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BIOB51 Term Test 1
| Question | Answer |
|---|---|
| Why is it often difficult to conceptualize biological evolution? | • Mechanisms are often challenging to describe (e.g., modes of speciation) • Issue with scale and the concept of time • Difficulty demonstrating and observing “evolution” in a teaching lab |
| What is the difference between a theory and a fact? | A theory is a well-established, well supported, well documented explanation for an observation and supported by facts A Law is a description of a well-supported well documented and supported by facts |
| What is the relationship between theory and law? | A theory is an explanation, law is a description Theory<Law |
| Why is it important that we have a grasp on the concept of time, in an evolutionary sense? | Because 5-7 million years ago humans and chimps shared an ancestor but in terms of time that is very small in evolution as we still share 99% of our genomes |
| How does an understanding of evolution inform us about all aspects of life and the interconnectivity of life? | • why the natural world is the way it is • similarities & differences among and between species • geographical distribution of species • incredible adaptations (& weaknesses) of living thing |
| Why do we know that whales are mammals? We discussed several features and examples. | Whales share numerous synapomorphies with mammals • Mammary glands • Three middle ear bones • Hair (in developing embryos) Astralagi Hindlegs growth in embryos Gradual transition to saltwater from freshwater in phylogeny tree ancestors |
| What is Pakicetus and how does it fit within the phylogeny of cetaceans? | Pakicetus Is a cetacean ancestor with a long snout and an involucrum, tympanic plate and middle ear cavity and the first terrestrial cetacean found |
| What is a synapomorphy? | is a derived form of a trait that is shared by a group of related species |
| What are isotopic analyses? | Is the analyses of 18O/16O in fossilized teeth |
| How was 18O/16O used in our understanding of saltwater and freshwater cetaceans? | The 18O/16O ratio was used as it is higher in saltwater and in teeth of marine animals so it was used to and found that earlier ancesters of whales were more in freshwater with a progression to saltwater in more recent ancestors of cetaceans. |
| How is it that modern cetaceans do not have hindlimbs? | They begin to form in embryo then get covere by thick layer of skin due to mutation in a regulatory gene |
| What is baleen? What clue does it provide about cetacean evolution? | Baleen began to appear in small patches and completely replaced teeth in mysticetes , genes for building teeth disabled |
| What are the main steps in the life cycle of SARS-CoV-2? | Virus enters host cell by binding to cell-surface, hijacks cellular machinery to express viral proteins and replicate the viral RNA, occasional mutation changing tip of spike protein, new virus released some with new protein |
| Describe viral reassortment | viruses to swap genes when two viruses infect a cell at once, their genes sometimes are shuffled together as they become packaged into protein shells. Example H7N9 combo of 4 bird strains |
| What is special creation? | A notion that western thought about nature of organisms for >2000 yrs 1. Species are independent (unrelated) 2. Life on Earth is young (~ 6000 years old) 3. Species are immutable (incapable of change) |
| Describe typological thinking as laid out by Plato | • Every organism an example of a perfect essence, or type, created by God • Types were essentially unchanging |
| Describe typological thinking + scale of nature as laid out by Aristotle | Aristotle ordered organisms into linear great chain of being (or scale of nature) • Species were fixed types • Species organized into sequence based on increasing size & complexity • Bottom: minerals & lower plants • Top: humans |
| What is the Great Chain of Being? | species as being arranged on a scale from lower to higher forms |
| Who was Carolus Linneaus? Why was his classification of life effective? | Father of modern taxonomy, used structural similarities to organize species |
| Understand the concept of Linnean taxonomy | linear acquired traits passed on |
| Understand the concept of a nested hierarchy | A grouping of organisms nested within themselves |
| Who was Georges Buffon? What were his observations about organisms in relation to environments? And the age of the Earth? | 70,000 yrs • Despite similar environments, different regions have distinct plants & animals • Life emerged as distinct types • transformed when environment changed |
| Who was Georges Cuvier? What was the impact of his observation of current vs. fossilized organisms? | • fossils resemble modern species (but not same) • many past species are extinct |
| How does extinction challenge the Great Chain of Being | it showed a flaw in the design of gods creations |
| Who was Mary Anning? What was her contribution to our understanding of evolution? | Discovered first fossil at 12 found marine reptiles , etc = supporting extinction theory |
| Who was James Hutton and what were his contributions? | • small changes that accumulate over time • Earth must be very old |
| Who was William Smith? What is stratigraphy? | • different layers contain distinct fossils • answers for extinction in rocks below • same layers of rock in different parts of England • layers identified by fossils they contained |
| What was Jean Baptiste Lamarck’s contribution to evolutionary thinking? What aspects about his theories were correct and incorrect? | • Life driven from simple to complex • Complex species descended from microbes • Microbes continually generated spontaneously • Organisms evolve by moving up chain over time • Progressive—producing larger, more complex or “better” over time |
| How did Lamarck propose that species change through time? | Moved up the latter of complex species and Adaptation occurs through inheritance of acquired changes • Giraffe needs to reach higher branches, so its neck stretches • elongated neck passed to offspring |
| Who was Charles Darwin? What was his contribution to understanding of biological evolution? | Went to medical school failed joined the clergyman and was invited to go on HMS Beagle in 1831 |
| What is the significance of the Voyage of the Beagle? | The experiences he had during his voyage around the globe would later lead him to a scientific revolution |
| How did Charles Lyell influence Darwin? What is uniformitarianism? | Population growth in humans can be limited by the supply of resources |
| What were Darwin’s notable observations in Patagonia (South America) and the Galápagos Islands? | He recognized the layers of rock that had gradually formed and were then reworked into mountains and valleys. He experienced an earthquake in Chile, changes to shore after. the birds were all finches. Despite their radically different beaks, |
| Who was Alfred Russel Wallace? What was similar (or different) about his thoughts and Darwin’s? | proposed similar evolutionary ideas • collections from South America & Malay Archipelago • observations of biodiversity • common ancestry, natural selection |
| What is population thinking (as outlined by Darwin & Wallace)? How is this different from typological thinking? | Change does not follow linear progression • Based on variation amongst individuals in populations • Individuals with certain traits produce more offspring than others without these traits |
| What is artificial selection? What does the “artificial” refer to? | Is human selection on traits not seen in nature |
| Who was Thomas Malthus? What is the “Principle of Populations”? How is this principle relevant to evolution? | Political economist, the PoP: • populations double every 25 years • food becomes limiting (lags behind) • leads to poverty, employment, misery Helped explain extinction and competition among species |
| What is meant by descent with modification? | • Species change through time • Species are related by common ancestry • Leads to descent with modification |
| Synapomorphy | = homology |
| homology | structural characters that are shared because they are inherited from a common ancestor |
| homoplasy | can result from the independent evolution of the same trait in two or more lineages |
| convergent evolution | independent evolution of a similar trait • streamlined body of fish & dolphins • flight in birds & bats |
| Why was Darwin/Wallace’s theory revolutionary? | 1. Overturned idea that species are unchanging 2. Replaced typological thinking with population thinking 3. it was scientific 4. Proposed mechanism that could account for change through time 5. Predictions could be tested throu. obser. & exper. |
| What are Darwin’s four postulates? | 1. Individuals within species are variable 2. Some variations are passed to offspring 3. In every generation, more offspring are produced than can survive 4. Survival & reproduction is not random |
| What is meant by the quote by Dobzhansky “Nothing in biology makes sense except in the light of evolution”? | the structures of living organisms only make sense when viewed as evolutionary adaptions to specific selection pressures |
| Based on his analyses of the Weald, how old did Darwin figure the Earth must be? | Counting sedimen. Rock layers in geo formations= age Water bodies accum. Sedimen. In predictable manner rate of accum.= measurable |
| Who was Lord Kelvin and what were his thoughts on the history of Earth? | He believe earth was ridged sphere , heat moves through solid predictable rate as solid cools, temp of mine shaft show length of Earth cooling |
| What is radiometric dating? | A form of using radioactive isotopes to date rocks |
| What are isotopes? | Scientists compare radioactive isotope to its decay product to date rocks |
| What is a half-life? | • time 1/2 radioactive atoms in sample to become non- radioactive • rate is exponential & constant |
| What is radioactive decay? | unstable isotopes decay at different rates |
| Why do most dead organisms fail to fossilize? | Bacteria present, sun wind or rain inhibit fossilization |
| Why is the fossil record incomplete? | Not all organisims fossilize ,some not found |
| How can we estimate the age of fossils? | Yes with radiometric dating and dating layers of rocks they are found in |
| What others can clues can fossils provide (besides morphology and time)? | Infer diet of extinct animal by using Carbon 12/13 ratios |
| What is the role of the hadrosaur crest? How was this deduced? | • Crest connected to the nasal cavity (CT scan) • Sound generated by blowing air • Ears tuned to this frequency |
| What is the Burgess Shale? What is its significance to our understanding of invertebrate life on Earth? | yielded more than 65,000 specimens of mostly soft-bodied animals representing at least 93 species from Cambrian period in BC Canada 505 million years ago |
| What are biomarkers? How are biomarkers relevant to evolutionary analysis? | distinctive molecules only produced through biological activity examples: DNA fragment in mammoths tooth Carbon isotopes in plants , okenane 1.4 billion years ago |
| What are carbon isotopic signatures? What is different about C3, and C4 plants? | Different plants collect different ratios of this and when consumed that same ratio is integrated into teeth and bones of consumer |
| What are the three domains of life? | Archaea, Eukarya and Bacteria |
| What are stromatolites? | early evidence of life |
| Earliest signs of life are microbial | • microbes Earth’s biomass & genet. diversity • Transition to multicellular life 2.1 billion ya • Multicellularity evolved independently many lines • Most evolved during the Cambrian period • including chordates (which includes humans) |
| What is a phylogeny? What is a phylogenetic tree? | Phylogeny: evolutionary history of a lineage or lineages ,can depict populations, genes, species, or higher taxonomic units Phylogenetic Tree: visual representation of a phylogeny |
| Know the components of a tree (clade, node, branch, root, taxa). Be able to identify them on a tree? | Clade: a common ancestor & all descendants Node: point at which lineage splits , represents common ancestors for all descendent lineages |
| What is the difference between an ancestral and a derived trait? | There and not there |
| What is meant by “free rotation around the nodes” ? | Shapes of trees can be modified without changing the relationships |
| Know the difference between a rooted and unrooted tree | rooted trees have an outgroup with ancestor to find the root of the tree unrooted trees do not have an outgroup so hard to find where tree began |
| Understand the concept that phylogenies represent hypotheses | • based on the best available evidence • based on the analysis of synapomorphies |
| Understand why trees do not need to include all of the taxa and all of the data | too much data |
| Understand the concept of a nested hierarchy | groups within groups |
| Understand the difference between monophyletic, polyphyletic, paraphyletic? Be able given an example or identify them on a tree. | Monoplyletic: taxo group consisting of acommon ancestor and all descendants Polyphyletic: taxo group of species descended from multiple ancestral lines Paraphyletic: common ancestor and some of its descendants |
| What is a polytomy? | Branch that is not Y Polytomies are an artifact – do not occur naturally an indication we need more information to better resolve the tree |
| Understand why many Linnean taxonomic groups are not monophyletic | linear ideology |
| What is a character? What is a character state? | Characters: identifiable heritable traits Character state: condition of the character |
| What is an outgroup? | used to infer what is ancestral and what is derived is a group of organisms (for example, a species) that is outside of the monophyletic group being considered. In phylogenetic studies, outgroups can be used to infer the ancestral states of characters |
| What is a character matrix? | 0/1 in traits or no traits |
| In general terms, how is a character matrix used to infer a phylogeny? | sorts with species having a character or lack of into a phylo tree |
| What is maximum parsimony? How does parsimony apply to evolutionary change? | The topology (tree) depicting the fewest evolutionary steps is often the most accurate Tree with fewest steps (12 vs. 20+) Each character state unique to single branch (not repeated) |
| What is an evolutionary reversal? | reversion back to an ancestral character state (e.g., by mutation) |
| Describe how mutations spread in viruses. | Mutations occur in replication and beneficial mutations increase with frequency due to natural selection and new protein spike not being recognized by the immune system , high reproduction, dominations populations in subsequent gens |
| What is the current hypothesis for the origin of SARS-CoV-2? | Current hypothesis is that it evolved from a bat corona virus |
| Know the components of a tree (clade, node, branch, root, taxa). Be able to identify them on a tree? | Branch: lineage evolving through time; connects successive speciation events or other branching events Root: common ancestor of all species in phylo tree Taxa: units of classification |
| Explain how comparisons of birds, bats, and pterosaurs can inform us about homology and homoplasy (convergent evolution). Explain this in the context of flight and forelimbs | birds, bats, and pterosaurs share a homoplasy in wings as all derived due to different pressures in lineages while the forelimb bones represent homology as all share a common ancestor in which these bones formations derived |
| What is a transitional species? | A species that helps complete a phylogeny tree example: Tiktaalik shares character states with all lobe-fin taxa and is the ancestor from which the tetrapod lineage arose |
| Why is coelacanth considered to be a living fossil? Why are they important for understanding the transition from water to land? | the closest living relatives of tetrapods |
| Describe the general differences between the pectoral fins of ray-finned fishes and lob- finned fishes. | Ray finned: connected to side of fish Lob-finned: have a chain of sturdy bones anchoring the fin. |
| Why is Tiktaalik an important transitionary fossil? | 375 mya scales (fish) gills (fish) flat head (crocodile) unusual fins (walking?) |
| Why is it often misleading to think of evolution as a linear progression? | newly discovered Qikiqtania wakei returned to sea while Tiktaalik moved on land |
| How did the bones in the mammalian inner ear evolve? | Mammalian ear bones are homologous to early synapsid jaw bones Early mammalian ancestors detected vibrations through lower jaw |
| What is the importance of Archaeopteryx and Zhenyuanlong in the fossil record? | Archaeopteryx-limbs projecting from wings, feathers and teeth Zhenyuanlong- vaned feathers quilled layers on forelimbs |
| How do we know that feathers evolved before flight? | Evidence of feathers 190mya Evidence of flight 150 mya |
| What is an exaptation? | natural selection co-opts a trait for a new function |
| What were the likely roles of feathers (before flight)? | • gliding while jumping • thermoregulation • species recognition • mate attraction • keeping eggs warm in nest |
| What is variation? What is heritable variation? Why is heritable variation important? | Darwin: heritable variation in populations was a necessary ingredient in natural selection |
| How much variation in there? | 9mil in one couple chromosome |
| Where does variation come from? | Heritable variation ultimately begins with mutation • Mutation = any change in our genomic DNA • Must reside in our DNA |
| Explain the role of mutation, recombination, and independent assortment in creating variation within the genome? | Mutation Recombination parts of chromosome mix independent assortment- two chromosomes chromids re-pair up |
| Mutation Recombination parts of chromosome mix independent assortment- two chromosomes chromids re-pair up | DNA, RNA and Proteins |
| What is the central dogma of molecular biology? | DNA->(transription)RNA->(translation) Protein <(replication) |
| What is DNA? What is its general structure? | deoxyribonucleic acid • deoxyribonucleotide (nucleotide) • sugar + phosphate group + base |
| What are nucleotides? What are the four nucleotides found in DNA? How do they attached to the ribose sugar? | Adenine (A) Guanine (G) - purines Thymine (T) Cytosine (C )- pyrimidines |
| What is the difference between a purine and a pyrimidine? | Purines- large Pyrimdine-small |
| What is complementary base pairing? | A-T , GC |
| What is meant by the sugar-phosphate backbone? | Deoxyribose sugar that the phosphate group and base attach to |
| Understand the basics of DNA replication (to the capacity we discussed in class) | |
| What is a chromosome? What is a chromatid? | chromosome- organized dna coiled chromatid- one have of a chromosome |
| How is DNA condensed? | Coiled around histone proteins |
| What is a karyotype? | individuals complete set of chromosomes |
| What does the term ploidy refer to? What is diploid? What is haploid? What is polyploid? | ploidy- higher combo of chromosomes diplod- 2 copies chromo haploid occurs alone |
| What is a gene? What are the major components of a gene? | a segment of DNA whose nucleotide sequences code for proteins or RNA or regulate the expression of other genes |
| What is RNA? How is RNA different from DNA? What is similar between DNA and RNA? | Copy of DNA single stranded and uracil replaces thymine, |
| What is transcription? | Transcription mRNA transcribes a single strange copy of DNA with a uracil in place |
| What are the three main types of RNA? What are their roles? | Messenger: • transcript copy of gene • encodes specific polypeptide Ribosomal: • primary component of ribosome • catalytic activity Transfer: • carries a.a. to ribosome for translation |
| What is micro RNA (miRNA)? How can miRNA affect gene expression? | gene regulation microRNA can block translation |
| What is translation? What is the role of the ribosome? | is when the ribosomes translate the RNA into a protein |
| What is an amino acid? How many amino acids are there? | 20 amino acids combinations |
| What is a polypeptide? | Protein |
| What is a codon? What is an anticodon? | codon:3 nucleuotides that form a genetic code for DNA or RNA molecule anticodon 3 nucleuotides that form a genetic code for RNA transfer molecule |
| What is the start codon? What is a stop codon? | start - begin coding for protein stop- stop the building of the protein |
| What is meant by “redundancy in the genetic code”? | There are more the one variation of codon that codes for the same amino acid |
| What are some of the roles of proteins? | structure and function of an organism; they can function as structural elements, enzymes, signals, or receptors |
| What are the four structures of proteins? | Adenine (A) Guanine (G) Thymine (T) Cytosine (C )- |
| What is a point mutation? Within coding regions, know how to identify and describe synonymous, nonsynonymous, and nonsense mutations? | Synonymous: does not change amino acid neutral Nonsynonymous: change in amino acid beneficial, neutral or deleterious nonsense mutations: early stop codon, usually deleterious |
| Know how to use the genetic code to determine the polypeptide sequence. | translator converts genetic code for 20 amino acids |
| What is meant by an ‘in-frame’ and ‘frameshift’ mutation. What is potential impact on the polypeptide? | Reading frame shifted from addition or deletion altering codons and always deleterious |
| What are chromosomal mutations? | duplication, deletion/insertion, inversion, and translocation |
| Know how to describe and identify duplication, deletion/insertion, inversion, and translocation. | Duplication: duplicated deletion/insertion: deleted chrome or added inversion: seg of chrome turns 180 translocation: portion of seg of chromes move to another chromosome |
| cis-regulatory | • near/within the focal gene • slightly upstream, downstream, intron • e.g. promotors, enhancers, silencers |
| trans-regulatory | • often far away (e.g. different chromosome) • bind to cis-regulatory elements • e.g. transcription factors, activators, repressors |
| Understand and be able to describe how gene expression can be regulated? What is an activator, enhancer, silencer, transcription factor? | activator- enhancer-where they activate gene expression silencer- transcription- |
| Understand and be able to describe how miRNA can block translation. | silence genes by binding to mRNA molecules that would otherwise be translated into proteins turning genes on and off in response to changes in the environment |
| What is the difference between an intron and an exon? How can organisms produce different proteins from the same gene? Why is this important? | Inton- non coding dna, rmoved by rna splicing Exon- coding dna, joined together after rna splicing |
| How might this play a role in evolution? | |
| What is alternative splicing? | a eukaryotic cell can combine different 510 subsets of exons from the same gene to produce different combinations |
| What is heredity? | organisms can pass this mutated DNA to their offspring along with their unmutated DNA |
| How is heredity different between prokaryotes and eukaryotes? | Bacteria and archaea reproduce by dividing and making a new copy of their genome for each daughter cell |
| What is genetic recombination? When does it happen? What is the consequence | paired chromosomes come together, and each pair may cross over and exchange segments of DNA |
| How does recombination generate variation? | random mix of chromosomes from mom and dad |
| How does independent assortment contribute to genetic variation? | each separate chromosome can result in almost 9 million possible combinations of maternally inherited and paternally inherited genes |
| What is a genotype? What is a phenotype? How are they related and how are they different? | Genotype: genetic makeup of an individual Phenotype: manifestation of the genotype of an organism (e.g., observable, measurable characteristic) • morphological (antlers) • developmental • physiological (metabo.) • behavioural mate. displ. |
| How can we link genotype with phenotype? | phenotypes emerge from genotypes |
| Who was Gregor Mendel? What were his contributions to genetics and why was this vitally important for our understanding of the process of evolution? | father of genetics monk,pea plants |
| What is pleiotropy? What is phenotypic plasticity? What are the similarities and differences between these terms? | Phenotypic plasticity refers to changes in the phenotype produced by a single genotype in different environments. |
| What is an allele? | • different forms of a gene |
| What is meant by dominant and recessive? | dom-exert more influence than their partner allele and produce their trait recessive-exerts less influence |
| What is homozygous and heterozygous? | Homozygous: individual with two of same alleles of given gene Heterozygous: individual having different alleles of a given gene |
| What were the four keys to Mendel’s success? | • simple discrete traits • two years of breeding • many many replications • took a mathematical approach |
| What is the addition rule? What is the multiplication rule? Know and understand when each rule is applied | addition- likelihood of either event occuring (summed) multipli.-likely hood of two events occuring together (multiplied) |
| What is true-breeding? What is a monohybrid cross? | true-breeding organisms are homozgyous for genes monohybrid cross when two individuals with homozgyous differing genes create a hybrid |
| What is meant by F1 and F2? | First generation and second generation |
| What is a polymorphism? | is the simultaneous occurrence of two or more discrete phenotypes within a population |
| What is a polyphenism? | The same genotype can produce both phenotypes, depending on the environment in which the aphid develops |
| Tetrapods>synapsids>mammals | |
| Ocean to land from aquatic-aquatic+terrestrial: 1. Dry land was devoid of life/ diversity in sea 2. Microbial mats left remains on land rocks 3. Early invertebrates such as insects or spiders left tracks on beach dunes | 4. Spores were embedded in plant tissues 5. The oldest fungi left behind fossils evidence 6. The first fossil of a dully terrestrial animal surfaced 7. A tetrapod left tracks that fossilized |
| Early chordates | 515 mya • coincides with early Cambrian • Embryos all have: • notochord • pharyngeal gill slits • post anal tail • Notochord – hollow nerve cord Haikouichthys |
| First terrestrial vertebrates | • Oldest vertebrate trackways 390 mya • Oldest fossils of tetrapods 370 mya Silvanerpeton • 350 mya many currently existing lineages had yet to evolve • Teleost fish (bony fish) • Mammals • Birds • Flowering plants Evolution of mammals |
| Synapsids | • ~320mya • dominant vertebrates for ~ 280 mya evolved from synapsids • first mammals 150 mya Dimetrodon |
| Diversification of mammals | • Major diversification after dinosaur extinction (65 mya) • Placental mammals & marsupials • Whales, bats, primates all emerged ~ 50 mya |
| Evolution of other major lineages | • Birds - 150 mya • descendants of dinosaurs • Flowering plants - 132 mya • grasses did not diversify until 20 mya • Insects - 400 mya • but most current lineages appear much later |
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