The horizontal axis is labeled Year, and the vertical axis is labeled Resistant Isolates, by percent. Eight tick marks appear on the horizontal axis and are labeled, from left to right, one through 8, in increments of one. Five tick marks appear on the vertical axis and are labeled, from bottom to top, zero through 20, in increments of 5. On the graph, there are 8 data points connected by a curve drawn through the points. The first and last data points are the start and end of the curve, and the approximate coordinates of the data points are as follows: Point One: one comma 2. Point 2: two comma 2 point five. Point 3: three comma 2 Point 4: four comma 3. Point 5: five comma 4. Point 6: six comma 7. Point 7: seven comma 14. Point 8: eight comma 21. Over several years, bacteria were isolated from members of a human population and tested for antibiotic resistance. The percent of bacterial isolates that were found to be antibiotic resistant is presented in the graph above for each year of the study. Which of the following conclusions is best supported by the information presented in the graph?

Iron is an essential nutrient that is acquired by organisms from the environment. When intracellular levels of iron are relatively high, living cells synthesize an iron-storage protein called ferritin. The induction of ferritin synthesis by iron was investigated in rats. Figure 1 shows the results of an experiment in which cellular levels of ferritin protein were measured in the presence or absence of iron and actinomycin D, a drug that inhibits transcription. Figure 2 shows the results of an experiment in which cellular levels of ferritin protein were measured in the presence or absence of iron and cycloheximide, a drug that inhibits translation. The horizontal axes are labeled Treatment, and the vertical axes are labeled Relative Protein Level. Five tick marks appear on the vertical axis, from bottom to top, the first tick mark is labeled zero, the third tick mark is labeled one point zero, and the fifth tick mark is labeled two point zero. The graph on the left is labeled Figure one. Ferritin Protein Levels. Four vertical bars appear along the horizontal axis, and the presence or absence of Iron and Actinomycin D is indicated above each bar. The data in the graph, from left to right, are as follows: Bar 1: Absence of Iron; Absence of Actinomycin D; Relative Protein Level one point zero. Bar 2: Presence of Iron; Absence of Actinomycin D; Relative Protein Level two point two. Bar 3: Absence of Iron; Presence of Actinomycin D; Relative Protein Level zero point nine. Bar 4: Presence of Iron; Presence of Actinomycin D; Relative Protein Level two point zero. The graph on the right is labeled Figure 2. Ferritin Protein Levels. Four vertical bars appear along the horizontal axis, and the presence or absence of Iron and Cycloheximide is indicated above each bar. The data in the graph, from left to right, are as follows: Bar 1: Absence of Iron; Absence of Cycloheximide; Relative Protein Level one point zero. Bar 2: Presence of Iron; Absence of Cycloheximide; Relative Protein Level two point five. Bar 3: Absence of Iron; Presence of Cycloheximide; Relative Protein Level zero point nine. Bar 4: Presence of Iron; Presence of Cycloheximide; Relative Protein Level zero point nine. The gene sequences responsible for the iron ­mediated changes in ferritin protein levels are highly conserved and are called iron response elements (IREs). IREs have been observed in a number of genes involved in iron transport and metabolism. The IRE sequences found in the ferritin gene are found in all multicellular organisms, whereas other non-ferritin IRE sequences are found only in certain vertebrate organisms. Which of the following is the best explanation for the observations?

Tay-Sachs disease is a rare inherited disorder caused by an autosomal recessive allele of the HEXA gene. Affected individuals exhibit severe neurological symptoms and do not survive to reproductive age. Individuals who inherit one copy of the allele (Tay-Sachs carriers) typically show no symptoms of the disorder. The frequencies of Tay-Sachs carriers in the general population of North America and in three different subpopulations are presented in the table. For general population the frequency is 0.004. For subpopulation 1 the frequency is 0.037. For subpopulation 2 the frequency is 0.035. For subpopulation 3 the frequency is 0.020. Which of the following is an ethical question about Tay-Sachs disease that cannot be answered using scientific methods?

The bottom row consists of grasses, bush, and tree. The second row from the bottom consists of squirrel, grasshopper, and rabbit. The third row from the bottom consists of a shrew. The fourth row from the bottom consists of a hawk, snake, insect eating bird, and deer. The top row consists of a lion. From the tree, arrows extend to the deer and squirrel. From the bush, arrows extend to the squirrel, grasshopper, rabbit, and deer. From the grasses, arrows extend to the grasshopper and rabbit. From the squirrel, an arrow extends to the hawk. From the grasshopper, arrows extend to the shrew and insect eating bird. From the rabbit, arrows extend to the snake and lion. From the insect eating bird, an arrow extends to the hawk. From the deer, an arrow extends to the lion. From the snake, arrows extend to the lion and hawk. From the shrew, arrows extend to the snake, hawk, and lion. The food web represented above does not include bacteria and fungi. Which of the following best describes a consequence of having no bacteria and fungi in the food web?

Experimental evidence shows that the process of glycolysis is present and virtually identical in organisms from all three domains, Archaea, Bacteria, and Eukarya. Which of the following hypotheses could be best supported by this evidence?

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?

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. Initially, which of the following isolating mechanisms is likely to have been the most important in preventing gene flow between the two populations of Rhagoletis?

Students investigated the effect of light on the carbon cycle in aquatic ecosystems by performing the controlled experiment summarized below. The students placed equal amounts of water (pH 7.0)  from a large aquarium in glass beakers. The students transferred aquatic plants from the aquarium to several of the beakers, and then they placed equal numbers of the beakers in the light or the dark (Figure 1: Groups I and II). Similarly, the students transferred goldfish from the same aquarium to other beakers, and then they placed equal numbers of those beakers in the light or dark (Figure 1: groups III and IV). Finally, the students placed an equal number of beakers containing water only in the light or dark (Figure 1: Groups V and VI). After exposing the samples to light or dark for one hour, the students recorded the pH of the water in each beaker. Carbon dioxide dissolved in water will lower the pH of an aqueous solution. In the experiment, the students used changes in pH to monitor changes in the amount of carbon dioxide in the water.  For each treatment group, the students calculated the mean pH and standard error, as documented in the table below. The odd-numbered groups are marked Light, and the even-numbered groups are marked Dark. Each group contains a beaker with the same amount of water. From left to right, the beakers are as follows:1, plant. 2, plant. 3, fish. 4, fish. 5, empty. 6, empty. Figure 1. Treatment groups Mean pH of Treatment Groups After 1 Hour Treatment group (n = 10) I II III IV V VI Mean pH 8.2 6.4 5.9 5.6 7.3 6.8 Standard error of the mean 0.3 0.3 0.2 0.3 0.5 0.4 Which of the following modifications to the experimental design will best help reduce the standard errors of the means?

True or false? “Endangered” is a more critical level of species extinction risk than “threatened.”

There are two horizontal axes, one above the graph and one below the graph. The horizontal axis below the graph is labeled “Days,” and the numbers 5 through 30, in increments of 5, are indicated. The horizontal axis above the graph is labeled “Moon Phase,” and the following four moon phases are labeled: “Full Moon,” “First Quarter,” “New Moon,” and “Third Quarter.” The positions of the moon phases are aligned at the following days: Full Moon, 5 days; First Quarter, 12 days; New Moon, 18 days; Third Quarter, 25 days. The vertical axis of the graph is labeled “Nighttime high tides through one lunar period, in feet,” and the numbers 3 through 7, in increments of 1, are indicated. The curve resembles a sinusoidal curve, and begins at the point 0 days with a height of 4.8 feet. The curve increases to a local maximum of 6.3 feet at the Full Moon, at the point 5 days. The curve then decreases to a local minimum of 4.1 feet at the First Quarter, at the point 12 days. The curve then increases to a maximum of 6.9 feet at the New Moon, at the point 18 days. The curve then decreases to a minimum of 3.9 feet after the Third Quarter, at the point 27 days. The curve then increases to 4.8 feet at its end point of 30 days. The California grunion (Leuresthes tenuis) is a small marine fish that lives in shallow waters near the ocean shore. Grunions swim as far onto the beach as possible to mate and lay their eggs (spawn). A researcher proposes that the spawning behavior takes place when the nighttime tides are highest during the month. Which of the following pieces of evidence would best support the researcher’s claim?