EBIO 1010: Final Exam Study Guide. Taxonomic Key. Practice Test. pdf version.
EBIO 1010: Final Exam Study Guide. Taxonomic Key. Practice Test. pdf version. EBIO 1010-02
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EBIO 1010 Final Exam Study Guide… woohoo you made it!!! Origin of Life Know the key characteristics and the origination of eukaryotes The earth is approximately 4.6 billion years old o Early atmosphere had high CO2 levels. Lacked oxygen gas. • So where did life come from? Emerged between 3.8 and 3.0 BYA o Hypothesis 1: life originated in seas due to organic molecules assembling to form a functional, independent unit o Hypothesis 2: extraterrestrial origin??? Meteorites with organic compounds brought life to earth • Primitive organisms may have been autotrophicà they produced their own food/energy • Shifts in climate (temperature and water availability) has led to multiple mass extinctions Life changes the planet • Photosynthesis changed Co2 into O2 which provided an environment for evolution of cellular respiration • All life originated from single celled organisms and evolved into 3 domains: o Eubacteria- “true” bacteria o Archaea- extremophiles. Oldest form of life o Eukarya- complex, most multicellular Eukaryotic Characteristics: • Compartmentalization o Allows for increased subcellular specializationà physical separation of transcription and translation adds additional levels of gene expression o Golgi apparatus and endoplasmic reticulum facilitate intracellular transport o Nuclear membrane allows for additional levels of control of transcription and translation o Mitochondria and chloroplasts (energy producing organelles) entered early eukaryotic cells by endosymbiosisà mitochondria were originally an independent organism living in symbiosis with the cells • Multicellularity o Allows for specialization of cells into tissues • Sexual reproduction o Allows for greater genetic diversity o Meiosis creates new combinations of genes o First eukaryotes were probably haploid Sexual reproduction and meiosis Understand that genetic variation is essential for evolution to occur Know that genetic variation results from mutations, genetic recombination during meiosis, and recombination in reproduction Learn the process of meiosis Know how the outcome of meiosis differs from mitosis Variation • Natural selection depends on variation • New variations are constantly generated by mutations o Replenish genetic variability that is constantly being reduced by natural selection • Individuals with adaptive variations are more likely to survive and reproduce, thus, passing on its successful genes to their descendants • Variation is a result of: o Mutations- random alternations in genetic information o Genetic recombination during meiosis- aka “crossing over” o Recombination in reproduction- creating an incredible number of new beings from a relatively small number of alleles Meiosis • Meiosis reduces the chromosome number of gametes from 2n to n (diploid to haploid) • Objective is to turn one diploid cell into four haploid daughter cells (gametes) • 2 complete cell divisions o Meiosis 1à reduce chromosome numbers o Meiosis 2à mitosis Mitosis • The object is to make two identical diploid daughter cells Darwin and Mendel Know that Darwin hypothesized that evolution occurred via natural selection Learn the three conditions for natural selection to occur Darwin • Rejected the idea of a divine plan behind nature… believed instead that adaptation resulted from ordinary laws of nature o Evolution must be tied to variation • Species were really just a local group of individuals, all of whom varied from one another in certain ways • In every natural population, some varieties must be better equipped to prevail in the struggle for existence • Realized that evolution was a selective process, what he called natural selection o Case study: Galapagos Finches 3 Conditions for natural selection to occur and to result in evolutionary change: 1. Variations must exist among individuals in a population 2. Variation among individuals must result in differences in the number of offspring surviving in the next generation 3. Variation must be genetically inherited Genetic Variation and Evolution • Genetic variation o Differences in alleles of genes found within individuals in a population o Raw material for natural selection • Evolution o How an entity changes through time o Development of modern concept traced to Darwin § “Descent with modification” Population genetics and selection Know that natural selection is not the only agent of evolutionary change Terms to Understand • Homozygote – having identical alleles for the same gene (AA or aa) • Heterozygote – having different alleles for the same gene (Aa) • Genotype – genetic information that constitutes a trait • Phenotype – physical appearance that results from expression of the genotype • Allele – alternative state of a gene Mutation: • Rates generally low • Other evolutionary processes usually more important in changing allele frequency • Ultimate source of genetic variation because it is the only process to make new alleles and genes • Makes evolution possible Gene Flow: • Movement of alleles from one population to another • Very powerful agent of evolutionary change • Animal physically moves • Mating of individuals from adjacent populations Genetic Drift: in small populations, allele frequency may change by chance alone • Founder Effect o Alters allele frequencies in small populations § Small number of individuals drifts to an area far away from the population. This group may not possess all the alleles of the parent population § Can lead to the loss of alleles in isolated populations • Bottleneck Effect o If organisms do not move from place to place, their populations may be drastically reduced due to extreme change in environment (i.e. flood, drought, disease) o Survivors may constitute a random genetic sample of the original population o This results in a loss of genetic variability Disruptive selection • Acts to eliminate intermediate types Directional selection • Acts to eliminate one extreme • Often occurs in nature when environment changes Stabilizing selection • Acts to eliminate both extremes • Makes intermediate more common Evidence for evolution and speciation Differentiate convergent and divergent evolution Contrast allopatric and sympatric speciation Evidence for evolution: • Comparative Anatomy • Fossil Record • Embryology • Biogeography • Biodiversity • Molecular Evolution Convergent Evolution • Two unrelated lineages converge on a common solution to an evolutionary problem o i.e. both bats and butterflies are able to fly, but did not descend from a common flying ancestor from whom they inherited this trait Divergent Evolution • When homologous structures are derived from common ancestor o i.e., we, as humans, have similar hand-bone structure to whales and bats, but they are evolved to be used for different things (swimming, flying, and grabbing) Sympatric speciation: species that occur together in an area • Definition: o Are distinctive entities o Are phenotypically different o Utilize different parts of the habitat o Behave separately • Sympatric speciation may occur over the course of multiple generations through disruptive selection o Cause a population to contain individuals exhibiting two different phenotypes o Could evolve into two species over many generations o Two phenotypes would have to evolve reproductive isolating mechanisms • Character displacement: • During sympatric speciation, natural selection favors those individuals of each species that use resources not used by the other species (i.e. to reduce competition) o Greater fitness o Trait differences in resource use will increase in frequency over time o Species will diverge Allopatric speciation: species do not have overlapping ranges… separated by a river or mountain range or one species develops on an island Adaptive Radiations • Closely related species that have recently evolved from a common ancestor by adapting to different parts of the environment • Key innovation (new trait) evolves within a species allowing it to use resources that were previously inaccessible • Requires both speciation and adaptation to different habitats • Can occur in sympathy or allopatry Prokaryotes and Protists Understand that prokaryotes are simple unicellular organisms Know why bacteria are important to ecosystems and humans Understand the difference between an autotroph and a heterotroph Prokaryotes: • Bacteria and Archaea (extremophiles) • Primitive cells, unicellular (nearly all) • Lack a cell nucleus- no nuclear membrane around chromosomes (prokaryote = before nucleus) • Lack cellular organelles bound by membranes (no chloroplasts, no mitochondria, etc…) • Most have a single circular chromosome • Divide by binary fission (not mitosis) Importance of bacteria • Created original oxygen atmosphere - ancient cyanobacteria • Critical in decomposition of organic matter - bacteria and fungi are the planetary recyclers • Support many food chains • Nitrogen fixation - turn atmospheric nitrogen (N ) 2nto a form that plants can use (NH 3 ammonium) o Cyanobacteria have heterocysts - enlarged structure where nitrogen fixation takes place • Make many common food products - yogurt, pickles, many types of cheeses - no bacteria, NO PIZZA !! • Remove pollutants from water, soil, air o Biostimulationà adds nutrients to encourage growth of naturally occurring microbes • Causes both epidemics and cures for medical issues Autotroph: creates own energy/food • Algae is an autotrophic protest because it is photosynthetic • Origin for all land plants Heterotroph: must eat/absorb energy from another source Introduction to Animalia and Phylum Porifera (sponges) Know what a body cavity is and how the coelom develops Understand deep divisions within Kingdom Animalia and be able to differentiate between Protostomes and Deuterostomes Body cavity→ the coelom. Protects organs and allows for specialization of organs • Acoelomates: no body cavity • Pseudocoelomates: body cavity between mesoderm and endoderm called the pseudocoelom • Coelomates: body cavity entirely within the mesoderm, called the coelom o Leads to open and closed circulatory systems to flow nutrients into and remove wastes out of the body Protostomes (first mouth) develop the mouth first from or near the blastopore. Anus (if present) develops either from blastopore or another region of embryo • Cells grow spirally • Cells are determinant Deuterostomes (second mouth) develop the anus first from the blastopore. Mouth develops later from another region of the embryo. • Cells grow radially • Cells are not determinant (i.e. stem cells) *see taxonomic key for deep divisions Phyla Cnidaria and Ctenophora Know characteristics of Cnidaria and Ctenophora Phylum Cnidaria Major evolutionary innovation : extracellular digestion of food inside of the animal • Digestion takes place partly in gastrovascular cavi ty • Cells then engulf fragments by phagocytosis Diploblastic→ endoderm and ectoderm • Bodies have distinct tissues but no organs o No reproductive, circulatory, or excretory systems • Dimorphic life cycle : larval and medusa forms Anatomy: • Body plan has single opening leading to gastrovascular cavity (site of digestion, most gas exchange, waste discharge, formation of gametes in many) • 2 layers to body wall: o Epidermis o Gastrodermis o Mesoglea between the layers.. Careful! This is not the mesoderm! • 2 basic body forms: o Polyps→ cylindrical and sessile o Medusae→ umbrella-shaped and free-living • Nematocysts o Mechanism of discharge unknown, some carry venom o Used to capture prey and fend off predators Life Cycle: • Some are only polyps, some are only medusae, but MOST alternate between the two forms • Sexes separate • Zygote develops into planktonic planula • Metamorphosis into polyp • Polyp produces medusae or other polyps asexually Cnidarian Classes: Class Anthozoa→ sea anemones, most corals, sea fans • Solitary and colonial polyps • Symbiotic dinoflagellates ( zooxanthellae) photosynthesize and provide nutrients to reef coral Class cubozoa→ box jellies • Strong swimmers, voracious fish predators • Stings may be fatal to humans Class Hydrozoa→ hydroids, hydra, portuguese man -of-war • Both polyp and medusae stages Class Scyphozoa→ jellyfish • Medusae more conspicuous and complex • Ring of muscle cells allows for rhythmic contractions for propulsion Phylum Ctenophora Known as comb jellies, sea walnuts, or sea gooseberries 8 rows of comblike plates of fused cilia that beat in a coordinated fashion. Many are bioluminescent Phylum Platyhelminthes Become aware of the diversity of phyla Platyhelminthes Phylum Platyhelminthes • Flatworms are ciliated, soft-bodied animals • Bodies are solid aside from an incomplete digestive cavity • Acoelomate • Many species are parasitic • Others are free-living: marine, freshwater, moist terrestrial Anatomy: • Only one opening to digestive cavity • Lack circulatory system- diffusion for gas transport • Gut functions in digestion and food distribution o Tapeworms (parasitic worms) lack digestive systems. They instead absorb nutrients directly through body walls • Excretory and osmoregulatory system • Simple nervous system • Reproduction o Most are hermaphroditic o Undergo sexual reproduction o Also have capacity for asexual regeneration Platyhelminthes Classes Class Turbellaria- flatworms • Mostly free-living o Dugesia→ common planarian in bio labs • Most are aquatic, marine • Some marine species eat cnidarians, incorporate cnidocytes in their own epidermis Class Trematoda- flukes (sp. Clonorchis, Schistosoma) • Endoparasites of many vertebrates • Complex life cycles with intermediate hosts o Usually the intermediate host is a mollusk and the final host is a vertebrate § Live in: digestive tract, respiratory system, reproductive system, urinary tract • Highly modified parasitic flatworms • Anatomy: o One or two large suckers to attach to host o Extra tough epithelium (neodermis) to resist digestion by their host’s enzymes • Clonorchis sinensis- Chinese liver fluke o 20 million cases in east Asia o Spread through using human feces to fertilize irrigated fields (spread via fish and snails) o Causes severe jaundice, liver cirrhosis o hermaphrodites→ 80% of the body is dedicated to reproduction • Schistosoma- blood flukes o Schistosomiasis- infect 200 million in the tropics § Veins of large intestine o Causes anemia, diarrhea, tissue damage, and brain damage Class Cestoda- tapeworms • Anatomy: o Long, flat bodies o Highly modified anterior end (scolex) with small barbs for attachment to intestinal walls of host o Segments called proglottids o Primitive excretory and nervous system o No mouth, no anus, no GVC, no respiratory system • Absorb food directly from the intestinal fluid of the host • Rely on diffusion for respiration and excretion • Hermaphroditic o Each proglottid has a complete set of male and female reproductive organs § Each proglottid can make 100,000 eggs § Mature proglottids break off • Beef Tapeworm o Up to 30 feet long o Cows get infected by eating grass contaminated with larvae o Tapeworms form cysts in beef muscles o Human infection is very common due to ingestion of cysts in undercooked meat Phyla Nematoda and Rotifera Become aware of the diversity of phyla nematoda and rotifera Learn about the parasitic lifecycles Phylum Nematoda • Anatomy: o Bilaterally symmetrical and unsegmented o Covered by a flexible cuticle that is molted as they grow o Pseudocoelomates § Allows nutrients to circulate and protects organs during movement § Digestive system well developed • Reproduction: Sexual dimorphism- male smaller with hooked end o Internal fertilization o Indirect development- egg, larva, adult • Lifestyles o Many are active hunters, preying on bacteria, protists and other small animals o Others are plant parasites o Some live within the bodies of larger animals § Many harmful parasitic species • Hookworms- common in school children o Once in the body, hookworms migrate through the blood to the lungs. They are then coughed up and swallowed down to the small intestine where it attaches itself to the lining of the intestine. Feeds on the host’s blood. o Female lays up to 10,000 eggs per day- shed in feces o s/s: pale, anemic, severe digestive problems, fatigued, abdomen protrudes • Trichinella- trichinosis o forms cysts in muscles. Infection from eating undercooked pork or wild game • Ascaris lumbricoides- intestinal roundworm o Infects 1 in 6 worldwide. Rare in areas with modern plumbing • Serious tropical nematode diseases: o Filariasis § Causes Elephantiasis… NOT “elephantisis” (misnomer) • Vectored by mosquitoes • Tiny worms clump up in lymphatic vessels, stopping the flow of fluids in and out of appendages (usually legs), causing the appendages to grow disproportionately to the rest of the body o Guinea Worm Disease (Dracunculus medinensis) § Worm eaten by tiny aquatic invertebrate called copepods § Humans drink water with infected copepods and digest copepods but not the worms § Worm matures and burrows underneath of skin. Migrates toward feet and ankles and secretes irritant that causes a blister to form. • Fun fact: many people will put their feet in water to stop the irritation, but the water only causes the blister to burst and the worm to release her eggs, perpetuating the cycle further. § The worm will burrow out of the host’s foot/ankle at the site of the blister very slowly (sometimes takes close to a year for the whole thing to come out). The practice is to slowly wind the worm around a stick. The worm is so thin, that it will easily break, leaving a long piece in the person’s leg. This often causes a bacterial infection. § A really fun fact: Guinea Worm is nearly eradicated with only 20 or so known cases as of the beginning of this year. Predicted to be the first parasitic disease to be eradicated, and will most likely be eradicated this year! Woohoo! (sorry I’m a public health major, so I love this stuff) Phylum Rotifera • Abundant in freshwater habitats • Microscopic • Pseudocoelomate- complete digestive tract • Feeding: o Use crown of cilia (corona) to feed o Muscular pharynx (mastax) grinds food o Sessile filter feeders, raptorial (pursue prey) or both o Cephalized with brain, one or more pairs of eyespots, sensory bristles Phylum Mollusca Learn the four dominant classes of Mollusca Know taxonomy diversity of morphologies Know the functions of the mantle, foot, and radula Phylum Mollusca • Anatomy: o Mantle→ thick epidermal sheet. Bounds mantle cavity. Secretes shell (if there is one o Foot→ primary means of locomotion for many. Divided into arms or tentacles in cephalopods o Internal organs→ coelom is highly reduced (small spaces around the excretory organs, heart, and part of the intestine) § Digestive, excretory, and reproductive organs are concentrated in a visceral mass § Ctenidia→ gills in aquatic mollusks. Also filter food in most bivalves. o Shell→ protects against predators and adverse environments. 2 layers of calcium carbonate o Radula→ Characteristic of most mollusks. Rasping, tongue-like structure used for feeding. Scrapes up algae. Modified to drill through clam shells. Bivalves do not have a radula o Open Circulatory System→ hemolymph sloshes around hemocoel. 3- chambered heart § Cephalopods have a closed circulatory system • Reproduction: o Most have separate sexes. A few are hermaphroditic. Most engage in external fertilization, but gastropods have internal fertilization • Trochophore: o Free-swimming larval stage. Similar to Annelida. Class Polyplacophora: Chitons • Soft body protected by 7 or 8 overlapping plates • Marine • Primitive group of mollusks • Can create suction with foot for attachment • Flat • Scrape algae from rocks with radula • *other mollusks are highly modified versions of this body plan* Class Bivalvia: Clams, Oysters, Scallops • Two shells (“valves”) hinged together and closed by powerful adductor muscles • Laterally flattened • Filter feeder so doesn’t need a radula • Incurrent siphon brings in oxygen and food- breathe with gills • Excurrent siphon carries of wastes and gametes • Bury in sand, breathe and eat through siphons • Some can bore into hard substances Class Gastropoda: Snails, Slugs, Limpets, Whelks, Conch, Abalone • Single shell may be coiled, or absent • Highly mobile via foot • Widest range of ecological niches among mollusks (80% of the phylum diversity) • Can be grazers, browsers, filter feeders, scavengers, detritivores, and carnivores • Torsion results in visceral mass being rotated 180 degrees • Feed with radula (modified into a drill in whelks to bore through other shells) • Pulmonate snails- adapted for life on land o Mantle cavity is lined with blood vessels like a primitive lung • Slugs seem to lack shells but actually have small plates underneath of the skin • Marine slugs are vividly colored and patterned Class Cephalopoda: Octopus, squid, ammonites • Active marine predators o Feed on fish, crustaceans, and other mollusks • Anatomy: o Muscular foot is divided into tentacles o Only mollusks with a closed circulatory system o Nautilus has shell, squid has inner, reduced shell, and octopus lacks shell o Tentacles lined with large suckers for locomotion, capture of prey o Prey torn apart by strong beak, shredded by radula o Have large, complex brains, excellent senses (typical of predators). § Eye is extremely sophisticated, looks and works like the vertebrate eye • Squid are the largest invertebrates (40-50 feet long) Phylum Annelida Know taxonomy of Annelida Class Polychaeta • Mostly marine→ many live in crevices and tubes • Anatomy o Well-differentiated head with sensory organs o Parapodia→ paired appendages o No clitellum o Many setae arranged in bundles on parapodia o Prostomium may or may not be retractile § Often bears eyes, tentacles, and sensory palps § Surrounds mouth and may have setae, palps, or chitinous jaws o Ciliary feeders may bear a tentacular crown • Circulation and respiration: have parapodia gills for respiration • Reproduction: o Have no permanent sex organs § Gonads appear as simple temporary swellings o Fertilization is external Clade Clitellata: Class Oligochaeta and Class Hirudinea • Form reproductive structure called a clitellum o Permanent in oligochaetes • Lack parapodia Class Oligochaeta: Earthworms • Burrow in moist, rich soil • Peristaltic movements o Contraction of circular muscles to lengthen body o Anchoring is accomplished by contraction of the longitudinal muscles in forward segments o Causes the segments to become short and wide, pushing against the burrow • Setae: o Bristle-like rods set in a sac and moved by tiny muscles o Project outward through small pores in cuticle o Aid anchoring by digging into walls of burrow • Nutrition: o Scavengers. Feed on decayed organic matter o Food is stored in a thin-walled crop o Gizzard grinds food into small pieces o Digestion and absorption occur in intestine • Circulation and Respiration: o Closed system o Gas exchanged across body surface • Nervous system: o Central nervous system and peripheral nerves o Lack eyes but have many photoreceptors in the epidermis • Reproduction: o Hermaphroditic but usually use sexual reproduction Class Hirudinea: Leeches • Most freshwater • Some carnivores, some parasites • Hermaphroditic o Form a clitellum during breeding season • Anatomy: o No setae- use suckers for attachment and movement o Gut specialized for storage of blood • Nutrition: o Not all are parasites. Many are predaceous o Some leeches feed on insect larvae, earthworms, and slugs • Reproduction o Hermaphroditic and practice cross-fertilization • Medicinal leeches- postoperative therapy Phylum Arhtropoda Learn characteristics of arthropods and differences between annelids Phylum Arthropoda • >3x as many species of arthropods as all other animal species o Most are insects • Rich fossil history (back to Precambrian era) • Eucoelomate protostomes with well-developed organ systems • Segmented with jointed appendages • Most diverse animal group Morphology • Success explained by: segmentation and exoskeleton • Jointed appendages→ may be modified into antennae, mouthparts, or wings • Bodies are covered with a tough cuticle made of chitin and protein→ exoskeleton Anatomy • Open circulatory system • Air piped directly to cells • Fusion of 3 segments into functional units→ tagmata o Head, thorax, and abdomen § head+thorax= cephalothorax Reproduction • Sexes are separate and pronounced→ sexual dimorphism • Internal fertilization in terrestrial forms How can you get bigger if your skeleton is on the outside? o must molt to grow (ecdysis) o Process of shedding outer covering and growing a new, larger one o Typically molt four to seven times o Vulnerable while molting Why are most arthropods tiny? o Size limited by reliance on diffusion to exchange gases o Exoskeleton would be so thick that a large insect couldn‘t move about o Escape detection by predators if small Phylum Echinodermata and Non-vertebrate chordates Understand differences between protostomes and deuterostomes (previously covered) Know Echinoderm morphology and taxonomy Phylum Echinodermata • Pentaradial symmetry as an adult, bilateral as larvae • Have an endoskeleton o Composed of calcium carbonate plates just beneath the skin o May be tightly or loosely joined o All members have mutable collagenous tissue • All systems organized with branches radiating from center • Water-vascular system o Aids in movement and feeding o Radially organized o Water enters through madreporite o Flows through stone canal to ring canal o Radial canal extends from ring canal into each body branch o Tube feet – may or may not have suckers. Have bulb (ampullae) • Open circulatory system o Large coelom functions in both respiration and circulation o Locomotion and feeding by means of tube feet • Regeneration o Many able to regenerate lost parts o Some reproduce asexually by splitting • Most reproduction is sexual o Separate sexes o Gametes released into water o Free-swimming larvae o Each class has a characteristic type of larva Class Asteroida: sea stars and sea daisies • Important predators in many marine systems • Most have 5 arms, some have multiples of 5 Class Echinoida: sea urchins and sand dollars • Lack arms • Double rows of tube feet • Protective moveable spines Class Ophiuroidea: brittle stars • Largest class • Arms are equal diameter their entire length • Very brittle • Probably most abundant group Class Holothuroida: sea cucumbers • Superficial 5 part radial symmetry • Skeletal plates under the skin reduced Phylum Chordata and Subphylum vertebrata Phylum Chordata • Chordates are deuterostome coelomates • Nearest relatives are echinoderms (the only other deuterostomes) • Fishes, amphibians, reptiles, birds, and mammals Distinguishing Features: These WILL be on the test! • Nerve cord→ nerve cord remains as the spinal cord and brain • Notochord→ replaced by vertebral column • Pharyngeal slits/ pouches→ lost except for one pair that become the Eustachian tube • Postanal tail→ regresses into the coccyx bone (tailbone) All chordates have all four of these characteristics at some time in their lives Subphylum Urochordata: tunicates and salps • Marine animals • Larvae are tadpole-like and have notochord and nerve cord. Free-swimming but do not feed • Adults typically lose the tail and notochord o Are immobile filter-feeders o Many secrete a tunic (cellulose sac) that surrounds the animal • Use pharyngeal slits to exchange gases and feed • Pharynx lined with cilia, draws water in through incurrent siphon, out through excurrent siphon • Suspended organic particles stick to layer of mucus in the pharynx Subphylum Vertebrata • Chordates with a spinal column • Distinguished from non-vertebrates by: o Vertebral column – Encloses and protects the dorsal nerve cord o Head – Distinct and well-differentiated possessing sensory organs • Also have: o Neural crest – unique group of embryonic cells that forms many vertebrate structures o Internal organs – liver, kidneys, endocrine glands, heart, and closed circulatory system o Endoskeleton – made of cartilage or bone § Makes possible great size and extraordinary movement Kingdom Fungi Know the characteristics that distinguish fungi from other eukaryotes Learn the phyla of Fungi Understand the economic and ecologic importance of fungi Defining Fungi • Single-celled (yeast) or multicellular • Sexual or asexual reproduction • Extract and absorb nutrients from th eir surroundings • Closest kingdom related to animals Phylum Chytridiomycota → Chytridiomycetes or Chytrids. • Aquatic, flagellated fungi • Closely related to ancestral fungi • Mave motile zoospores (spores with flagella for movement) Phylum Zygomycota - Bread molds • Fungi that produces zygotes • Lack septa in hyphae except when reproducing • Not monophyletic- still under research • Sexual reproduction o Fusion of gametangia forms a zygosporangium o Haploid nuclei fuse (karyogamy) to form diploid (2n) zygote nucleus o Zygosporangium develops and inside the zygospore develops o Meiosis followed mitosis occurs during germination of zygospore § Releases haploid spores • Asexual Reproduction is more common o Sporangiospores have sporangia that release spores Phylum Glomeromycota • Glomeromycetes are a tiny group of fungi • Form intracellular associations with plant roots called arbuscular mycorrhizae o This is a type of symbiosis o Mutualism § Fungus cannot survive without the host plant • Fungus gets carbohydrates and plant gets phosphorus o Potentially capable of increasing crop yields with lower phosphate and energy inputs o Important for evolution of land plants o No above ground fruiting structures Phylum Basidiomycota- mushrooms, toadstools, puffballs, shelf fungi, etc. • Basidiomycetes are some of the most familiar fungi • Many are food source for people o Some, on the other hand, are hallucinogenic or deadly poisonous • Named for basidium- club-shaped sexual reproductive structure • Reproduction: o Karyogamy occurs within basidia § Only diploid cell in life cycle o Meiosis follows o The four haploid products are incorporated into basidiospores o Spore germination leads to the production of monokaryotic hyphae § Results in monokaryotic mycelium, or primary mycelium o Different types of monokaryotic hyphae may fuse § Results in a dikaryotic mycelium, or secondary mycelium § Heterokaryotic mycelium § Basidiocarps (mushrooms) are formed entirely of secondary mycelium Phylum Ascomycota- yeasts, common molds cup fungi, truffles, and morels • Serious plant pathogens • Penicillin (used in antibiotic medicines) is produced by genus Penicillium • Named for ascus- microscopic, saclike reproductive structure o Karyogamy occurs within asci § Only diploid nucleus of life cycle o Asci differentiate in ascocarp o Meiosis and mitosis follow, producing 8 haploid nuclei that become walled ascospores • Asexual reproduction o Conidia formed at the ends of modified hyphae called conidiophores o Allow for rapid colonization of a new food source Yeast • Unicellular • Most reproduce asexually via budding • Yeasts can ferment carbohydrates o Break down glucose into ethanol and CO2 o Used to make bread, beer, and wine • Used for genetic research→ first eukaryotes to be manipulated extensively o Saccharomyces cerevisiae was the first eukaryote to have genome sequenced Ecology • Principal decomposers • Fungi symbiosis o Obligate symbiosis- essential for fungus’s survival o Facultative symbiosis- nonessential • Interactions o Pathogenetic- pathogens harm host by causing disease o Parasitic- cause harm to host (but do not cause disease) o Commensal- relationships benefit one partner but does not harm the other o Mutualistic- relationships benefit both partners § Lichens • Symbiotic relationship between a fungus and a photosynthetic partner (usually green algae or cyanobacteria) o Usually ascomycetes • Unable to grow normally without the photosynthetic partner • Sensitive to pollutants Economic Importance- edible, fermentation, used in making many cheeses Agricultural Importance- many fungi are agricultural pests Medical Importance- fungal diseases (yeast infections, ringworm), fungal antibiotics (penicillin, streptomycin), psychoactive drugs • Fungal diseases are difficult to treat because of the close phylogenetic relationship between fungi and animals Ecological Importance- primary planetary decomposers. Only fungi can digest lignin (the substance that gives wood its stiffness) Here’s the TED talk video on fungus that we watched in lab! https://www.youtube.com/watch?v=XI5frPV58tY Introduction to Kingdom Plantae Differentiate the sporophyte and gametophyte stages of plants Learn the basics of plant structure Adaptations to Terrestrial Life • Protection from desiccation o Waxy cuticle and stomata • Moving water through the body o Tracheophytes have tracheids § Xylem- takes water from the roots to the leaves § Phloem- takes photosynthetic nutrients from the leaves to the rest of the plant • Dealing with UV radiation caused mutations o Shift to a dominant diploid generation • Haplodiplontic life cycle (alternation of generations) o Multicellular diploid stage- sporophyte § Produces haploid spores via meiosis § Diploid spore mother cells (sporocytes) undergo meiosis in sporangia • Produce 4 haploid spores→ first cells of gametophyte generation o Multicellular haploid stage- gametophyte § Spores divide by mitosis § Produces gametes by mitosis § Gametes fuse (fertilization) to form diploid zygote • First cell of next sporophyte generation Gametangia that make sperm cells (antheridia) look different than those that make egg cells (archegonia) Alternation of Generations So, all plants have an alternation of generations. This idea was incredibly confusing to me at first because the teacher was like “the plant’s offspring are different organisms” and I’m here like “well how is this different from any other reproductive cycle because I really hope my children are different organisms from me also”. But the way that I think of it now is that it would be like I had a kid and they were super different looking from me and functioned differently from me but then my kid’s offspring (so my grandchildren) would have similar anatomy and function to my own. That’s kind of how plants work. The offspring of the sporophyte is a gametophyte; the two have different anatomy and function. And then that gametophyte’s offspring is a sporophyte. Basic Plant Anatomy: • Vascular Plant o Root system (anchor) o Shoot system (support) • 3 basic tissue types o Dermal- outer protective cover o Ground- function in storage, photosynthesis, and secretion o Vascular- conducts fluids and dissolved substances throughout the plant body • Tissues consist of one or more cell types • Tissue systems – each of these tissue types extends through root and shoot systems • Meristems→ undifferentiated cells that can divide infinitely and give rise to many types of differentiated cells… they’re like stem cells for plants o Extension of shoot and root systems produced by apical meristems § Located at tips of stems and roots and is covered by a root cap or leaf primordia for protection Vascular tissue • Xylem- principal water-conducting tissue. Also conducts inorganic ions such as nitrates, and supports the plant body o Vessels- continuous tubes of dead cylindrical cells arranged end-to- end o Tracheids- dead cells that taper at the end and overlap one another o Transpiration- diffusion of water vapor from plant • Phloem- principal food-conducting tissue in vascular plants Roots→ 4 parts: root cap, zone of cell division, zone of elongation, zone of maturation Stems→ support, undergo growth from cell division in apical and lateral stems, develop into leaves, other shoots, and even flowers Leaves→ initiated as primordia by the apical meristems, principal site of photosynthesis, determinate in structure (growth stops at maturity) • 2 different morphological groups o Microphyll- leaf with one vein branching from the stem and not extending the entire length (Phylum Lycophyta, whisk ferns) o Megaphylls- several to many veins Bryophytes Know the classification of Bryophytes Primitive traits • Rely primarily on diffusion • Limited to moist environments • Bryophytes need water to reproduce - sperm are flagellated and must swim to the egg • Lack a true root-shoot system- roots are tiny rhizoids (epidermal cells that anchor the plant to the soil) • Sporophytes are not free living Phylum Bryophyta - Mosses • Moss species are dioecious (distinct male and female plants) o Male- have antheridia at the top o Female- have archegonia at the top • Mosses can reproduce sexually or asexually (by fragmentation) • Ecological importance o Retains moisture and nutrients in ecosystems o Functions as a seedbed for higher plants o Most abundant plant in polar ecosystems • Life Cycle: o Gametophyte is the dominant stage § Spores germinate into tiny green threads called protonema (looks like green algae) § Buds develop into adult gametophytes Phylum Hepaticophyta - Liverworts • Lobes suggest the shape of a liver • Simplest bodies of any green plant. Looks like a flat scaly leaf with prominent lobes • Store food as oil, not starch • Some lack stomata and waxy cuticle • Life cycle o Similar to mosses. Gametophyte is dominant stage o Archegonia hang from the underside of tiny umbrellas o Can grow vegetative buds called gemmae cups that break off and grow into a new plant Phylum Anthocerophyta - Hornworts • Gametophytes look like liverworts, but send up a tiny moss-like sporophyte • More closely related to mosses, because they have stomata • Symbiotic with cyanobacteria which fix nitrogen for the hornworts Introduction to Tracheophytes and Pterophytes Distinguish bryophytes from tracheophytes Know the classification of ferns and fern allies Many similarities to bryophytes • Ferns and fern 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 Differences between bryophytes and ferns • Sporophyte is the dominant stage in ferns • Ferns and fern allies are monoecious- antheridia and archegonia on same plant • Gametophytes are free -living plants, very small, only develop in moist areas • Sporangia attached to sporophylls • Sporophylls organized into club -shaped strobilus Plant growth assisted by rhizomes, modified underground stems that help spread it around Phylum Lycophyta - Club Mosses • Sister group to ferns and other fern allies • Tropical species are mostly epiphytes (plants that grow on other plants) • Temperate species grow in forest understory in small clusters • Lycophylls (microphylls)- small, simple leaf with one vascular strand (vein) • Have sporophylls organized into strobili o These fall to the ground when ripe and release spores • Gametophytes are independent, free-living, look nothing like the parent plant Phylum Sphenophyta- Horsetails • Closely related ferns • Equisetum is the only surviving genus of this phylum o May be the oldest living plant on Earth • Anatomy o Leaves are little more than flattened stems o Hollow stems are ribbed, jointed, whorl of leaves arise at each joint o Stems are very rough to the touch o Highly branched vegetative stalks (look like a horse’s tail) o Unbranched reproductive stalks, tipped with a large strobilus bearing sporangia o Homosporous spores dispersed by elaters (like little springs that launch the spores), develop into a tiny green gametophyte Phylum Psilophyta - Whisk Ferns • Closely related to ferns • Only living vascular plants that lack true leaves or true roots • Found in tropical, subtropical habitats, and is a common weed in greenhouses • Small sporangia are bright yellow, form along the upper stems • Gametophytes are tiny thread-like plants that lack chlorophyll o Symbiosis with fungi to get nutrients Phylum Pterophyta - ferns • Clusters of sporangia are called sori (sorus) • Sorus often protected by an umbrella-like structure called an indusium • Mostly homosporous, though some are heterosporous • Fern life cycle differs from that of a moss→ much greater development, independence, and dominance of the sporophyte. Gametophyte lacks vascular tissue o Spores germinate into a tiny heart-shaped autotrophic gametophyte called a prothallus o Archegonia and antheridia on lower surface- archegonia at the notch of the heart, antheridia near the rhizoids o Sperm swims across to reach the egg o Early stage of sporophyte is called a fiddlehead because it looks like the spiral on a violin Introduction to seed plants and gymnosperms Understand evolution of seed plants and the function of the seed Know the classification of gymnosperms Gymnosperms- “naked seed” • First truly terrestrial plant • Plants with “naked seeds” • 4 living groups • Lack flowers and fruits • Have ovule exposed on a scale (modified leaf) Phylum Coniferophyta - pines, spruces, firs, cedars, and othe s • Coastal redwood- tallest living vascular plant (100 meters) • Bristlecone pine- oldest living tree (4,900 years) • Found in colder and sometimes drier regions of the world • Gametophytes o male→ pollen grains § Develop from microspores in male cones by meiosis o Female § Pine cones form on the upper branches of the same tree § Larger than males and have woody scales § Two ovules develop on each scale • Each ovule contains a megasporangium o Each megasporangium will become a female gametophyte Phylum Cycadophyta - Cycads • Sporophytes resemble palm trees • Palm-like shrubs and trees, with crown of very thick leaves atop unbranched stems • Dioecious, separate male and female plants • Leaves are incredibly well def ended o Sharp tips on leaves. Toxic secondary compounds, including neurotoxins and carcinogens Phylum Gnetophyta • Xerophytes- plants adapted to arid conditions • Only gymnosperms with vessels in their xylem • Ephedra, like whisk fern, is a “stem plant”, photosynthetic with no leaves o Source of the drug ephedrine… pulled from markets in 2004 because it was causing strokes and heart attacks in diet pills • Common in deserts of the American West and Mexico, grows everywhere except Australia Phylum Ginkophyta • Only one living species remains - Ginko biloba • Dioecious- male and female reproductive structures form on different trees • Seeds are covered by a fleshy coat o The Ginko Conspiracy… They removed the female ginko tree that shades Tulane’s President’s fancy Lexus… Angiosperms (flowering plants) Understand evolution of flowering plants and their defining structures Flowers house the gametophyte generation • Morphology: o Modified stems bearing modified leaves o Primordium develops into a bud at the end of a stalk called the pedicel o Pedicel expands at the tip to form a receptacle, to which other parts attached o Flower parts are organized in circles called whorls § Outermost whorl- sepals § Second whorl- petals § Third whorl- stamens (androecium) • Pollen is the male gametophyte • Each stamen has a pollen-bearing anther and a filament (stalk) § Innermost whorl- gynoecium/carpel • Consists of one or more carpels • House the female gametophyte o Ovule- enclosed in diploid tissue at the time of pollination, develop into seed o Carpel- a modified leaf that covers seeds, develops into fruit wall § 3 major regions: • Ovary- swollen base containing ovules • Stigma- tip where pollen lands • Style- neck or stalk Phylum Anthophyta • Water lilies one of the first clades to evolve • Angiosperms quickly became the dominant plants, although gymnosperms continue to rule in cold, dry, or sandy habitats • Oldest known angiosperm- Archaefructus. Discovered in mainland China • Flowering plants are superior competitors o Able to survive in a greater variety of habitats o Mature more quickly o Produce greater number of seeds o Fruit for seed dispersal o Wider-bore vessels to conduct water o Animals aid in pollination- can survive as small scattered populations, whereas wind-pollinated species need dense populations • Can be perennials or annuals • Leaves are thin blades, diversity of shapes Coevolution occurs when an evolutionary change in one organism leads to an evolutionary change in another organism that interacts with it • Evolution of fruit dispersal aligns with evolution of animal population o Fruits function to disperse seeds→ animals eat fruit, but don’t digest seeds o Tiny hooks and spines attach to animal o Also dispersed by wind or water • Flowers that rely on animal pollination have showy petals to attract the pollinators… advertise their reward of nectar, sugar water, to attract pollinators Flowering plants go to great lengths to avoid pollinating themselves • Chemical- pollen and ovule are chemically incompatible • Architectural- stamens and stigma are arranged to avoid contact • Temporal- pollen and stigma mature at different times Seeds are an important adaptation • They maintain dormancy under unfavorable conditions • They protect the young plant when it is most vulnerable • They provide food for the embryo until it can produce its own food • They facilitate dispersal of the embryo Fruits • Contain 3 genotypes • Most simply defined as mature ovaries (carpels) • During seed formation, the flower ovary begins to develop into fruit • It is possible for fruits to develop without seed development o Bananas are propagated asexually • Dispersal: o Ingestion and transportation by birds or other vertebrates o Hitching a ride with hooked spines on birds and mammals o Burial in caches by herbivores o Blowing in the wind o Floating and drifting on water Angiosperms Reproduction and Classification Understand that double fertilization is a defining characteristic of angiosperms Angiosperm Reproduction • Single megaspore mother cell in ovule undergoes meiosis o Produces 4 megaspores § 3 disappear § Nucleus of remaining megaspore divides mitotically • Daughter nuclei divide to produce 8 haploid nuclei o 2 groups of 4 • Integuments become seed coat o Form micropyle • Embryo sac= female gametophyte o 8 nuclei in 7 cells o 8 haploid daughter nuclei (2 groups of 4) § 1 from each group of 4 migrates toward center • Functions as polar nuclei- may fuse § Egg • 1 cell in group closest to micropyle • Other 2 are synergids § Antipodals • 3 cells at other end • Pollen production occurs in the anthers o Diploid microspore mother cells undergo meiosis to produce four haploid microspores o Binucleate microspores become pollen grains • Pollination o Mechanical transfer of pollen from anther to stigma o Pollen grains develop a pollen tube that is guided to the embryo sac o One of the two pollen grain cells lags behind § This generative cell divides to produce two sperm cells § No flagella on sperm • Double Fertilization o One sperm unites with egg to form the diploid zygote o Other sperm unites with the two polar nuclei to form the triploid endosperm § Provides nutrients to embryo • Sporophytes form sporangia o Stamens are highly modified sporophylls o Sporangia are located on the stamens, inside the anthers. Each anther holds four microsporangia • Microspore mother cell divides by meiosis to form four haploid microspores o Each microspore develops into a multicellular pollen grain o Pollen grains are the male gametophytes o Microspore divides into a tube cell (will form pollen tube) and a sperm cell (nucleus will act as sperm) • Mature male gametophyte is reduced to only three cells • Double Fertilization!!! • Life cycle: Behavior Learn about the natural history of behavior and contrast proximate and ultimate causation behavior Understand that animals can learn and are capable of cognition Know what behavioral genetics is and discuss scientific studies that provide evidence to link genes and behavior Learn how animals communicate and the importance of communication Understand and describe aspects of behavioral ecology Understand how sexual selection occurs and differentiate intra- and intersexual selection Behavioral Ecology • Biological communities are shaped by the interactions of the animals that compose them • Much animal behavior is instinctive or innate (hard-wired, genetically determined • More complex the animal, the greater the amount of learned behaviors • Behavioral ecology examines the ways in which behavior is adaptive, how behavior varies, and how it evolves • Behavior of any animal in the community affects the behavior of many other animals o Competitors, predator/prey, parasite/host, many examples of coevolved behaviors Behavior is the immediate way an animal responds to its environment • Tracking cues and signals like odors, sounds, and visual signals • Associated with food, predators, and mates Proximate causation • Mechanisms that are the reason for behavior o Increased level of testosterone o Neural connections Ultimate or evolutionary causation • Why did this behavior evolve? • Determine how behavior influences reproductive success or survival How behavior is analyzed • Physiologyà How it is influenced by hormones, nerve cells, and other internal factors • Ontogenyà How it develops in an individual • Phylogenyà Its origin in groups of related species • Adaptive significanceà Its role in survival and fitness Ethology • Study of the natural history of behavior Innate behavior • Instinctive, does not require learning • Preset paths in nervous system • Geneticà fixed action pattern Behavioral Genetics • Instinct theory assumes that genetics plays a role in behavior • Deals with the contribution that heredity makes to behavior o Nature- genes guide development of nervous system and potentially the behavioral responses o Nurture- animals may also develop in a rich social environment and have experiences that guide behavior • Artificial selection data have shown that behavioral differences among individuals result from genetic differences Learning • Altered behavior as a result of previous experiences • Non-associative learningà does not require an association between two stimuli or between a stimulus and response o Habituationà decrease in response to a repeated stimulus. No positive or negative consequences § Radio waves actually have an audible sound, but because we were born into them, our ears have adapted to ignore the waves so we don’t hear them. There’s a sound proof room in Chicago that blocks the radio waves from entering, creating a perfectly quiet environment. Most people can only sit in there for 1-2 minutes before they start hearing voices… • Associative learningà association between a stimulus and a response o Conditioned behavior through association § Classical/ Pavlovian conditioning • Paired presentation of two different kinds of stimuli with an association formed between them • Pavlov’s Dogs o Unconditioned stimulus: meat powder o Unconditioned response: salivating o Conditioned stimulus: bell ringing o Conditioned response: after time, the dog salivates with only the ringing of the bell § Operant Conditioning • Animal learns to associate its behavior response with reward or punishment • B.F. Skinner and the Skinner Box o Rats learned to associate pressing the lever (the behavioral response) with obtaining food (the reward)
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