Researchers investigated the habitat preferences of two species of garter snakes, Thamnophis sirtalis and Thamnophis atratus. To create a choice chamber, the researchers built a meshed enclosure and positioned one end of the enclosure at the edge of a small pond. Zone I of the enclosure was located in the water, whereas zone IV of the enclosure was located 2–3 meters away from the water, as represented in the figure below. Snakes inside the enclosure were able to move freely between zones. From left to right, the zones are labeled 4 through 1. The side length of each square is 1 meter. A large semicircular shaded region, labeled “Pond,” completely covers square 1 and a very small part of square 2. The “Pond” region also extends beyond square 1 to the outside of the enclosure. In a series of experiments, the researchers introduced a single snake into zone IV of the enclosure at 7:00 A.M. The researchers recorded the location of the snake at six time points throughout the day. In a related experiment, the researchers introduced two snakes, one of each species, into the enclosure at the same time and observed the location of each of the two snakes at the same six time points as before. The researchers repeated both the one-snake and two-snake experiments using different individual snakes of each species. The results are presented in the table. The title of the table is ZONES MOST FREQUENTLY OCCUPIED BY GARTER SNAKES IN A MESHED ENCLOSURE. The top row contains the column labels, from left to right: column one, Time of Day; column two, Zone Most Frequently Occupied by T. atratus; column three, Zone Most Frequently Occupied by T. sirtalis; column four, Zone Most Frequently Occupied by T. Based on the data in the table, which of the following best describes the habitat preference of T. atratus when introduced alone inside the meshed enclosure?

Ascorbic acid (vitamin C) is an organic molecule necessary for the health of plants and animals. The majority of animals, including most mammals, synthesize ascorbic acid from organic precursors, but some primates are unable to synthesize ascorbic acid and must instead acquire it from dietary sources, such as certain fruits and vegetables. The L-gulonolactone oxidase (GULO) gene encodes an enzyme that catalyzes a required step in the biosynthesis of ascorbic acid. Most mammals carry a functional copy of the GULO gene, but some primates carry only a GULO pseudogene, which is a nonfunctional variant. A comparison of GULO genes and GULO pseudogenes from different animals can provide insight into the evolutionary relatedness of the animals. In Table I, selected members of some mammalian groups are listed, along with an indication of their ability to synthesize ascorbic acid. Table II shows an alignment of amino acid coding sequences from homologous regions of the GULO genes and GULO pseudogenes of the organisms listed in Table I. Figure 1 represents the universal genetic code. The title of the table is SELECTED MAMMALIAN GROUPS. The top row contains the column labels, from left to right: column one, Group; column two, Selected Members; column three, Biosynthesis of Ascorbic Acid. From top to bottom, the data is as follows: Row two: Group, Nonprimate mammals; Selected Members, Elephant, mouse; Biosynthesis of Ascorbic Acid, Yes. Row three: Group, Primate mammals; Selected Members, Lemur; Biosynthesis of Ascorbic Acid, Yes. Row four: Group, Primate mammals; Selected Members, Orangutan, chimpanzee; Biosynthesis of Ascorbic Acid, No. Row five: Group, Primate mammals; Selected Members, Human; Biosynthesis of Ascorbic Acid, No. It lists the relative positions of nucleotides in a non-template (coding) sequence. The table consists of six rows and twenty-seven columns. The row headers are as follows: elephant, mouse, lemur, orangutan, chimp, and human. The column headers run from 5 prime to 3 prime, displaying the positions from 1 (at 5 prime) through 27 (at 3 prime). The row-wise entries from the table are as follows. Row 1, Elephant. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: C (shaded), 6: C (shaded), 7: C, 8: A, 9: T, 10: C (shaded), 11: T (shaded), 12: G (shaded), 13: A, 14: A, 15: G, 16: A (shaded), 17: A (shaded), 18: G (shaded), 19: T, 20: C, 21: G, 22: G (shaded), 23: A (shaded), 24: A (shaded), 25: T, 26: A, 27 (3 prime): C. Row 2, Mouse. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: G (shaded), 6: C (shaded), 7: C, 8: A, 9: C, 10: C (shaded), 11: T (shaded), 12: G (shaded), 13: A, 14: A, 15: G, 16: A (shaded), 17: A (shaded), 18: G (shaded), 19: T, 20: C, 21: T, 22: G (shaded), 23: A (shaded), 24: G (shaded), 25: T, 26: A, 27 (3 prime): C. Row 3, Lemur. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: G (shaded), 6: C (shaded), 7: C, 8: A, 9: C, 10: C (shaded), 11: T (shaded), 12: G (shaded), 13: A, 14: A, 15: G, 16: A (shaded), 17: G (shaded), 18: G (shaded), 19: T, 20: C, 21: C, 22: G (shaded), 23: A (shaded), 24: G (shaded), 25: T, 26: A, 27 (3 prime): C. Row 4, Orangutan. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: G (shaded), 6: C (shaded), 7: en-dash, 8: A, 9: T, 10: T, 11: G (shaded), 12: G (shaded), 13: A (shaded), 14: A, 15: G, 16: A, 17: A (shaded), 18: A (shaded), 19: T (shaded), 20: C, 21: T, 22: G, 23: A (shaded), 24: G (shaded), 25: G (shaded), 26: A, 27 (3 prime): C. Row 5, Chimp. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: G (shaded), 6: C (shaded), 7: en-dash, 8: A, 9: T, 10: T, 11: G (shaded), 12: G (shaded), 13: A (shaded), 14: A, 15: G, 16: A, 17: A (shaded), 18: A (shaded), 19: T (shaded), 20: C, 21: T, 22: G, 23: A (shaded), 24: G (shaded), 25: G (shaded), 26: A, 27 (3 prime): C. Row 6, Human. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: G (shaded), 6: C (shaded), 7: en-dash, 8: A, 9: T, 10: T, 11: G (shaded), 12: G (shaded), 13: A (shaded), 14: A, 15: G, 16: A, 17: A (shaded), 18: A (shaded), 19: T (shaded), 20: C, 21: T, 22: G, 23: A (shaded), 24: G (shaded), 25: G (shaded), 26: A, 27 (3 prime): C. A footnote below the table reads: For each D N A segment, the alternating shaded and unshaded nucleotides indicate the triplet codons of the open reading frame, shown from left (5 prime) to right (3 prime) as the non-template (coding) strand. An “en-dash” indicates the absence of a nucleotide. The left side of the table is 5 Prime First Base, and labels the main rows, from top to bottom, U, C, A, G. The top side of the table is labeled Second Base, and labels the main columns, from left to right, U, C, A, G. The right side of the table is labeled, 3 Prime Third Base, and labels each of the main rows U C A G. The data in the table reads as follows; First Base U and Second Base U with Third Base U, results in U U U phenylalanine; with Third Base C results in U U C phenylalanine; with Third Base A, results in U U A leucine, and with Third Base G, results in U U G leucine First Base C and Second Base U with Third Base U, results in C U U leucine; with Third Base C, results in C U C leucine; with Third Base A, results in C U A leucine, and with Third Base G, results in C U G leucine First Base A and Second Base U with Third Base U, results in A U U isoleucine; with Third Base C, results in A U C isoleucine; with Third Base A, results in A U A isoleucine; and with Third Base G, results in A U G methionine or start First Base G and Second Base U with Third Base U, results in G U U valine; with Third Base C, results in G U C valine; with Third Base A, results in G U A valine, with Third Base G, results in G U G valine First Base U and Second Base C with Third Base U, results in U C U serine; with Third Base C, results in U C C serine; with Third Base A, results in U C A serine; and with Third Base G, results in U C G serine First Base C and Second Base C with Third Base U, results in C C U proline; with Third Base C, results in C C C proline; with Third Base A, results in C C A proline; and with Third Base G, results in C C G proline First Base A and Second Base C with Third Base U, results in A C U threonine; with Third Base C, results in A C C threonine; with Third Base A, results in A C A threonine; and with Third Base G, results in A C G threonine First Base G and Second Base C with Third Base U, results in G C U alanine; with Third Base C, results in G C C alanine; with Third Base A, results in G C A alanine; and with Third Base G, results in G C G alanine First Base U and Second Base A with Third Base U, results in U A U tyrosine; with Third Base C, results in U A C tyrosine; with Third Base A, results in U A A stop; and with Third Base G, results in U A G stop First Base C and Second Base A with Third Base U, results in C A U histidine; with Third Base C, results in C A C histidine; with Third Base A, results in C A A glutamine; and with Third Base G, results in C A G glutamine First Base A and Second Base A with Third Base U, results in A A U asparagine; with Third Base C, results in A A C asparagine; with Third Base A, results in A A A lysine; and with Third Base G, results in A A G lysine First Base G and Second Base A with Third Base U, results in G A U aspartate; with Third Base C, results in G A C aspartate; with Third Base A, results in G A A glutamate; and with Third Base G, results in G A G glutamate First Base U and Second Base G with Third Base U, results in U G U cysteine; with Third Base C, results in U G C cysteine; with Third Base A, results in U G A stop; and with Third Base G, results in U G G tryptophan First Base C and Second Base G with Third Base U, results in C G U arginine; with Third Base C, results in C G C arginine; with Third Base A, results in C G A arginine; and with Third Base G, results in C G G arginine First Base A and Second Base G with Third Base U, results in A G U serine; with Third Base C, results in A G C serine; with Third Base A, results in A G A arginine; and with Third Base G, results in A G G arginine First Base G and Second Base G with Third Base U, results in G G U glycine; with Third Base C, results in G G C glycine; with Third Base A, results in G G A glycine; and with Third Base G, results in G G G glycine. Comparison of DNA sequences in Table II suggests that a functional GULO gene in lemurs can have a G, C, or T at position 21 but only a G at position 22. Which of the following pairs of predictions is most helpful in explaining the discrepancy?

Which of the following is NOT a reason humans should care about biodiversity?

A naturalist studying competitive interactions between flower-visiting animals in a meadow observes that hummingbirds always prevent butterflies from feeding on blue flowers. What would most likely occur upon removal of hummingbirds from the meadow?

The graph is titled Wolf and Elk Population Sizes in Yellowstone National Park. The horizontal axis is labeled Year, and has values from left to right of 1993 to 2006. Each year is represented with a tick mark, and the years 1995, 2000, and 2006 are labeled appropriately. The left vertical axis is labeled Wolf Population and has values from bottom to top of 0 to 20 in increments of five. The right vertical axis is labeled Elk Population and has values from bottom to top of 0 to 120, in increments of 20. Two separate lines with points are shown on the graph. The first line is dashed and is labeled Elk. The second line is solid and is labeled Wolves. The approximate values of each respective line are as follows. Year, 1993; Elk Population, 90. Year, 1993; Wolf Population, 2. Year, 1994; Elk Population, 95. Year, 1994; Wolf Population, 2. Year, 1995; Elk Population, 80. Year, 1995; Wolf Population, 2. Year, 1996; Elk Population, 75. Year, 1996; Wolf Population, 6. Year, 1997; Elk Population, 60. Year, 1997; Wolf Population, 7. Year, 1998; Elk Population, 55. Year, 1998; Wolf Population, 8. Year, 1999; Elk Population, 57. Year, 1999; Wolf Population, 11. Year, 2000; Elk Population, 70. Year, 2000; Wolf Population, 10. Year, 2001; Elk Population, 60. Year, 2001; Wolf Population, 16. Year, 2002; Elk Population, 55. Year, 2002; Wolf Population, 17. Year, 2003; Elk Population, 40. Year, 2003; Wolf Population, 18. Year, 2004; Elk Population, 38. Year, 2004; Wolf Population, 22. Year, 2005; Elk Population, 44. Year, 2005; Wolf Population, 18. Year, 2006; Elk Population, 28. Year, 2006; Wolf Population, 12. Figure 1. Wolf and Elk Population Sizes in Yellowstone National Park The graph is titled Browsing of Aspen in Yellowstone National Park. The horizontal axis is labeled Year, and has values from left to right of 1993 to 2006. Each year is represented with a tick mark, and the years 1995, 2000, and 2006 are labeled appropriately. The vertical axis is labeled Percent Aspen Browsed and has values from bottom to top of 0 to 100 in increments of twenty. Two separate lines with points are shown on the graph. The first line is dashed and is labeled Riparian. The second line is solid and is labeled Uplands. The approximate values of each respective line are as follows. Year, 1998; Percent Aspen Browsed in Uplands, 98. Year, 1998; Percent Aspen Browsed in Riparian, 98. Year, 1999; Percent Aspen Browsed in Uplands, 98. Year, 1999; Percent Aspen Browsed in Riparian, 96. Year, 2000; Percent Aspen Browsed in Uplands, 96. Year, 2000; Percent Aspen Browsed in Riparian, 93. Year, 2001; Percent Aspen Browsed in Uplands, 95. Year, 2001; Percent Aspen Browsed in Riparian, 85. Year, 2002; Percent Aspen Browsed in Uplands, 93. Year, 2002; Percent Aspen Browsed in Riparian, 83. Year, 2003; Percent Aspen Browsed in Uplands, 91. Year, 2003; Percent Aspen Browsed in Riparian, 81. Year, 2004; Percent Aspen Browsed in Uplands, 87. Year, 2004; Percent Aspen Browsed in Riparian, 48. Year, 2005; Percent Aspen Browsed in Uplands, 73. Year, 2005; Percent Aspen Browsed in Riparian, 25. Year, 2006; Percent Aspen Browsed in Uplands, 65. Year, 2006; Percent Aspen Browsed in Riparian, 16. Figure 2. Browsing of Aspen in Yellowstone National Park The graph is titled Growth of Aspen in Yellowstone National Park. The horizontal axis is labeled Year, and has values from left to right of 1993 to 2006. Each year is represented with a tick mark, and the years 1995, 2000, and 2006 are labeled appropriately. The vertical axis is labeled Aspen Height in centimeters, and has values from bottom to top of 0 to 250 in increments of fifty. Two separate lines with points are shown on the graph. The first line is dashed and is labeled Riparian. The second line is solid and is labeled Uplands. The approximate values of each respective line are as follows. Year, 1998; Aspen Height in Centimeters in Uplands, 35. Year, 1998; Aspen Height in Centimeters in Riparian, 35. Year, 1999; Aspen Height in Centimeters in Uplands, 32. Year, 1999; Aspen Height in Centimeters in Riparian, 38. Year, 2000; Aspen Height in Centimeters in Uplands, 29. Year, 2000; Aspen Height in Centimeters in Riparian, 48. Year, 2001; Aspen Height in Centimeters in Uplands, 35. Year, 2001; Aspen Height in Centimeters in Riparian, 58. Year, 2002; Aspen Height in Centimeters in Uplands, 45. Year, 2002; Aspen Height in Centimeters in Riparian, 75. Year, 2003; Aspen Height in Centimeters in Uplands, 50. Year, 2003; Aspen Height in Centimeters in Riparian, 95. Year,2004; Aspen Height in Centimeters in Uplands, 70. Year, 2004; Aspen Height in Centimeters in Riparian, 135. Year, 2005; Aspen Height in Centimeters in Uplands, 90. Year, 2005; Aspen Height in Centimeters in Riparian, 180. Year, 2006; Aspen Height in Centimeters in Uplands, 120. Year, 2006; Aspen Height in Centimeters in Riparian, 225. Figure 3. Growth of Aspen in Yellowstone National Park Wolves, a top predator, were reintroduced to Yellowstone National Park in 1995 after a 50-year absence. In a multiyear study, the numbers of wolves and elk were monitored. The data are shown in Figure 1. In two different environments scientists monitored the percent of aspen trees browsed by herbivores (Figure 2) as well as the growth of the trees (Figure 3). The upland environments consist mostly of flat forested areas. The riparian environments are areas along streams with steep, wooded banks. Based on the data, which of the following is the best explanation for the changes in the elk population size between 2000 and 2005?

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 populations have significantly decreased in size between 1996 and 2011?

A colony of termites was exposed to an atmosphere of 100 percent oxygen for three days. The insects were not immediately harmed by the treatment, but the protozoa that lived in the termites’ guts were eliminated. The treated termites continued to behave normally and to eat wood, but they began to starve after a short time. When the treated termites were instead fed wood contaminated with the feces of untreated termites, the treated termites regained the ability to digest wood and no longer starved. The best analysis of the results of the experiment is that

The three-spined stickleback (Gasterosteus aculeatus) is a small fish found in both marine and freshwater environments. Marine stickleback populations consist mostly of individuals with pronounced pelvic spines, as shown in Figure 1. Individuals in freshwater stickleback populations, on the other hand, typically have reduced pelvic spines, as shown in Figure 2. Each figure shows an image of a stickleback fish with a genetic structure below it. The left figure is labeled Figure 1. Marine stickleback. A long Pelvic Spine on the fish is labeled. The genetic structure below the fish contains three enhancers, a promoter, and a gene. From left to right, the Enhancer Sequences are labeled Hindlimb, Pituitary, and Jaw. To the right of the Enhancer Sequences is a Promoter with an arrow moving up and to the right, over the top of the Pitx1 gene. The right figure is labeled Figure 2. Freshwater stickleback. A short Pelvic Spine on the fish is labeled. The genetic structure below the fish contains three enhancers, a promoter, and a gene. From left to right, the Enhancer Sequences are labeled Hindlimb, Pituitary, and Jaw. The Hindlimb enhancer is crossed out with an X, and it is labeled Disabled Due to Mutation. To the right of the Enhancer Sequences is a Promoter with an arrow moving up and to the right, over the top of the Pitx1 gene. As represented in Figure 1 and Figure 2, the phenotypic difference between marine and freshwater sticklebacks involves Pitx1, a gene that influences the formation of the jaw, pituitary gland, and pelvic spine. Enhancer sequences upstream of the Pitx1 genetic locus regulate expression of the Pitx1 gene at the appropriate times and in the appropriate tissues during development. Previous studies have found that a mutation in the hindlimb enhancer interferes with the formation of a pronounced pelvic spine. Which of the following describes a possible selective mechanism to explain why freshwater sticklebacks typically have reduced pelvic spines?

There is an arrow extending from Germany to the United Kingdom, and another arrow extending from Germany to Spain. Blackcap birds (Sylvia atricapilla) migrate out of Germany before wintertime. Prior to the 1960s, all members of a particular blackcap population flew to Spain, which had an abundant natural food source. Now, some members of the same blackcap population fly to the United Kingdom, where food placed in feeders by humans is abundant. The blackcaps return to the same forests in Germany to nest during the breeding season. Some blackcaps that migrate to the United Kingdom have become distinguishable by certain physical and behavioral traits from blackcaps that migrate to Spain. Which of the following best predicts the effect on the blackcap population if humans in the United Kingdom continue to place food in feeders during the winter?

Which of the following is not a potential problem posed by non-native species?