sterile cells & inner column of sterile cells
        
        called columella
        
        ring of these cells undergoes meiosis & produces haploid spores
        
        between food & sporangium is narrow stalk
        
        (called the seta)
        
        all moss sporophytes have this simple structures
        
        none ever branched, nor has leave/bracts/buds
      - has true epidermis w/ stomata on base (at least) of sporangium
      - apex of sporangium differentiates into lid, operculum
        
        separates from rest of sporangium as cells are torn apart
        
        develops 2 rows of peristome teeth
        
        teeth respond to humidity
        
        bend outward to open when air dry
        
        bend inward to trap spores when air humid
      - spores released when light, dry, nonsticky, & easily carried by air
      - apex also often covered by calyptra
        
        layer of cells derived from neck of archegonium
  - - - 2 basic groups
        
        leafy liverworts
        
        gametophore greatly resembles moss’s
        
        leaves differ w/ two rounded lobe leaves
        
        no midrib
        
        no conducting tissue
        
        may bear gametangia either mixed w/ regular leaves or positioned on side branches
        
        thallose liverworts
        
        less resemblance to moss
        
        not leafy, flat/ribbon like/or heart shaped
        
        body referred to as ”thallus”
        
        antheridia & archegonia may be grouped & surrounded by tube of chlorophyllous cells
        
        both groups gametophyte phase initiated when spores germinate
        
        establish small temporary protonematal phase
        
        protonemata never as extensive/ratified/long lived as mosses
        
        gametophores may be either bisexual or unisexual
    - - little variability
      - basic morphology like that of mosses
      - sporoganium lacks a columella
        
        some cells differentiate into elaters
        
        single, elongate cells w/ spring-shaped walls
        
        elaters uncoil when sporangium opens & pushes spores out
  - - - always thin, especially along edges
        
        center becomes 4-5 cells thick
        
        upper surface in many smooth, some thin
        
        gametophyte is parenchymatous
        
        does not tolerate drying
      - internally have numerous chambers
        
        young plants mucilage chambers formed as cells break down & contents altered into mucilage
        
        become invaded by cyanobacteria
      - antheridia initials not surface cells
        
        special mucilage chamber forms near upper surface
        
        cells lining chamber grow into it becoming antheridia
      - archegonia formed from superficial cells, do not completely surround egg
        
        egg lies below short neck & canal surrounded by vegetative thallus cells
        
        zygote divides longitudinally, not transversely
    - - not similar to mosses or liverworts
      - have foot embedded in gametophyte tissue, no seta/discrete sporangium
        
        above foot meristem continuously produces new sporangium tissue
        
        sporangium long, horn-like cylinder
        
        have columella #have columella like moss
- - - - in many cacti branches are poorly attached to trunk, encouraging fragmentation
        
        large spreading/vining plant’s individual parts become self-sufficient by establishing adventitious roots
        
        if middle portions of plant die ends separate & act as individuals
      - in some saxifrage/grass/pineapples plantlets formed where flowers would be expected
      - in willows/thistles adventitious shoot buds form roots & then grow into plants
        
        may occur while parent plant is still alive, small cluster of trees might be one individual
        
        look like small bulbs, called bulbils
  - - - all plants (trees,shrubs,herbs) in sporophyte phase
        
        always diploid
        
        have organs with cells capable of meiosis
        
        results in haploid spores
        
        cannot undergo syngamy
        
        each undergoes mitosis & grows into entire new haploid plant (gametophyte)
        
        gametes are formed by haploid plants by mitosis
        
        gametes undergo syngamy to form zygote, creates new diploid sporophyte
        
        many plants oogamous
        
        have “male” microgametophytes
        
        form microspores
        
        have “female” megagametophytes
        
        form megaspores
        
        known as heterospory
        
        sperm produced by one type of individual, egg produced by another
      - aka sporophyte generation
      - when life cycle has 2 generations said to be alternation of generations
        
        gametophytes & sporophytes not similar, alternation of heteromorphic generations
    - - pedicel: flower stalk
      - receptacle: end of axis, where flower parts attach
      - 4 types of floral appendages
        
        most flowers have all types, complete flowers
        
        some do not, incomplete flowers
        
        sepal
        
        lowermost & outermost of floral appendages
        
        modified leaves surround & enclose other flower parts as they mature
        
        typically thickest/toughest/waxiest of flower parts
        
        protect flower bud as it develops
        
        all sepals together referred to as calyx
        
        petals
        
        found on receptacle, make up the corolla
        
        sepals & petals together make up perianth
        
        leaf-like, broad/flat/thin
        
        but, contain pigments other than chlorophyll
        
        have few/no fibers
        
        tend to be thinner & more delicate
        
        stamens #essential organ
        
        located above the petals
        
        known collectively as androecium
        
        often referred to as “male” part of flower due to pollen production
        
        technically untrue bc flower is part of sporophyte & only does not have a sex
        
        2 parts
        
        filament: stalk
        
        anther: where pollen is actually produced
        
        composed of diploid cells
        
        4 long columns of tissue become distinct as they prepare for meiosis
        
        called microspore mother cells or microsporocytes
        
        continue to enlarge & undergo meiosis each producing 4 microspores
        
        1 more item...
        
        neighboring tapetum cells act as nurse cells
      - carpels: constitute gynoecium located @ highest level on receptacle #essential organ
        
        3 main parts
        
        stigma: catches pollen grauns
        
        style:elevates stigma
        
        ovary: megaspores produced here
        
        contained placentae which bear ovules
        
        ovule has central mass of parenchyma called nucellus
    - - microgametophytes develop from microspores
        
        microspore nucleus divides mitotically producing large vegetative cell & small generative cell
        
        generative cell divides to form two sperm cells
        
        microgametophyte consists of vegetative cell & sperm cells (microgametes)
        
        walls form around nuclei & megaspore becomes megagametophyte with 7 cells, one binucleate
        
        7 cells
        
        3 more items...
      - as pollen lands on stigma it produces pollen tube to penetrate stigma
        
        grows downward & is nourished/protected by style tissue
        
        sperm cells carried to ovule by tube
      - megagametophytes develop from megaspore
        
        multinucleate megagametophyte known as embryo sac
        
        nuclei migrate thru cytoplasm pulled by microtubules until 3 lie at each end & 2 in the center
    - - involves 2 processes
        
        plasmogamy: fusion of protoplasts of gametes
        
        karyogamy: fusion of nuclei
      - pollen tube grows downward thru style towards ovule, guided to micropyle
        
        penetrates nucellus & reaches egg apparatus, enters one synergid
        
        pollen tube tip bursts releasing 2 sperm cells
        
        1 sperm migrates thru synergid protoplasm towards egg
        
        sperm cell’s plasma membrane breaks down & loses most of protoplasm
        
        sperm nucleus enters egg, fuses with egg nucleus creating diploid zygote nucleus
        
        in angiosperms only, 2nd sperm nucleus migrated to central cell to undergo karyogamy w/ both polar nuclei
        
        establishes large endosperm nucleus (triploid)
        
        known as double fertilization
    - - zygote begins to divide by nuclear & cellular division
        
        grows into small cluster of cells, part becoming embryo the other becoming suspensor
        
        cells at one end of suspensor divide mitotically developing into embryo
        
        first arranged as small sphere, known as globular stage
        
        in torpedo stage embryo is elongate cylinder
        
        short axis is established
        
        1 more item...
        
        mature embryo becomes quiescent & partially dehydrates
        
        funiculus may break leaving hilum scar
        
        other end intimated 2 primordia that grow into 2 cotyledons in basal angiosperms & eudicots
        
        give embryo a heart shape, called heart stage
        
        dicots only 1 cotyledon primordia grows out
        
        short stalk-like structure, pushes embryo deep into endosperm
      - co-enocytic stage never occurs in embryo
      - in monocots:
        
        during germination cotyledon acts as digestive/absorptive tissue
        
        albuminous seed
      - in (most) eudicots:
        
        cotyledons store nutrients used during & after germination
        
        exalbuminous seed
    - - ovary matures into fruit
        
        3 layers distinct during growth
        
        exocarp
        
        outer layer (skin/peel)
        
        mesocarp
        
        middle layer (flesh)
        
        endocarp
        
        innermost layer (pit/stone)
        
        entire fruit wall: pericarp #called pericarp regardless of origin of tissue
      - stigma, style, sepals, petals, & stamens wither away
  - - - pollination of carpal by pollen from different individual
        
        creates new combinations of genes
      - self-pollination: pollination if carpal by pollen from same plant #form of asexual reproduction
        
        same as asexual reproduction
        
        allows plant to propagate genes rather than lose them
    - - anthers release pollen while stigma tissues still immature
        
        anther at top of flower while stigma near base
        
        when stigma & style mature may be no living pollen left
    - - self-pollination inhibited by compatibility barrier
        
        one system as pollen tube grows stigma&style test proteins on tube’s surface
        
        if protein produced by incompatible gene then stigma/style block growth
      - chemical reaction between pollen & carpels to prevent pollen growth
    - - flowers lacking either/both stamens/carpels known as imperfect flowers
      - stamen/carpels essential organ
      - known as perfect flower if it has both
      - sepals/petals considered nonessential organs
      - dioecy: species with separate staminate/carpellate individuals
      - monoecy: species with individuals having both staminate/carpellate
    - - changed the pollination game
        
        many plants/pollinators underwent coevolution
      - plants became more distinct to ensure pollinators deposited pollen on correct species
        
        actinomorphic: radially symmetrical flowers
        
        zygomorphic: bilaterally symmetrical flowers
    - - sepals often reduced/absent
        
        zygomorphy provides no advantage
      - huge number of pollen needed to increase chances of success
    - - flower must protect ovules/ovary from pollinators
      - long styles/filaments adaptation to separate
      - inferior ovary: ovary located below organs protected by thick layer of tissue
        
        epigynous flower parts
      - superior ovary: ovary obviously other flower parts, no fusion
        
        hypogynous flower parts
      - half-inferior ovary: partially buried ovary
        
        perigynous flower parts
  - - - helps small flowers be seen
      - plant able to accurately control timing of initiation/maturation/opening of flowers
      - produces enough nectar to get pollinators to visit other plant
      - 2 basic arrangements:
        
        determinate inflorescence: only has limited potential for growth bc apex is converted to flower
        
        usually terminal flower opens first, then lower ones successively
        
        indeterminate inflorescence: lowest open first, new flowers still being insisted at apex
  - - - pericarp tissues of fruit regardless of origin
      - true fruit: fruits containing only ovarian tissue
      - accessory fruit: fruit w/ any nonovarian tissue present
        
        also called false fruit, apples mainly composed of sepals&petals
      - simple fruit: developed from single ovary/fused ovary if one flower
      - aggregate fruit: separate carpels of one gynoecium fuse during development
      - multiple fruit: in development all individual fruits of inflorescence fuse into one
    - - dry: not one typically eaten by natural seed-distributing animals
      - fleshy: usually eaten during natural seed distribution process
        
        most fleshy fruits indehiscent
      - dehiscent fruits: break open & release seeds
      - indehiscent fruits: do not break open & release seeds
      - fruits/seeds carried by wind must be light
        
        often have wings or parachutes
- - - - aquaporins: special channels that aid water movement in & out of cells
    - - freely permeable: allow all solutes to diffuse through
      - completely impermeable: do not allow anything to pass through
        
        occur as isolation barriers
      - selectively permeable: allow only certain substances to pass through
        
        all lipid/protein cell membranes are this
    - - ex. proton pumping in photosynthesis & respiration
      - cell membrane always impermeable to molecule being transported
  - - - molecule secreted & probably absorbed by neighboring cell
        
        if molecule secreted by active transport, origin cell probably impermeable to it in that area #impermeable because active transport pumps against concentration gradient
      - contact faces between two cells so extensive the probability is greater molecule will diffuse into next cell or re-enter origin cell
    - - in glands, apoplast mostly intercellular space
      - in nonglandular areas, apoplast mostly cell wall
    - - opening:
        
        K+ actively transported into guard cells by surround cells
        
        K+ cannot leave due to impermeable plasma membrane
        
        K+ pumping possible, taken from surround cells
        
        water potential in guard cells becomes more negative
        
        thrown out of hydraulic equilibrium
        
        water diffuses out of surround cells into guard cells
        
        1 more item...
        
        water potential in adj. cells becomes less negative
      - closing: reverse of opening, K+ pumped out of guard cell & water follows
      - in equilibrium when stomata fully open or fully closed
  - - - pressure flow hypothesis: membrane-bound molecular pumps & active transport thought to be important
      - sources: where water & nutrients are transported from
        
        spring & summer: leaves dominant source
        
        early spring: storage sites; tubers, corms, wood & bark parenchyma, fleshy taproots
        
        some species sugars actively transported into sieve elements
        
        other species, phloem loaded by polymer trap mechanism
        
        conducting cell membrane permeable to mono/disaccharides, not polysaccharides
        
        simple sugars diffuse into conducting cells & polymerized into polysaccharides
        
        sugar accumulated in cell & osmotic/water potential becomes more negative
        
        hydraulic disequilibrium b/t sieve elements & surrounding cells
        
        water diffuses into sieve elements
        
        2 more items...
        
        massive loading causes pressure to build quickly, large volume of material flows from source
        
        pressure can be as high as 2.4 MPa
        (human blood pressure about 0.016 MPa) #megapascals unit pressure is measured in
      - mass transfer: amount of transported materials by phloem per hour
      - sinks: sites that receive transported phloem sap
    - - cohesion-tension hypothesis: leaf cell water potential becomes negative, drawing water from tracheids
        
        water in upper tracheary elements must lift weight of entire water column
        
        for every 10 meters of height leaf water potential must be at least 0.1 MPa more negative than root water potential
        
        due to tension on these molecules pressure potential is negative
        
        as water moves into leaf mesophyll xylem water potential becomes more negative
        
        upper treachery ele, become negative & draw water up from xylem
        
        xylem draw water from root cortex, root cortex from root epidermis
        
        water potential of root epidermis & root hairs more negative than soil, water moves into root
      - transcuticular transportation: water lost directly through cuticle
      - transstomatal transpiration: water lost through flexed guard cells opening stomatal pore #dependent on guard cell activity
        
        this water loss influences water movement through xylem
      - water molecules adj. to cell walls tend to remain fixed to walls & create friction
        
        to overcome friction & gravity leaf water potential must be 0.2 MPa more negative than root water potential for every 10 meters
  - - - heating it
      - putting it under pressure
      - elevate it
    - - cooling it
      - reducing pressure
      - lowering elevation
    - - ψπ + ψp + ψm = ψ
        
        ψπ: osmotic potential, effect that solutes have on water potential
        
        pure water osmotic potential is 0.0 MPa
        
        always negative
        
        ψp: pressure potential, effect that pressure has on water potential
        
        water under pressure, pressure & water potential increase
        
        ψm: matric potential, water’s adhesion to nondissolved substances
        
        always negative
        
        less important in living cells
        
        usual equation for living cells ψπ + ψp = ψ
- - - - only have thin primary cell wall
        
        most common cell type
      - Parenchyma Tissue:
        
        mass of parenchyma cells
        
        most common tissue type
      - Subtypes:
        
        Chlorenchyma Cells
        
        involved in photosynthesis, contain numerous chloroplasts
        
        Glandular Cells
        
        secrete nectars, oils, fragrances, mucilage & resin
        
        contain large amounts of twosomes & endoplasmic reticulum
        
        transport sugar & minerals into the cell, changes them metabolically, then sends back out
        
        Transfer Cells
        
        mediate short distance transport of materials by plasma membrane
    - - have primary wall & elastic secondary wall
        
        walls can be deformed but will return to original size & shape when released
      - develop from parenchyma cells in mature organs after achieving proper size & shape
      - Two Cell Subtypes:
        
        Conducting
        
        transports water
        
        type of vascular cell #schlerenchyma cells
        
        Mechanical
        
        Fibers
        
        long & flexible
        
        Sclereids
        
        short & cuboidal
        
        form hard, impenetrable surface (nut shells/peach pits)
        
        usually dead at maturity
    - - has primary cell wall, thin in someplace thick in others (usually corners)
        
        plasticity of these cells essential to growth of certain plant species
        
        turgid parenchyma & this cell type provide pressurized support to hold shoots up
        
        requires more glucose to produce due to thick walls
  - - - node: present where leaves are attached
      - internode: regions between nodes
      - axillary bud: within the leaf axil; miniature shoot with dormant apical & young leaves
        
        leaf axil: stem area just above the point a leaf attaches
        
        bud scales: covers the bud with small, corky, waxy modified leaves
        
        terminal bud: terminal end of each stem
      - phyllotaxy: arrangement of leaves on a stem
        
        one leaf per node: alternate phyllotaxy
        
        two leaves per node: opposite phyllotaxy
        
        three or more per node: whorled phyllotaxy
        
        leaves arranged in only two rows: distichous phyllotaxy
        
        leaves arranged in four rows: decussate phyllotaxy
        
        leaf located slightly to the side of leaves above & below: spiral phyllotaxy (most common)
      - rhizomes: fleshy horizontal stems that can spread underground (ex: bamboo)
        
        tubers: also horizontal, only grow for short time (ex: potatoes)
        
        bulb: short shoots with thick fleshy leaves (ex: garlic)
        
        corm: vertical thick stems with thin papery leaves (ex: crocus)
  - - - subapical meristem: just below apical meristem, visible differentiation begins
      - protoxylem, first xylem, found here
        
        cells exterior to these known as metaxylem, largest tracheary elements
    - - much smaller than metaxylem
    - - provascular tissues: young xylem/phloem cells
        
        ground meristem: early stages of pith & cortex development
  - - - consists of living parenchyma cells
      - cortex: interior to epidermis, can be simple or complex
        
        in fleshy stems cortex parenchyma is aerenchyma
        
        aerenchyma: open tissue with large interior cellular air spaces
    - - function: block some incoming sunlight, makes landing/walking on difficult
        
        forms the cuticle, makes wall impermeable to water
    - - guard cells absorb water & become curved, opening the stomatal pore
        
        carbon dioxide enters, oxygen exits
    - - Two Types:
        
        xylem #first xylem called protoxylem
        
        conducts water & minerals #bstem cell water potential lowers drawing water in, cohesion tension theory
        
        two types of conducting cells: tracheids & vessel elements
        
        both known as tracheary element
        
        tracheids obtain water from other tracheids below them
        
        vessel elements lack end walls, instead moving water through perforations
        
        phloem
        
        distributes sugars & minerals
        
        two types of conducting cells: sieve cells & sieve tube members (generally lack nuclei)
        
        sieve cell: elongated, spindle shaped cell with sieve areas all over surface
        
        controlled by albuminous cells
        
        sieve tube members: sieve areas on the two ends of cell large with wide pores
        
        controlled by companion cells
    - - primary xylem & primary phloem occurring together, arranged in ring surround pith
- - - - leaf traces: one/three/five or more vasc. bundles
      - usually contains large amounts of collenchyma
      - stalk that joins leaf to stem
    - - ground tissues interior to leaf epidermis
        
        spongy mesophyll: in lower portion of leaf, loosely arranged cells in leaf
        
        palisade parenchyma: upper layer of cells, main photosynthetic tissue
        
        separated slightly to increase surface area for CO2 dissolution #modified mesophyll layer in succulents essential for water retention
    - - mid-rib: aka midvein, eudicot usually has one, usually involved in conduction #how midrib is formed
        
        lateral veins: usually involved in conduction, emerge from midvein
        
        minor veins: branch from lateral veins, important for releasing water & loading sugar
        
        contain primary xylem on upper side & primary phloem on bottom
      - found between palisade parenchyma & spongy mesophyll
      - bundle sheath: fibers arranged around vasc. tissue, usually midvein & lateral veins #bundle sheath made of fibers
      - contain primary xylem on upper side & primary phloem on bottom
    - - transpiration: water loss through the epidermis
      - single layer of cells that covers leaves (upper & lower)
  - - - leaf primordium: cells interior to protoderm grow outward, forms protrusion
        
        extends upward as narrow cone, grows rapidly
        
        cells in center differentiate into provascular tissue, then primary xylem/phloem
        
        leaf primordium grows & increases in thickness, establishing most of midrib
        
        petiole becomes distinct from midrib
        
        stomata, trichomes, & vascular bundles differentiate
        
        cells continue to divide & expand, enlarging lamina rapidly
        
        consists of leaf protoderm & leaf ground meristem
    - - leaf primordium: cells interior to protoderm grow outward, forms protrusion
        
        apical meristem cells adjacent to primordium grow upward, giving hood-like shape
        
        more cells become involved until primordium is a cylinder that completely/almost encircles shoot apical meristem
        
        shoot apex enlarges, forms new stem tissue, initiates next leaf primordium
        
        protoxylem & protophloem constantly stretched & disturbed in basal meristem
        
        will develop as tube inside previous leaf’s sheathing base
        
        outer surface: abaxial epidermis
        
        inner surface: adaxial epidermis
  - - - has many small blades (leaflets)
        
        attached by petiolule to the rachis
      - pinnately compound: leaflets attached individually along rachis
      - palmately compound: all leaflets attached at same point
    - - flat, light-harvesting portion of leaf
      - dorsal surface: lower side of leaf blade
        
        aka abaxial epidermis
      - ventral surface: upper side of leaf blade
        
        aka adaxial epidermis #inner/outer rather than upper/lower
      - aka lamina
    - - holds blade into light
    - - parallel venation: larger veins run side by side with few obvious interconnections
      - reticulate venation: veins occur in netted pattern (in angiosperms & eudicots)
    - - usually found in petiole, cells cut off leaf when useful life is over
        
        leaf scar: cells surrounding petiole base swell/become corky to protect wound
  - - - leaves are harder than normal with sclerenchyma often present just below epidermis
        
        leaves known as sclerophylls
        
        cuticle usually very thick
      - Conifer Leaves:
        
        leaves are sclerophylls; thick cuticle, epidermis & hypoepidermis have thick cell walls
        
        mostly perennial
        
        most contain bitter chemicals to discourage predation
    - - small, form a tight layer around stem tip
      - protects dormant shoot apical meristem from low temps & drying wind
      - often forms corky layer for better protection
    - - thick/fleshy leaves that reduces surface-to-volume ratio
        
        inside, mesophyll contains few air pockets, reducing internal evaporative surface area
        
        mesophyll is more transparent, thus light can penetrate further into leaf
      - good for water retention, but reduced capacity for CO2 uptake
    - - modified leaves of axillary buds for protection
    - - modified leaf, grows indefinitely
      - capable of sensing contact with an object
        
        use sense of touch to coil around objects for support
    - - evolved in plants growing in habitats lacking nitrates/ammonia
        
        allow plants to obtain nitrogen for amino acids & nucleotides
      - Two Types:
        
        active traps: capable of movement during capture
        
        Dionaea muscipula leaves held open by turgid pressure
        
        when two trigger hairs are stimulated midrib motor cells lose water rapidly
        
        two halves of lamina close, trapping the insect
        
        glands then secrete digestive fluids
        
        passive traps: incapable of movement
        
        Nepenthes lamina is tubular, secretes watery digestive fluid
        
        epidermis in digestive region absorptive, not impermeable
- - - - small/meristemic when first formed
        
        develop dense starch grains which settle to lower side of cell, detecting gravity
        
        as cells get closer to edge, starch grains digested & cell’s dictyosomes secrete mucigel
        
        middle lamella break down & releases cells
    - - produces root tissue in meristem which extend into other regions
        
        quiescent center:
        
        mitotically inactive central region of root apical meristem
        
        form new apical meristem if original is damaged
    - - just behind apical meristem
      - some meristemic activity, mainly cells enlarging
        
        zone of maturation:
        
        root hairs grow outwards, increase absorption of water/minerals
        
        merged gradually with zone of maturation
        
        minerals transferred from epidermis to vascular tissue
        
        2 Types of Transport
        
        apoplastic transport: diffusion through walls/intercellular space
        
        symplastic transport: absorbed into cytoplasm of cortical cell, transferred from cell to cell
        
        endodermis: innermost cortical cells differentiate into this #hyphae penetrate to the endodermis in this relationship
        
        have tangential walls, radial walls are covered in lignin & suberin
    - - layer of suberin applied over all radial surfaces & inner tangential face of cell
        
        layer of lignin over same surfaces
        
        another layer of suberin
        
        forms watertight sheath around vascular tissues
        
        prevents root pressure from forcing water to leak out into cortex
      - irregular process, some cells finish earlier than others
        
        passage cells: thought to represent passageways for mineral absorption
        
        now suspected they are just slow to develop
  - - - taproot:
        
        develops from embryonic root (aka radicle)
        
        grows extensively after germination
        
        most seed plants have single prominent taproot
        
        has numerous lateral or branch roots
        
        can develop their own lateral rootd
      - fibrous root system:
        
        mass of many similarly sized roots
        
        occurs in most monocots and some eudicots
        
        radicle dies following germination
        
        root primordial at base grow out in first stages of FRS
      - adventitious roots:
        
        do not rise of preexisting roots, not radicles
        
        root primordia initiated in the stem tissue as plant ages
        
        increase the absorptive and transport capacities of root system
    - - root tip:
        
        region where growth in length occurs
      - root cap: #lateral root emerges with root cap
        
        thick layer of cells
        
        protects root apical meristem
        
        mucigel: secreted by dictyosomes of roots cap #mucigel secreted during process
        
        lubricates passage of cells through soil
      - zone of elongation:
        
        behind root apical meristem & root cap
        
        cells undergo division & expansion here
      - root hair zone:
        
        region where many epidermal cells extend out as trichomes
  - - - cells become more densely cytoplasmic
        
        resume mitotic activity in just a few cells
        
        creates small root primordium
        
        organizes into root apical meristem & pushes out
        
        breaks through cortex, epidermis, and endodermis
        
        emerges with root cap
        
        protoxylem & protophloem elements begin to differentiate
        
        establish connection to vascular tissue of parent root
      - have smaller vacuoles
  - - - provide long-term storage for carbohydrates
        
        carbohydrates stored in root are used to produce a new shoot in the spring
      - accumulate during summer photosynthesis
    - - adventitious root that arises from a stem or trunk, penetrates the soil, and helps support the plant
      - transport additional nutrients & water to stem
      - buttress roots: plate like roots for stability
        
        upper side grows more rapidly than other parts of the root
    - - root epidermis (velamen) composed of many layers of dead cells
      - creates water proof barrier to retain water
    - - uppermost portion of roots slowly contract
        
        stem pulled downward
      - caused by changes in shape of cortex cells
        
        simultaneously shorten & expand radially, losing up to two thirds of height
    - - relationship most roots of seed plants have with soil fungi
        
        ectomycorhizal relationship: fungal hyphae penetrate outermost root cortex cells
        
        in woody forest plants
        
        endomycorrhizal association: hyphae penetrate the root cortex to the endodermis
        
        invade cell forming structure called arbuscule which provides plant with phosphorus
    - - nitrogen fixation: chemical conversion of atmospheric nitrogen
      - bacteria in soil secrete substance to curl roots
        
        bacterium attaches to convex side and uses infection thread to push into cell
        
        bacterium sits in thread while it burrows to inner cortex
        
        root nodule formed by cortical cells
        
        bacterium enters cytoplasm & proliferates
        
        plant cells filled with bacterial cells capable of converting N2 into nitrogenous compounds for the plant
- - - - & the manner in which the abundance of a particular allele increases, decreases, or stays the same w/ time
    - - mutation:
        
        all genomes subject to mutagenic factors
        
        causes existing alleles to decrease in frequency, new alleles to increase
      - accidents:
        
        events to which an organism cannot adapt
        
        ex. fire
        
        gene pool altered if area of accident included new mutated allele, or higher frequency of an allele
      - artificial selection:
        
        process in which humans purposefully change allele frequency of a gene pool
        
        ex. selective breeding: organisms with desired trait intentionally bred together
      - natural selection:
        
        usually described as “survival of the fittest”
        
        really means survival of the best adapted #when well adapted allele frequencies remain relatively stable
        
        2 conditions must be met:
        
        population must produce more offspring than can possible grow & survive to maturity in the habitat
        
        progeny must differ from each other in their types of alleles
        
        not always external forces
    - - in many cases one single factor not the cause of loss of individuals, but multiple factors
  - - - aster seed populated the island rapidly due to lack on competition
        
        descendants of first seed have diversified into 3 distinct genera, each w/ many species
    - - ex. Cacti
        
        mutations that disrupted formation of lamina advantageous
        
        cacti lost their leaves in as a little as 10 million years
  - - - distinct from species it was at beginning
    - - gradual change in allele frequency in single population
        
        gene flow: movement of alleles physically through space
        
        pollen transfer: alleles carried by pollen can travel great distances
        
        seed dispersal: seeds/fruit spread by wind, floods, & stream flow
        
        vegetative propagation: possible if species produces mobile pieces that reproduce vegetatively
    - - two separate species evolve differently from a common ancestor
      - reproductive isolation: alleles that arise in one part of range do not reach individuals in other part
      - Abiological Reproductive Barriers:
        
        physical nonliving feature that prevents 2 populations from exchanging genes
        
        speciation resulting from this called allopatric/geographic speciation
      - Biological Reproductive Barriers:
        
        any living/biological phenomenon that prevents successful gene exchange
        
        two groups become reproductively isolated while growing together called sympatric speciation
        
        can be caused by different flowering times
      - prezygotic isolation mechanisms: pollen prevented from moving from plant to plant, pollination/fertilization do not occur
        
        acts before zygote can be formed
      - postzygotic internal isolation: populations so genetically distinct they cannot interbreed
        
        hybrid sterility: spore mother cells in anthers & ovules in sterile hybrids unable to complete meiosis
        
        hybrid inviability: alleles of two parents so incompatible zygote/embryo dies early in dev.
      - Adaptive Radiation:
        
        species rapidly diverges into many new species over extremely short time (few million years)
        
        occurs when species enters new habitat where little stress/competition exists
        
        ex. Galápagos Islands
    - - two distinct, unrelated species occupy the same/similar habitats, nat. selection happens to favor same phenotypes
        
        two species then evolve to the point they resemble each other
  - - - Chemicals in Atmosphere:
        
        early atmosphere mostly hydrogen
        
        most of first atmosphere lost into space
        
        second atmosphere produced by released gasses from rock matrix & bombardment by meteorites
        
        also known as reducing atmosphere due to lack of molecular oxygen & presence of powerful reducing agents
      - Energy Sources:
        
        UV & gamma radiation from sun
        
        heat from the coalescence of gas & dust to form earth
        
        radioactive decay of heavy elements (uranium & radium)
      - Time Available for the Origin of Life
        
        no time limit due to lack of free molecular oxygen
      - Chemosynthesis:
        
        life originated from spontaneously reacting chemicals that become more complex with time
      - Early Metabolism:
        
        aggregates complete heterotrophs
        
        scarcity of resources encouraged natural selection
    - - monomers in early ocean had to polymerize if life is to arise
        
        polymerization requires high concentration of monomers
        
        tide pools considered possible concentration spots
        
        frozen pools/ponds possibly concentration site as ice is almost purely water
        
        clay newly considered concentration spot as binding to clay similar to binding to enzyme
    - - aggregation of chemical components into masses that have some organization & metabolism
        
        aggregates not considered alive due to lack of ability to story genetic info
        
        one eventually develops heritable information molecule useful to aggregate #natural selection favors this trait & so it gets passed on
        
        glycolysis likely evolved early due to presence in virtually all organisms
    - - evolution of chlorophyll a & photosynthesis caused 2 things
        
        allowed the world to rust by liberating oxygen
        
        created conditions that selected for evolution of aerobic respiration
      - oxygen oxidizes all iron in ocean then accumulated in atmosphere
        
        results in oxidizing atmosphere
- - - - earliest fossil of vascular land plants: Cooksonia
        
        extinct plant genus
        
        Rhynia & Aglaophyton similar to Cooksonia
      - Lyonophyto & Sciadophyton gametophytes
        
        stem ends flattened cup-shape, contain gametangia (antheridia & archegonia)
        
        never contain sporangia
      - Xylem Structure of Early Vascular Plants
        
        2 Types of Xylem organization
        
        both, center is solid mass of xylem w/ no pith
        
        endarch protostele: protoxylem located @ center & metaxylem differentiates on outer edge of mass #equisetophyte stem endarch #fern stem endarch
        
        exarch protostele: metaxylem @ center, protoxylem on edges
        
        developed later: siphonostele, pith present in center
        
        (called protostele)
    - - small herbs without secondary growth
        
        grew in small bunches approx. 15cm high
      - similar to rhyniophytes
        
        3 differences
        
        sporangia lateral, not terminal
        
        sporangia open transversely along top edge
        
        xylem exarch protostele
      - upper portions of stems had cuticle, epidermal cells, stomata
        
        lower portion of stems did not
      - some had outgrowths called enations, ranged from small to long thin scales #
  - - - enations large, up to 4cm long
        
        contained single well-developed trace of vasc. tissue
      - called microphylls in Lycophyta
    - - many lycophytes sporangia clustered in cones or strobili
      - necessary precondition for the evolution of seeds
      - Lepidostrobus & Lepidophloios megaspores developed into megagametophytes (w/o enlarging)
    - - Lycopodium: common in forests from tropical to arctic
        
        all living species (approx. 200) small herbs
        
        all homosporous
        
        microphylls spirally arranged on stems
        
        secondary growth never occurs
      - Selaginella: less common in temperate N. America
        
        heterosporous, megagametophyte develops in megaspore wall
        
        megaspore not retained on sporophyte, not seed-like
        
        distinguished from lycopodiums by small flap of tissue, ligule, on upper surface of its leaves
      - Isoetes: grow in wet, muddy areas that occasionally dry
        
        often called quillworts
        
        small, corn-like stem
        
        roots attached below, leaves attached above
        
        hetersporous, almost every leaf contains sporangia
  - - - includes genera Trimerophyton, Psilophyton, and Pertica
        
        Pertica displays pseudomonipodial branching (single main trunk)
      - overtopping: unequal branching in which one stem is more vigorous
    - - 3 distinct types of homoplasic structures called leaves
        
        leaves on gametophytes of nonvascular plants
        
        enations/microphylls of zosterophyllophytes & lycophytes
        
        megaphylls, evolved from branch systems
        
        present in all seed plants/ferns/equisetophytes
        
        evolution summarized by telome theory
        
        subdivisions of lateral branch become aligned in one plane
        
        parenchyma develops between telomes & lower branches
        
        all megaphyllous plants form monophyletic clade called euphyllophytes
    - - megaphyllous plants united by 3 synapomorphies
        
        roots have exarch xylem
        
        have megaphylls
        
        have a 30-kilobase inversion in large single-copy region of plastid DNA
      - many monilophytes known as ferns
    - - living plants all herbs without secondary growth, usually less than 1m tall
      - true roots present
      - stem has pith, protoxylem forms next to pith
        
        endarch siphonostele
      - sporangia always occur in groups of 5 to 10
        
        located on umbrella-shaped sporangiophore
      - homosporous
    - - early ferns appear in Devonian Period
      - most familiar fern: leptosporangiate
      - can be found in almost any habitat, though forests/lakesides typical
      - all perennial & herbaceous
        
        none woody, but can reach size of small tree
      - sporophyte consists of single axis (vertical shoot or horizontal rhizome)
        
        bears both true roots & megaphyllous leaves
        
        vasc. system of stem is endarch siphonostele
        
        at nodes leaf trace diverges from siphonostele, leaves small section as just parenchyma
        
        leaves can be leathery/delicate/thick/thin
        
        underside of leaf are sori, clusters of sporangia where meiosis occurs
        
        leaf primordia have distinct apical cell
        
        known as leaf gap
      - have 2 types of sporangia
        
        eusporangium initiated when surface cells undergo periclinal division
        
        outer cells develop into sporangium wall, inner into sporogenous tissue
        
        leptosporangia initiated when single surface cell divides periclinally & forms small protrusion
        
        after several more divisions it results in small set of sporogenous cells & thin sterile cell covering
- - - - habitat: set of conditions in which an organism completes its life cycle
        
        no plant is migratory, but portions of plant are
        
        spores, pollen, fruits, seeds, etc move thru habitat
        
        for migratory animals, summer/winter area & migration routes are all habitat components
    - - Climate: includes temp, rainfall, relative humidity, wind, etc
        
        tolerance range: range between high & low extremes that a plant grows #affects species composition
      - avg. temp not as important as range of extremes
      - Soil Factors: soil varies in mineral composition and nutrients available
        
        A Horizon
        
        uppermost soil layer, consists of litter & debris
        
        B Horizon
        
        zone where material from A horizon accumulate
        
        rich in nutrients & contains humus and clay
        
        C Horizon
        
        composed mostly of parent rock & rock fragments
      - Latitude & Altitude: affects amount of sunlight/seasons the plant experiences
      - Disturbances: fire, landslides, avalanches, floods, etc.
    - - Plant Itself: by existing in the habitat the plant modifies it
      - Other Plant Species: several species occurring together increases possibility for interaction
        
        mutualism: when interaction is positive for both organisms
        
        competition: interaction is negative, species use same resources #allelopathy gives plants competitive advantage
        
        competitive exclusion: whichever species is less adapted is excluded from ecosystem by better adapted species
        
        niche: conditions that specific species is adapted to occupying
  - - - limiting factor: one factor that determines health of plant
        
        any factor can act as limiting factor
    - - random distribution: used whenever there is no obvious identifiable pattern in position of plants
      - clumped distribution: spacing between plants small or large, but not consistent
      - uniform distribution: all individuals evenly spaced from neighbors
      - allelopathy: use of chemicals by one plant to inhibit nearby growth of other plants
        
        allelochemics: chemicals used in allelopathy
    - - def: relative proportions of young, middle-aged, and old individuals
      - 2 Factors
        
        generation time:
        
        length of time from the birth of one individual until the birth of its first offspring
        
        biotic potential:
        
        number of offspring produced by individual that live long enough to reproduce
        
        does not equal the # of seeds produced
        
        represented as ”r”
        
        large # of healthy/viable seeds = large r/biotic potential
      - carrying capacity:
        
        symbolized by ”K”
        
        the # of individuals in each pop. that can live in particular ecosystem
    - - r-selection: #more successful in less stable operational habitat
        
        disturbance usually creates r conditions
        
        r-selected species:
        
        produce many small seeds at once
        
        mature quickly
        
        typically annuals/small shrubby perennials
      - K-selection:
        
        K-selected species:
        
        mature slowly
        
        produce few larger seeds
        
        face more competition from other plants
        
        usually occurs in crowded habitat close to carrying capacity
  - - - def: physical size/shape of organisms & distribution in relation to each other
      - 3 Most Useful Categories
        
        Trees
        
        Shrubs
        
        Herbs
      - system of life forms defined by C. Raunkiaer (1934)
        
        geophytes: places buds below ground
        
        bulbs/rhizomes
        
        phanerophytes: winterizes buds
        
        trees/vines
        
        classified by means in which plant survives stressful seasons
    - - def: changes that an ecosystem undergoes with time
      - can be as short as a day or decades long
      - seasons part of temporal structure
    - - refers to number & diversity of species that coexist in ecosystem
      - depends on climate, soil quality, and species tolerance range
    - - basically feeding levels, also called trophic pyramid
      - primary producers: bring energy into system (autotrophs)
        
        primary consumers: consume prim. producers (usually herbivores)
        
        secondary consumers: consume prim. consumers (usually carnivores)
        
        decomposers: break down remains of all trophic levels
      - energy flow: flow of energy throughout trophic levels
        
        only 10% of energy consumed is passed to next level
      - carbon flow: flow of carbon throughout trophic levels