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Bio 240 Exam 1
Random terms
| Question | Answer |
|---|---|
| Principle of uniformitarianism? | This states that the mechanisms of change are constant over time. |
| What is catastrophism? | It is speculating that each boundary between strata represents a catastrophe. |
| Two important implications for Darwin? | – Descent with modification explains life’s unity and diversity – Natural selection is a cause of adaptive evolution |
| Evolution | Change in genetic composition of a population across generations. |
| Population | a group of individuals of the same species.Individuals do not evolve! |
| Requirements for Hardy-Weinberg equilibrium | – No mutations – Random mating – No natural selection – Extremely large population size – No gene flow |
| Three major factors alter allele frequencies and bring about most evolutionary change | – Natural selection – Genetic drift – Gene flow |
| What is Genetic drift? | It describes how allele frequencies fluctuate unpredictably from one generation to the next. |
| What is the founder effect? | This occurs when a few individuals become isolated from a larger population. |
| The bottleneck effect is? | a sudden reduction in population size due to a change in the environment. |
| What is gene flow? | It is a change in the allele frequency due to transfer of alleles into or out of the pool. |
| What is the only mechanism that consistently causes adaptive evolution | Natural selections unique property . |
| What is relative fitness? | It is the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals. |
| What is Directional selection? | This favors individuals at one end of the phenotypic range. |
| What is Disruptive selection? | This favors individuals at both extremes of the phenotypic range. |
| What is Stabilizing selection? | This favors intermediate variants and acts against extreme phenotypes. |
| What is Adaptive evolution? | This occurs as the match between an organism and its environment increases. |
| What are Mechanisms that maintain genetic variation in a population? | >Diploidy • Heterozygote advantage • Frequency-dependent selection • Neutral variation |
| What is frequency-dependent selection? | The fitness of a phenotype declines if it becomes too common in the population. |
| 3 main objectives of systematics? | -To define characters and delimit spaces -To organize species into higher taxonomic categories, from genus to kingdom -The taxonomic structure should reflect phylogeny |
| What are the three major species concepts? | – Morphological species – Biological species – Evolutionary species |
| Problems with Morphological species grouping? | Does not address relatedness• Does it represent multiple species or one morphologically variable species?• Does not address convergent evolution• Some species are morphologically identical yet they do not interbreed and exchange genetic information |
| Problems with Biological species grouping? | doesn’t work for plants who often ‘hybridize’• For most living species, we do not have data on the ability of individuals to interbreed; e.g., 750,000 species of insects • Does not work for asexual organisms • Does not work for fossils |
| Problems with Evolutionary species grouping? | most groups few data available to interpret relatedness and ancestry•not work well for fossils can use only morphological data from body parts that fossilize• must still decide how much genetic variation is required to delimit between distinct species |
| Most Systemists agree? | that species exist, and that there is little or no genetic exchange between different species |
| What inhibits genetic exchange? | Reproductive Isolation. |
| What is habitat isolation? | Two organisms that use different habitats even in the same geographic area are unlikely to encounter each other to even attempt mating. |
| What is temporal isolation? | Two species that breed during different times of day, different seasons, or different years cannot mix gametes. |
| What is mechanical isolation? | Closely related species may attempt to mate but fail because they are anatomically incompatible and transfer of sperm is not possible. |
| What is Gametic isolation? | occurs when gametes of two species do not form a zygote because of incompatibilities preventing fusion or other mechanisms. |
| What is hybrid inviability? | Genetic incompatibility between the two species may abort the development of the hybrid at some embryonic stage or produce frail offspring. |
| What is hybrid breakdown? | In some cases, first generation hybrids are viable and fertile. – However, when they mate with either parent species or with each other, the next generation are feeble or sterile. |
| For the first two billion years of evolutionary history? | Earth’s only organisms were microscopic, unicellular and aquatic |
| What was the early earth like? | very hot from excessive volcanic activity • numerous meteor impacts • high solar radiation • very little oxygen – consequently no ozone layer to protect from... |
| MostscientistsfavorthehypothesisthatlifeonEarth developed? | from nonliving materials that became ordered into aggregates (protobionts) that were capable of self-replication and metabolism. |
| The 4 stages in which the earth developed primordial cells? | the abiotic synthesis of small organic molecules (2) joining these small molecules into polymers (3) origin of self-replicating molecules (4) packaging of these molecules into “protobionts.” |
| In 1953, Stanley Miller and Harold Urey? | Theydischargedsparks in an “atmosphere” of gases and water vapor, then collected the cooled water and any resultant compounds including amino acids and other organic molecules. |
| Hypothesis that the first genes were short strands of RNA? | – Small RNA molecules can form abiotically by polymerization of free nucleotides – RNA molecules can self-replicate – RNA can fold into 3-D structures that act as simple enzymes |
| RNA molecules have both? | a genotype(nucleotide sequence) and a phenotype (three dimensional shape) |
| Living cells may have been preceded by? | Protobionts |
| Protobionts do not reproduce precisely, but they do? | osmotic potential, voltage potential, catalytic capabilities |
| The beginnings of biotic diversity? | Evenifonlyonesuchprotobiontaroseinitiallybythe abiotic processes that have been described, its descendents would vary because of mutation, errors in copying RNA |
| First Crisis?result? | loss of abiotically-formed ATP. step-by-step evolution of glycolysis. |
| Second Crisis? result? | lossofabiotically-formedorganic compounds used in glycolysis. evolution of autotrophs. |
| photoautotrophs? | Firstautotrophsprobablyusedlighttodriveelectrons from H2S to fix CO2 into sugars |
| cyanobacteria? | Firstphotoautotrophsthatusedlighttodrive electrons from H20 instead of H2S to fix CO2 into sugars |
| Third Crisis? result? | accumulationofO2intheatmosphere caused the death of many organisms.evolution of aerobic respiration |
| Theevolutionoftheeukaryoticcellledtothe development of several unique cellular structures and processes? | – membrane-enclosed nucleus – endomembrane system – mitochondria and chloroplasts – cytoskeleton, 9 + 2 flagella – multiple chromosomes of DNA with organizing proteins – life cycles with mitosis, meiosis, and sex |
| The small size and simple construction of a prokaryotes imposes limits on? | the number of different metabolic activities that can be accomplished at one time. |
| Trend One | was the evolution of colonial prokaryotes, where individuals form thin filaments or sheets of cells. |
| Trend Two | was the evolution of complex communities of prokaryotes, with species benefiting from the metabolic specialties of others. |
| Trend Three | was the compartmentalization of different functions within single cells, an evolutionary solution that contributed to the origins of eukaryotes. |
| Autogenic Origin? | Modification of the plasma membrane into specialized structures; e.g., nucleus, endoplasmic membrane system |
| Endosymbiotic Origin? | Endocytosis of prokaryotes that develop into symbiotic organelles; e.g., mitochondria and chloroplasts |
| The nucleus and endomembrane system possibly developed? | through invagination of the plasma membrane |
| Mitochondriaandchloroplasts(plastids)evolved from? | endosymbiotic bacteria. |
| aerobic heterotrophic prokaryotes.? | Theproposedancestorsofmitochondria |
| photoautotrophic prokaryotes.? | Theproposedancestorsofchloroplasts |
| Theserialendosymbiosistheorysupposesthat? | mitochondria evolved before chloroplasts. These organelles and bacteria are similar is size. – Enzymes and transport systems in the inner membranes of chloroplasts and mitochondria resemble those in the plasma membrane of modern prokaryotes. |
| eukaryotic undulipodia is? | Cilia and Flagella |
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