Two populations of a species of squirrel are geographically isolated from each other. Although they have the same population density, one population is significantly larger in number than the other. A new bacterial disease, which is easily spread and extremely virulent, affects both populations at the same time. Which of the following is the best prediction of how the new disease will affect the two populations?

In an investigation of interspecies competition, researchers grew the unicellular protozoan Paramecium aurelia in a 5 mL culture and Paramecium caudatum in a separate 5 mL culture. P. aurelia and P. caudatum were grown together in a third 5 mL culture. Each day a small sample of each culture was removed so the total number of individuals could be estimated, and the remainder of the population was transferred to fresh growth medium. The experimental results are represented in the graphs below. The horizontal axis is labeled “Time, in days,” and the numbers 1 through 25 are indicated. The vertical axis is labeled “Number of Individuals per 5 milliliters,” and the numbers O through 700, in increments of 100, are indicated. The data represented by the points on the graph are as follows. Point 1, 1 day, O individuals perO milliliters. Point 2, 2 days, 10 individuals per 5 milliliters. Point 3, 3 days, 20 individuals per 5 milliliters. Point 4, 4 days, 60 individuals per 5 milliliters. Point 5, 5 days, 90 individuals per 5 milliliters. Point 6, 6 days, 190 individuals per 5 milliliters. Point 7, 7 days, 260 individuals per 5 milliliters. Point 8, 8 days, 320 individuals per 5 milliliters. Point 9, 9 days, 410 individuals per 5 milliliters. Point 10, 10 days, 500 individuals per 5 milliliters. Point 11, 11 days, 570 individuals per 5 milliliters. Point 12, 12 days, 610 individuals per 5 milliliters. Point 13, 13 days, 510 individuals per 5 milliliters. Point 14, 14 days, 580 individuals per 5 milliliters. Point 15, 15 days, 550 individuals per 5 milliliters. Point 16, 16 days, 550 individuals per 5 milliliters. Point 17, 17 days, 510 individuals per 5 milliliters. Point 18, 18 days, 570 individuals per 5 milliliters. Point 19, 19 days, 510 individuals per 5 milliliters. The horizontal axis is labeled “Time, in days,” and the numbers 1 through 25 are indicated. The vertical axis is labeled “Number of Individuals per 5 milliliters,” and the numbers O through 250, in increments of 50, are indicated. The data represented by the points on the graph are as follows. Point 1, 1 day, 0 individuals per 5 milliliters. Point 2, 2 days, 10 individuals per 5 milliliters. Point 3, 3 days, 10 individuals per 5 milliliters. Point 4, 4 days, 10 individuals per 5 milliliters. Point 5, 5 days, 20 individuals per 5 milliliters. Point 6, 6 days, 60 individuals per 5 milliliters. Point 7, 7 days, 110 individuals per 5 milliliters. Point 8, 8 days, 140 individuals per 5 milliliters. Point 9, 9 days, 165 individuals per 5 milliliters. Point 10, 10 days, 190 individuals per 5 milliliters. Point 11, 11 days, 220 individuals per 5 milliliters. Point 12, 12 days, 200 individuals per 5 milliliters. Point 13, 13 days, 200 individuals per 5 milliliters. Point 14, 14 days, 180 individuals per 5 milliliters. Point 15, 15 days, 190 individuals per 5 milliliters. Point 16, 16 days, 180 individuals per 5 milliliters. Point 17, 17 days, 190 individuals per 5 milliliters. Point 18, 18 days, 205 individuals per 5 milliliters. Point 19, 19 days, 208 individuals per 5 milliliters. The horizontal axis is labeled “Time, in days,” and the numbers 1 through 25 are indicated, The vertical axis is labeled “Number of Individuals per 5 milliliters,” and the numbers O through 450, in increments of 50, are indicated. A key indicates that one line represents P aurelia, and the other line represents P caudatum. Both lines begin at 1 day, and 0 individuals per 5 milliliters. The line representing P caudatum spikes momentarily above the line representing P aurelia after 2 days, but then falls back down toward the horizontal axis and remains below the line representing P Aurelia until both graphs end. The data represented by the points on each line are as follows. Point 1, 1 day. P aurelia, 0. P caudatum, 0. Point 2, 2 days. P aurelia, 10. P caudatum, 145. Point 3, 3 days. P aurelia, 25. P caudatum, 10. Point 4, 4 days. P aurelia, 55. P caudatum, 30. Point 5, 5 days. P aurelia, 95. P caudatum, 50. Point 6, 6 days. P aurelia, 200. p caudatum, 90. Point 7, 7 days. P aurelia, iss. p caudatum, 110. Point 8, 8 days. P aurelia, 220. p caudatum, 125. Point 9, 9 days. P aurelia, 295. p caudatum, 100. Point 10, 10 days. P aurelia, 240. P caudatum, 90. Point 11, 11 days. P aurelia, 300. P caudatum, 70. Point 12, 12 days. P aurelia, 300. P caudatum, 90. Point 13, 13 days. P aurelia, 340. P caudatum, 60. Point 14, 14 days. P aurelia, 390. P caudatum, 70. Point 15, 15 days. P aurelia, 340. P caudatum, 55. Point 16, 16 days. P aurelia, 360. P caudatum, 56. Point 17, 17 days. P aurelia, 335. P caudatum, 48. Point 18, 18 days. P aurelia, 360. P caudatum, 50. Point 19, 19 days. P aurelia, 305. P caudatum, 50. Point 20, 20 days. P aurelia, 350. P caudatum, 50. Point 21, 21 days. P aurelia, 325. P caudatum, 48. Point 22, 22 days. P aurelia, 350. P caudatum, 20. Point 23, 23 days. P aurelia, 350. P caudatum, 20. Point 24, 24 days. P aurelia, 325. P caudatum, 40. Point 25, 25 days. P aurelia, 350. P caudatum, 25. Which of the following statements best justifies the use of the experimental results in an investigation of interspecies competition?

In the Florida Everglades, Burmese pythons are an invasive species. They were introduced into southern Florida in 1992. These pythons feed on many of the native Florida species, establishing the pythons as the top predator in the environment. By the year 2000, their population had increased dramatically. Figures 1 and 2 display data collected by ecologists studying the results of the Burmese python invasion. Figure 1 shows counts of animals collected from nighttime road surveys in southern Florida, which are used to estimate population size. Figure 2 shows data collected from mosquitoes captured from the wild. DNA sequencing was used to identify the species of blood that the mosquitoes had in their stomachs, identifying various hosts used by the mosquitoes. The categories are labeled along the horizontal axis as follows: White-Tailed Deer, Raccoon, Coyote, Cotton Rat, and Rabbit. Each category has two bars indicated on it, which are each labeled 1996 and 2011 respectively. Each bar has an error range indicated. The vertical axis is labeled Number Observed, per 100 kilometers of road, and the numbers 0 through 3, in increments of 1, are indicated. The data for each bar is presented as follows. Note that all values are approximate. White-Tailed Deer. 1996, 2.7, plus or minus 0.3. 2011, 0.8, plus or minus 0.4. Raccoon. 1996, 1.2, plus or minus 0.2. 2011, 0. 4, plus or minus 0.2. Coyote. 1996, 1.2, plus or minus 0.4. 2011, 0.7, plus or minus 0.3. Cotton Rat. 1996, 0.65, plus or minus 0.2. 2011, 2.5, plus 0.5, minus 0.1. Rabbit. 1996, 1.7, plus or minus 0.3. 2011, 1.3, plus or minus 0.25. Figure 1. Comparison of observations of selected mammals in 1996 and 2011. The horizontal axis is labeled Year, and the years 1979 and 2016 are indicated. The vertical axis is labeled Host Use, in percent total bloodmeals, and the numbers 0 through 90, in increments of 10, are indicated. The 4 line segments are each determined by two points, and are labeled as follows: Cotton Rat, Human, White-tailed deer, and Raccoon. Each line segment is described as follows. Note that all values are approximate. All line segments begin in 1979 and end in 2016. The Cotton Rat line segment is above the Human line segment and crosses the White-tailed deer line segment. The Human line segment crosses the White-tailed deer and Raccoon line segments. The White-tailed deer line segment is above the Raccoon line segment. The line segment labeled Cotton rat begins at the point 1979, comma 15 percent, and moves upwards and to the right to end at the point 2016, comma 80 percent. The line segment labeled Human begins at the point 1979, comma 0 percent, and moves upwards and to the right to end at the point 2016, comma 10 percent. The line segment labeled White-tailed deer begins at the point 1979, comma 30 percent, and moves downwards and to the right to end at the point 2016, comma 2 percent. The line segment labeled Raccoon begins at the point 1979, comma 10 percent, and moves downwards and to the right to end at the point 2016, comma 0 percent. Figure 2. Change in host preference by Culex cedecei between 1979 and 2016. Numbers do not add up to one hundred percent because these represent a subset of all the host species. In 1996, the native Culex cedecei mosquitoes in southern Florida preferentially took blood meals from white-tailed deer and raccoons. It was predicted that changes in host population size would alter these host preferences. Additionally, it is known that cotton rats are often infected by the Everglades virus, which normally exists in animals, but is capable of infecting humans. Ecologists predict that increased feeding on cotton rats by C. cedecei may significantly increase the tendency of this virus to infect humans. Which of the following most accurately explains an impact of Burmese pythons on the Everglades community in southern Florida using the data provided?

Analysis of DNA sequences from two individuals of the same species results in a greater estimate of genetic variability than does analysis of amino acid sequences from the same individuals because

The growth curve starts at the intersection of the x and y axes and increases exponentially then flattens out halfway up the y-axis. Figure two is a graph with x-axis labeled time and y-axis labeled algae population. The growth curve starts at the intersection of the x and y axes and increases exponentially then flattens out halfway up the y-axis. Phosphate is added after the growth curve flattens out, then increases exponentially again and flattens out at the top of the y-axis. Figure I shows the growth of an algal species in a flask of sterilized pond water. If phosphate is added as indicated, the growth curve changes as shown in Figure II. Which of the following is the best prediction of the algal growth if nitrate is added instead of phosphate?

A number of different phylogenies (evolutionary trees) have been proposed by scientists. These phylogenies are useful because they can be used to

LAC OPERON STRUCTURE The L A C operon has a region labeled Regulatory Gene that contains loci P subscript 1 and l a c 1. The L A C operon has a 2nd, separate region that contains five loci, in order from left to right on the DNA strand, P subscript l a c, operator, l a c Z, l a c Y, l a c A. The functions of the loci of the lac operon shown in the diagram are described in the table below. Functions of the loci of the lac operon Locus Function PI Attachment site for RNA polymerase lacI Encodes a repressor protein that prevents transcription of the structural genes of the lac operon Plac Attachment site for RNA polymerase Operator Binding site for the repressor protein lacZ Encodes beta-galactosidase, the enzyme that digests lactose to glucose and galactose lacY Encodes lactose permease, the channel through which lactose moves into the cell lacA Encodes galactoside transacetylase The diagram above represents a segment of the E. coli chromosome that contains the lacI gene and part of the lac operon, a coordinately regulated set of genes that are required for the metabolism of lactose. The presence of lactose, which causes the repressor to be released from the operator, results in increased transcription of the lac operon. Which of the following is the most likely consequence of a mutation at the operator locus that prevents binding of the repressor protein?

Population ecologists are typically not very interested in the actual number of individuals in a population at a given time. What they are really interested in is

Individuals of a particular species of ground beetle are either light tan or dark brown. Light-tan beetles are predominant in habitats with light-colored sandy soils, and dark-brown beetles are predominant in habitats with dark-colored loam soils. In an experiment designed to determine the survival rates of light-tan beetles and dark-brown beetles in different habitats, 500 light-tan beetles and 500 dark-brown beetles were released in each of four habitats. Each beetle had been marked with a small spot of red paint on the underside of its abdomen before it was released. One week after the beetles had been released, any marked beetles that could be found were recaptured. The results are presented in the table below. It is assumed that differences in the numbers of beetles recaptured are directly related to differences in survival rates. Columns 2 thru 5 have 2 sub-columns each. The top row contains the column labels: columns one is blank; Column two: Habitat 1: Sandy soil, no insectivorous birds present. Column three: Habitat 2: Sandy soil, insectivorous birds present. Column four: Habitat 3: Loam soil, no insectivorous birds present. Column five: Loam soil, insectivorous birds present. From top to bottom the data is as follows: Row two: Color of Beetle: Habitat 1, sub-column one, Light tan; sub-column two, Dark brown. Habitat 2, sub-column one, Light tan; sub-column two, Dark brown. Habitat 3, sub-column one, Light tan; sub-column two, Dark brown. Habitat 4, sub-column one, Light tan; sub-column two, Dark brown. Row three: Number Released: Habitat 1, sub-column one, five hundred; sub-column two, five hundred. Habitat 2, sub-column one, five hundred; sub-column two, five hundred. Habitat 3, sub-column one, five hundred; sub-column two, five hundred. Habitat 4, sub-column one, five hundred; sub-column two, five hundred. Row four: Number Recaptured: Habitat 1, sub-column one, one hundred thirty; sub-column two, one hundred fourteen. Habitat 2, sub-column one, one hundred twenty-three; sub-column two, twenty-two. Habitat 3, sub-column one, sixty-five; sub-column two, seventy-four. Habitat 4, sub-column one, thirteen; sub-column two, eighty-seven. Which of the following can be inferred from the data in the table?

Sickle-cell anemia results from a point mutation in the HBB gene. The mutation results in the replacement of an amino acid that has a hydrophilic R-group with an amino acid that has a hydrophobic R-group on the exterior of the hemoglobin protein. Such a mutation would most likely result in altered