ls1 midterm 2 #2

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LS1 Spring10 Name & ID___KEY_____________________ Page 1 of 10 VERSION A • Don’t open your exam until instructed to. • Write your name and student number on every page of the test before handing in the test. You will lose 5 points if you don’t! Enter you name, uid, and which version of the exam you have on the scantron. You will lose 5 points if you don’t! Use a pencil on the multiple choice; pen or pencil on the short answer. • Mark scantrons neatly, one answer per question. Erase changes completely. • Answer written questions in space provided. Do not write on the back, in the margins, or in space allotted for another question. Only answers on the front side of pages will be graded. NO EXCEPTIONS. If you must cross something out and run out of space to answer the question in the space provided, you must request another blank exam page. No electronic devices at your desk, including calculators and cellphones. No food, no bottles with labels. If you need to use the restroom, turn in your exam to a TA. Only one student may leave at a time. You may not leave the room with any electronic devices. Place a check next to your section Wednesday Thursday Friday Slichter 2870 Young 2343 Slichter 2870 Young 2343 Slichter 2870 ___2A: 12:00 ___2B: 2:00 ___2C: 10:00 ___2E: 2:00 ___2G: 4:00 ___2D 10:00 ___2F: 2:00 ___2H: 4:00 ___2I: 9:00 ___2K: 11:00 ___2J: 9:00 ___2K: 11:00 • Good luck! I hereby certify that I have neither given nor received any aid on this exam, and that I have read and understand the instructions above. Sign your name here:_____________________________________

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LS1 Midterm 2 #2

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  • LS1 Spring10 Name & ID___KEY_____________________

    Page 1 of 10

    VERSION A

    Dont open your exam until instructed to.

    Write your name and student number on every page of the test before handing in the test. You will lose 5 points if you dont!

    Enter you name, uid, and which version of the exam you have on the scantron. You will lose 5 points if you dont!

    Use a pencil on the multiple choice; pen or pencil on the short answer. Mark scantrons neatly, one answer per question. Erase changes completely.

    Answer written questions in space provided. Do not write on the back, in the margins, or in space allotted for another question.

    Only answers on the front side of pages will be graded. NO EXCEPTIONS. If you must cross something out and run out of space to answer the question in the

    space provided, you must request another blank exam page.

    No electronic devices at your desk, including calculators and cellphones. No food, no bottles with labels. If you need to use the restroom, turn in your exam to a TA. Only one student may leave

    at a time. You may not leave the room with any electronic devices.

    Place a check next to your section

    Wednesday Thursday Friday

    Slichter 2870 Young 2343 Slichter 2870 Young 2343 Slichter 2870

    ___2A: 12:00

    ___2B: 2:00

    ___2C: 10:00

    ___2E: 2:00

    ___2G: 4:00

    ___2D 10:00

    ___2F: 2:00

    ___2H: 4:00

    ___2I: 9:00

    ___2K: 11:00

    ___2J: 9:00

    ___2K: 11:00

    Good luck!

    I hereby certify that I have neither given nor received any aid on this exam, and that I have read and understand the instructions above.

    Sign your name here:_____________________________________

  • LS1 Spring10 Name & ID___KEY_____________________

    Page 2 of 10

    PUT YOUR NAME ON EVERY PAGE OF THE EXAM BEFORE STARTING.

    Exam is 175 pts total

    Part 1 Multiple Choice. 25 questions, 5 pts each

    1. Which of the following is not a function of feathers? a. Insulation. b. Flight c. Mating Display d. Sensory e. camouflage

    2. Which of the following describes the most likely sequence of events in a speciation event a. Genetic drift, genetic isolation, divergence b. Genetic isolation, genetic drift, divergence c. Genetic isolation, divergence, genetic drift d. Divergence, genetic drift, isolation e. Divergence, genetic isolation, genetic drift

    3. The evolution of specialized adaptation reflected in the fossil record of horses is best characterized by which environmental/ecological changes? a. Glaciation events caused population bottlenecks that left behind only the largest

    individuals b. Environments grew cool and dry, and forests were replaced by more

    open habitats c. Horses in early lineages were outcompeted by other mammals better adapted for

    browsing d. Both a and b e. Both b and c

    4. Which statement about genetic drift is correct? a. Genetic drift results from migration of new individuals into a population. b. Genetic drift increases adaptation of individuals to their environment. c. The direction of evolutionary change due to genetic drift is random. d. Genetic drift becomes increasingly important with increasing population size

    5. How many chromosomes would be found in an allopolyploid plant if its parents had diploid numbers of 6 and 10, respectively? a. Haploid number of 8 b. Diploid number of 8 c. Haploid number of 16 d. Diploid number of 16

  • LS1 Spring10 Name & ID___KEY_____________________

    Page 3 of 10

    6. Which of these lists contains the four elements necessary for natural selection? a. Uniform population, heritable traits, selection, differential survival or

    reproduction b. Variation in population, heritable variation, selection, differential

    survival or reproduction c. Variation in population, heritable variation, selection, unlimited survival and

    reproduction d. Variation in population, environmental variation, selection, differential survival

    or reproduction 7. Which of the following best describes the Cell Theory?

    a. all cells have membranes or walls; all organisms are composed of cells b. All cells arise from pre-existing cells, all cells have DNA c. All cells have DNA; all cells divide d. All organisms are composed of cells, cells arise from pre-existing cells

    8. Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant (A1) and recessive (A2) alleles according to the Hardy-Weinberg model? a. f(A1) = 0.9997, f(A2) = 0.0003 b. f(A1) = 0.9800, f(A2) = 0.0200 c. f(A1) = 0.9700, f(A2) = 0.0300 d. f(A1) = 0.9604, f(A2) = 0.0392 e. f(A1) = 0.9600, f(A2) = 0.0400

    9. Which is the best definition of adaptive radiation?

    a. An adaptive radiation is a group of rapid speciation events. b. An adaptive radiation occurs when a single lineage produces many

    ecologically diverse descendant species in a relatively short period of time.

    c. An adaptive radiation is the evolution of a novel trait that makes new ecological opportunities available

    d. An adaptive radiation is a star phylogeny.

    10. Which statement is correct? a. Synapomorphies identify monophyletic groups b. A synapomorphy is an ancestral trait. c. Synapomorphies are examples of homoplasy d. A synapomorphy may arise due to covergent evolution

  • LS1 Spring10 Name & ID___KEY_____________________

    Page 4 of 10

    11. Why would gene duplication events, such as those seen in the Hox gene complex, set the stage for adaptive radiation? a. There are more copies of genes, meaning speciation had occurred by polyploidy. b. The original gene copy is the out-group, and the new gene copies are the adaptive

    radiation. c. Without duplicated genes, species would be vulnerable to extinction. d. One copy of a gene can perform the original function while other

    copies are available to take on new functions.

    12. Which of the following statements best describes the rationale for applying the principle of parsimony in constructing phylogenetic trees? a. Parsimony allows the researcher to "root" the tree. b. Similarity due to common ancestry should be more likely than

    similarity due to convergent evolution. c. The molecular clock validates the principle of parsimony. d. The out-group roots the tree, allowing the principle of parsimony to be applied

    13. In looking at the fossil record of horses, why does the presence of extinct and

    transitional forms support the theory of evolution? a. It supports the hypothesis that only individuals with larger bodies were capable

    of surviving, and that bigger is always better in evolution. b. It supports the hypothesis that evolution follows a linear path of simple to more

    complex c. It supports the hypothesis that species have changed over time d. It supports the hypothesis that species always evolve to become more and better

    adapted over time.

    14. In 1983 a population of dark-eyed junco birds became established on the campus of the University of California, San Diego (UCSD), which is located many miles from the junco's normal habitat in the mixed-coniferous temperate forests in the mountains. Juncos have white outer tail feathers that the males display during aggressive interactions and during courtship displays. The UCSD campus male junco population tails were, on average, 36% white, whereas the tails of males from nearby mountain populations averaged 4045% white. If this observed trait difference were due to a difference in the original colonizing population, it would be due to a. disruptive selection. b. sexual selection. c. sexual dimorphism. d. a genetic bottleneck. e. founder effect.

    15. If the juncos at UCSD, over time became reproductively isolated from the mountain

    population, which of the following could be said to have occurred? a. Allopatric speciation b. Peripatric speciation c. Parapatric speciation d. Sympatric speciation

  • LS1 Spring10 Name & ID___KEY_____________________

    Page 5 of 10

    16. You sequence the genes that code for an important glycolytic enzyme in a moth, a

    mushroom, a worm, and an alga and find a high degree of sequence similarity among these distantly related species. This is an example of ________. a. structural homology. b. developmental homology. c. genetic homology. d. convergent evolution.

    17. Which of the following is a fitness trade-off?

    a. In some hornbill species, the male helps seal the female in a tree with her nest until the young are ready to fledge.

    b. Moths are the best pollinators for datura flowers, but bees are the best pollinators for orchids.

    c. Some lemmings run into the sea when overgrazing threatens the species. d. Algal genotypes that can grow fast in nitrogen-limited environments

    are easier for predators to digest.

    18. Which of the following characters necessary for flight does NOT appear in the non-flying Theropod dinosaur lineages? a. Relatively long arms as compared to legs b. Thin-walled bones c. Flexible wrists with a semi-lunate bone d. Furcula e. Enlarged sternum

    19. Three populations of crickets look very similar, but the males have courtship songs that sound different. What function would this difference in song likely serve if the populations came in contact? a. A prezygotic isolating mechanism b. A postzygotic isolating mechanism c. All of the above

    20. A small number of birds arrive on an island from a neighboring larger island. This

    small population begins to adapt to the new food plants available on the island, and their beaks begin to change. About twice a year, one or two more birds from the neighboring island arrive. What effect do these new arrivals have? a. Their arrival speeds the process of speciation. b. Their arrival tends to promote adaptation to the new food plants. c. Their arrival tends to slow adaptation to the new food plants. d. Their arrival represents a colonizing event

  • LS1 Spring10 Name & ID___KEY_____________________

    Page 6 of 10

    21. How does a scientific theory differ from a scientific hypothesis? a. They are the same thing b. A theory is an explanation for broad set of observations and

    phenomena, hypotheses treat more specific issues c. A hypothesis is an explanation for broad set of observations and phenomena,

    theories treat more specific issues d. Theories define scientific laws, hypotheses are used to set up experiments

    22. The Luria and Delbrck experiment on fluctuation in bacteria demonstrated that a. Bacteria always evolve resistance to antibiotics b. Resistance to antibiotics is a random mutation c. Bacteria requires exposure to antibiotics for resistance to develop d. Bacteria will mutate when exposed to antibiotics e. Resistance to antibiotics is a directed mutation

    23. You find a new fossil deposit, containing many species with shells but no soft-bodied

    species. What is the most logical conclusion? a. There were no soft-bodied organisms at this time and location. b. Conditions were not right to fossilize soft-bodied organisms. c. There was a mass extinction event among hard-bodied but not soft-bodied

    species at this location 24. Evolution occurs primarily at the level of the

    a. Individual b. Population c. Species d. Phenotype e. Allele

    25. Why is reinforcement an appropriate name for the concept that natural selection should favor divergence and genetic isolation if populations experience postzygotic isolation? a. Selection should reinforce high fitness for hybrid offspring. b. Selection should reinforce the fact that they are good species under the

    morphological species concept. c. It reinforces divergence that began when the species was

    geographically isolated d. Selection acts because hybrid offspring do not develop at all or are sterile when

    mature

  • LS1 Spring10 Name & ID___KEY_____________________

    Page 7 of 10

    Short Answer. 1. (15 pts) The graph below shows the distribution of a trait before selection occurs. The

    dotted line indicates the average value of the trait before selection.

    On each of the 3 graphs below, draw a possible distribution for each of the 3 types of selection. Draw only 1 distribution per graph. Indicate the new average value of the trait relative to the old value

    Type of Selection__directional_________ Effect on Variation _reduces____ Note: The curve could also be shifted to the left hand side of the graph. Do not need to indicate changes in variance on graph, only changes in average and overall shape of curve, e.g. from bell to double humped for disruptive selection 2 pts for each graph shape & placement of new mean. 2 pts for correct name, 1 pts for variation effect.

    Value of Trait

    # o

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    Average value of trait before selection

    Value of Trait

    # o

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    Average value of trait before selection

    Average value of trait after selection

  • LS1 Spring10 Name & ID___KEY_____________________

    Page 8 of 10

    Type of Selection__Stabilizing___ Effect on Variation ___reduces______

    Type of Selection__Disruptive__ Effect on Variation __increased or maintained______ Note: Disruptive selection increases variation. However, the book on page 442 incorrectly states that it maintains variation (although a figure on the following page correctly notes that it increases variation). So well accept either answer.

    Value of Trait

    # o

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    divi

    dual

    s

    Average value of trait before selection

    Value of Trait

    # o

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    Average value of trait before selection

    Average value of trait after selection (no change)

    Average value of trait after selection

  • LS1 Spring10 Name & ID___KEY_____________________

    Page 9 of 10

    2. Vestigial traits a. (8 pts) What are vestigial traits? Why are they considered evidence for evolution?

    A trait that has that has no function or little function, and appears to be a reduced version of a functioning trait in other organisms. They are considered evidence for evolution because a logical explanation for their appearance is that they were inherited from a common ancestor, and that the descendents were modified through time by evolution

    b. (8 pts) Describe two examples of a vestigial trait

    Numerous, including any of the following (4 pts each): Goosebumps in humans Tail bones in humans Wisdom teeth in humans Pamirus longus in humans Hip and leg bones of both snakes and cetaceans Wings of ostriches, emus, etc (note penguin wings are not vestigial) Eye sockets of blind cave fish Egg tooth of marsupials

    Correct answer should include trait and in which organism it is vestigial

    3. (18 pts) Name the three most recent geologic eras and their start time in millions of years before present. What major events mark the start of each era? Cenozoic- 65.5- mass extinction Mesozoic- 251- mass extinction Paleozoic- 542- Cambrian explosion- diversification of animal body plans 2 points for each era, 1 point for each date. 3 points each for each event.

  • LS1 Spring10 Name & ID___KEY_____________________

    Page 10 of 10

    4. Hardy Weinberg a. (15 pts) List five evolutionary mechanisms that can cause a population to deviate from Hardy-Weinberg Equilibrium Natural selection Genetic drift Gene flow Mutation Sexual selection

    3 pts each

    b. (8 pts) Name the non-evolutionary mechanism that can cause a deviation from Hardy-Weinberg Equilibrium. How can it cause a deviation from Hardy-Weinberg Equilibrium and not be an evolutionary mechanism? Inbreeding. Inbreeding causes an increase in homozygosity. Therefore it skews genotype frequencies. However, it does not by itself change allele frequencies. For evolution to occur, a change in allele frequency must occur.

    2 pts for inbreeding. 3 points for increase in homozygosity. 3 pts for noting it does not change allele frequency and therefore does not cause evolution.

    5. (8 pts) Name and describe two essential elements of a good experimental design.

    Any two of the following (4 pts each): Replication: The experiment is repeated across several units. Controls: A test group identical to the treatment except for the factor being studied or other key elements of the procedure. Repeatability (or repetition): The ability to repeat the experiment and get similar results.