Page | 1 Biology 130,Fall 2012: Second exam An exam is an opportunity where your preparation meets my challenge Selection operates directly on ; and indirectly on . A. genotype if phenotype is genetically determined; phenotype B. genotype if phenotype is not genetically determined; phenotype C. phenotype; genotype if phenotype is genetically determined D. phenotype; genotype if phenotype is not genetically determined E. genotype; genotype if phenotype is genetically determined In a certain population, 40 of every 1,000 births results in an individual that suffers from cystic fibrosis. What is the allele frequency for the recessive allele that causes cystic fibrosis? A. 0.004 B. 0.02 C. 0.2 D. 0.4 E. 0.8 In a certain population, the allele causing sickle cell anemia has a frequency of 0.2. If the population is in genetic equilibrium for this allele, what fraction of the population would have malarial resistance? (Recall that the sickle-allele is recessive for red blood cell shape and dominant for malaria resistance). A. 0.04 B. 0.08 C. 0.16 D. 0.32 E. 0.36 The Hardy-Weinberg principle is useful because: A. it explains the existence of variation in populations. B. it proves that Mendel was correct for populations. C. it describes most populations. D. it explains the existence of so many species. E. it identifies those factors that can change allele or genotype frequencies In a certain population 4 alleles are segregating at a particular locus with the following allele frequencies: AM: 0.3; AT: 0.2; AP: 0.1; AK: 0.4. What is the expected frequency of AM AK heterozygotes? A. 0.12 B. 0.24 C. 0.48 D. 0.7 E. cannot be determined from the data Due to various causes, including hunting, drainage of wetlands, and DDT poisoning, the population size of whooping cranes was reduced to about a dozen during the 1970s. The population size has since rebounded, and there are now hundreds of whooping cranes. Which of the following would you not expect to see in whooping cranes? A. Very low levels of genetic variation B. Very few heterozygous individuals C. Differences in allele frequency between current populations of cranes and historical populations D. Considerable genetic polymorphism E. All of the above would be seen in whooping cranes. Which of the following is not an observation or inference on which the concept of natural selection is based? A. There is heritable variation among individuals in a population B. There is a struggle for limited resources, and only a fraction of offspring survive C. Variation among individuals is produced by the environment D. Individuals whose inherited characteristics best fit them to the environment will generally leave more offspring E. Organisms interact with their environment Environment can/does influence phenotype, but the concept of natural selection as an evolutionary force is concerned with genetically based phenotypic variation. Darwin, influenced by the political economist Thomas Malthus, noted that all populations have potential to grow; however Darwin and numerous other naturalists also observed that in nature most populations over time. A. limited; are relatively stable B. unlimited; grow more slowly C. limited; fluctuate unpredictably D. unlimited; are relatively stable E. limited; decrease slowlyPage | 2 The following eight questions deal with genetics in populations of snails. In these populations there is a gene named tipi with two alleles which influences the shape of the shell. Snails homozygous the f+ allele have conical shells; snails homozygous for the f allele have flattened dome shaped shells; and heterozygotes have rounded dome shaped shells (Figure 1). Figure 1: Shell shape and genotype Which of the following is the best hypothesis for the relationship between the f+ and f alleles in determining shell morphology in the snail population? A. f+ is dominant, f is recessive B. f is dominant, f+ is recessive C. The two alleles are incompletely dominant D. shell morphology is under environmental control, not genetic. E. There is insufficient information to form a hypothesis Three allopatric populations of the snail species in Great Smoky Mountains National Park were studied to determine the effects of the two alleles on fitness. One population lived in the northern coniferous forest, one in a northern hardwoods forest, and one in a red oak forest (Figure 2). The three populations were each very large, more than 10,000 individuals, and there was no evidence of non-random mating nor of differential predation on snails with different shell shapes. One thousand individuals from each population were sampled in order to estimate genotypic frequencies. Average number of maturing offspring for each genotype in each environment was determined by setting up enclosures in the three environments and monitoring reproductive success and offspring mortality of females of known genotype. Number of individuals monitored ranged from a low of 12 for the f+f genotype in the northern coniferous forest to a high of 33 individuals of the ff genotype in the red oak forest. The genotype frequency data and offspring data are in Table 1. Figure 2: Vegetation Communities in Great Smoky Mountains National Park Table 1 Genotypic Frequencies Average # of Offspring f+f+f+f ff f+f+f+f ff Northern Coniferous 0.1 0.72 0.18 20 90 30 Northern Hardwoods 0.42 0.17 0.41 80 10 12 Red Oak 0.36 0.48 0.16 80 82 78 Which population(s) appear(s) to be in genetic equilibrium? A. Northern Coniferous B. Northern Hardwoods C. Red Oak D. All E. None What is the absolute fitness of the ff genotype in the Red Oak community? A. 78 B. 1.0 C. 0.98 D. insufficient data to estimate What is the relative fitness of the ff genotype in the Northern Coniferous community? A. 30 B. 1.0 C. 0.33 D. 0.21 E. insufficient data to estimate What type of natural selection appears to be occurring in the Red Oak forest population? A. Directional B. Disruptive C. Stabilizing D. NonePage | 3 What type of natural selection appears to be occurring in the Northern Hardwoods forest population? A. Directional B. Disruptive C. Stabilizing D. None What type of natural selection appears to be occurring in the Northern Coniferous forest population? A. Directional B.