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BIOL 103 Practice Questions for Test 1

For all math, SHOW YOUR WORK
For all short answer, GIVE SPECIFIC EXAMPLES.

  1. Captain Kirk brings one Fribble to the planet Quohog, which has plenty of food and no predators.  If each Fribble produces six offspring every eight hours (then the parent dies), how many Fribbles will there be by the end of the week?  What is their doubling time?

  2. If a town of 10,000 people doubles every five years, how big will it be in 2026?  Suppose instead toxic waste contamination kills off 20% per year; how many will be left?
  3. Well's Time Traveler saw the sun appear to grow large and red. Why did this happen, in the author's view? How will our sun actually turn red some day? Why was the process of stellar evolution essential for human evolution? (Wells didn't know this, but we do.)

  4. Why does natural selection favor individuals who overpopulate their habitat and cause precipitous population decline?  What is the real reason the lemmings "jump in the sea"? Do the lemmings have alternatives? Explain.

  5. James Wait (Mr. Flemming) dies of familial hypercholesteremia (a gene copy that fails to make low-density-lipoprotein receptor protein). The condition is dominant and not X-linked.

    If he had a son, what is the son's chance of getting a heart attack in his forties?

    Suppose in a given population the defective allele frequency (p) is one in three hundred.
    What fraction of the population shows the disease?

    Suppose we find that the rare individuals who inherit two copies of the LDL defective allele are extremely sick and die by age 30. How does this modify our definition of "dominant" inheritance for this disease?

  6. What is the role of population size, gene frequencies, and genetic drift in evolution of new species? Explain.

  7. If natural selection means "survival of the fittest," than how can one "fittest" species evolve into more than one? How can more than one be "the fittest"? Explain.

  8. In the X-Files, the giant fluke evolved to look like a primate. What do we call this kind of evolution? Can you imagine (in a followup episode) a possible explanation (however unlikely) for how this might occur? Would the fluke ever be able to interbreed with real primates? Why or why not?

  9. In Galapagos, explain how Mary ensures the future of the human species, and how her actions differ from "Eve." Why does natural selection sometimes favor individuals who help neighbors raise offspring, instead of raising their own? What conditions favor this kind of selection?

  10. Explain how each of the following traits is determined by genes and/or environment: Huntington’s disease; Diabetes; Cancer; Spoken language.

  11. Explain reductive (or degenerative) evolution.  Why does it work?  Cite examples from Wells’s The Time Machine and from Vonnegut's Galapagos.

  12. Explain the difference between genetic and cultural evolution.  Use an example to show how these may be confused.

  13. Why do individuals move out of successful populations (migrate or disperse)?  Give examples of physical and biological modes of dispersion or migration.  For biological modes, give examples involving parasitism or mutualism.  Explain why each is parasitic or mutualistic.

  14. Vonnegut offers several hypotheses to explain how tortoises traveled to Galapagos.  Explain evidence supporting and evidence refuting each hypothesis.  Which hypotheses can neither be refuted nor proved?  Why not?

  15. Suppose you ingest 500 Salmonella bacteria in contaminated turkey, and in three hours you feel sick; there are now 500,000 bacteria. What is their doubling time in your body, in minutes?

  16. A male bird is equally likely to offer food to his own chicks, or to his mother's chicks. Why? Explain by calculating his percent relatedness to his own chicks, and to his mother's chicks. (Assume that both hens are 100% faithful to their mates. In real life, about 90% may be typical.)

  17. According to a study published in the Weekly World News, 1/5 of Americans have been abducted by aliens. Suppose that the trait desired by aliens is genetic, with recessive inheritance; and that every person homozygous for this trait gets abducted.

    What is the allele frequency (p) of the alien abduction trait?

    What percentage of Americans are carriers of the alien abduction trait; that is, they don't get abducted, but could pass it on to a child?
    If some of those abducted never come back, what will happen to the Hardy-Weinberg equilibrium? What do we call this effect?

    In one very small, isolated town, the entire population claims to have experienced abduction. What do we call this effect?

  18. Suppose that gray-furred lemmings double in one year, but brown-furred lemmings increase by a factor of 2.2.

    a. If the proportions of gray and brown lemmings start out equal, and if they breed for four years, what will be the ratio of brown to gray lemmings?

    b. Suppose the lemming population crashes after four years, then builds up to the same total as before. After five crashes, what fraction of the total lemmings will be brown?

    c. What alternative behaviors may lemmings exhibit, instead of crashing?

  19. Many human societies promote “cross cousin marriage.”

    a. What fraction of your genes do you share with your first cousin?

    b. Under what conditions would marrying your cousin be favored biologically? Under what conditions would it be detrimental?

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