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Mutations in DNA are usually caused by chemical or radiation damage to DNA molecules, followed by imperfect repair of the damage. Immediately after this kind of imperfect repair, there may be a mismatched base pair in the DNA. The illustration below shows an example of a mismatch, with the relevant pair bases in bold. The top D N A strand is labeled Normal, and has the base pair G C in bold. The bottom D N A strand is labeled Normal, and has the corresponding base pair G C in bold. Which of the following best represents the DNA of the two daughter cells produced when a bacterial cell with this particular mismatch replicates its DNA and divides?

The three-spined stickleback (Gasterosteus aculeatus) is a small fish found in both marine and freshwater environments. Marine stickleback populations consist mainly of individuals with armor-like plates covering most of their body surface (completely plated). Approximately 10,000 years ago, some marine sticklebacks colonized freshwater environments. After many generations in the freshwater environments, the freshwater stickleback populations lacked the armor plating (low plated) typical of marine stickleback populations. Over the period between 1957 and 2005, one freshwater population, in Lake Washington, a lake in a coastal region of the northwestern United States, changed from having a majority of individuals of the low-plated phenotype to having more individuals of the completely-plated phenotype than of the low-plated phenotype. Figure 1 shows the distribution of plated phenotypes in Lake Washington sticklebacks at four time points between 1957 and 2005. There are 5 tick marks along the horizontal axis. Centered between each tick mark, from left to right, are the numbers 1957, 1968, 1976, and 2005. The vertical axis is label Percentage of Fish, and the numbers appearing on it, from bottom to top, are zero,20, 40, 60, 80, and 100. The graph shows 11 bars and a key indicates black bars are completely plated, shaded bars are partially plated, and white bars are low plated. From left to right, the data reads as approximately:1957: completely plated,no bar; partially plated, 10; low plated, 90.1968: completely plated, 7; partially plated, 24; low plated 70. 1976: completely plated, 40; partially plated, 35; low plated 24. 2005: completely plated, 50; partially plated, 35; low plated 15. A single gene, ectodysplasin (EDA), is thought to be responsible for the variation in the number of armor plates in sticklebacks. Figure 2 shows a phylogenetic tree constructed by comparing DNA sequences of the EDA gene from a number of stickleback populations with low-plated or completely plated phenotypes. Figure 3 shows a phylogenetic tree constructed by comparing the sequences of 25 genes that were randomly selected from the same populations as shown in Figure 2. In both figures, shaded populations display the completely plated phenotype. The figures show two phylogenetic trees titled Figure 2, Phylogeny based on EDA gene only, and Figure 3, Phylogeny based on 25 random genes. Shaded populations indicated completely plated phenotypes. Figure 2 on the left divides Populations 1 through 8 as low plated, and Populations 9 through 15 as completely plated.A large branch connects all low plated phenotypes to all completely plated phenotypes. On the top branch, a tree connects Populations 1 and 2 only, and a branch then connects them to Population 3. A branch then connects Populations 1 through 3 to Population 4. A tree connects Populations 5 and 6 only, and a branch is then connected from Populations 5 and 6 to Populations 1 through 4. This tree is then connected to Population 7.On the bottom branch, a tree connects Populations 8 and 9, and a tree connects Populations 10 and 11. A branch then connects Populations 8 and 9 to Populations 10 and 11. This branch is then connected to Population 12. A tree connects Populations 8 through 12 to Population 13, a branch connects Population 14 to Populations 8 through 13, and a branch connects Population 15 to Populations 8 through 14. Figure 3 on the right has a tree that connects Population 15 to Populations one through 14. A tree connects Populations 4 and 6 and a single branch extends to the tree connecting Population 15 to Populations one through 14. A tree connects Populations 14 and 7, and a branch connects this set to Population 5. A branch then connects this set to Population 12, another branch connects this set to Population 13, and another branch connects this set to Population 8. A tree connects Populations 11 and 9, a branch connects this set to Population 10, another branch connects this set to Population 1, another branch connects this set to Population 3, and another branch connects this set to Population 2. A tree connects Populations 14, 7, 5, 12, 13, and 8 to Populations 11, 9, 10, 1, 3 and 2. A completely-plated stickleback from a marine population was mated to a low-plated stickleback from a freshwater population. The resulting F1 hybrids all displayed a completely plated phenotype. When the F1 hybrids were allowed to interbreed, the resulting F2 generation included completely plated offspring and low-plated offspring in an approximate 3:1 ratio. The phylogenetic trees in Figures 2 and 3 depict two different phylogenies of the same populations of sticklebacks. Which of the following questions will best help determine which tree represents the most accurate phylogeny?

In a transformation experiment, a sample of E. coli bacteria was mixed with a plasmid containing the gene for resistance to the antibiotic ampicillin (ampr). Plasmid was not added to a second sample. Samples were plated on nutrient agar plates, some of which were supplemented with the antibiotic ampicillin. The results of E. coli growth are summarized below. The shaded area represents extensive growth of bacteria; dots represent individual colonies of bacteria. Wild type E. coli are plated on plates 1 and 2, and E. coli with plasmid containing the ampicillin resistance gene is plated on plates 3 and 4. Plate 1 has no ampicillin,and is shaded representing extensive growth of bacteria. Plate 2 has ampicillin and is white with no colonies. Plate 3 has no ampicillin and is shaded representing extensive growth of bacteria. Plate 4 has ampicillin and has a dozen dots representing individual colonies of bacteria. Plates I and III were included in the experimental design in order to

All of the following were likely present on the primitive Earth during the evolution of self-replicating molecules EXCEPT

A widely accepted hypothesis about the origin of life on Earth is that life arose approximately 3.5 billion years ago as the result of a complex sequence of chemical reactions that took place spontaneously in Earth’s atmosphere. Another hypothesis about the origin of life suggests that life began somewhere else in the universe and arrived on Earth by chance. Which of the following questions might scientists ask to most reliably determine if there has ever been life on Mars?

A scientist is evaluating a proposal for raising large numbers of fish in ocean pens for human consumption. As part of the evaluation, the scientist is designing a plan for investigating how the fish in the ocean pens might affect nearby ecosystems. Which of the following is the most appropriate factor to use as the dependent variable in the experimental investigation?

Malaria is caused by several different species of Plasmodium, a protozoan parasite. Plasmodium resistance to the common drugs used to treat malaria has increased in recent years. In a scientific study, Plasmodium samples were analyzed in blood drawn from a large number of infected patients before drug treatment and subsequently from the subset of infected patients with drug-resistant Plasmodium. DNA sequences of four different Plasmodium genes thought to be involved in resistance were compared between samples from patients with drug-sensitive Plasmodium and patients with drug-resistant Plasmodium. Which of the following best supports the hypothesis that preexisting mutations confer drug resistance?

The cladogram shown below depicts an accepted model of the evolutionary relationships among selected species. The figure shows a cladogram with the root at the bottom left and three branches. From left to right, the branches are as follows: Horse, with a point labeled W; Gorilla, with a point labeled X, and Human, with a point labeled Y. Past the branches, the main line is labeled Chimpanzee, with a point labeled Z. The amino acid at position 104 in the beta-hemoglobin protein for each of these four organisms is listed below. Amino acid at position 104 in the beta-hemoglobin protein Species Amino Acid 104 Horse Arginine Gorilla Leucine Human Arginine Chimpanzee Arginine The validity of the cladogram is best supported by molecular evidence for which of the following changes in the amino acid composition of the beta-hemoglobin protein during the evolution of these species?

In a certain flock of sheep, 4 percent of the population has black wool and 96 percent has white wool. Assume that the population is in Hardy-Weinberg equilibrium. What percentage of the population is homozygous for white wool?

To investigate the influence of predation risk on ray behavior, a student observed and counted the large marine animals swimming in a shallow, nearshore section of a coral reef ecosystem. The time of each observation was recorded relative to the time of high tide. The student noted that at low tide, when the water level is low, many of the large animals are forced out of the study area and into the deeper waters of the outer reef. During high tides, when the water level is high, the large animals are able to reenter the study area. Over a three-day period, the student observed a total of 604 individual rays belonging to three species: cowtail rays, giant shovelnose rays, and black stingrays. For each ray that was sighted, its body length was estimated and its status as either alone (ungrouped) or found with other rays (grouped) was noted. Occasionally, rays were observed sifting through the sandy substrate of the study area to capture food items such as molluscs and crustaceans. In one instance, an injured ray with bite marks that were likely sustained in a shark attack was sighted. In addition to the rays, the student observed lemon sharks (n = 46) and blacktip reef sharks (n = 39). The results of the study are presented in the figures below. The horizontal axis is labeled “Mean Body Length, in meters,” and the numbers 0 through 1.5, in increments of 0.5, are indicated. The vertical axis gives the three categories of the graph, each of which contains two subcategories. The three categories are Cowtail Rays, Giant Shovelnose Rays, and Black Stingrays. The subcategories are Ungrouped and Grouped. The data are presented as follows. Note that all values are approximate. Cowtail Rays: Ungrouped have a mean body length of 1.5 meters, and the error bar spans plus or minus 0.03. Grouped have a mean body length of 1.35 meters, and the error spans plus or minus 0.05. Giant Shovelnose Rays: Ungrouped have a mean body length of 1.6 meters, and the error bar spans plus or minus 0.04. Grouped have a mean body length of 1.35 meters, and the error spans plus or minus 0.08. Black Stingrays: Ungrouped have a mean body length of 1.4 meters, and the error bar spans plus or minus 0.02. Grouped have a mean body length of 1.3 meters, and the error spans plus or minus 0.05. Figure 1. Comparison of mean body lengths of the grouped and ungrouped rays that were observed in a nearshore section of a coral reef ecosystem. Error bars represent 2SEx̄ The graph shows the mean number of rays per group in the study area relative to stages of the tide cycle. The horizontal axis is labeled “Time Relative to High Tide, in hours,” and the numbers negative 3 through positive 1, in increments of 1, are indicated. The vertical axis is labeled “Mean Group Size,” and the numbers 0 through 6, in increments of 1, are indicated. The line is composed of five points connected by line segments, and error bars are shown for each point. The five points are listed as follows. Note that all values are approximate. Point 1. Time relative to High Tide, negative 3 hours. Mean Group Size, 0.9 plus or minus 0 point 4. Point 2. Time relative to High Tide, negative 2 hours. Mean Group Size, 2 point 5 plus or minus 0 point 2. Point 3. Time relative to High Tide, negative 1 hours. Mean Group Size, 4 point 4 plus or minus 0 point 9. Point 4. Time relative to High Tide, 0 hours. Mean Group Size, 4 point 6 plus or minus 0 point 1. Point 5. Time relative to High Tide, positive 1 hours. Mean Group Size, 3 point 6 plus or minus 0 point 3. Figure 2. Mean numbers of rays per group in the study area at different stages of the tide cycle. High tide occurs at T = 0 hours. The graph shows the relative proportions of rays in groups at different stages of the tide cycle. A key indicates that three different lines represent giant shovelnose rays or black stingrays or cowtail rays. The horizontal axis is labeled “Time relative to High Tide, in hours,” and the numbers negative 3 through positive 1, in increments of 1, are indicated. The vertical axis is labeled “Relative Proportion of Rays Found in Groups” and has an arrowhead at the top end. The line for each type of ray is composed of five points connected by line segments, and error bars are shown for most points. The data for each time point are as follows. Point 1. Time relative to High Tide, negative 3 hours. The proportion of each type of ray is similar, and there are very few of each type. Point 2. Time relative to High Tide, negative 2 hours. The number of cowtail rays increased slightly, and there are about twice as many giant shovelnose rays and six times as many black stingrays as cowtail rays. Error bars are shown for only the cowtail rays and giant shovelnose rays. The upper end of the cowtail rays error bar touches the lower end of the giant shovelnose rays error bar. Point 3. Time relative to High Tide, negative 1 hours. The number of cowtail rays is double the number at negative two hours, and there are about three times as many giant shovelnose rays and five times as many black stingrays as cowtail rays. Error bars are shown for each point. The error bar range for the cowtail rays is very narrow; the error bars for the black stingrays and giant shovelnose rays are broad, but do not overlap. Point 4. Time relative to High Tide, 0 hours. The number of cowtail rays is about three quarters the number at negative one hours, and there are about twelve times as many giant shovelnose rays and nine times as many black stingrays as cowtail rays. The error bar range for the cowtail rays is very narrow; the error bars for the black stingrays and giant shovelnose rays are broad, and the upper end of the black stingrays error bar touches the lower end of the giant shovelnose rays error bar. Point 5. Time relative to High Tide, positive 1 hours. The number of cowtail rays is just slightly greater than the number at 0 hours, and there are about seven times as many giant shovelnose rays and five times as many black stingrays as cowtail rays. The error bar range for the cowtail rays is very narrow; the error bars for the black stingrays and giant shovelnose rays are broad, and the upper end of the black stingrays error bar touches the lower end of the giant shovelnose rays error bar. Figure 3. Relative proportions of rays in groups at different stages of the tide cycle for each of the three different populations. High tide occurs at T = 0 hours. The graph shows the mean numbers of lemon sharks and blacktip reef sharks at different stages of the tide cycle. A key indicates that one line represents lemon sharks, and the other line represents blacktip reef sharks. The horizontal axis is labeled “Time Relative to High Tide, in hours,” and the numbers negative 3 through positive 1, in increments of 1, are indicated. The vertical axis is labeled “Mean Number of Sharks,” and the numbers 0 through 10, in increments of 1, are indicated. The two curves are composed of five points connected by line segments. No error bars are shown. The five points of each line are listed as follows. Note that all values are approximate. The following five points are indicated on the line representing lemon sharks. Point 1. Time relative to High Tide, negative 3 hours. Mean Number of Sharks, 4.2. Point 2. Time relative to High Tide, negative 2 hours. Mean Number of Sharks, 9. Point 3. Time relative to High Tide, negative 1 hours. Mean Number of Sharks, 1.5. Point 4. Time relative to High Tide, 0 hours. Mean Number of Sharks, 0. Point 5. Time relative to High Tide, positive 1 hours. Mean Number of Sharks, 1. The following five points are indicated on the line representing blacktip reef sharks. Point 1. Time relative to High Tide, negative 3 hours, Mean Number of Sharks, 0.3. Point 2. Time relative to High Tide, negative 2 hours, Mean Number of Sharks, 0.3. Point 3. Time relative to High Tide, negative 1 hour, Mean Number of Sharks, 4. Point 4. Time relative to High Tide, 0 hours, Mean Number of Sharks, 7. Point 5. Time relative to High Tide, positive 1 hour, Mean Number of Sharks, 9. Figure 4. Mean numbers of lemon sharks and blacktip reef sharks in the study area at different stages of the tide cycle. High tide occurs at T = 0 hours. Which of the following scientific claims about interacting populations of giant shovelnose rays and blacktip reef sharks is best supported by the results shown in Figures 3 and 4?