Bio 114 Exam 5

24 July 2022
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One of the characteristics of retrotransposons is that
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they code for an enzyme that synthesizes DNA using an RNA template
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Which of the following is a major distinction between a transposon and a retrotransposon?
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a transposon moves via a DNA intermediate and retrotransposon via an RNA intermediate
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Multilane families include 2 or more nearly identical genes or genes sharing nearly identical sequences. A classical example is the set of genes for global molecules, including genes on human chromosomes 11 and 16. Several of the different global genes are expressed in humans, but at different times in development. What mechanism could allow for this?
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differential gene regulation over time
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What is the precent identity between the ? and ? globin sequences?
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76%
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What percent identity is implied by the dashes?
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100% identity
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Notice that the cells in the lower left half of the table are blank. Why?
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they represent duplicates of the comparisons in the upper right half of the table
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Based on the premise, identify which 2 globin genes are the most recently duplicated. What is percent amino acid identity between them?
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?1 and ?2 , with 100% amino acid identity
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Which 2 globin genes are most divergent from each other? What is the percent amino acid identity between them?
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?1 and ?2 , with 100% amino acid identity
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Does the order of pairs in the table above describe the same relative "closeness" of globin family members as shown in the model?
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yes. pairs of globins at the top of the table are drawn with the closest connections in the model
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Which of the following percent identities is a good cut-of value separating within-family parings from between-family pairings?
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50%
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During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large, hand-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result from natural selection?
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more small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks
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In the hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (i.e., they locate their prey by sight). If a population of algae-eaters experiences prediction pressure from pike-cichlids, which of the following should least likely be observed in the algae-eater population over the course of many generations?
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Selection for larger female algae-eaters, bearing broods composed of more, and larger, young
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Which statement best describes the evolution of pesticide resistance in a population insects?
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Offspring of insects that are genetically resistant to the resistant to the pesticide become more abundant as the susceptible insects die off
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Of the following anatomical structures, which is homologous to the wing of a bird?
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flipper of a cetacean
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Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are
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examples of convergent evolution, and adaptations to a common environment
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Within a few weeks of treatment with the drug 3TC, a patient's HIV population consists entirely of 3TC-resistant viruses. How can this result best be explained?
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a few drug-resistant viruses were present at the start of treatment, and natural selection increased their frequency
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About which of these did Darwin have a poor understanding?
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the sources of genetic variations among individuals
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Which of these evolutionary agents is most consistent at causing populations to become better suited to their environments over the course of generations?
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natural selection
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Which is a true statement concerning genetic variation?
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it must be present in a population before natural selection can act upon the population
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What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time?
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the 2 phenotypes are about equally adaptive under laboratory conditions
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Generation-to-generation change in the allele frequencies in a population is
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microevolution
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When we say than an individual organism has a greater fitness than another individual, we specifically mean that the organism
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leaves more viable offspring than others of its species
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If the frequency of a particular allele that is present in a small, isolated population of alpine plants decreases due to a landslide that leaves an even smaller remnant of surviving plants bearing this allele, then what has occurred?
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a bottleneck, genetic drift, and microevolution
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Prezygotic barriers
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behavioral isolation, mechanical isolation, habitat isolation, temporal isolation, gametic isolation
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Postzygotic barriers
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reduced hybrid fertility, reduced hybrid viability
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Behavioral isolation
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differences in mating rituals or displays EX.) beetle mating displays show different spot patterns
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Mechanical isolation
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reproductive structure incompatibility EX.) flowers accommodate different insect pollinaters
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Habitat isolation
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differences in habitat occupied EX.) 2 fish species spawn at different depths
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Temporal isolation
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differences in the timing of mating EX.) birds are active during different times of day
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Gametic isolation
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sperm and egg are incompatible EX.) a coral's sperm can't fertilize during different times of day
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Reduced hybrid fertility
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hybrid offspring are produced but are sterile EX.) offspring of 2 newts are sterile
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Reduced hybrid viability
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hybrid offspring are produced but are feeble or unable to compete for mates EX.) lion-tiger hybrids don't reach maturity
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Which of the following statements about species, as defined by the biological species concept, are correct?
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biological species are defined by reproductive isolation; the biological species is the largest unit of population in which successful reproduction is possible
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Which of the various species concepts distinguishes 2 species based on the degree of genetic exchange between their gene pools?
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biological
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A defining characteristic of allopatric speciation is
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geographic isolation
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What is genetic drift?
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a change in allele frequencies caused by random events
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Why are the large finches now living on the Galapagos Islands different from the original source population from a nearby island?
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natural selection favored individuals that were more fit in the new environment, the separation of habitats reduced gene flow between the populations, genetic drift occurred in the two populations
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The last ice age produced many different species mainly because populations dispersed and colonized new habitats
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false
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Which of the following statements about reinforcement is true?
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reinforcement is a type of natural selection
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A subset of a population of birds leaves its habitat on the mainland and colonizes a nearby island. The birds, after a period of time, become reproductively isolated. The island sinks and the population returns to its original habitat. Which of the following statements about these bird populations is true?
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the populations will not be able to interbreed because they are different species
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A population of birds colonizes an area in which the insects upon which they feed live inside trees. Which of the following events accounts for an observed increase in average beak size in the bird population over time?
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increased fitness of large-beaked birds, leading to natural selection
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A flood that separates a population of frogs into opposite sides of a lake is an example of a vicariance event that may result in allopatric speciation.
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true
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Why might the number of genes in the genome underestimate the number of different proteins that an organism makes?
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many genes undergo alternative splicing, so that different proteins with different exon combinations are produced from the same gene
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What information can be learned by comparing genomes from distantly related groups of organisms such as eukarya and archaea?
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these comparisons can help clarify evolutionary relationships between organisms that diverged from each other many millions or even billions of years ago
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What does the similarity in the DNA sequence of homeobox genes in distantly related species indicate about the evolution of these genes?
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the homeobox DNA sequence must have evolved very early in the history of life on Earth
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NCBI provides
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BLAST, a database of protein structures, and Genbank
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The occasional mixing and matching of different exons within a gene or between 2 different (nonallelic) genes can be caused by errors in meiotic recombination. This process is called
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exon shuffling
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What factor accounts most for the difference in genome size between vertebrates and prokaryotes?
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vertebrates have more noncoding DNA sequences
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2 families of globin genes exist in humans. In each family, there are multiple copies of the genes. How did these multiple copies come about?
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a common ancestral gene was duplicated early in the evolutionary history of the globin gene and then multiple times since
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Which statement correctly describes the difference between transposons and retrotransposons?
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transposons move around in a genome by means of DNA intermediate, and retrotransposons move around in a genome by means of RNA intermediate
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Multigene families arise as a result of
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errors during DNA replication and recombination
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In the science of genomics, scientists
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study whole sets of genes and their interactions
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Chromosomal rearrangements may be important in evolution because
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chromosome rearrangements lead to gene duplication, thus generating a "spare" copy of the gene that is free to evolve and acquire a new function
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What can be learned from comparing the genomes of distantly related species, such as yeast and humans, or plants and fruit flies?
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conserved genes provide insight into their evolutionary relationships
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Alu elements
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are derived from or related to transposable elements
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What is not true regarding multigene families?
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multigene families arise as a result of transposition from one part of a genome to another
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What tool or resource is useful for identifying previously unknown protein-coding genes in a genomic DNA sequence?
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software that searches for translational start and stop signals
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Which statement best describes one of the differences between prokaryotic and eukaryotic genomes?
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prokaryotic genomes do not include noncoding regions (introns) while eukaryotic genomes do
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The majority of human genome consists of all but which of the following?
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exons
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How do transposable elements promote functional genetic diversity in a population?
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a transposable element may cause genetic diversity by any of the listed methods
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Transposons were discovered by which of the following scientists?
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Barbara McClintock
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The brine shrimp Artemia and the grasshopper, an insect, have very similar homeobox genes but very different body forms. What accounts for the differences?
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small changes in regulatory sequences of particular genes cause changes in gene expression patterns that can lead to major changes in body form
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The ____ is the highly conserved sequence element found within homeotic genes
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homeobox
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How can the varying fitness of double-mutant yeast cells provide insights into interactions between gene products?
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if double-gene mutations produced smaller colonies than single-gene mutants, then the 2 genes and their products likely interact; if double-gene mutants produced larger colonies than single-gene mutants, then the 2 genes and their products likely interact; if double-gene mutants produced colonies equal in size to single-gene mutants, then the 2 genes and their products do not interact
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Why might a dog genome sequencing project prove particularly informative, compared to other mammalian genomes?
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genetic variation between breeds may be linked to phenotypic variation
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Repetitive DNA is DNA that
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consists of sequences present in multiple copies in the genome
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The human genome consists of approximately 21,000 genes, which is only slightly more than the genome of the nematode Caenorhabditis elegans, which has 20,100 genes. How can 2 organisms with similar numbers of genes be so different in overall complexity?
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Human genes typically contain multiple exons, which can be spliced together in different ways, leading to the production of many more proteins than the number of proteins in the nematode; extensive RNA splicing, which generates more than 1 polypeptide from a single gene, occurs in humans but is not typically seen in nematodes; post-translational modifications of proteins are more common in humans than in nematodes; RNAs that play regulatory roles in humans are not typically present in nematodes
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How does sequence by synthesis techniques differ from previous sequencing methodologies?
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simultaneous sequencing of many small fragments of DNA, thereby reducing the amount of time required to sequence a genome
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Detailed comparison of the human and chimpanzee genomes has revealed that
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most differences are in the form of chromosomal rearrangements
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The number of genes in an organism's genome is not a perfect indication of the organism's complexity because
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alternative splicing can increase the number of polypeptides made from a single pre-mRNA; post-translational modifications can increase the types of proteins produced by a single gene; individual polypeptides can interact to form multiple types of protein complexes; individual genes can be expressed in more or less complex ways in different organisms
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How many genes is the human genome thought to contain?
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approx. 20,000-22,000
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Which of the following is not an observation or inference on which natural selection is based?
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poorly adapted individuals never produce offspring
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A population of zooplankton is exposed to a small number of predatory fish that feed on the larger-sized (adult) zooplankton. Which of the following predictions would most likely occur based on the principles of natural selection?
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adult zooplankton will start to reach sexual maturity when they are still relatively small
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Carolus Linnaeus is considered to be the founder of ____, and he
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the binomial classification system; thought that resemblances among different species reflected the pattern of their creation
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Organisms found only in specific places in the world are referred to as
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endemic
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Which of the following is not an observation or inference that Darwin made while developing his theory of evolution?
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interactions between individuals and their environment cause individuals to evolve
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Even thought rodents known as sugar gliders and flying squirrels are members of distinctly different groups of organisms and live on different continents, they possess similar characteristics. This is an example of
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convergent evolution
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The bacteria Staphylococcus aureus has developed resistance to some antibiotic drugs. How did this resistance come about?
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some members of the bacteria population possessed some sort of genetic variation for antibiotic resistance that was selected for when the bacteria was exposed to the drugs
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An important challenge to traditional (pre-1860) ideas about species was the observation that seemingly dissimilar organisms such as hummingbirds, humans, and whales have similar skeletal structures. This most directly suggested to biologists that
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dissimilar organisms might have evolved from a distant, common ancestor
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What insight did Darwin gain from reading Thomas Malthus's essay on human suffering?
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organisms have the capacity to overproduce
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Which of the following is correct regarding natural selection?
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natural selection is a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than do individuals without those traits; over time, natural selection can increase the correspondence between organisms and their environments; if an environment changes, or if individuals move to a new environment, natural selection may result in adaptation to these new conditions, sometimes giving rise to new species; individuals do not evolve, populations do
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What does each branch point on an evolutionary tree represent?
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the common ancestor of the lineages beginning there and to the right of it
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How does our understanding of genetics today refute Lamarick's principle of the inheritance of acquired characteristics?
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experiments in genetics show that traits acquired during an individual's lifetime are not inherited in the way proposed by Lamarck
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In Darwin's view of descent with modificaiton
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natural selection can improve the match between an organism and its environment
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The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all 3 kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data?
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natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy
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On an evolutionary tree
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homologous characteristics form a nested pattern
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Paleontology, the study of fossils, was developed by
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Georges Cuvier
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Darwin's explanation of how adaptations arise centered on
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natural selection
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Animals that possess homologous structures
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probably evolved from the same ancestor
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During periods of rapid environmental change, what may happen to a species that was well-suited to the former environment?
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the species may go extinct; individuals with particular traits that provide an advantage in the new environment will have higher reproductive success; the population may change so much in adapting to the new environment that it is considered a new species; traits that were favorable in the original environment may be detrimental in the new environment
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Darwin originally defined evolution as
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descent with modification
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What does it mean to describe evolution as a scientific theory?
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evolution is a broad model that is supported by many observations and much experimental evidence
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At the time Darwin voyaged on the HMS Beagle, the popularly accepted theory in Western culture that explained the origin of Earth's plants and animals held that the various species
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had been created by divine intervention an few thousand years before
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The breeding of plants and animals for particular traits by humans is called
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artificial selection
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How did Hutton and Lyell's ideas influence Darwin's thinking?
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Darwin reasoned that the Earth must be very old and that slow, subtle processes could produce substantial biological changes
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A ____ is the smallest unit that can evolve
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population
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All known organisms transcribe genetic information to protein molecules via the same genetic code. This finding strongly supports the hypothesis that
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all organisms are descended from a single common ancestor
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Adaptations are
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inherited characteristics of organisms that enhance their survival and reproduction in specific environments
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The modern idea of extinction as a common occurrence in Earth's history was 1st proposed in the early 19th century writings of
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Cuvier
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Which of the following people developed the idea known as the scala naturae, or scale of nature?
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Aristotle
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Homologies that appear to have marginal, if any, importance to an organism are called
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vestigial structures