Ebio Final Study Guide
Ebio Final 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 33 page Study Guide was uploaded by Lauren Notetaker on Monday May 2, 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 79 views. For similar materials see Evolutionary Biology in Science at Tulane University.
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Date Created: 05/02/16
Ebio Final Study Guide May 5, 2016 Goodluck!! • Pt 1 matching phylum name with term 20 • Pt 2 ﬁll ins from evolution ecology terms 90 • Pt 3 economic, ecological, evolutionary importance of organism 20 • Pt 4 How to be an organism one plant one animal challenge and solution 20 What to Expect: 150 points • 90 min • Matching and importance questions answers will go to phylum level only ◦ Annelida - oligochaeta ◦ Mollusca - gastropoda ◦ No classes or orders (I have some classes in the study guide in case that helps for memory) ◦ Snail clue - mollusk ◦ Matching terms will be limited to reproductive terms (life cycle stages and anatomy (protonema, larva, cop hook, clitellum, zygospore etc) • No taxonomy question (no listing phyla) • No life cycle diagrams • No natural history (characteristics) questions • Fill ins will be drawn exclusively from the evolution and ecology material ◦ No microorganisms • Last question drawn from the challenge/solution material in the ﬁrst animal lecture and the ﬁrst plant lecture • No bacteria, archaea, or protists • No fruits and seeds Pt 1 matching phylum name with term 20 Phylum Rotifera - rotifers - parthenogenic: unfertilized egg goes right into adult female - Sexual reproduction: hypodermic needle dicks!! Phylum Annelida - Earthworms, Leeches - clitellum - transverse ﬁssion Phylum Porifera - sponges - amoebycytes and choanocytes - transport sperm, create spicules Phylum Cnidaria - jellyﬁsh - Asexual reproduction: budding - Sexual reproduction: polyps -> medusae - Planula Larvae Phylum Platyhelminthes - ﬂatworms - Asexual reproduction: transverse ﬁssion; budding - proglottids - Sexual reproduction: hypodermic needle dicks!! Phylum Nematoda - nematodes - copulatory hook Phylum Arthropoda - spiders, crabs, etc. - internal fertilization - pedipals - Naupilus Larvae Phylum Mollusca - clams, snails, octopi - external fertilization - Trochophore Larvae Phylum Chordata - lancelets, tunicates, vertebrates - Neoteny: when the juvenile form becomes capable of sexual reproduction and bypasses the adult stage altogether - amniotic egg - placenta - marsupial Phylum Echinodermata - starﬁsh, urchins - Asexual reproduction: fragmentation - larvae Phylum Hemichordata - Diplural Larvae Phylum Chytridiomycota - allomyces - zoospore -“little pot” Phylum Glomeromycota - mycorrizae Phylum Zygomycota - bread molds - zygospores -> sporangia - stolon -rhizoid - sporangiophore - sporangium Phylum Ascomycota - mushrooms - ascocarp - conjugation - conidiophores Phylum Myxomycota - plasmodial slime molds - plasmodium - cytoplasmic streaming Phylum Bryophyta - mosses - Antheridium/archegonium - gemmae cups - sporophyte - protonema - operculum Phylum Hepaticophyta - liverworts - gemmae cups - elators Phylum Lycophyta - club moss - microphylls with only a singular vascular strand Phylum Anthocerophyta - hornworts -rhizoids Phylum Pterophyta - ferns - ﬁddlehead (juvenile sporophyte) - sori - prothallus Phylum Sphenophyta - horsetails -scouring rush Phylum Anthophyta - ﬂowering plants - style - carpel - ovule - integument - embryo sac - stigma - pistil - ovary - pollen grains - endosperm (double fertilization) - gametophyte - tube/sperm nucleus Phylum Psilophyta - whisk ferns Phylum Cycadophyta - cycads - micro/macrosporangiate cones Phylum Ginkophyta - ginkos - pollen tube Phylum Coniferophyta - conifers - ovulate/seed cone (female) - pollen cone (male) - megaspore/microspore - staminate cone Phylum Gnetophyta - ephreda, gnetum, welwitschia -dioecious Pt 2 ﬁll ins from evolution ecology terms 90 ECOLOGY ecosystem - all of the biological communities in a given area together with their physical habitat biological community - all the organisms that appear in a particular habitat that interact with one another community structure - how many different species in the community + how many individuals of each different species; Elton thought food determined structure food chain - linear sequence of predator and prey in an ecosystem; who eats who food web - interconnection of all the food chains in an ecosystem pyramid of numbers - (Elton) animals on Bear Island came in discrete sizes, much bigger or smaller than others; larger the animals, the scarcer they were; explained by Lindeman's Pyramid of Energy pyramid of energy - (Lindeman) ecosystems were systems that transformed energy; as energy passes from trophic level to the next, some energy is lost at each level trophic level - feeding level producers - autotrophs; self-feeder; produce their own energy consumers - heterotrophs; herbivores and carnivores; organisms eat other organisms to survive herbivore - plant-eating carnivore - meat-eating gross primary production (GPP) - solar energy assimilated by plants net primary production (NPP) - GPP - solar energy plant uses for itself = NPP; wetlands, tropical forests, coral reefs have the highest NPP; desert, open ocean have the lowest NPP secondary carnivore - carnivore that eats carnivores endothermic - warm-blooded ectothermic - cold-blooded predator-prey ratio - the number and relative mass of predators and prey in the ecosystem; total biomass predator/ total biomass prey; ectothermic communities have high PPR; endothermic have low PPR collection bias - overestimating the number of large carnivores balance of nature - balance between organisms and their environment extrinsic limiting factors - act from outside the population abiotic factors - sunlight, water, nutrients, food, resources biotic factors - competition, predation, symbiosis intrinsic limiting factors - changes in reproductive physiology; changes in behavior; act from inside the population density-dependent limiting factor - forest ﬁres, tidal waves; have same effect regardless of population density non-equilibrium theory - stressed the importance of disturbances disturbance - forces that disrupt a natural ecosystem; abiotic- forest ﬁres, ﬂoods; biotic- diseases, parasites competition - occurs when two or more organisms use the same resource in a way that affects the birth rate or death rate of the competitors; important in regulating growth of natural populations intraspeciﬁc competition - between members of the same species; most intense because needs match exactly the needs of other members of your species interspeciﬁc competition - between members of different species niche - functional role of an organism in an ecosystem niche overlap - intensity of competition between organisms depends on the extent of this habitat - address; where an organism lives fundamental niche - full potential of a species realized niche - competition forces organisms into narrower niche competitive exclusion - occurs when one species is a better competitor than another and forces it into local extinction coexistence - living together peacefully mixed-species foraging ﬂock - higher rates of food capture than solitary birds; specialize in different feeding zones resource partitioning - exploit the resource in a different way character displacement - modify your physical shape through natural selection scramble competition (exploitation) - exploit resources by using them up contest competition - engage in a face to face contest over limited resources territory - any area that an animal defends against other animals ﬂoaters - only territory holders will mate, so bachelor males become this predator - any organism that eats another organism prey - organism that is injured or killed true predator - kill it and eat it parasitoid - insects lay their eggs in hosts, young hatch, eat host alive herbivore - prey upon plants active pursuit - chase it and kill it solo pursuit - lone predators pack pursuit - group of predators ambush predator - hide and wait for prey to come to you warning coloration - prey defense strategy coevolution - predators coevolve with their prey; the thicker the armor, the sharper the claw predator/prey cycles - populations of predators and prey settled down into a regular series of cycles; ex. lynx and hare keystone predators - some predators are so important that the proper functioning of the ecosystem depends upon them behavioral ecology - examines the ways in which behavior is adaptive, how behavior varies, how it evolves megachiropterans - bats that eat mainly ﬂowers, fruit, nectar microchiropterans - smaller bats that feed on insects, most of which are captured in ﬂight echolocation - ability to hunt by sound sexual selection - special case of natural selection male-male competition - males compete for female attraction; bright plumage, beautiful song, elaborate courtship displays female choice - females actively select their desired mates good genes model (Borgia) - male's appearance, his ability to thrive, suggest that he has good genes, great for making your babies handicap model (Zahavi) - if male can carry around huge tails or antlers and still avoid predators, feed himself, etc. he must be really great aesthetic preference model (Darwin) - maybe females are simply making an aesthetic choice- they like the way you look runaway selection (Fisher) - trait becomes reinforced generation after generation until it is greatly exaggerated, can be a dangerous burden dominance hierarchy - males of non-territorial species must ﬁnd other ways to compete for mates; ﬁghting pecking order - ﬁght one another to establish a dominance hierarchy within the pack or herd courtship display - elaborate, ritualized behaviors that include songs, dances repertoire - the number of songs a male bird can sing; directly correlated with reproductive success in many species tidbitting - offer a potential mate a juicy morsel; show her you are interested, more importantly shows you know how to ﬁnd groceries in the wild leks - courtship arenas where birds compete by gathering together in one spot and performing for groups of females bowerbirds - Australian bird that builds a house (bower) to attract a mate bower - tiny house made of upright sticks decorated with items polygynous - one male mates with several females practice bower - juvenile male bowerbirds build these transfer effect certain physical traits attract a mate and these traits become replaced by external objects, such as bower decorations EVOLUTION Prebiotic Evolution - evolution of complex networks of organic compounds before the origin of life Spontaneous Generation - Early attempt to answer cosmic question of where the spark of life came from Stanley Miller Young - grad student, looking for a thesis project. He heard of experiments in prebiotic synthesis Miller/Urey Experiment - 1953; Modeled Earth's primordial atmosphere in the lab. Purpose was to see if combination of chemicals would spontaneously form more complex organic molecules. Panspermia - theory that life was seeded on Earth and other planets from outer space. Term coined by Tyndall Chain of Being - Species were ﬁxed, distinct types, that could be arranged in a linear sequence, like the links in a chain Argument from design - all of nature is designed in accord with a predetermined, benevolent, and supernatural plan Linnaeus - set out to reveal part of the divine plan by collecting and classifying plants. Terrible student, too distracted by nature. Believed species were ﬁxed and distinct types, and therefore could not change or evolve. System of Hybridization - idea that new species must be hybrids of existing species Lamarck - one of the ﬁrst to realize that organisms were shaped by their environment, could evolve. Best known for his Theory of the Inheritance of Acquired Characteristics - Changes in the living body could be passed on to descendants Theory of Organic Progression - once generated, organisms changed along ﬁxed and parallel paths Charles Darwin - Rejected the idea of a divine plan behind nature, broke with the Argument from Design and the Chain of Being. Formed Natural Selection. Wrote the Origin of Species. Believed that adaptation resulted from ordinary laws of nature. Removed man from the center of creation. H.M.S. Beagle - Set sail for South Africa. Trip to last for 5 years, set sail December of 1831. Reached Galapagos Islands in Sept 1835. Cap. Robert Fitzroy - looked for naturalist/gentleman's company. Predecessor had committed suicide in his cabin on the previous voyage. Didn't get along with Darwin. Origin of Species - Published by Darwin in 1859. Sparked a great debate over mechanism of evolution, not its existence. Book revealed Theory of Evolution by Natural Selection. Thomas Malthus - Published An Essay on the Principle of Population. Born 1766, second son of seven children Struggle for Existence - Idea that Population would increase geometrically, but resources could only increase arithmetically over time. Lead to growing gap between too many people and too few resources. Survival of the ﬁttest - nature must somehow select those individuals best ﬁt to survive natural selection - those well adapted individuals would have more offspring than others, passing on their variation to the next generation. Gregor Mendel - 1866; Experimented with garden peas, discovered the mechanism of heredity. Blended Heredity - A gradual and continuous process of inheritance, both parents contribute Gemmules - Tiny particles that carry information on heredity. Darwin believed they ﬂoated throughout different parts of the body and knew how to make body part. Went to reproductive organisms during sex. allele - different versions of the same gene dominant allele - (T)(W) the allele that expresses it phenotypic effect. Even heterozygous with a recessive allele. recessive allele - (t)(w) an allele whose phenotypic effect is not expressed in a heterozygote heterozygous - (T)(t) one dominant and one recessive allele homozygous - (T)(T) / (t)(t) both dominant OR both recessive mutation - changes in genetic information modern synthesis - the fusion of abstract models of genes moving through populations, with the population perspective of ﬁeld biologists variation - Evolution depends on these differences in parents and their offsprings or among individuals in a population. Organisms containing different characteristics due to mutations. population - a group of organisms of the same species that interbreed and live in the same place at the same time. evolution - a gradual change in phenotypic frequencies in a population that resulted in individuals with improved reproductive success. species - a group of organisms that have the same DNA and can reproduce to create fertile offspring speciation - a process whereby over time one species changes into a different species or two different species Darwin's Theory of Evolution by Natural Selection - a species evolves into a new species because it has adapted to survive in existing conditions Biological Species Concept - Species are populations of similar organisms that can interbreed with one another but are reproductively isolated from other such populations by one or more isolation mechanism Homologous chromosome - 2 copies of each chromosome, one from each parent found in high organisms. Contain the same genes at the same loci, but the same loci may have different alleles on each homologous chromosome. chromatid - one of the two side by side replicas produced by chromosome replication before division. Two chromatids make a chromosome. amino acid - a linear series of proteins protein - a large molecule composed of one or more chains of amino acids in a speciﬁc order determined by base sequence. Make up a body. nucleotide - series of organic compounds found in DNA: attached to the backbone of sugar and phosphate molecules. Adenine pairs with Thymine and Guanine pairs with Cytosine DNA - two strands of coiled helix, each made up of nucleotides RNA - a single strand of nucleotide Codon - a sequence of three nucleotides Mutation - random alterations in genetic information genetic recombination - inﬁnite new combination of genes due to Meiosis shufﬂing sexual recombination - creates new beings from a small amount of alleles mitosis - object is to make two identical diploid daughter cells meiosis - turn one diploid cell into four haploid daughter cells (gametes) haploid - organism with 1 type of chromosome (n) diploid - organism with 2 types of chromosome (2n) reduction division - the exchange of genes or groups of genes (crossing over) when homologous chromosomes are brieﬂy joined together independent assortment - the random direction each chromosome takes during reduction division Hardy-Weinberg Equilibrium - 1908 evolution is mathematically impossible. Only works in large populations. If large populations mate randomly, the proportion of two alleles will never change. Gene Frequency - the ratio of a particular allele to the total of all other alleles of the same gene in a given population population genetics - study of allele frequency distribution and change under the inﬂuence of the four main evolutionary processes; natural selection, genetic drift, mutation and gene ﬂow gene ﬂow - the exchange of genes between local populations immigration - genes coming into a local population from a different population emigration - genes going out of a local population to a neighboring population inbreeding - the mating of genetically related individuals monogamy - one mating partner serial monogamy - having one mate at one time, but having many over a life time polygamy - multiple mating partners at once polygyny - one male, many females polyandry - one female, many males founder effect - Genetic drift shown in a population due to random events. The gene pool in an isolated population will always be a random subset of the gene pool of the parent population. genetic drift - change in allele frequencies in small isolated populations due to random events isolating mechanism - any factor that acts to reduce or block the ﬂow of genes between two populations geographic isolating mechanism - populations that are isolated due to the geographic placement reproductive isolating mechanism - any environmental, mechanical, behavioral or psychological barrier that prevents two individuals of populations from reproducing temporal isolating mechanism - populations become isolated in time. Shift in time of breeding season is an example behavioral isolating mechanism - changes in behavior, especially courtship and mating behavior mechanical isolating mechanism - the parts no longer ﬁt together; extreme difference in size, shape or change of shape of genitalia ecological isolating mechanism - don’t meet don't mate. Some organisms specialized to live in a particular place species - organisms that belong to the same biological group that can interbreed and reproduce fertile offspring directional selection - an average value of a trait is shifted in a particular direction (higher or lower) stabilizing selection - acts to stabilize population around some average value disruptive selection - environment selects for the two extremes, against the average, splitting the population into 2 types industrial melanism - replacement of a light morph by a morph in an industrialized area microevolution - evolution at or below the level of species macroevolution - evolution above the level of species adaption - when an organism becomes more equipped to survive in its environment homologous structures - structures that are derived from a common ancestor but may have different uses analogous structures - structures of different species having similar or corresponding functions but are not from the same origin divergent evolution - the evolution of a species into two or more species that continually evolve in different directions (homologous structures) convergent evolution - 2 unrelated populations evolve similar structures to solve a problem but have no common ancestry (analogous structures) Pt 3 economic, ecology, evolution importance of organism 20 Phylum Porifera - Sponges • bath sponges • evolutionary pioneers - ﬁrst “stem cells” (amoebocytes) - cell adhesion - self vs. non-self (immunity) - programmed cell death - we share 70% of genes Phylum Cnidaria - Class Anthozoa • Colonial forms form vast coral reefs of CaCO3 (calcium carbonate) • Coral reefs are among the most productive ecosystems on Earth • Reefs support commercial ﬁsheries around the world • Reef ﬁsh and invertebrates are harvested for the aquarium pet trade Phylum Platyhelminthes - Class Trematoda Clonorchis sinensis - Chinese liver ﬂuke • - Infects 20 million East Asians - Spread through using human feces to fertilize irrigated ﬁelds (spread via ﬁsh & snails) - Causes severe jaundice, liver cancer • Schistosoma - Schistosomiasis - Infects 200 million people in the tropics - Causes anemia, diarrhea, brain damage Phylum Platyhelminthes - Class Cestoda • tapeworm Up to 30 feet long - proglottids shed in feces • - Dried cow pies scatter proglottids over grass - Cows get infected by eating grass - Tapeworms form cysts in beef muscles - Can infect humans who eat rare beef Phylum Platyhelminthes • Maybe evolved from planula-like ancestor • Ciliated ball of cells that could arch up to form a primitive GVC Phylum Rotifera • rotifers • Probably evolved from primitive ﬂatworms • Both have similar pharynx structure, numerous cilia, and ﬂame cells Trochozoa - Phylum Mollusca (clams, snails, octopi) • Trochozoans are united by their shared larval form, the trochophore larva • Both groups probably evolved from ﬂatworms Phylum Mollusca Mollusks are delicious!! Escargot, scallops, oysters, calamari • etc... • Multibillion dollar seafood industry, oysters cultivated since 1 B.C. • Pearls found in both fresh and saltwater forms • Bivalves ﬁlter tremendous amounts of water, help remove pollutants, cleanse aquatic ecosystems • Dye “Tyrian purple” was one of the most important trade goods in the ancient world Phoenicians harvested Tyrian purple from the mollusk Murex • • Used from about 1600 B.C to about 1500 A.D., when it was replaced by cheaper pigments Class Cephalopoda • Giant nerve cell in squid was used for early work in neurophysiology Phylum Annelida - Class Oligochaeta - Critically important in aerating the soil - 22-40 metric tons of soil per hectare pass through the guts of earthworms every year - If all the dirt ever churned up by worms were stacked up, it would cover the entire land surface of the Earth 300 miles thick, 50 times the height of Everest!! - Important in bait industry (worm ranching or vermiculture) Phylum Annelida - Class Hirudinea - Bite of the leech is antiseptic - Leeches release an anticoagulant in their saliva, keeps the blood ﬂowing - For centuries doctors used leeches to bleed their patients (often to death) to get rid of “bad blood” (imbalance of humours) - At height of the leech craze in the 1830’s, France was importing over 50 million medicinal leeches per year - Medicinal leech is now a threatened species! - Medicinal leeches (Hiruo medicinalis) undergoing a revival - Used to drain blood clots and to drain postoperative swelling, bleeding - Unlikely to evolve resistance - secretions go after seven critical steps in the clotting process! Nematodes Root nematodes cause over $5 billion crop damage per year Several medically important parasites Aerate the soil (like earthworms) Recycle bacteria and fungi into animal tissue Arthropods Seafood industry, edible insects Pollinate commercial crops (fruit) Carry or cause many diseases, such as malaria, typhus, Lyme disease, bubonic plague Pollinate ﬂowering plants Critical in most food chains Primary converters of plant to animal tissue Phylum Echinodermata - Class Holothuridea - Sea cucumbers are a prized (and expensive) gourmet delicacy in the Orient - Sold as trepang or beche-de-mere Phylum Echinodermata - Class Echinoidea - can occur in large numbers and devastate kelp beds and coral reefs - Economically important – harvested for their gonads (ewww…); popular sushi dish - Sea urchin roe is not actually roe (eggs) but gonads - Popular dish in the Orient (Japanese sushi called “uni”), Spain, Greece, Italy and Chile - Thought to be an aphrodisiac - Contains one of the cannabinoids (chemicals in marihuana) Phylum Echinodermata - Class Holothuridea - Sea cucumbers are a prized (and expensive) gourmet delicacy in the Orient - Sold as trepang or beche-de-mere ——— 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 South America 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 (mostly Ascomycota) 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, aspergillum, candida (yeast infection), athlete’s food 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 Ferns Allies - 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… Pt 4 How to be an organism one plant one animal challenge and solution 20 ANIMAL All organisms face the same basic challenges: Find and digest food Find a mate and reproduce Avoid being eaten while doing 1 and 2 Maintain balance with ﬂuids and salts Circulate nutrients Remove waste products Three fundamental modes of existence Sessile (Attached) or Motile Aquatic or Terrestrial Small or Large Sessile organisms tend to be radially symmetric Advantages: Awareness of food, mates in all directions No investment in limbs, wings, etc… Problem: Limited to food that ﬂoats by Solution: Become a ﬁlter feeder Problem: Can’t escape danger Solution: Defend yourself (stinging cells etc.) Problem: How to reach your mates? Solution: External fertilization Be a hermaphrodite - every gamete you get you can work with Problem: How to disperse your young? Solution: Have a motile larval stage Problems: Limited to food that ﬂoats by Can’t escape danger How to reach your mates? How to disperse your young? Solutions: Become a ﬁlter feeder Defend yourself (stinging cells etc.) Rely on external fertilization, be a hermaphrodite Have a motile larval stage Motile organisms tend to be bilaterally symmetric More efﬁcient shape for moving through the environment (especially in water) Actively seek out food and mates Run away from predators Animals in motion have a speciﬁc direction Anterior - Posterior Dorsal - Ventral Animal awareness becomes concentrated in the direction of motion – sense organs are right up front Animals tend to become cephalized – they develop a head, a brain, and a central nervous system Aquatic or Terrestrial Problems posed by transition from water to land Transition posed new problems that both plants and animals had to solve Required a radically different set of evolutionary adaptations to make that ﬁrst step onto dry land Desiccation - drying up Gravity Excretion Desiccation Problem: Tissues dry out Solution: Develop a protective layer of epidermal cells – evolve a skin Problem: Need moisture to exchange gases Solution: Keep respiratory surfaces on the inside Problem: Gametes dry out, can no longer rely on external fertilization in water Solution: Internal fertilization Problem: Embryos dry out Solution: Amniotic eggs enclosed in shell for plants: Seeds Problems: Tissues dry out Need moisture to exchange gases Gametes dry out, can no longer rely on external fertilization in water Embryos dry out Solutions: Develop a protective layer of epidermal cells – evolve a skin Keep respiratory surfaces on the inside Internal fertilization Amniotic egg, seed Gravity Problem: You can no longer rely on the natural buoyancy of water Solutions: Skeletal system – endoskeleton or exoskeleton Root-shoot system for plants Excretion Problem: Aquatic organisms rely on ammonia, which requires a large amount of water to dissolve Solution: Use urea or uric acid, which require less water to dissolve Problem: When they excrete, animals lose essential salts that are dissolved in waste water Solution: Pass waste water through simple tubes (nephridia) to recover the salts Small or Large Problem 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 Allometric relationship: Surface area of a sphere = 4 ∏r Volume of a sphere = 4/3 ∏r Problems: Larger animals have more volume relative to their surface area Some cells or tissues will be far away from the outside surface Diffusion will not be fast enough to move food, gases wastes to and from inner cells Solutions: Fold the digestive, respiratory, and excretory surfaces to increase surface area Be very thin or very ﬂat Develop a vascular system – tubes to carry materials back and forth Develop a coelom – hollow ﬂuid-ﬁlled core All of the amazing diversity we see in nature, all of the millions of different ways to be a living thing, represent the many ways in which organisms have solved these basic environmental challenges PLANT 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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