ECOL_182_Exam3

ECOL_182_Exam3 - MIDTERM EXAM 3 Robichaux Section 10 April...

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Unformatted text preview: MIDTERM EXAM 3 Robichaux Section 10 April 2008 YOUR NAME: ____________________________________________________________ Last name First name YOUR UA NetID: ______________________________ YOU MUST CHOOSE THE SINGLE BEST ANSWER FOR EACH QUESTION. YOU MUST USE A NUMBER 2 PENCIL. 1. In the global carbon cycle, the biological process primarily responsible for returning carbon from terrestrial organisms to the atmosphere is a. denitrification. b. respiration. c. photosynthesis. d. none of the above. 2. As discussed in lecture, the two large reservoirs of carbon in the global carbon cycle are carbon-containing minerals in rocks (including fossil fuels) and a. dissolved carbon in the oceans. b. fixed carbon in terrestrial organisms. c. carbon dioxide in the atmosphere. d. none of the above. 3. According to the discussion in lecture, which of the following appears to be a primary cause of the increase in atmospheric carbon dioxide concentrations since the Industrial Revolution? a. combustion of fossil fuels. b. burning of forests, especially tropical forests in recent times. c. global warming, which has decreased photosynthesis and increased respiration in many terrestrial ecosystems. d. all of the above. e. a and b, but not c. 4. Based on the discussion in lecture about the Earth system, a. the increase in atmospheric CO2 concentrations as a result of human activities is contributing to an increase in the average temperature of the Earth system. b. global warming may lead to rising sea levels associated with the increased melting of the high-latitude ice sheets than cover land masses. c. carbon dioxide allows the shorter wavelengths of sunlight to penetrate the atmosphere, but absorbs and re-radiates back to Earth the longer wavelengths of radiation given off by the Earth’s surface. d. all of the above. e. a and b, but not c. 5. Based on the discussion in lecture, the formation of a “dead zone” in the Gulf of Mexico has been caused by a. an increase in pesticide residues carried into the Gulf by the Mississippi River. b. an increase in the average water temperature in the Gulf as a result of global warming. c. oil spills from refineries along the Louisana coast. d. none of the above. 1 6. Based on the discussion in lecture about the Earth system, a. Earth’s atmosphere contains similar amounts of CO2 and N2 . b. plants are able to utilize CO2 in photosynthesis, but are unable to use N2 directly as a nutrient. c. nitrogen fixation involves the chemical reduction of N2 . d. all of the above. e. b and c, but not a. 7. In the process of nitrification a. ammonia (NH3 ) and related ammonium ions (NH4 +) are converted first to nitrite (NO2 -) then to nitrate (NO3 -) ions. b. N2 is converted into ammonia (NH3 ). c. nitrate (NO3 -) ions are converted into N2 . d. none of the above. 8. In the process of denitrification a. N2 is converted into ammonia (NH3 ). b. nitrate (NO3 -) ions are converted into N2 . c. ammonia (NH3 ) and related ammonium ions (NH4 +) are converted first to nitrite (NO2 -) then to nitrate (NO3 -) ions. d. none of the above. 9. Based on the discussion in lecture, a. some free-living soil bacteria fix atmospheric N2 . b. Rhizobium bacteria living in mutualistic association with the roots of legumes fix atmospheric N2 . c. some atmospheric N2 is fixed by non-biological means, including lightning, forest fires, and volcanic eruptions. d. all of the above. e. b and c, but not a. 10. In a life table, fecundity is a. the proportion of the original cohort alive at the beginning of each age class. b. the per capita intrinsic rate of increase within each age class. c. the number of offspring produced by the average individual within each age class. d. b and c, but not a. e. none of the above. 11. For a given age class in a life table, the realized fecundity is 0.4. If the survivorship is 0.8, then the fecundity is a. 0.4 b. 0.5 c. 0.32 d. 2 e. none of the above. 12. Based on the mathematical formulas and their parameters discussed in lecture, the average number of offspring produced by an average newborn individual in a cohort during its entire lifetime equals a. b b. rm c. S lx mx d. B e. none of the above. 2 13. Annuals plants and oysters are similar in that both typically produce very large numbers of offspring with little energy or parental care being provided to them. In annual plants and oysters, a. the risk of mortality is constant, such that the number of individuals surviving to the next age class is a constant proportion of the previous age class. b. most mortality occurs in young age classes, with survivorship being much higher for individuals making it through young age classes. c. most individuals survive for most of the potential life span, with most mortality occurring in old age classes. d. a and b, but not c. e. none of the above. 14. For a population in which S lx mx < 1.0 across cohorts, the size of the population a. increases with time. b. decreases with time. c. remains constant with time. d. none of the above. 15. For a population growing exponentially in an environment with unlimited resources, the rate of population growth (∆N/∆t) equals a. (b-d) b. r c. both of the above d. none of the above 16. As discussed in lecture, the intrinsic rate of increase a. is much lower for rats than for bacteria. b. is much higher for some beetles than for humans. c. equals the maximal value of r and occurs under optimal conditions for the population. d. all of the above. e. b and c, but not a. 17. When the number of individuals is plotted against time for a population exhibiting exponential growth, the slope of the curve a. increases until population size reaches an intermediate value, then decreases at higher values of population size. b. remains constant as population size increases. c. increases continuously as population size increases. d. none of the above. 18. In the logistic equation for population growth, DN/Dt equals a. rN[K-N] b. rN[(K-N)/K] c. rN[(N-K)/N] d. none of the above 19. For a population exhibiting logistic growth, the rate of population growth a. is constant with increasing population size. b. increases continuously with increasing population size. c. increases until population size reaches an intermediate value, then decreases at higher values of population size, eventually decreasing to zero. d. none of the above. 20. At carrying capacity for a population exhibiting logistic growth a. the rate of population growth is maximal. b. the S lx mx = 1.0 across all cohorts in the population. c. population size is maximal. d. all of the above. e. b and c, but not a. 3 21. If the per capita birth rate or per capita death rate exhibits density-dependence, then the population will tend toward an equilibrium density. At the equilibrium density a. the per capita birth rate equals the per capita death rate. b. the rate of population growth is zero. c. the S lx mx = 1.0 across all cohorts in the population. d. all of the above. e. b and c, but not a. 22. Based on the discussion in lecture, a. the age structure in most developing countries is such that the human population will continue to grow into the latter part of this century even if the per capita birth rate declines. b. much of the growth in the human population during the next 50 years will be in Asia, Sub-Saharan Africa, and Latin America. c. technological advances, especially in medicine and agriculture, have significantly lowered per capita death rates in the human population, such that the population has recently grown nearly exponentially. d. all of the above. e. b and c, but not a. 23. Based on the discussion in lecture, the origin of organelles in eukaryotic cells exemplifies a. interspecific competition. b. parasitism. c. intraspecific competition. d. mutualism. e. none of the above. 24. In which type of interaction does one species benefit from the interaction, whereas the other species is harmed by the interaction? a. parasitism. b. predation. c. competition. d. a and b, but not c. e. none of the above. 25. In the Lotka-Volterra competition equations, which of the following terms does NOT appear in the equation for the rate of population growth (DN2 /Dt) of species 2? a. carrying capacity of species 1 (K1 ) b. population size of species 1 (N1 ) c. per capita rate of increase of species 2 (r2 ) d. competition coefficient (a2 1) 26. In the Lotka-Volterra competition equations, a decrease in the value of a1 2 causes a. a decrease in DN1 /Dt b. no change in DN1 /Dt c. an increase in DN1 /Dt d. none of the above 27. In the Lotka-Volterra competition equations, an increase in the value of N2 causes a. no change in DN1 /Dt b. a decrease in DN1 /Dt c. an increase in DN1 /Dt d. none of the above 4 28. Based on the discussion in lecture about the barnacle species Chthamalus stellatus and Balanus balanoides growing in the rocky intertidal zone, a. the larvae of Chthamalus settle over a narrower range in the intertidal zone than that in which the adults are found. b. Balanus has a lower tolerance to desiccation than Chthamalus; in the higher intertidal zone, where desiccation levels are increased, Balanus is unable to remain established in the presence of Chthamalus. c. when biologists experimentally removed Balanus from the lower intertidal zone, they found that young Chthamalus were able to establish and grow in the latter zone. d. all of the above. e. b and c, but not a. 29. Based on the discussion in lecture about Gause’s classic experiments with two species of Paramecium, a. when the two species were grown together in a heterogeneous environment, competition occurred, but both species were able to persist. b. when each species was grown alone in an environment with limited resources, it exhibited exponential population growth. c. when the two species were grown together in a homogeneous environment with limited resources, one species competitively excluded the other species. d. all of the above. e. a and c, but not b. 30. Based on the discussion in lecture about the interaction between snowshoe hares and Canadian lynx, a. the population fluctuations exhibited by snowshoe hares are a function not only of the lynx/hare interaction but also of the interaction between the hares and their food supplies. b. the peaks in population sizes of the hares and lynx occur at the same times, as is typical of predator/prey oscillations. c. the population size of the hares oscillates over time whereas the population size of the lynx is stable, reflecting the fact that the lynx eat a wide range of prey species. d. a and b, but not c. e. none of the above. 31. Based on the discussion in lecture, which of the following is an example of a mutualistic interaction? a. the presence of nitrogen-fixing bacteria in the roots of some plant species b. plant-pollinator interactions c. lichens d. all of the above e. a and b, but not c. 32. Based on the discussion in lecture, a. evolution is descent with modification. b. evolution is a change in the genetic composition of the population over time. c. gene flow appears to be an important mechanism of evolution in many natural populations. d. all of the above e. a and b, but not c. 33. Which of the following violates one of the conditions necessary for Hardy-Weinberg equilibrium? a. Mating is random. b. There is mutation. c. Population size is very large. d. There is differential migration. e. b and d, but not a and c. 5 34. A zebra population exhibits Hardy-Weinberg equilibrium. A single gene locus in the population has the alternate alleles Z and z. If the frequency of the allele z is 0.2, then the frequency of the allele Z is a. 0.2 b. 0.6 c. 0.4 d. 0.32 e. none of the above 35. For the zebra population in question 34, the equilibrium frequency of the genotype zz is a. 0.2 b. 0.16 c. 0.04 d. 0.01 e. none of the above. 36. In addition, for the zebra population in question 34, the equilibrium frequency of the genotype Zz is a. 0.16 b. 0.64 c. 0.4 d. 0.48 e. none of the above 37. With outbreeding a. mating individuals are less closely related than those drawn at random from the population. b. there is a change in allelic frequencies. c. the frequency of the heterozygotes decreases. d. all of the above. e. a and c, but not b. 38. Based on the discussion in lecture about genetic drift, a. the rate at which genetic variation is lost is inversely proportional to the effective population size. b. genetic drift affects allelic frequencies but not genotypic frequencies. c. if population size is small, sampling errors arising from chance may cause the frequencies of some alleles in a sample of gametes to be higher or lower than those in the parental population. d. all of the above. e. a and c, but not b. 39. A small population of lemurs has 2 breeding females and 8 breeding males. The effective population size is a. 3.2 b. 10 c. 6.4 d. 1.6 e. none of the above 40. Based on the discussion in lecture about evolution, a. evolution by mutation acting alone appears to be relatively uncommon in natural populations. b. effective population size is influenced by variation in the number of gametes produced per individual. c. inbreeding causes a change in both allelic and genotypic frequencies. d. all of the above. e. a and b, but not c. 6 41. Based on the discussion in lecture about natural selection, a. natural populations of sexually reproducing species typically contain large amounts of genetic variation affecting most aspects of organismal form and function. b. the ultimate source of genetic variation affecting fitness is mutation. c. there must be genetic variation affecting fitness before natural selection can operate. d. all of the above. e. a and c, but not b. 42. In directional selection a. there is a change in the mean trait value in the population. b. there is an increase in the variance for the trait values in the population, but no change in the mean trait value. c. there is a reduction in the variance for the trait values in the population, but no change in the mean trait value. d. none of the above. 43. Based on the discussion in lecture about quantitative traits, a. quantitative traits are determined by the combined influence of the environment and the genotype at many different loci. b. quantitative traits include measurable characters such as beak depth, tail length, swimming speed, and cognitive ability. c. quantitative traits are those for which there are not discrete phenotypic classes. d. all of the above. e. a and b, but not c. 44. Based on the research of the Grants and their students on medium ground finches on Daphne Major Island in the Galapagos, a. parents with deeper beaks tend to have offspring with deeper beaks. b. birds with deeper beaks are able to crack and eat larger and harder seeds. c. significant variation in beak depth exists in the population. d. all of the above. e. b and c, but not a. 45. When the Grants and their students examined the beak depths of adult finches that survived the severe drought of 1977, they found that mean beak depth in the population a. had decreased. b. had not changed. c. had increased. 46. When the Grants and their students compared the beak depths of finches hatched (or born) during the year after compared to the year before the drought, they found that a. mean beak depth had decreased as a result of stabilizing selection. b. mean beak depth was unchanged, reflecting the low heritability of beak depth in the population. c. mean beak depth had increased as a result of directional selection. 47. You measure wing length for parents and offspring in a population of falcons, where wing length is a quantitative trait. You plot the midoffspring trait values against the midparent trait values. From the relationship, you determine that 65% of the variation among the parents is due to variation in their environments. The heritability of wing length is thus a. 0.65 b. 0.35 c. neither of the above 48. Based on the discussion in lecture, the heritability of the trait in question 47 equals a. the mean offspring trait value minus the mean midparent trait value. b. the y-intercept of the relationship in your plot. c. the mean midparent trait value minus the mean offspring trait value. d. none of the above. 7 49. Especially in human populations without access to modern medicine, babies born lighter or heavier than the population mean have significantly higher mortality. This pattern of mortality has resulted in a. directional selection for birth weight. b. stabilizing selection for birth weight. c. neither of the above. 50. Because of the pattern of mortality discussed in question 49, the variance in birth weight a. has remained constant over time. b. has decreased over time. c. has increased over time. d. none of the above. 8 ...
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