Ebio Exam 3 Study Guide
Ebio Exam 3 Study Guide EBIO 1010 - 02
University of Louisiana at Lafayette
Popular in Evolutionary Biology
Popular in Science
Joseph Merritt Ramsey
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This 15 page Study Guide was uploaded by Lauren Notetaker on Saturday April 9, 2016. The Study Guide belongs to EBIO 1010 - 02 at Tulane University taught by Bruce Fleury in Spring 2016. Since its upload, it has received 52 views. For similar materials see Evolutionary Biology in Science at Tulane University.
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Date Created: 04/09/16
Ebio Exam 3 • Covers all material under kingdom fungi and kingdom plantae (plants=75 fungi = 25) • No questions from fruits and seeds and no plant structure • Pt 1 matching 20 Each phyla of fungi has a characteristic reproductive structure Pt 2 ﬁll ins taken from plant/fungi terms 34 • • Ferns and fern allies; fungi • One example of each • Pt 3 taxonomy - phyla with examples, common names OK for ex 18 • Pt 4 plant life cycle to label 6 • Pt 5 economic, ecological, evolutionary importance of organisms 12 • Pt 6 general questions form lecture material on how to be a plant 10 PART 1 FUNGI Phylum Chytridiomycota – chytrids Protozoan-like cell with a single posterior flagellum Reproduce with a motile zoospore Used to be considered an “orpan phylum” of Kingdom Protista Basal group – close to the “root” of the fungal tree of life… Importance: Many are parasites on algae, other plants (black wart disease in potatoes ex.), nematodes, frogs Important in decompostion of many “tough” materials – pollen, chitin, keratin etc… Found in guts of herbivores, help them to digest plant fibers Phylum Glomeromycota - Glomus Ecologically very important - consists mostly of the fungi that form mycorrhizae on tree roots (endomycorrhizae) Can’t survive without the host plant (mutualism) Asexual reproduction only Mycorrhizae grow around and inside of the roots of most plants (>85% of land plants) endomycorrhize or arbuscular mycorrhizae ectomycorrhize Phylum Zygomycota – bread molds Zygomycetes form reproductive structures called zygospores Zygospore looks like two ice cream cones smashed together Sporangia germinate from zygospores Bread mold mycelium consists of several modified hyphae Stolon – runner-like, spreads the mold Rhizoid – “sort of like a”; root like, anchors the mold Sporangiophore – stalk holds sporangium Sporangium – tiny round ball full of spores PhylumAscomycota – yeast, morels yeasts, morels, truffles, ergot (sac fungi) Often called sac fungi, body called ascocarp “Sac” is reproductive structure called ascus, forms ascospores Wide range of body types, from single cells (yeast) to mushroom-like morels Lichens are a symbiotic relationship between fungus (98% of lichens have ascomycetes) green algae or cyanobacteria Three body types - Crustose – thin encrustation Foliose – leaf-like Fruticose – thin branches Lichens are the textbook example of mutualism – symbiosis in which both partners benefit May actually be the result of a parasitic invasion of an algae by a fungi Settled down into a “controlled parasitism”, now can’t live without one another Importance Lichens weather rocks, secrete acids to dissolve rock so they can take root, makes opportunities for seeds and roots of plants Lichens are an important source of food for caribou (reindeer moss), musk ox, and other animals Sensitive to air pollution, so useful as ecological barometers Dutch Elm Disease – imported from Holland, devastated U.S. shade trees, elms nearly gone Chestnut blight wiped out most U.S. chestnuts, once one of the most common forest trees, attacked by fungus when tree matures Truffles - sell for up to $100 apiece! Form a mycorrhizal relationship with the roots of oaks and other trees Ergot fungus infects rye and other grains, especially in cold damp climates Used in Europe for centuries to induce labor Ergot poisoning changed the course of history - causes miscarriages in larger doses, changed Russian population patterns over a wide area Fatal in large doses, leads to convulsions, gangrene, and death - in 994 over 40,000 people died of ergot poisoning in France In small doses, caused very strange behavior in peasants eating rye bread (poor man’s wheat) – wild dancing, running naked through the streets, talking to invisible beings Natural source of d-lysergic acid diethylamide - LSD (Ergot fungus – Claviceps) Victims of ergotism were thought to be possessed by the devil Salem witch trials now thought to be the result of ergotism Many medically important ascomycetes – Penicillium, Aspergillus, Candida (yeast infection), athlete’s foot Most fungal pathogens are ascomycetes Yeast form tiny buds that break off and grow into larger cells Reproduce sexually by conjugation Tip of reproductive hyphae with two nuclei forms a complete cross wall Tip of hyphae now called an ascus Nuclei fuse into diploid zygote Zygote divides by meiosis to form four haploid spores (ascospores) Each haploid spore undergoes mitosis Total of eight haploid spores in each ascus Phylum Basidiomycota – mushrooms mushrooms, shelf fungi, rusts, smuts, puffballs, Coprinus (club fungi) Often called club fungi because of club-shaped reproductive structures called basidium (-ia), make basidiospores Reproduction Basiodiomycetes form a fruiting body called a basidiocarp or mushroom Underside of the mushroom is filled with thin vertical plates called gills Gills hold club-shaped basidia Conjugation forms dikaryotic (+ or -) hyphae Nuclei in basidia fuse into diploid zygote Zygote divides by meiosis to form four haploid spores Basidiospores form at the tips of the basidia Asexual reproduction very rare in this group Hyphae grow underground, grow out from the center at equal rate Most of the fungus is underground, only the fruiting body (mushroom) emerges from the soil - Why? Need to disperse spores through the air! Growth pattern means that when mushrooms emerge, they form a nearly perfect circle Largest organism on Earth is not the Blue Whale or the redwood tree Biggest creatures on earth are fungi! Armarillia (honey mushroom) in Michigan is 1,500 years old, estimated weight of over 22,000 pounds! Top honors go to the fungi – one underground root parasite in Oregon’s Blue Mountains Organism is at least 2,400 years old, and extends below 2,200 acres of conifer forest! Many edible species Most important fungi in forest ecology – many other fungi can digest wood, but basidiomycetes do it best PART 2 The study of fungi is called mycology Fossil record is very poor for fungi Soft bodies (preservation bias) Most primitive forms were probably tiny Not many people looking for them (interest bias) Used to think that they were green plants that had lost their chlorophyll They were first classified as plants (Division = older botanical version of a phylum) Recent molecular studies have shown that fungi are more closely related to animals Fungi, animals, and protists called choanoflagellates form a monophyletic group called Opisthokonta Named after the flagellated cells they share in common, with one posterior flagella Fungi are heterotrophs, usually parasites or saprobes Saprobes are organisms that get their nutrients from dead or decaying matter All fungal digestion is extracellular – fungal strands secrete digestive enzymes to dissolve its host (food) Arthrobotrys is the John Wayne of fungi It captures tiny nematode worms in miniature lassos, little loops that can clamp down on anyone trying to wiggle through !! The body of a fungus can consist of single cells (yeast), more often a tangle of tiny filaments called hypha (pl. hyphae) The intertwined hyphae that form the body of the fungus are collectively called a mycelium Hyphae also form special reproductive structures that are characteristic of the different phyla Many fungi grow as single cells - yeast form, including some basidiomycetes and ascomycetes (mushrooms) Many ascomycetes are dimorphic, alternate between yeast and hyphae body types Fungi have cell walls (like plants, bacteria, some protists) Cell walls of fungi are mostly made of chitin, some polysaccharides When is a cell not a cell?? - fungi have cross walls that are non existent or not closed The cross walls (septum, pl. septae) of fungi are rarely complete Usually an opening between adjacent cells (ascomycetes, basidiomycetes) Some fungi have no interior cell walls, just an open multinucleate tube (zygomycetes, chytridiomycetes) Because of this unusual arrangement, mitosis is different in fungi (happens in nuclei) Cells (hyphae) don’t divide per se Nuclear membrane stays intact Mitosis takes place entirely within the nuclei This open architecture explains why fungi can grow so quickly growing tips find new food, nothing to stop it or slow it down Cytoplasm can stream quickly back and forth, carrying nutrients to the growing tips of the hyphae Fungi nucleus is always haploid (1N) Only the zygote is diploid (2N) Diploid zygote divides by meiosis to form haploid spores Spores germinate into haploid hyphae Septae (cross walls) are only complete when certain hyphae form reproductive structures - hyphae sealed off at the tip Each phyla of fungi has a characteristic reproductive structure Fungi reproduce asexually by forming haploid spores - conidia Fungi reproduce sexually by fusion of nuclei – conjugation No male or female fungi, we call mating strains + or – Two mating strains extend a projection of their hyphae towards one another The two projections meet, fuse at the tips Cross walls form to isolate this structure Fused structure is called gametangium (-ia) Type of reproductive structure used to classify fungi into Phyla Two nuclei in gametangium fuse together Diploid zygote undergoes meiosis to form haploid spores Spores germinate into adult haploid hyphae Spores are haploid cells in a protective envelope that can develop directly into haploid adults Spores are formed in a special structure called a sporangium (-ia) In many fungi, the two nuclei don’t fuse right away; linger side by side They exist side by side in each cellular compartment They divide separately by meiosis as the hyphae grow Fungi with only one nucleus in each cell are called monokaryotic not on test Fungi with two nuclei in each cell are called dikaryotic (basidiomycetes and ascomycetes) Nuclei will eventually fuse together to form a zygote, later in the life cycle KINGDOM PLANTAE Plants differ mainly in subtle aspects of their metabolic chemistry Like animals, plants are descended from the protists Unlike animals, however, plants evolved from autotrophic protists So plants have a slightly different set of priorities - they don’t need to worry about where there next meal is coming from Plants are all sessile organisms (tumbleweeds to the contrary) Like sessile animals, plants can stay in one place and feed Like sessile animals, plants need no central nervous system, or any nerves at all for that matter, mostly chemical response to stimuli Primitive plants are dispersed by spores Spores are haploid cells that can develop directly into adult plants Plant spores are protected by an outer layer of sporopollenin, a tough biopolymer that prevents dessication and other hazards Spores are incredibly small and light, easily dispersed by wind, water, animals Higher plants evolved seeds Seeds are protected by a tough seed coat Seeds are dispersed by wind, water, animals Fruits attract animals to disperse seeds Vascular plants are called tracheophytes (= tube plants) Drinking tubes called tracheids Found in earliest fossil land plants Angiosperms also have more advanced xylem cells called vessels Leaves must get water from the roots to photosynthesize Water enters by osmosis (pressure) Water tension gets higher as the column of water gets higher, works against osmosis Plants have a size-related problem not shared by animals Many of the things plants need for respiration and photosynthesis are dilute or in short supply Invest lots of energy in thin sheets of tissue, so cells are 99% water vacuoles (cheap…) Plants have one unique characteristic, something they do not share with animals - alternation of generations Multicelluar haploid phase alternates with multicellular diploid phase (haplodiplontic) Only the green, red, and brown algae show a similar life cycle alternation of generations Haploid adult (1N) is called a gametophyte Gametophyte makes gametes by mitosis Gametes fuse into a diploid zygote (2N) Diploid adult 2N) is called a sporophyte Diploid zygote develops into an adult sporophyte Sporophyte makes haploid spores (meiosis) Spores grow into adult gametophytes In animals, the gametes fuse directly into a zygote, after a very brief free-living existence In fungi, the gametes (nuclei) never leave the hyphae, linger for a while, then fuse In plants, the gametes grow up into fully functional organisms! In primitive plants the gametophyte is the dominant stage In higher plants the sporophyte is the dominant stage In very primitive plants like mosses, the leafy green plant we see is the gametophyte The sporophyte is the little brown stalk that sticks out of the top In flowering plants, the bushy green plant we see is a sporophyte Gametophyte is reduced to a few cells Female gametophyte is permanently buried in the tissues of the sporophyte Male gametophyte reduced to pollen grain Gametes are produced in a gametangium (-ia) Gametes must fuse together to develop into a diploid adult Spores are produced in a sporangium (-ia) Spores develop directly into haploid adults Agametangium that produces sperm is called an antheridium (-ia) Agametangium that produces eggs is called an archegonium (-ia) In primitive plants, its hard to tell one spore from another = homosporous In higher plants, male and female spores look different = heterosporous Spores are formed by meiosis in special structures called sporangia Sporangia are often attached to special modified leaves called sporophylls Sporophylls (“spore leaves”) are often organized into a club-shaped strobilus (-i) Pine cones and flowers are complex variations on primitive strobili Land plants evolved from green algae Both have cell walls made of cellulose Both have chlorophyll a and b Both have alternation of generations Both store glucose as starch Specialization means certain cells must die so that other cells can live Bryophytes share several primitive traits Rely primarily on diffusion Limited to moist environments Lack a true root-shoot system Sporophytes are not free living Bryophytes rely on diffusion to take in water and to exchange gases Bryophytes are usually small - inconspicuous Advantage of being small - don’t have to invest in support structures and vascular tissues Bryophytes have a central strand of primitive vascular tissue Not true vascular tissue, much simpler than that of higher plants Moss plants are male or female (dioecious) “roof” Male plants have antheridia at the top Female plants have archegonia at the top The evolution of the spore was the key to the bryophytes emergence onto land The evolution of vascular tissue and seeds let tracheophytes become fully terrestrial Many similarities to bryophytes Ferns and allies have free-swimming flagellated sperm, larger non-motile egg Sperm must swim through water, so ferns and allies are limited to moist environment Sporophyte develops directly from the gametophyte, no protection from desiccation Differences between bryophytes and ferns Sporophyte is the dominant stage in ferns (instead of gametophyte) Ferns and fern allies are monoecious - antheridia and archegonia on same plant Gametophytes are free-living plants, very small, only develop in moist areas Differences between bryophytes and ferns Sporangia attached to sporophylls Sporophylls organized into club-shaped strobili Spread by rhizomes, modified underground stems that help spread it around Before ferns evolved, bryophytes were the dominant plants on Earth Tracheophytes quickly became the dominant flora More highly evolved root-shoot system Efficient vascular tissues Larger size Seed plants also no longer rely on flagellated sperm to reproduce The entire male gametophyte (pollen grain) moves through the air to reach the egg Pollen grain is carried by wind, water, animals - pollination All adult sporophytes of seed plants bear sporangia in a strobilus (pine cone, flower) Sporangia of seed plants, like those of primitive plants, produce haploid spores by meiosis All seed plants are heterosporous Spores develop from a spore mother cell Microspores develop in a microsporangia, from a microspore mother cell Megaspores develop in a megasporangia, from a megaspore mother cell Spores develop into tiny gametophytes, smaller than those of ferns and fern allies Microspores develop into male gametophytes Megaspores develop into female gametophytes Seed plants are the final stage in the long transition in alternation of generations The sporophyte is the dominant stage in seed plants, gametophytes greatly reduced Megasporangium is covered by a protective layer of cells called an integument Integument is open at one end - micropyle Megasporangium plus the integument is called the ovule* Leaves are incredibly well defended Sharp tips on leaves Toxic secondary compounds, including neurotoxins and carcinogens Pollen sacs and ovules in scale-like cones Microsporangiate cones - male Megasporangiate cones - female Wind pollinated, strategy requires immense amounts of airborne pollen to get lucky Early cycads may have attracted beetles to pollinate them, beetles like to eat pollen (high in protein) May be the beginning of animal pollination, successfully exploited by flowering plants Ephedra, like whisk fern, is a “stem plant”, photosynthetic stem with no leaves most important Common in deserts of theAmerican West and Mexico, grows everywhere exceptAustralia Welwitschia (pseudo fed) looks like it came from another planet Welwitschia grows in the deserts of southwesternAfrica Ancient group, evolved ~ 290 mya (Permian) Conifers are the only gymnosperms that are still successful competitors with angiosperms Conifers evolved in a cool, dry period Conifers evolved special water-conducting cells called tracheids Male cone is smaller, bears microsporangia Microsporangia contain microspore mother cells Mother cells divide by meiosis to form haploid microspores Microspores develop into the male gametophyte, the pollen grain Wings on pollen - seed dispersal? - may help grain float up to the micropyle Female cone is larger, bears megasporangia Megaspore mother cell produces four haploid megaspores by meiosis three megaspores degenerate Remaining megaspore develops into the female gametophyte Female gametophyte consists of two archegonia, with an egg in each Ovulate cones open to receive pollen ( gymnos = naked seed), then close again Pollen grain lands on cone, grows long pollen tube, takes up to 15 months to reach the archegonia (long engagement) Flowers consist of four sets of modified leaves on a shortened stem Sepals - protect floral parts in the bud Petals - attract pollinators Stamens - anthers and filaments Carpels - form the pistil (stigma, style, ovary) Edges of the leaf folded over and fused together to form a protective chamber Goethe’s “foliar theory of the carpel” is still the best hypothesis for explaining the evolution of the carpel Sporophylls are leaves modified to hold spores Carpels are leaves modified to hold seeds PART 5 Fungi are agriculturally important Many fungi are edible, some are delicious, like truffles and shitake Many fermented food products are made with fungi, such as fermented tofu, soy sauce, kim-chee, and saki (rice wine) Many fungi are serious agricultural pests, like the rusts and smuts Fungi are used in making many cheeses (Camembert, Roquefort) Many medically important fungi: Fungal diseases Yeast infections (ouch) Ringworm (caused by a fungus, not a worm) Histoplasmosis (fungal infection of lungs) Fungal antibiotics – penicillin, streptomycin Psychoactive drugs - ergot, fly agaric, psilocybin Psychoactive drugs - Amanita mushrooms (fly agaric) red with white spots Used for centuries by tribes in Siberia to induce visions Viking berserkers used Amanita to pump themselves up for plunder Psychoactive drugs - Psilocybe mushrooms Source of psilocybin Sacred mushroom used for thousands of years in Mexico,American southwest, Central and SouthAmerica Thought to reveal the future Primary planetary decomposers (together with bacteria) Only fungi can digest lignin (substance that gives wood its stiffness) Fungi are partners in important symbiotic relationships Lichens (mostlyAscomycota) Mycorrhizae – root fungi (mostly Glomeromycota) Phylum Ascomycota Importance Lichens weather rocks, secrete acids to dissolve rock so they can take root, makes opportunities for seeds and roots of plants Lichens are an important source of food for caribou (reindeer moss), musk ox, and other animals Sensitive to air pollution, so useful as ecological barometers Dutch Elm Disease – imported from Holland, devastated U.S. shade trees, elms nearly gone Chestnut blight wiped out most U.S. chestnuts, once one of the most common forest trees, attacked by fungus when tree matures Truffles - sell for up to $100 apiece! Form a mycorrhizal relationship with the roots of oaks and other trees Ergot fungus infects rye and other grains, especially in cold damp climates Used in Europe for centuries to induce labor Ergot poisoning changed the course of history - causes miscarriages in larger doses, changed Russian population patterns over a wide area Fatal in large doses, leads to convulsions, gangrene, and death - in 994 over 40,000 people died of ergot poisoning in France In small doses, caused very strange behavior in peasants eating rye bread (poor man’s wheat) – wild dancing, running naked through the streets, talking to invisible beings Natural source of d-lysergic acid diethylamide - LSD (Ergot fungus – Claviceps) Victims of ergotism were thought to be possessed by the devil Salem witch trials now thought to be the result of ergotism Many medically important ascomycetes – Penicillium, Aspergillus, Candida (yeast infection), athlete’s foot Most fungal pathogens are ascomycetes bryophtes bryophyta Ecological Importance Pioneer species on bare soil Retains moisture and nutrients in ecosystems Seed bed for higher plants Most abundant plant in polar ecosystems Peat bogs cover 1% of the Earth’s land surface, area = half the United States !! Peat bogs are very acidic, pH = 4 or lower, most acidic natural environment cranberries and blueberries grow Economic Importance Sphagnum moss is commercially important Compressed into peat, used for fuel Cotton absorbs 4-6 times its weight in water, but Sphagnum absorbs > 20 times its weight!! used for diapers enriching garden soil dressing wounds in war FernsAllies - Economic Importance Most of our modern coal deposits were formed by horsetails, club mosses, and other trees during the Carboniferous (end of the Paleozoic) Lycophytes are a sister group to ferns and other fern allies (monilophytes) Tropical species are mostly epiphytes (plants that grow on other plants) Temperate species grow in forest understory in small clusters Club mosses (Lycopodiales) are homosporous Selaginella and Isoetes are heterosporous Ferns are important in garden industry, florist trade Many herbal remedies derived from ferns Many fern species are edible (fiddleheads) Fern leaf blade is called a frond, leaflets are called pinnae Angiosperms - Economic Importance Food - fruits, vegetables, grains, nuts, spices fruit - from pistol vegetable - technically no such thing as a veggie Wood - homes, tools, ships… Oils and waxes - olive oil, perfumes, soap… Drugs - coffee, chocolate, wine, beer… Medicines - quinine, digitalis, codeine… PART 6 Problems: Can’t escape danger How to reach your mates? How to disperse your young? Solutions: Defend yourself (thorns etc.) Motile sperm Motile dispersal stage (spores, seeds) Problems: Tissues dry out Need moisture to exchange gases Can no longer rely on external fertilization in water Solutions: Develop a protective layer of epidermal cells – cuticle, bark, protect embryos (spores, seeds) and sexual structures Keep moist surfaces inside (breathing holes); cuticle with stomata/guard cells Internal fertilization, motile gametes *Spores and seeds keep embryos from drying out before they can germinate *Sexual structures encased in a jacket of protective cells to keep them from drying up - antheridia and archegonia Problem: You can no longer rely on the natural buoyancy of water Solutions: Root-shoot system of plants Roots anchor plants in the soil, shoots are stiffened stems - hold solar panels to the sky Stem stiffener is lignin, traces in fossil plants back to ~ 400 mya (Silurian) Waste products of photosynthesis? Oxygen and water! Complex metabolic chemistry of plants produces many toxic organic compounds, called secondary metabolites These secondary metabolites are mainly toxic to animals, but not to plants Plants have turned their metabolic wastes into a sophisticated chemical defense system Retain toxic compounds to keep animals from nibbling on them Many common drugs are plant byproducts, secondary compounds such as phenols and alkaloids Alkaloids include psychotropic drugs like mescaline Problems: Small organisms can rely on diffusion to move materials in and out Diffusion is too slow for large organisms, interior cells would starve or poison themselves in their own wastes Solutions: Be very thin or very flat - leaves are flat extensions of the epidermis = big surface area for photosynthesis Develop a vascular system - tubes to carry materials back and forth (xylem & phloem) Vascular plants are called tracheophytes (= tube plants) Drinking tubes called tracheids Found in earliest fossil land plants Angiosperms also have more advanced xylem cells called vessels All tracheophytes have tracheids (including angiosperms) Vessels found mostly in angiosperms, lacking in gymnosperms and more primitive plants Vessels probably evolved independently several times (gnetophytes ex.)
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