Bio 94 Burley Midterm 2
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This 13 page Study Guide was uploaded by Karina Martin on Sunday February 21, 2016. The Study Guide belongs to 05220 at a university taught by Nancy Burley in Winter 2016. Since its upload, it has received 164 views.
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Date Created: 02/21/16
1 CHAPTER 30 PROTISTS a Protists = first eukaryotes i Paraphyletic group ii Mostly singlecelled (but large) iii Membranebound nucleus and other organelles iv Cytoskeleton (protein fibers imbedded in cytoplasm) v Plastid vi Earliest fossils 2.1 by old vii 60,000 known species viiiMove by pseudopodia, flagella, cilia ix Other innovations: meiosis, multicellularity b Evolution of early eukaryotes i Ancestral protist 1 flexible cell surface (heterotrophs) 2 large size, cytoskeleton 3 nuclear envelope, (novel) flagellum, storage vacuoles ii Mitochondrion (aerobic respiration) 1 Two hypotheses: a mitochondrion evolved de novo b mitochondrion evolved by endosymbiosis of aerobic bacteria and anaerobic protest 2 Protists acquired mitochondria from alphaproteobacteria and chloroplasts from cyanobacteria. iii Endosymbiosis one organism lives inside another 1 Benefits of endosymbiosis a to bacterium b to protist host 2 Chloroplasts also evolved by endosymbiosis a Primary (“plant” and cyanobacterium) one time b Secondary (protist and plant) – several iv Evidence about structure of mitochondria consistent with hypothesis of endosymbiosis: 1 Size 2 Replication pattern 3 Ribosomes 4 2 membranes 5 Genome similar in form & gene sequences to bacteria c LGT in Bacteria i Lateral gene transfer – bacteria can acquire genes from each other and from the environment d Other Protist Innovations i Structures for support and protection 1 Synapomorphies that identify monophyletic groups ii Sexual reproduction 1 meiosis and syngamy 2 Why Reproduce sexually? a Meiosis produces genetically more variable offspring b Advantageous in changing environments. c For example, (Some) offspring more resistant to parasites that infected parents. d Because parasites evolve faster than hosts, parasites constantly changing. e Food scarcity, high population density linked to switching from asexual to sexual reproduction iii Multicellularity 1 celltocell communication, cell specialization, cell adhesion e Ecological Roles i Food chain: producers & consumers ii Parasites/pathogens iii Mutualists iv Decomposers v Nutrition not reliable taxonomic trait 2 CHAPTER 31 – GREEN PLANTS a Plantae i land plants 1 Evolved from freshwater algae 2 Monophyletic (clade) 3 Embryophytes a fertilization and early development take place on parent b zygote/embryo stays with parent c doesn’t have to manufacture its own food or nutrition (gets that from mother plant) 4 Chloroplasts contain chlorophyll a and b, betacarotene 5 Cell wall composition, chloroplasts synthesize & store starch, sperm structure, etc. ii green algae 1 Chloroplasts contain chlorophyll a and b, betacarotene 2 Cell wall composition, chloroplasts synthesize & store starch, sperm structure, etc. 3 Single cells to multicellular 4 Marine and freshwater forms 5 Paraphyletic iii red algae iv glaucophyte algae b Green Algae and Land plants have synapormorphies linking one to the other: i Chloroplasts contain chlorophyll a and b betacarotene ii Cell all composition, chloroplasts synthesize c History of Green Plants i Adaptive Radiation Timeline 1 No need to know actual dates, but know the order a Origin of Land Plants i First evidence of land plants: cuticle, spores, sporangia b SilurianDevonian Explosion i Most major morphological innovations: stomata, vascular tissue, roots, leaves c Carboniferous i Lycophytes and horsetails abundant; extensive coalforming swaps d Gymnosperms Abundant i Both wet and dry environments blanketed with green plants for the first time e Angiosperms Abundant i Diversification of flowering plants 2 Trends: a ↑ independence from water b ↑ size c ↑parental contribution to zygote 3 Fossil Record a Green algae fossils – 725 million years ago (mya) b Land plants fossils – 475 mya c Several major adaptations evolved once d Transition to Land i In algae: 1 Spore a a single cell produced by meiosis (reduction division diploid to haploid) i can develop into multicellular adult b haploid, not formed by fusion of gametes c spores can also be produced by mitosis d present in ancestors of extant green algae e on surface, have durable substance called sporopollenin 2 Sporopollenin a durable polymer, watertight material that encases spores and pollen i an outer wall of spores and pollen b prevents drying out c protects reproductive cells from dehydration ii Protists already had spores and flagellated sperm (flagellated sperm in Charophyceae, flag spores in other green algae) iii Benefits to moving onto land 1 More sunlight and CO2 a More photosynthesis 2 There was dehydration, but land plants evolved iv Innovation of Land Plants 1 UV absorbing compounds flavonoids a Land plants have flavonoids a group of plant metabolites thought to provide health benefits through cell signaling pathways and antioxidant effects 2 Cuticle – waxy coating on outermost cell layer a Help resist drying interferes with gas exchange 3 Stomata – structures on plant surface permitting gas exchange for photosynthesis – pores with guard cells a Helps gas exchange occur for photosynthesis b When stomata closes (guard cells), water doesn’t escape e Alternation of Generations i Only happens in plants ii Evolved once in land plants through convergent evolution iii Multicellular haploid stage (gametophyte) alternates with multicellular diploid stage (sporophyte) 1 Sporophyte cannot make another sporophyte; the same goes for gametophytes 2 Meiosis and Mitosis are involved iv SPOROPHYTE (2N) (MEIOSIS) SPORES (1N)(single celled) (MITOSIS) GAMETOPHYTE (1N) (MITOSIS) GAMETE 2X (1N) (SYNGAMY) ZYGOTE (2N) (MITOSIS) SPOROPHYTE (2N) v There are four diagrams we need to know 1 NonVascular Plants a Gametophyte dominant b Homosporous c No cone d No flowers e No vascular tissue f Rhizoids, but no roots, stems, leaves i Rhizoids: specialized rootlike tissue, anchor gametophyte (but don’t absorb water/minerals) g Obtain water by diffusion (mostly) h No support against gravity i Small size, Resistant to desiccation, Need water for reproduction 2 Seedless Vascular Plants a Sporophyte dominant b Homosporous c No cone d No flowers e Vascular tissue: conducts water/solutes throughout plant; lignin provides strength i allowed plants to defy gravity & improved water conduction 3 Gymnosperms a Sporophyte dominant b Seeds c Heterosporous d Cones e No flowers f Vascular tissue 4 Angiosperms a Sporophyte dominant b Heterosporous c No cones d Flowers e Vascular tissue f Seeds f PlantAnimal Coevolution i Coevolution: 2 interacting species influence each other’s adaptations on a sustained basis ii Mutualistic coevolution 1 Both species benefit a Angiosperms with pollinators iii Antagonistic coevolution (“arms race”) 1 Evolution of adaptations and counteradaptations between competing species or between predators and their prey g Plant defenses against herbivory i Mechanical 1 Thorns, spines, prickles, etc. ii Chemical 1 alkaloids, amines, diterpenoids, saponins, carenolides, phenols, curcubitacins, canogenic glycosides 2 One organism’s toxin is another’s medicine… h Uses of Seed Plants i Ecosystem services: 1 O2, soil composition, water retention, primary producers, carbon cycle ii Food, fiber, fuel to humans iii Source of compounds for medicine & industry 3 CHAPTER 32 – FUNGI a Intro to Fungi i Poor fossil record ii Came about ~ 1.5 billion years ago (bya) according to molecular evidence 1 Oldest fossils ~ 650 my iii There are 80,000 species that have been described b Traits/Characteristics i unicellular (“yeast”) or multicellular (mycelium composed of hyphae) ii Heterotrophic Extracellular digestion iii Cell walls – similar to plants but made of chitin (animals) iv Store food as glycogen (animals), not starch (plants) v Have (Chytrid) flagellum like animals vi Clade = Opisthokonta vii Hyphae = thin, branching filaments, divided by septa; pores allow flow of cytoplasm between cells 1 Hyphae grow towards food; die back 2 High surfaceto –volume ratio c Lifestyles i Decomposers (saprophytes) 1 Organisms that absorb dead plants 2 Digest lignin and cellulose 3 Cycle carbon into sugars (glucose) 4 Cycle N and minerals ii Parasites/predators 1 To plants 2 To animals 3 Frequency dependent selection 4 To protists 5 Other fungi iii There are lots of fungi that can kill animals 1 Most fungi types specialize/focus on one species iv Mutualists 1 mycorrhizae – association between fungi and living roots of most (> 90%) vascular plants; d Types i Ectomycorrhizae 1 hyphae surround plant cells – (Nitrogen, some Phosphorous) ii Endomycorrhizae (Arbuscular) 1 hyphae penetrate plant cells – (mostly Phosphorous) e Uses i baking ii brewing iii antibiotics, drugs, steroids, etc. (penicillium, the Pill) iv commercial acids (citric acid in Coke – Aspegillus) v stinky cheeses (blue, Camembert) vi cheese substitutes, popcorn topping, mycroprotein (Ascomycotes) vii microremediation 4 CHAPTER 33 – ORIGIN OF METAZOANS a Metazoans i Multicellular animals 1 1.3+ million species b Traits of Metazoans i chemoorganoheterotrophs ii lack cell walls (instead have structural proteins) iii development: cleavage and gastrulation iv Diploid phase dominates life cycle v Sexual reproduction vi Nerves and muscles c Origins of Metazoans i Monophyletic ii Ancestor = colonial protest similar to extant choanoflagellates d When did they evolve? i Best estimate of origin of kingdom Animalia: 1 535 – widely accepted fossils 2 750 mya (recently discovered tiny fossils) 3 Approx. 1 bya (molecular evidence) ii How does molecular evidence give us a different estimate? 1 Molecular clock a hypothesis that amino acid base substitutions accumulate as a linear function of time. b Method to estimate divergence dates of lineages (when one lineage splits into 2) i Valid when: # of nucleotide substitutions is a linear function of time ii Useful: when common ancestor of taxa of interest is not known iii Reliability: when multiple clocks give similar dates c Molecular clock evidence indicates animal lineage originated 1+ bya 2 Mutations are random – but over long spans – may occur at “constant” rate e Cambrian Explosion i What happened? 1 The simultaneous appearance of metazoan phyla in fossil record and rapid diversification (starting ~543 mya) 2 Larger, more complex, FOSSILIZABLE animals suddenly appeared (tougher exterior, harder parts) ii Contributors 1 Increase in free oxygen (cynobacteria, 2.5 bya; eukaryotic algae, 1.8+ bya) 2 Colonization of new biotic niches a As some organism got larger, new biotic niches were created b Example: Parasites: 7 spp mites on 1 sp parrot 3 Intensification of coevolutionary “arms races” among animals a previously only softbodied animals, probably not active hunters 4 Proliferation of hox genes a Specify axis and segment identity (location) within embryo to develop certain structure 5 Interacting factors extensive positive feedback iii Process whose result is reinforcing, accelerating the process. 5 CHAPTER 34 – ANIMALS a Metazoan diversity i 34 phyla of animals ii Phylogeny: based on DNA sequences iii Survey 9 phyla iv 1.3 million named species b Major Steps in Metazoan Evolution i Step 1 1 Multicellularity, with celltocell communication, increasing cell specialization a Sponges (Phylum: Porifera) i No plane of symmetry ii Lack nerves, muscles iii Several cell types iv Suspension feeders v Sexual and asexual reproduction ii Step 2 1 Presence of germ layers (diploblasty) a Phylum: Cnidaria i 2 germ layers ii First true Hox genes iii Nerves and musclelike tissue iv Most Cnidarians possess radial symmetry iii Step 3 1 Triploblasty a Triploblasts – 3 germ layers b Ectoderm – skin, nervous system c Endoderm – lining of digestive tract d Mesoderm – muscle, circulatory system, bone, organs e Cephalization f CNS – orient and move in one direction g Coelom a fluidfilled body cavity completely lined by mesoderm h 99% of extant animals iv Coelom categories 1 Acoelomates 2 Coelomates 3 Coelom reduced/lost several times v Hydrostatic skeleton 1 system of body support with body wall surrounding fluid under compression 2 Allows “worms” to move. vi Protostomes: 2 radiations 1 22 phyla 2 Most have “worm: design: tube within tube 3 Broad radiation of mouth parts, feeding styles 4 Protostomes = “first mouth” mouth 5 Deuterostomes = “second mouth” anus
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