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BIOL 201 Final Exam Review (got 92% in the course)

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BIOL 201
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Biology 201 Final Review: Aarssen Lectures 1-12 + Grogan Fungus Lectures Lecture 1 - Origin, Evolution and Classification of Land Plants. - The link between life and non-life, photosynthesis: the conversion of light energy and fixation of carbon, chemical energy, carbon skeletons, oxygen - Invasion of the land: the “Blob” - Simple design of photosynthesis machines, mitosis to grow laterally across soil: minimized wind exposure, maximized water absorption and light uptake. - Spongiophyton: no vascular tissue, all surface cells are photosynthetic , pores to uptake CO2 - Why is there no Blob - i) mechanical constrains: requires continuous uptake of water and minerals from soil. ii) Inherent limits to tolerance of environmental variation: cannot have one plant that is adapted to live in all conditions. iii) inherent limits to longevity: immortality if possible for very few multicellular organisms. - Why is there diversity - Mutation: genes are subject to random change; beneficial mutations will remain in a population and begin speciation. These include: Changes in physiological tolerance( exploitation of different environments), Roots( more reliable and deeper extraction of water and minerals), Small propagules(small structure that detachs from the main plant to give rise to new plants)( allows dispersal over land and have a protective covering), Increased height( increases light uptake against competition, and dispersal of propagules). - Meristems: where mutations accumulate because it is the site of genetic processes: consists of undifferentiated cells, the way plants have evolved certain phenotypes is dependent on meristem function. - Evolution by natural selection: i) there is a variation in traits between individual organisms due to differences in genetic material that originate initially as mutation. ii) these genetic differences are inherited. iii) some heritable differences are responsible for differential survival and reproduction( goal: to make symgamy and meiosis happen, without species has high risk of extinction) - Mutation  variation  natural selection  evolution organic diversity. - Acquiring genetic variability: the role of sex - Since the environment is not homogeneous, it only makes sense that there is a mixture of genetic types. - Two ways to have genetically variable offspring: i) acquire different mutations in different mitosis centers(meristems) all the cells produced there will have said mutation ( this is very slow). ii) make new combinations of genes by sexual reproduction, independent assortment of chromosomes and crossing over are present in meiosis ( instead of mitosis). - Advantage of sex required getting ‘small’ during some point( for genetic recombination and dispersal of propagules) since combining genes happens during the fusion of two gametes ( haploid) to form the zygote(diploid) . They also need to get tall for success in competition for light and greater dispersal of seeds. - Sexual cycles and alternation of generations in land plants - Three types of cycles: Zygotic, Gametic, and Sporic - The Origin of Alternation of Generations or Sporic meiosis. - Two similar eukaryotic(haploid) cells mate and for a 2n zygote, initiation diploidy and providing two advantages: i) allows sex ( more variability) and ii) protection against deleterious mutations ( dominance and sexual selection acts as a sieve) - Some evolutionary lines elaborate the haploid generation, and others the zygote. The mani evolutionary line was toward alternation , from the sygotic pattern by delay in meiosis until the multicellular diploid generation had developed so that both generations are multi-cellular. - Origin of Land Plants - Algal ancestors: chlorophyta ( green algae) has the same pigments, stacked thylakoids and starch storage products as higher plants. The class charophyceae have the same :phragmoplast at cytokinesis, sterile sheath of cells surround the gametes, oogamous ( large female games, small male gametes), zygote is formed and retained in the plant. - Stages in the evolution series from algae to early land plants: fertilization within oogonium from zoospores  Mc diploid and emergent sporangium  cuticle forms around portion out of water and spores are released  the byrophytes ( early land plants ) begin to develop  early vascular plants form roots, and conduction tissues to obtain and distribute water. - Classification of the land Plants: - Thallophytes : lower plants ; Fertilization outside the plant and no embryo ( algae fungi and slime molds) - Embryophytes: higher plants/land plants, fertilization occurs within the plant, embryo developes and is retained within the plant. They include bryophytes and tracheophytes - Bryophytes: not very tough , very weather sensitive. phylums: Anthocertophyta (Hornworts), Marchantiophyta( liverworts) bryophyte (mosses). - Tracheophytes: produce tracheal tissue ( vascular plants) include the pteridophytes (non-seed plants ) Lycopodiaphyta (club mosses)& monilophyta (whisk ferns, ferns and horsetails.) and the spermatophytes (seed plants ) gymnosperms( non-flowering, Cycads, Ginkgo, Conifers, gnetophytes) and the angiosperms( flowering plants) anthophyta. Lecture 2: The Byrophytes - General Characteristics - non-vascular, gametic metois, anchored to substrate with rhizoids: these do not partake in water of nutrient conduction. They absorb water and inorganic ions directly through the gametophyte surface. Dries up and becomes dormant in absence of water, and resumes growth when water becomes available again. Very resistant to dessication, can survive for long periods without water. They possess a sterile jacket of cells surrounding gametes( to protect them from desiccation). Gametes ( antheridium = male gametangia, archegonium = female gametangia) produced in haploid phase, sperm needs water to be able to reach the egg. Vegetative reproduction by the gemmae, asexual reproduction by fragmentation or by using the gemmae to self fertilize and produce new gametophytes. - Liver worts - Thallose liverworts: most common, undifferentiated , grows on moist soil and rocks, dichotomous: 2 branches ( Marchantia), unisexual gametophytes( each gametophyte only produces one of either sperm or eggs). The sporangium’s entire purpose is to make a sac for meiosis to occur. - Meiosis spores haploid gametophytegametesSyngamyzygotediploid sporophyte sporangium  meiosis. - Leafy Liverworts: photosynthetic tissue( no vascular tissue so not true leaves), grow on the leaves and bark of trees in humid or moist environments, most common in the tropics. - Spore discharge in the liverworts: involves elators( hygroscopic: change in response to humidity/ moisture) sporangium splits open when dry/mature, and releases hundreads of spores. Contains nostoc ( a cyanobacterium) embedded in mucilage, cells in the thallus including the epidermis screte mucilage which is essential for water retention. Most gametophytes are unisexuals, some are bisexual. - Hornworts - Anthoceros: the genus name for most if not all hornworts. Resemble thalloid liverworts, bisexual gametophytes, archegonia and atherida embedded within the thallus, undifferentiated flat thallus ( blob), long sporangium: upright elongated structures with a cylindrical capsule at the tip and a foot at the base. columella: central column of sterile cells( maybe an ancestor of higher plants as this is similar to a stem). Foot penetrates the gametophyte tissue and forms a placenta across which the sporophyte obtains nourishment from the gameophyte, during development a basal meristem( active in favorable condtions) between foot and meristem, helps elongate sporangium. All stages of spore development from meiosis near the base to mature spores above can be seen in a single sporangium. - Mosses - Classes: Bryidae( true mosses) , Sphagnidae (peat mosses), andeaeidae( granite mosses). - Bryidae: stem structure, not quite as good at transport as vascular tissue, seta = stalk, hydroids(kinda like xylem, doesn’t look like it but still conducts water) lack lignin( permeable and thin) , polytrichum: gametophyte “stem” cross section with central conductuing tissues. Leptoids are kinda like phloem( transports photosynthates, more so than the rest of the stem structure). Variety in peristomes: ring of teeth, movements of teeth in response to splitting cell layer near capsule in dry environents releases spores to be dispersed by wind. - Meiosis spores haploid gametophytegametesSyngamyzygotediploid sporophyte sporangium  meiosis. - Sphagnidae: sexual reproduction involves formation of antheridia and archegonia at the ends of special branches at the tips of the gametophytes. Sporophytes: capsules with short stalk are attached to the pseudopodium ( remainder of the stalk- gametophyte). Unsual protonema: first stage of development of the gametophyte – does not consit of multicellular branced filaments like most mosses- just a plate of cells that grows by a marginal meristem, in which most of the cells can divide in one of only 2 directions. - Spore Discharge in mosses: as capsule dries it contracts changing from a spherical to a cylindrical shape and compresses trapped gas within the capsule. This gas reaches high pressure and blows off the operculum( lid on the top of the sporophyte capsule) with the explosive release of spores. Lecture 3: Vascular plants - No plants made seeds 300million years ago or flowers. - World became crowed with land plants so it was harder to compete for light, had to get tall. Most common reason for extinction is because they failed at this life cycle, did not have successful gamete production and syngamy. - Evolved roughly 400mya. In the beginning of the land plant the picture would be made up of bryophytes and vascular plants. - The dominate generation in vascular plants is the sporophyte ( sporangium produced on sporophyte which houses spores to keep cycle going). - First land plants ~400mya , no photosynthesis, nothing in the terrestrial environment would evolve with them, they produced oxygen, set the stage for fossil fuels, oxygen atmosphere and the evolution of animals. - Origin - Theory one: algae split into Bryophytes( still around , small and successful) and Tracheophytes( they really provide most f the carbon build up that allows for fossil fuels and oxygen). Xylem= transports water and nutrients upwards and provides physical support. Phloem: transports sugars and proteins. - Theory 2: usually use fossil record if we have it, we can use inference, piecing together a hypothesis based on debate. Anthoceros-like ancestor  Vascular plants. Similarities : i) sporophyte has a central columella which may have easily evoloved into a internal conductive system of xylem and phloem ( sterile) ii) sporophyte has cutile and stomata with guard cells. ( stomata controls entry of CO2 and release of water)) iii) sporophyte has an intercalary meristem which provides indeterminate growth ( important in higher plants, here the sporophyte continues to grow , pushing up the sporophyte ) - The First Vascular plants and early evolution. - The oldest fossil plant is the cooksonia. - Three extint phyla : common features include no roots, no leaves, cuticle , dichotomously branching stem , sascular tissue was a protostele, and they were homosporous. - Rhyniophyta: Cooksonia(Most of the tips of the dichotomies produce sporangium) , Rhynia(produce vegetative and sporangium on tips, more specialized), & Homeophyton( sporangium are in cluseters on tips). - Zosterophyilophyta: Sporangium, where meiosis takes place. Evolution is bringing them to a localized place to keep them together and protected, didn’t have leaves but had to increase surface area to capture light, didn’t have leaves but had to increase surface area to capture light , photothesis takes place in stem. Some had spine like outgrowths roviding increase surface area for light harvesting. - Trimerophyta: larger with a main axis ( 1-3m tall), increased diameter of stele, increased xylem lignification( gives added structural support), lateral brances specialized in photosynthesis, clusters(grouping of sporangia). - Major Evolutionary trends in Vegetative traits - Roots: Reliable water source is in the ground, vascular plants at first did not have roots, worked out OK but not great. Early vascular plants had rhizomes with only rhizoids functioning only for attachment to the substrate specialized rooting organs with vascular tissue. - Evolution of the Axis: A) increase in height: dichotomously branching  sympodial axis( zig zag)  monopodial axis( straight center). B) Increase in girth: evolution of thicker, heftier branches, thinckened girth stem with vascular tissue, the tissue that gives it the strength is around the outside, greater strength per mass ( prevents falling over and being top heavy). - Evolution of Vascular Tissue: A) evolution of the siphonostele, protostele siphonostele  eustele. B) Evolution of xylem tracheid cells and xylem vessel: increasing amount of secondary wall thickening ( lignin) C) Secondary Growth: secondary growth from vascular cambien, a secondary lateral meristem allowing greater increase in stem girth. M cambium ( intiated by the primary cortex)  cork (phellum, toward the outside and dies to form protective layer) and secondary cortex(phelloderm, towards the inside). Replacement tissues to replace damaged tissues as growth pushes outwards. Allows fore more vertical growth. - Evolution of the leaf: A) origin of the microphyll, increased SA for gas exchange, outgrowths of cortex and epidermis, later extension of vascular tissue, reduction of dichotomous branches( these shoots become a microphyll that serves the function of not producing sporangium but adding more SA B) origin of the megaphyll: 3-D arrangement of dichotomous branches flattened arrangement in a single plane  filling in of space between branches with parenchyme  reduction at dichotomies produces a pinnately veined megaphyll. - Summary of evolutionof vegetative traits: Obtaining water roots  immobility crowdedness  tall height from apical dominance and lignin in support tissues  conducting water up and photosynthesis down & stems buckling  support from the vascular cambium ( xylem and phloem) and stem strength from siphonosteles rupturing of external cortex , loss of water, pathogen entry and fire damage  expanded outer cortex from cork cambium and bark from cork cambium  loss of photosynthetic function in stem  formation of leaves to increase SA in higher areas. - Major Evolution trends in reproductive traits - Reduction in size and life span of gametophyte generation and increasing dependence on sporophyte , not much going on in gametophyte therefore reduction of size, loss of sperm cell motility. Loss of archegonia and antherida, Homospory  heterospory: two kinds of spores produced in two kinds of sporangia and which develop into separate male and female gametophytes respectively. Lecture 4: Seedless Vascular Plants - The ancestors of all these plants were the only plants on eather 300mya ago( have a long history in fossil records), most of the phyla have gone extinct, the evolution of seed plants were responsible for many of these phyla extinction. - Whisk Ferns – order Psilotales (peridophyta) - Characteristics: underground rhizoids, dichotomous branching, protostele, leaves : psilotum(none, only scale like outgrowths lacking veins & Tmesipteris( spirally arranged microphyll-like (with one vein), homosporous. Small gametophyte blob (green largely undifferernted but has an important role of producing gametes. Antheridia break open and release sperm, spore must swim to find archegonia, if they find archegonia on the same plant = selfing, need moisture. - Origin: Theory one: from Phynia-like ancestors ( No fossil record of psilophyta since the Devonian period (400mya), where rhynia was found. Theory two: result of reduction from other pteridophyte groups( as they are less structurally complex then other pteretophyte groups). - Interpretation of Psilotum sporangium: inference (don’t really have snapshots of these throughout evolution. By localizing sporangia, it may have helped during water shortages and protection against herbivory. Sympodial branching system with overtopping fertile and sterile branches shortened by reduction  contined shortening and fusion of 3 sporangia 3 lobed sporpangium in axil of reduced sterile branch. Advantages of lobed sporangium: protection from desiccation and less conspicuous to consumers - Similarities between gametophytes and sporophyte : i) both have rhizoids( help plant attach to substrate) ii) both are radially symmetrical ( dicated by meristemic growth( archeridia and archeonia ) iii) both have dichotomous branching. iv) some gametophytes have vascular tissues ( like sporophyte). Biggest gametophyte in seedless plants, starts as a spore  grows into blob structure. - Implications : suggest that gametophyte of early vascular plants were similar in some ways to the structure of sporophytes. However later selection: increased sporophyte size and reduced gametophyte size. ( selection presusres that might limit the success of sporophytes differed from those that might limit gametophytes.) - Meiosis spores haploid gametophytegametesSyngamyzygotediploid sporophyte sporangium  meiosis. Gametophytes are very vulnerable to lack of moisture so they get smaller to conserve moisture. ( seed plants evolved to solve this) Sporophyte avoided death without sex by getting bigger - Horsetails – Order Equisetales ( Pteridophyta) - Characteristic: Extend back to the Devonian period maximum abundance and diversity in carboniferous period ( 300mya), only one living genus, rhizomes that have emerged true roots( true roots have xylem and phloem), stems joined with or without branches at nodes, leaves are microphyll, alternate with brances at nodes, eventually dry out and photosynthesis occurs mainly in surface layers of the stem, believe to originated from a reduced of dichotomous branches. - Stem anatomy: as tissue grows the pith breaks down and becomes just open air(hollow tubes are stronger per weight than solid) , helps to keep the plant upright, more photosynthesis occurs in stem( chloroplast packed around epidermis), vascular tissues is arranged in a ring ( eustele) Has a lot of lignin, nick named scouring rush, - Reproductive structures: sporangia arranged in a spiral, dangle from plate with sporangiophore in the middle, Strobilus ( a sporal arrangement of sporagiophores), have elaters, attached to spore, when they are wet the elator arm like structures spread out and allows wind to disperse the spore , hydroscopic - Formation of Sporangiophores: sympodial branching system reduction of branches, recuraction of sporangial stalks,  reduction and fusion of sporangial axes, packs together sporangiophores. Makes them less conspicuous to consumers in sporangium, more resistant to dessication. - Life Cycle: early life sporophyte is dependent on gametophyte but eventually it will have its own roots, all started in archegonia where successful fertilization allowed for the production of sporophytes, gametophyte gives rise to young sporangium ,homosporous : 1 kind of sporangium  1 kind of spore  one gendered gametophyte. - Extinct forms: Calamites( up to 20m tall, flourish during the carboniferous period, only herbaceous species are leaft in the extant flora, massive trees. - Ferns ( several orders, Pteridophyta ) - Characteristics: largest groups of seedless vascular plants, date back to mid- devonian , sizes range from 2cm long to 24m tall, stm reduced or exsists as a creaping rhizome, leaves are megaphylls and called fronds, young leaces are coiled in the bud and uncoiling is refered to as circinate vernation. Successful clonal propagation seen in growth of horizontal roots, don’t need sex to make babies, naked sperm have to find moisture to swim around to find egg. - Origin: monilophyta have prostele, siphonostel and eustele, 2 rings of phloem = characteristic feauture of vegetative ferns , suggest it’s the prodiuct of natural selection , why / how did they evolve? Follows the evolution of the dichotomous branched , early vascular plants, a lot of ferns were trees mya (having a hefty stem with vascular tissue would have been important). Ferns bulked up but having tissue grow over bundles of dichotomous branches. Amphiphloic siphonostele= concentric phloem flanking xylem, Dictoyostele selected for lignin protecting pith. - Sporangia: sorus= cluster of sporangia, diversity of sorus, used for identifiying features of different groups of ferns, sori are on adult sporophytes, they are sporangiophores that contain a cluster of sporangia. - Origin of fern megaphyll and sporangia position: dichotomously branching system(sporangia at the tips of branches)  straightening of main axis and planation of reduced lateral fertile branch system ( planation: branch system is now in a plane as opposed to 3D)  webbing gives a leaf-like blade with marginal sporangia. Megaphyll efficient gas exchange and photosynthesis ( high SA) , key reason ferns are still around. - Annulus: pod of spores, cell cack in annulus is moist, evaporates as it gets older causing it to break open, outer walls are thin, once annulus breaks open there is further evaporation to catapult the spores out. - Tree Ferns: Growth is entirely by apical meristem( no vascular cambium, stems cannot get any thicker ) , Arboresecent forms have gone extinct within all the seedless vascular plant groups with the exception of ferns, ferns are the only group that hasn’t lost their trees. - Fern Allies( club mosses, etc) Largest group , they have their own phylum( lycopodiophyta) - Lycopodium (club moss) - Characteristics: rhizomes with true roots, dichotomous branches with microphylls , variation of the protosteles, most photosynthesis occurs in microphylls but can occur in stem, homosporous bisexual gametophyte, sporangia on upper surface of leaf-like sporophyll arranged loosely in a spiral arrangement on a stroblilus at the end of the branch, sporophyll=microphyll with sporangium - Interpretation of Sporangium : stalked sporangium above leaf-like outgrowth  sporangium moved to auxiliary position, vascular extension into microphyll sporangium moved onto adaxial surface of microphyll. Advantages include reduced desiccation of sporangium, improved more by close packing of sporophylls on a strobilus and less conspicuous to consumers. - Arborescent Lycopodiophyta ( tree like): Lepidodendron ( dominant tree), up too 20m tall, flourished during carboniferous period, only herbaceous speices are still present. - Selaginella: Heterosporous : different spores produce separate male and female gametophytes , prevents inbreeding as different sexes are on different - Gametophytes: Very reduced with no morphological similarity to the sporophyte as in psilotum, develop endosporally i.e within the confines of the spore wall, megagametophyte also develops while the megaspore is still within the megasporangium, gametophyte spends it entire life in the ( mega an micro) spore wall. Flagellated sperm still have to swim to find archegonia Lecture 5: Evolution of the Seed Plants ( Spermatophytes) - Progymnosperms - Appeared in Devonian, exisited throughout the carboniferous (400-300mya), intermediated between early vascular plants and later gymnosperms, large gymnosperm like axix with secondary thickening from a vascular cambium, Hence they were first true “trees” but they produced spores not seeds, they could increase the girth of the bottom of the tree to support its upward growth. - Sperm is in a vulnerable stage , but seed plants take care of this, seeded plants caused the extinction of other less evolved plants by being more successful and obtaining all the nutrients, gametes produced from gametophytes on different male and female sporophytes, this allowed for more diversity as it promoted sexual reproduction. - In seed plants the entire male gametophyte reaches the ovule, no long need flagellated sperm to travel through water. Megagametophyte produces eggs and nourishes the new embryo when it develops. - Evolution solved the problem of gametes in the seed plants through sporangium (houses for vulnerable gametes), diploid sporophyte plant produce sporangium ( where fertilization occurs). - The Seed Habit - Comparison with Petidophytes: Seedless Vascular: 1 kind of sporophyte (one kinda of spore), they produce tons of spores (cheap), most of them die out but they only need one spore to fertilize and spread genetics, exosporal= develops outside the spore wall. Selaginella: only produces 4 spores, retained within the megaspore wall (beginnigns of seeded plants), dehiscent= splits open, sporophyte is dominant. Spermatophytes: rest of the megaspores abort, one remaining megaspore develops into female gametophyte housed within the megasporangium, sporangium does not split open, gametophyte spends entire life immersed in the tissue of the sporophyte. - Two major developments: i) Heterosporyand retention of reduced endosporal female gametophyte and subsequent embryo within an indehiscent sporangium. ii) integumentation of megasporagium: the tissue that wraps the gametophyte, provides protection and nutrition to the developing cell. The seed is the fertilized ovule( containing the zygote or developing embryo) and the integument becomes the seed coat. - Interpretation of the integument: The extinct plants look just like ferns, there could be some relationship, could be the first seed plant to produce integemented sporangium, dichotomous branching system with fertile and sterile branches reduction to a single functional megasporangium surroned by sterile b
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