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Biology Exam #1
Chapter 22, 25-31
| Question | Answer |
|---|---|
| systematics | branch of bio that deals with naming and classification |
| what is one unifying concept in biology? | all life connected through evolutionary history - Tree of Life |
| phylogeny | description of evolutionary history among organisms |
| node | where lineages diverged |
| root | common ancestor on phylogenetic tree |
| Time is shown on which axis in a phylogenetic tree? | horizontal |
| taxon | designated species or group |
| clade | grouping including common ancestor & descendants |
| sister species/clades | two species/clades that are each other's closest relatives |
| homologies | features shared by 2 or more species derived from common ancestors |
| Example of homology? | vertebral column in vertebrates |
| derived trait | trait in descendant differing from ancestral form |
| ancestral trait | trait present in ancestral trait |
| synapomorphies | derived traits shared among a group seen as evidence of common ancestry |
| convergent evolution | independently evolved traits subjected to similar selection pressures |
| example of convergent evolution? | physical appearance of mantispid & preying mantis |
| example of synapomorphy? | hair in marsupial & placental mammals (shows that they are related) |
| homoplasy | character shared by set of species not present in common ancestor |
| examples of homoplasy? | wings of birds & bats evolution of eye |
| evolutionary reversal | character reverts from derived state back to ancestral state |
| example of evolutionary reversal? | re-emergence of teeth in lower jaw of frogs |
| what helps construction of phylogenetic trees? | synapomorphies |
| parsimony principle | simplest explanation of observed data is preferred - minimize number of evolutionary changes |
| Occam's razor | best explanation fits data with fewest assumptions |
| morphological data | physically observable data |
| limitations of morphology | doesn't take into account variation due to environment or lack of similarities b/w distantly related species |
| example of development pattern? | notochord in sea squirts & vertebrates |
| paleontology | fossils can provide info on morphology, time, & place of past organisms |
| limitations of paleontology | -fossil record is fragmentary & missing for some groups -organisms decompose quickly after death -geologic processes transform & destroy rocks |
| what is morphology good for? | analyzing closely related species |
| what is paleontology good for? | determining derived & ancestral traits seeing where lineages diverged |
| why is behavior not necessarily a good reference for phylogenetic trees? | some behavior is learned & not inherited |
| what molecular data is used to construct phylogenetic trees? | DNA sequences |
| maximum likelihood | probability of observed data evolving on tree |
| what was the effect of incorporating mathematical models into constructing phylogenetic trees? | accelerated revision of taxonomic trees |
| give an example of using molecular data to construct a phylogeny of plants | ribosomal DNA used to see evolution of using selfing (self compatibility) to reproduce as opposed to outcrossing (ancestral state) |
| sensory exploitation hypothesis | preexisting bias of female sensory system before certain traits even evolved (sexual selection) |
| give example of sexual selection | female platyfish preferred males with artificial swords -> led to evolution of male swordtails |
| give example of how phylogenetic methods can help reconstruct amino acid sequences | opsin pigment protein in ancestral archosaur |
| what is used to help biologists determine timing of evolutionary splits? | molecular clocks |
| molecular clock hypothesis | rates of molecular change are constant enough to predict timing of evolutionary divergence |
| how are molecular clocks calibrated? | using independent data (e.g. fossil records, known divergences, biogeographic dates) |
| example of how molecular clocks have been used | determining when HIV-1 emerged |
| who came up with the biological classification system? | Carolus Linnaeus |
| what does the biological classification system invented by Linnaeus consist of? | binomial naming system - genus + species |
| taxonomic hierarchy (8) | Domain Kingdom Phylum Class Order Family Genus Species |
| monophyletic | clade of ancestral species & descendents |
| polyphyletic | group not including common ancestor |
| paraphyletic | group not including all descendants of common ancestor |
| which of the 3 classifications is considered acceptable? | monophyletic |
| phylogenetic trees are _________ about evolutionary relationships...what does this mean? | hypotheses; subject to change |
| where is Earth's history recorded? | strata of rocks |
| radioisotopes | determine actual age of rock due to its predictable decay pattern |
| half-life | time interval over which 1/2 remaining radioisotope decays & changes into another element |
| ratio of 14C:12C | stays constant while organism is alive & decreases after it dies |
| what time period is 14C used for? | fossils up to 60,000 years |
| which radioisotopes are used for older fossils? | 234U (500,000), 238U (4.5 billion), 40K (4.5 billion) in igneous rocks |
| why can't sedimentary rocks be dated accurately? | materials in rocks existed for varying lengths of time |
| order of eras(2) | Precambrian, Paleozoic, Mesozoic, Cenozoic |
| periods of Precambrian (3) | Hadean, Archean, Proterozoic |
| periods of Paleozoic (6) | Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian |
| periods of Mesozoic (3) | Triassic, Jurassic, Cretaceous |
| periods of Cenozoic (2) | Tertiary, Quaternary |
| plate tectonics | idea that land masses have moved over time |
| lithosphere | Earth's crust made of solid plates |
| magma | fluid layer of liquid rock that plates float on |
| how is magma circulated? | heat from radioactive decay in Earth's core creates convection currents |
| continental drift | movement of plates |
| effects of continental drift (3) | -forming mountain ranges & deep rift valleys/trenches -biodiversity -influences climate, sea levels, oceans |
| how was O2 introduced? | bacteria used H2O as source of H+ in photosynthesis making O2 as a waste product |
| what was the evidence for O2? | cyanobacteria formed stromatolites found in fossil records and oceans today |
| O2 allowed for __________ reactions to __________________ | oxidation; synthesize ATP |
| advantages of aerobic metabolism? | faster and more energy harvested |
| effects of more O2? | -larger & more complex cells -750 mya -> multicellular organisms |
| when & why did O2 levels increase later? | Carboniferous & Permian periods; large vascular plants |
| how are coal deposits formed? | extensive burial of plant debris in swamps where organic material was not decomposing |
| when did O2 levels drop & why? | Permian period; drying of swamps |
| evidence of large meteorite collisons | large craters & disfigured rocks with He & Ar isotope ratios characteristic of meteorites |
| when did life first evolve? | 3.8 bya in Archean period |
| when/in which period did eukaryotes evolve? | 1.5 bya in Proteozoic period |
| biota | all life |
| flora | plants |
| fauna | animals |
| where does fossilization occur? | anaerobic sites where decomposition is slow |
| large number of fossils are..? | marine organisms with hard shells/skeletons & insects |
| fossils most abundant for species that are..? | -long living -with hard shells/skeletons -widely distributed |
| which organisms are not likely to represented in fossils? | -soft bodied -short lived -locally distributed |
| Precambrian era | -Hadean -> life microscopic/prokaryotic -Archean -> eukaryotes evolved -Proterozoic -> multicellular, soft-bodied animals |
| Cambrian period | -O2 approaching modern levels -Gondwana formed -Cambrian explosion |
| Ordovician period | -radiation of marine organisms -glaciers -> low sea levels -> mass extinction |
| Silurian period | -marine life -vascular plants -terrestrial arthropods |
| Devonian period | -Laurasia & Gondwana move towards each other -evolutionary radiations of corals & cephalopods -plants with roots accelerated weathering & soil -ancestors of gymnosperms -amphibians -meteorite impact -> mass extinction -> loss of 75% of marine animals |
| Carboniferous period | -large glaciers -swamp forests (tree ferns & horsetails) -terrestrial animals diversified -winged insects -insect herbivores -amphibians split from amniotes |
| amniotes | vertebrates with well-protected eggs that can be laid in dry places |
| Permian period | -Pangaea -reptiles split from amniotes -> mammals -ray finned fishes -volcanic eruptions -> ash blocked sun -> climate cooling -> glaciers -O2 levels dropped -> greatest mass extinction |
| Mesozoic era | -continents drifted -sea levels rose -phytoplankton emerged -> coccolithophores, dinoflagellates, diatoms -new seed plants -biota provincialized |
| Triassic period | -Pangaea breaks apart -conifers -radiation of reptiles -meteorite impact -> mass extinction |
| Jurassic period | -Laurasia & Gondwana -ray finned fishes radiated -lizards, pterosaurs, dinosaurs -mammals -flowering plants |
| Cretaceous period | -continuous sea -warm & humid -dinosaurs diversified -meteorite -> mass extinction of large animals & insects |
| Cenozoic era | -today's continents -radiation of mammals -flowering plants dominated -symbiotic associations between plants and N-fixing bacteria |
| Tertiary period | -herbaceous forms -large all-animal radiation |
| Quaternary period | -Pleistocene -> climate cooling, ice ages -Holocene -> hominid evolution & radiation |
| 3 great evolutionary radiations | -Cambrian explosion -Paleozoic fauna -Modern fauna in Triassic |
| 5 extinctions & why | -Ordovician -> glaciers -Devonian -> meteorite -Permian (greatest) -> low O2 -Triassic -> meteorite -Cretaceous (big animals & insects) -> meteorite |
| when did prokaryotes appear? | 3.5 bya |
| key roles of prokaryotes (4) | -organic breakdown -nutrient cycling -diseases -bioremediation |
| 3 main differences b/w prokaryotes & eukaryotes | -no cytoskeleton & nucleus -DNA circular with 1 chromosome -no membrane-enclosed organelles |
| what were the 3 domains & how were they organized? | bacteria, archaea, eukarya differences in rRNA |
| which 2 domains are more closely related? | archaea & eukarya |
| lateral gene transfer | genes from one species incorporated in another |
| how does lateral gene transfer work? | transfer by plasmids/virus, uptake of DNA through transformation |
| which genes not likely to undergo lateral gene transfer? | ones that are adapted with higher fitness |
| how do scientists study prokaryotes? | collecting random samples from environment |
| three shapes in bacteria | sphere/coccus. rods, helical |
| shapes for archaea? | random, lots of diversity |
| cell walls of bacteria made of? | peptidoglycan |
| cell walls of archaea? | pseudopeptidoglycan |
| 2 types of gram stain | (+) thick layer of peptidoglycan (purple) (-) thin layer of peptidoglycan (red) |
| thermophiles | early bacteria/archaea, heat lovers |
| spirochetes | -gram (-) -chemoheterotropic -axial filaments that rotate -human parasites/pathogens/free-living -e.g. Leptospiru |
| chlamydias | -gram (-) -all parasites -life cycle has 2 forms: elementary/reticulate -some pathogens |
| high-GC gram (+) | -high G-C/A-T ratio -branching filaments -some antibiotics -e.g. Mycobacterium tuberculosis, Streptomyces |
| cyanobacteria | -photoautotrophs -polluted waters -some heterocysts (fix N) -e.g. Anabaena |
| low-GC gram (+)/firmicutes | -low GC/AT ratio -both gram (+) & (-)/no cell wall -e.g. Mycoplasmas, Staphylococcus, anthrax, botulism -some produce endospores (heat resistant) |
| proteobacteria | -purple -largest group -some fix N (e.g. Rhizobium) -e.g. E. coli -some human pathogens (e.g. plague, cholera, Salmonella) -ancestor photoautotrophic |
| where do most archaea live? | extreme environments |
| two groups of archaea | Euryarcheota & Crenarcheota |
| two characteristics of archaea | -no peptidoglycan -distinct lipid composition of cell membrane (monolayers & bilayers) |
| what connects membrane of bacteria & eukaryotes? | ester linkages |
| what connects membrane of archaea? | ether linkages (synapomorphy) |
| crenoarcheota | -thermophilic -acidophilic -e.g. Sulfolobus, Ferroplasma |
| euryarcheota | -some methanogens -some extreme halophiles (pink) -e.g. Thermoplasma (no cell wall, aerobic metabolism, coal deposits) |
| methanogens | -produce methane -reduce CO2 -increased by cattle farming & growing rice |
| two types of anaerobes | -obligate anaerobes (oxygen will kill) -facultative anaerobes (switch between aerobic & anaerobic) |
| photoautotrophs | -photosynthesis -e.g. Cyanobacteria -bacteriochlorophyll (no O2, live under algae) -some use H2S & produce sulfur |
| photoheterotrophs | -use light -get carbon from organic compounds made by others -e.g. purple nonsulfur bacteria |
| chemolithotrophs/chemoautotrophs | -oxidizes inorganic substances -fixes CO2 -archaea -e.g. deep-sea hydrothermal vent ecosystems oxidize H2S |
| chemoheterotrophs | -get energy & carbon from organic compounds |
| biofilm | gel-like polysaccharide matrix used for protection |
| how do prokaryotes communicate? | chemical signals |
| quorum sensing | -monitor size of population -secrete biofilm when reached |
| bioluminescence | -emit light when quorum has been sensed -e.g. Vibrio |
| decomposers | metabolize dead organic matter & return CO2 |
| 2 characteristics of pathogenic prokaryotes | -invasiveness - ability to multiply (e.g. anthrax) -toxigenicity - ability to produce toxins (e.g. diptheria) |
| 2 types of bacterial toxins | -endotoxins - lipopolysaccharides released when gram (-) bacteria grow/lyse (e.g. Salmonella, Escherichia) -exotoxins - soluble proteins that are highly toxic/fatal (e.g. tetanus, botulism, cholera, plague, anthrax) |
| why is "prokaryote" controversial? | it says what it's not & not what is is |
| what is the phylogeny of the protists? | paraphyletic |
| another name for unicellular protists | microbial eukaryotes |
| how did eukaryotes appear? (5) | -flexible cell surface (surface area increases & allows for endocytosis & growth) -cytoskeleton -nuclear envelope -digestive vacuoles -organelles |
| endosymbiotic theory | -phagocytic eukaryotes -mitochondria detoxify O2 |
| primary endosymbiosis | chloroplasts descended from gram (-) cyanobacterium |
| evidence for primary endosymbiosis | -peptidoglycan in glaucophytes -chloroplasts in red algae retain some original pigments |
| secondary endosymbiosis | -uptake of chloroplast containing cell -e.g. euglenid |
| plankton/phytoplankton | free-floating aquatic organisms/photosynthetic |
| 2 categories of protists | protozoans - ingestive heterotrophs algae - photosynthetic protists |
| alveolates | -unicellular -most photosynthetic -synapomorphy = alveoli |
| 3 groups of alveolates | -apicomplexans (parasites, e.g. Plasmodium) -dinoflagellates (free-living, e.g. red tides, endosymbionts in corals/coral bleaching) -ciliates (2 types of nuclei, e.g. Paramecium, Trichocysts) |
| stramenopiles | -common marine/freshwater algae -synapomorphy = 2 flagella with rows of tubular hair on longer one |
| 3 clades of stramenopiles | -diatoms (dish-like silica, primary producers, symmetrical, both reproductions) -brown algae (multicellular, marine, attaches using holdfast/alginic acid, e.g. fucoxanthin, Sargassum) -oomycetes (molds/mildews, nonphotosynthetic, diploid, saprobic) |
| rhizaria | -unicellular -aquatic -amoeboid -pseudopodia |
| 3 clades of rhizaria | -cercozoans (amoeboid & flagellated, freshwater & marine) -foraminiferans (shells of CaCO4, pseudopods, marine, calcium deposits e.g. Dover) -radiolarians (glassy internal endoskeleton, ornate, marine, thin pseudopods) |
| excavates | -all single celled -not photosynthetic except Euglenids -diplomonads & parabasalids don't have mitochondria (derived) -kinetoplastids medically important |
| 5 groups of excavates | diplomonads, parabasalids, heteroloboseans, euglenids, kinetoplastids |
| diplomonads | -unicellular -lack mitochondria -parasitic -e.g. Giardia lamblia (intestinal disease) |
| parabasalids | -unicellular -lack mitchondria -undulating membranes for locomotion -e.g. Trichomonas vaginalis |
| heteroloboseans | -amoeboid & flagellated -e.g. Naegleria gruberi |
| euglenids | -unicellular -flagellated -reproduce asexually -autotrophic & heterotrophic -free-living |
| kinetoplastids | -unicellular -2 flagella -1 mitochondrion with kinetoplast -all symbiotic -some pathogenic (Trypanosomes, Leishmaniasis) -change cell surface molecules frequently |
| amoebozoans | -amoeboid -pseudopods for locomotion |
| 3 groups of amoebozoans | -loboseans -plasmodial slime molds -cellular slime molds |
| plasmodial slime molds | -coenocytes (diploid)/plasmodium -move by cytoplasmic streaming -endocytosis -sclerotium when unfavorable -fruiting structures/swarm cells |
| loboseans | -unicellular -independent -phagocytosis -diverse lifestyle -e.g. Entamoeba histolytica |
| cellular slime molds | -myxamoebas (haploid) -endocytosis to feed -fission to reproduce -slug/pseudoplasmodium when unfavorable & fruiting bodies -can also sexually reproduce |
| phytoplankton | -primary producers in oceans -majority are diatoms |
| synapomorphy for plants | chloroplasts |
| synapomorphy for green plants | chlorophyll b & starch |
| synapomorphy for land plants | development from embryo protected by tissues |
| glaucophytes | -sister group to plantae -contain peptidoglycan in membrane |
| red algae | -multicellular -contain phycoerythrin pigment (deeper = redder) -marine -uses holdfast |
| chlorophytes | -largest group of green algae -aquatic -great diversity -e.g. Volvox, Ulva lactuca |
| coleochaetophytes | -retain eggs of parental organisms |
| stoneworts | -retain eggs of parental organisms -synapomorphy = branched, apical growth form -share characteristics with land plants |
| land plants/embryophytes | -synapomorphy = embryo -larger plants needed to transport water, support, disperse gametes -life cycle with alternation of generations |
| characteristics of land plants (7) | -cuticle -stomata -gametangia (prevent gamete drying) -embryos -pigments (protect from UV) -thick spore walls -mutualistic relationships with mycorrhizal fungi help nutrient uptake |
| alternation of generations | -multicellular diploid = sporophyte -multicellular haploid = gametophyte -mitosis -> gametes -> diploid zygote -meiosis -> spores -> haploid |
| moss life cycle | -cells in sporangium undergo meiosis -> haploid spores -mitosis -> spores develop into haploid gametophyte/protonema -> archegonium (F) & antheridium (M) -gametes fuse -> zygote -> sporophyte |
| reduction of gametophyte generation | -nonvascular = gametophyte longer -sporophyte dependent on gametophyte |
| which came first? nonvascular or vascular? | nonvascular |
| nonvascular land plants | -lack true plant structures -live in moist habitats -uses diffusion -water needed for reproduction |
| 3 types of nonvascular plants | -liverworts (leafy & thalloid, short, reproduce asexually by fragmentation/gemmae) -mosses/bryophytes (stomata, no lignin, grow by apical cell division, e.g. Sphagnum) -hornworts (single chloroplast, no stalk for sporophyte but basal region) |
| synapomorphy for vascular plants | vascular system to transport water & food |
| 2 tissue types for vascular system | -xylem (conducts water & minerals from soil to plant, has lignin) -phloem (photosynthesis products) |
| tracheid | -principal water-conducting elements of xylem -allowed for growth & spore dispersal |
| Rhyniophytes | -simple vascular system -dichotomous branching -lacked leaves & roots |
| branching system of sporophytes | -anchored by rhizomes & rhizoids -branching, independent sporophyte |
| 3 types of lycophytes | -club mosses, spke mosses, quillworts -sister group to vascular plants |
| lycophytes | -dichotomous branching -microphylls (simple leaf-like structures) -dominant during Carboniferous -e.g. Lepidodendron/canned coal |
| 2 types of monilophytes | -horsetails -ferns |
| horsetails | -Equisetum -silica in cell walls -true roots -sporangia on sporangiophore -reduced megaphylls & grow in whorls |
| ferns | -one cell thick -terrestrial & some aquatic -sporophytes large & long -moist habitats (need water) -sporangia on sori under leaves -leaf starts as fiddlehead |
| fern life cycle | -spore mother cells -> haploid spores (meiosis) -gametophytes -> antheridia & archegonia -zygote -> independent sporophyte |
| clade of monilophytes & seed plants & its synapomorphy | Euphyllophytes; overtopping growth for light (allowed megaphylls to evolve) |
| which period did land plants flourish? | Carboniferous |
| Fungi | -evolved from unicellular protists w/ flagellum -synapomorphies= absorptive heterotrophy and chitin in cell walls |
| Saprobes | absorb C & nutrients directly from dead organic material (typical of fungi) |
| Mutualists | both partners benefit (some fungi are these) |
| Some fungi are PREDATORY | trap microscopic protists and animals (use sticky secretion or constricting ring to catch passing organisms and nematodes respectively) |
| Chitin | -used for structural support -fungi have this but usually lack cellulose -also found in arthropods |
| Are fungi primitive | NO. approx. 100,000 species known, but number could actually be 1.5 M (30% are parasitic) |
| Components of a fungus? | -Mycelium (body composed of hyphae) -Hyphae (tubular filaments that contain chitin and responsible for reproduction) |
| Different types of hyphae among fungi | -Septate hyphae (separated by incomplete cross walls or septa with pores) -coenocytic (lack septa, multiple nuclei) -haustoria (nutrient absorbing hyphal tips that penetrate host cells w/o breaking them/ found in parasites) |
| Fungal mycelia | Large surface area-to-volume ratio -good for absorptive nutrition -high water loss -hyphae can grow 1 km per day |
| Rhizoids | modified hyphae for anchoring |
| Saprobic fungi | -decomposers of the Earth -return C to air as respiratory CO2 -contributes to soil formation & recycling of nutrient elements |
| Parasitic fungi | Facultative (can grow on other organisms but also on own) and obligate (grow only on specific host species) |
| How do parasitic fungi function? | -invade plants or insects by finding an opening or using haustoria -some are pathogenic (kill or sicken host species) |
| Difference b/w symbiotic and mutualistic relationship? | symbiotic- permanent relationship b/w 2 species mutualistic- relationship in which both benefit |
| Lichens | mutualistic relationship between fungus and photosynthetic organism (most are ascomycetes and around 30,000 species) |
| Details on lichens | -fungi get fixed C from the photosynthetic cells -some inhabit extreme environments -sensitive to toxic compounds |
| Mycorrhizae | -fungal relationship b/w plant roots and fungal hyphae -ectomycorrhizae (wrap around and penetrate soil around plant roots) -arbuscular mycorrhizae (hyphae penetrate cell wall of plant roots but not plasma membrane) |
| Why are mycorrhizae important? | -they increase water and nutrient (like N) uptake -protect plants against disease organisms -evolution of these essential for plant colonization of land |
| Six major fungal groups? | Microsporidias, chytrids, Zygospore fungi, arbuscular mycorrhizal fungi, sac fungi, and club fungi |
| Dafug is Dikarya? | Monophyletic group comprised of ascomycota (sac fungi) and basidiomycota (club fungi) |
| Microsporidia | -intracellular parasites of animals -1500 species -among smallest eukaryotes -polar tube used to infect hosts -lack true mitochondria but have mitosomes -parasitic n nature |
| Chytrids | -mostly aquatic and microscopic -zoospores & gametes have flagella - <1000 species -sexual & asexual -NO dikaryon phase -Chytridiomycosis- disease in amphibians, affects 30% of world's amphibians |
| Zygospore fungi | -Reproduction=unicellular zygospore w/ many diploid nuclei -coenocytic hyphae -this and after are terrestrial and don't require water for fertilization-black bread mold -no fleshy fruiting body -parasites of spiders & insects/mutualists with other fungi |
| Arbuscular mycorrhizal fungi | -form arbuscular mycorrhizae in plant roots -only asexual species are known - <200 species but very common -Coenocytic hyphae -glucose for NRG - |
| Sac Fungi (ascomycota) | -Septate hyphae -some are filamentous (reproduce asex. by conidia) -Dikaryon -sexual reproductive saclike structure (ascus) contains haploid ascospores |
| Club fungi (Basidiomycota) | -Septate hyphae -30,000 species -Dikaryon -Dikaryon phase can last centuries -Sexual Reproductive structure=basidium (supports haploid basidiospores and site of nuclear fusion/meiosis) |
| Different ways of fungal asexual reproduction | -production of haploid spore w/i Sporangia -production of haploid spores at tips of hyphae called Conidia -cell division by unicellular fungi: Fission (equal division) and Budding (unequal) -Conidia give molds their color -Breakage of the mycelium |
| Sexual reproduction in Fungi | It is rare/unknown and happens between different mating types (genetically but not physically different) |
| Plasmogamy | when hyphae of different mating types meet and fuse cytoplasms, but not nuclei |
| Sexual reproduction cycle | Plasmogamy>Dikaryotic Stage>Karyogamy>Zygote forms>Meiosis>Mitosis |
| Two types of Ascomycota (sac fungi) | Euascomycetes: -cup fungi (truffles) -ergot, mildews, and molds -asci in a fruiting body called an ascocarp Hemiascoycetes: -no ascocarp -most unicellular (i.e. yeasts) |
| Mold | -fast growing, asexual fungus -used for antibiotics & cheese -"imperfect fungus" b/c only asexual |
| Yeast | -unicellular zygomycetes, ascomycetes, and basidiomycetes -refers to a lifestyle, not a taxonomic group |
| Lichens | -about 15,000 known species -found in ascomycetes & basidiomycetes |
| Why use fungi as model organisms? | -easily cultured -short generation time -small genome |
| Characteristics of an animal? | -multicellular, heterotrophic, eukaryotes -use proteins (i.e. collagen) instead of cell walls -specialized nervous/muscle tissue -most reproduce sexually -embryo develops from a zygote and many undergo a larval stage |
| Synapomorphies of animals | -collagen and proteoglycans in cell wall -unique cell junctions: tight junctions, desmosomes, gap junctions -Hox genes - |
| Ancestor of animal clade? | colonial, flagellated protist similar to choanoflagellates |
| Cleavage :D | first few divisions of a zygote |
| types of cleavage | Radial cleavage- zygote and descendant cells divide completely & evenly (ancestral for animals except sponges) Spiral- complex, derived for of radial cleavage Incomplete cleavage- dividing cells form an embryo on top of a yolk mass (found in reptiles) |
| Types of cell layers in early development of animals | Diploblastic: 2 cell layers- endoderm and ectoderm (ancestral) Triploblastic: 3 cell layers- ecto-, endo-, and mesoderm |
| What's a blastopore? | The indent on a hollow ball one cell thick. It is a result of gastrulation. |
| Development patterns for triploblastic animals | -Protostomes: mouth develops first -Deuterostomes: anus then mouth develops |
| Five key features of animal body plan | -symmetry -body cavity structure -segmentation -external appendages -development of nervous system |
| Common symmetries in animals | -Radial symmetry (one main axis around which body parts are rearranged) -Bilateral symmetry (can be divided into mirror image halves on one plane) |
| Bilateral symmetry | -runs anterior to posterior -also divided into dorsal (top) and ventral (bottom) |
| Cephalization | concentration of sensory organs and nervous tissue at anterior (head) end (evolutionarily favored) |
| Three basic body plans of animals | Acoelomate, Pseudocoelomate, coelomate |
| Acoelomate | -no fluid filled body cavity -space filled with mesenchyme -movement by cilia |
| Pseudocoelomate | -fluid-filled body cavity called pseudo cell -muscles only on the outside |
| Coelomate | -body cavity is a coelom -lined with peritoneum -more control of movement of fluids |
| Purpose of body cavities | -act as hydrostatic skeletons -muscle contractions move fluid - |
| Purpose of segmentation | -facilitates specialization of body regions -allows animals to alter body shape& control movements |
| Purpose of appendages | -allows locomotion (essential for finding food/mates & avoiding predators) -useful in catching prey, reproduction, and sensing environment |
| Nervous systems | Sponges have none, jellyfish have nerve nets, and most have central nervous system (controls muscle coordination and sensory info) |
| Animal feeding types | Sessile (stationary and make food come to you) and Motile (moving throughout environment to catch food) |
| Animal Feeding Strategies | Filter feeders, herbivores, predators, parasites, and omnivores |
| Larva | immature stage that differs from the adult and typically undergoes metamorphosis |
| Sessile marine animal larvae | Many sessile marine animals have a radially symmetrical larvae called a trochophore. Others have a bilaterally symmetrical larva called a nauplius. |
| Dispersal | Movement of organisms from parents or population |
| Life cycle tradeoffs | characteristics in one life stage that improve performance in one activity but reduce it in another activity (i.e. NRG for building a shell can't be used for growth) |
| Reproductive Trade-offs | Female produce many small eggs w/ small NRG stores or few large eggs w/ large NRG stores |
| Different incubation periods in birds | -in some, young are helpless when hatched (Altricial) and must be cared for -those with longer incubation periods, hatchings can forage right away (Precocial) think of them as awkward vs. precocious |
| Bilaterians | -Large monophyletic group -synapomorphies: all tripoblastic, at least HOX genes, and bilateral symmetry |
| Non-bilaterians | Sponges (simplest animals, no differentiated tissue) and eumetazoans (i.e. ctenophores placozoans) |
| Sponges | -approx. 8500 species -have skeletal systems called spicules |
| 3 groups of sponges | -Glass sponges and desmosponges have spicules of silicon dioxide -Calcerous sponges have spicules of calcium carbonate |
| More on sponges (cuz they're sooo fucking interesting...) | -filter feeders that using flagella called choanocytes that help them catch food -most are marine -reproduce asexually by budding or fragmentation and sexually by letting water transport sperm |
| Ctenophores | -approx. 250 species -diploblastic -mesoglea separates two cell layers -have ctenes (comb-like rows of cilia, used for locomotion) - |
| Placozoans | -simple w/ few cell types -no mouth/gut/nervous system -adheres to aquaria walls -swimming pelagic stage recently discovered |
| Cnidarians | -approx. 12,500 species -jellyfish, corals, anemones -gut is a blind sac called gastrovascular cavity -diploblastic -tentacles have specialized cells called nematocysts that inject toxins |
| Cnidarian life cycle | -dominated by diploid part -sessile polyp stage (stalk attaches to substrate) -Motile medusa stage (free-swimming and produces gametes) -egg develops into a free-swimming planula that grows into polyp |
| 3 major clades of cnidarians | Anthozoans, Scyphozoans, and Hydrozoans |
| Anthozoans | -include sea anemones (all solitary), sea pens (colonial w/ anchoring and feeding polyps), and coral (have photosynthetic dinoflagellates as endosymbionts) |
| Scyphozoans | -jellyfish -medusa stage dominates -egg becomes planula that turns into polyp that buds off small medusae |
| Hydrozoans | -either dominant polyps or only medusa stage -most are colonial -some polyps only for feeding/others develop into polyps |
| New research of Ctenophores?!?!? | suggests they may be placed at base of animal tree!!!! |
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Tiffanyy
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