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Rhagoletis pomonella is a parasitic fly native to North America that infests fruit trees. The female fly lays her eggs in the fruit. The larvae hatch and burrow through the developing fruit. The next year, the adult flies emerge. Prior to the European colonization of North America, the major host of Rhagoletis was a native species of hawthorn, Crataegus marshallii. The domestic apple tree, Malus domestica, is not native to North America, but was imported by European settlers in the late 1700s and early 1800s. When apple trees were first imported into North America, there was no evidence that Rhagoletis could use them as hosts. Apples set fruit earlier in the season and develop faster, where hawthorns set later and develop more slowly. Recent analysis of Rhagoletis populations has shown that two distinct populations of flies have evolved from the original ancestral population of flies that were parasitic on hawthorns. One population infests only apple trees, and the other infests only hawthorns. The life cycles of both fly populations are coordinated with those of their host trees. The flies of each population apparently can distinguish and select mates with similar host preferences and reject mates from the population specific to the other host tree. There is very little hybridization (only about 5 percent) between the two groups. The divergence between the two populations of Rhagoletis must have occurred very rapidly because

The graph below shows changes in a population of wild sheep that were introduced to the island of Tasmania in the early 1800’s. The horizontal axis is labeled year from 1820 to 1940 with tick marks in increments of ten. The vertical axis is labeled number of sheep in thousands from zero to two thousand five hundred, with tick marks in increments of 500. The population curve starts at zero in 1820, increases slowly then increases rapidly to two point two five million by 1850. This increase is enclosed in a bracket. After 1850 the population curve fluctuates between two point two five million and one point two five million, with a horizontal dashed line through the middle of these population fluctuations. The dashed line on the graph represents the

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?

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 best explains the contribution of the lac operon to the metabolic efficiency of a bacterial cell?

Staphylococcus aureus is a pathogenic bacterium that can infect a wide range of host species, including humans. S. aureus has a particular protein that binds with hemoglobin from the host organism. Hemoglobin is the iron-containing protein used to transport oxygen in the blood. Since iron is important for growth, S. aureus have evolved the ability to absorb the iron from the host’s hemoglobin. Different S. aureus strains preferentially infect different hosts and have different amino acid sequences at their hemoglobin-binding domains (Table 1; letters indicate different amino acids). In an experiment, different S. aureus strains were mixed with hemoglobin from macaque monkeys and their binding ability was measured (Figure 1). The differences in amino acid sequences contributed to the differential binding abilities observed. Table 1. Selected amino acid sequences and preferred host for four strains of S. aureus S. aureus Strain Amino Acid Sequence Host Species 1 Q Q F Y H Y A R S Species A 2 R Q A Y H Y A R T Species B 3 Q Q A Y H Y A R T Macaque 4 R Q A A H Y Q L T Species C The figure presents a bar graph. The horizontal axis is labeled S. aureus Strain, and the numbers 1, 2, 3 and 4 are indicated. The vertical axis is labeled Percent Hemoglobin Binding, and the numbers 0 through 100, in increments of 10, are indicated. The data represented in the graph are as follows. Note that all values are approximate. S. aureus Strain 1, 25 percent hemoglobin binding. S. aureus Strain 2, 60 percent hemoglobin binding. S. aureus Strain 3, 97 percent hemoglobin binding. S. aureus Strain 4, 35 percent hemoglobin binding. Figure 1. Macaque hemoglobin binding ability of different strains of S. aureus Which of the following processes is most consistent with the differences in the amino acid sequences listed in Table 1?

Staphylococcus aureus is a pathogenic bacterium that can infect a wide range of host species, including humans. S. aureus has a particular protein that binds with hemoglobin from the host organism. Hemoglobin is the iron-containing protein used to transport oxygen in the blood. Since iron is important for growth, S. aureus have evolved the ability to absorb the iron from the host’s hemoglobin. Different S. aureus strains preferentially infect different hosts and have different amino acid sequences at their hemoglobin-binding domains (Table 1; letters indicate different amino acids). In an experiment, different S. aureus strains were mixed with hemoglobin from macaque monkeys and their binding ability was measured (Figure 1). The differences in amino acid sequences contributed to the differential binding abilities observed. Table 1. Selected amino acid sequences and preferred host for four strains of S. aureus S. aureus Strain Amino Acid Sequence Host Species 1 Q Q F Y H Y A R S Species A 2 R Q A Y H Y A R T Species B 3 Q Q A Y H Y A R T Macaque 4 R Q A A H Y Q L T Species C The horizontal axis is labeled S. aureus Strain, and the numbers 1, 2, 3 and 4 are indicated. The vertical axis is labeled Percent Hemoglobin Binding, and the numbers 0 through 100, in increments of 10, are indicated. The data represented in the graph are as follows. Note that all values are approximate. S. aureus Strain 1, 25 percent hemoglobin binding. S. aureus Strain 2, 60 percent hemoglobin binding. S. aureus Strain 3, 97 percent hemoglobin binding. S. aureus Strain 4, 35 percent hemoglobin binding. Figure 1. Macaque hemoglobin binding ability of different strains of S. aureus Which of the following experiments would be most appropriate to determine whether populations of S. aureus are continuously adapting in order to obtain iron from hosts more effectively?

The figure below represents a food web in a particular ecosystem. Each letter represents a species. The arrows indicate the direction of energy flow. A is arranged at the bottom of the food web with decomposers on the right. The other letters are arranged from the far left above A, starting with E, then D up and to the right, then at the top of the web above A is C, with B to the right and lower than C, but above decomposer. The letter A has an arrow pointing up to D, an arrow pointing up to C and an arrow pointing to decomposer on the right. C has an arrow to decomposer. D has an arrow pointing left to E, an arrow pointing right to C, an arrow pointing right to B and an arrow pointing to decomposer. E has an arrow pointing to decomposer. C has an arrow pointing to decomposer. B has an arrow pointing to C and an arrow pointing to decomposer. Members of which species are most likely to be omnivorous?

Students subjected three samples of five different molecules to gel electrophoresis as shown in Figure 1. The three lanes of the gel are numbered 1, 2, and 3 for each of the three samples. Along the left side of the gel, from top to bottom, are the letters A, B, C, D, and E, representing the positions of the five molecules in the samples. A plus symbol is above the top of the gel, and a minus symbol is below the bottom of the gel. Open rectangles representing the sample loading wells are located in each lane, in a horizontal position between the letters B and C. Black rectangles in each represent the molecules in the samples. The data are as follows. In lane 1, there is a black rectangle at position A and a second black rectangle at position B. In lane 2, there is a black rectangle at position C and a second black rectangle at position D. In lane 3, there is a black rectangle at position E. Figure 1. Gel electrophoresis of three prepared samples Which of the following statements best explains the pattern seen on the gel with regard to the size and charge of molecules A and B?

A tobacco plant can be made to express a gene from fireflies, resulting in the emission of light. Which of the following is the basis for this phenomenon?

Figure 1 compares two models of speciation, A and B. Speciation model A has 9 butterflies that begins with one lightly shaded butterfly. After this butterfly is one node that branches into two paths, one to the left and one to the right, each with 4 butterflies. In the branch on the left, the first butterfly from the bottom repeats the lightly shaded butterfly, the next butterfly in the pathway has reduced shading and the remaining 2 butterflies have no shading. In the branch on the right, the first butterfly from the bottom is a tiny bit darker than the original butterfly. The next butterfly up is slightly darker than the preceding butterfly with a medium shading, the next butterfly has a darker medium shading and the last butterfly is the darkest. Speciation model B has 6 butterflies and begins with a lightly shaded butterfly. At the first node, there is a branch to the left and to the right. In the branch on the right, the first butterfly is a heavily shaded butterfly, and the next is another heavily shaded butterfly. Taking the left branch from the first or lowest node, is another node that branches to the left and to the right. From this node, the branch on the right repeats the shading of the original butterfly and the branch on the left, the first butterfly has reduced shading and the next butterfly has reduced shading. Figure 1. A comparison of two speciation models Which of the following best explains how the ecological conditions are likely to be different in the two models?