AP Bio Exam
The diagram above represents a model of signal transduction pathways ( I and II) in a cell that is targeted by two different hormones (H1 and H2). The components of the signal transduction pathways are identified in the figure legend. Each cellular molecule in both pathways can exist in an inactive or active form. When the components in pathway I are sequentially activated, the TAP molecules promote cell division. When the components in pathway II are sequentially activated, downstream signaling by the G protein is inhibited. Based on the model, which of the following mutations is most likely to result in a cell that will generate a cancerous tumor?
A mutation in the gene encoding G-PIP that results in a nonfunctional protein.
A represented in the model above, B cells are activated by direct contact with antigens or stimulated helper T cells (TH). Based on the model, which of the following best describes an outcome of B cell activation?
Activated B cells differentiate into plasma cells and memory cells.
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?
Beta-galactosidase will be produced, even in the absence of lactose.
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 grow 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. If the mixed populations were cultured for an additional 25 days, which of the following predictions would be consistent with the data?
One population would stabilize at a large size, and the other population would be eliminated from the culture.
Which of the following communities is likely to be most stable?
One with high species diversity
Which of the following questions about the origin of life on Earth is most scientifically testable?
Can simple organic molecules form spontaneously in an oxygen-free atmosphere?
Which of the following questions will best direct an investigation of the mechanism of ATP synthase?
Is the phosphorylation of ADP by ATP synthase dependent on the formation of a proton gradient?
Which of the following best describes how myelination affects the transmission of nerve impulses?
It speeds up the transmission of impulses by acting as an electrical insulator.
The manner in which several different ions and molecules move through a cell membrane is shown in the diagram above. For each ion or molecule, the relative concentration on each side of the membrane is indicated. Which of the following accurately describes one of the movements taking place?
Na+ transport out of the cell requires ATP hydrolysis.
Which of the following best describes an event during step 2 in the simplified model above?
Noncoding sequences are removed from a newly synthesized RNA molecule.
The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles: a dominant, wild-type allele that enables an individual (taster) to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual (non-taster) to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the non-taster allele. The nucleotide present at the three positions are shown in the table below. A cladogram representing the evolutionary relatedness of selected primates is shown below. In a sample of 2,400 people, 1,482 were found to have the dominant (taster) phenotype. Assuming that the population is in Hardy-Weinberg equilibrium, approximately how many individuals in the sample are expected to be heterozygous for TAS2R38?
1,133
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. Bacterial cells that contain green fluorescent protein (GFP) will fluoresce under ultraviolet light. Which of the following is the most likely outcome of replacing the lacZ gene in the E. coli lac operon with the gene encoding GFP?
Bacteria growing in the presence of lactose will fluoresce under ultraviolet light.
Which of the following correctly compares the two processes shown above?
Both processes increase genetic variation.
In the American Southwest, annually emerging cicadas are dependent upon the cottonwood trees in the floodplain. Adult male cicadas perch in the cottonwood trees and chirp to attract females. Females lay their eggs in the branches of the cottonwood, and upon hatching, the cicadas nymphs drop to the ground, burrow into the soil, feed on the tree roots, and later emerge as adults. Other organisms in the floodplain community prey on the cicadas, as shown in the food web. Human activity has caused a decrease in the amount of flooding and an increase in the incidence of wildfires in the floodplain. In an investigation into the recent changes in the floodplain ecosystem, researchers monitored the soil temperature, amount of cottonwood ground coverage (ie. area of the ground that is shaded by leaves), and cicada emergence for a period from mid-June until late July. The results of the investigation are represented in Figure 2 and Figure 3. To assess the impact of wildfires on soil temperature and cicada emergence, the researchers compared mean emergence dates for two natural sites where portions had been affected by wildfire. In addition, cicada emergence was monitored at an experimental site where the soil temperature was experimentally maintained. The data are shown in the table. The data from the temperature-controlled experimental plots can best be used to support which of the following conclusions about cicadas development?
Cicada nymphs mature to adults faster in warmer soil than in cooler soil.
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 Earths atmosphere. Another hypothesis about the origin of life suggest that life began somewhere else in the universe and arrived on Earth by chance. Which of the following questions might scientist ask to most reliably determine if thee has ever been life on Mars?
Did Mars have the element present in its atmosphere to support life?
Which of the following is true about the structure of the prokaryotic cell represented in the figure?
It has a cell wall exterior to the plasma membrane and contains ribosomes
The figure above represents a rough endoplasmic reticulum. Which of the following best describes the role of the structure labeled Y?
Structure Y is the location where proteins are synthesized.
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 grow 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. Based on the experimental results, which of the following statements best describes the relationship of the two populations that were studied in the investigation?
The population have a competitive relationship in which each species limits the ability of the other to reproduce.
The following DNA sequence is a small part of the coding (non-template) strand from the open reading frame of the B-hemoglobin gene. Given the codon chart listed below, what would be the effect of a mutation that deletes the G at the beginning of the DNA sequence?
The reading frame of the sequence would shift, causing a change in the amino acid sequence after that point.
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 grow 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. Which of the following statements best justifies the use of the experimental results in an investigation of interspecies competition?
When two populations use the same sources of energy, resource availability in a shared environment limits the growth of both 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 grow 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 difference in carrying capacity between the two species when cultured separately is closest to which of the following values?
350 individuals per 5.0 mL
Damaged tissue releases chemicals that activate platelets and stimulate the formation of blood clots. Which of the following predictions about the activity of platelets best describes a positive feedback mechanism?
Activated platelets releaser chemicals that activate more platelets.
Evolutionary biologist have observed variation in the average age and size of mature individuals in a population of small freshwater guppies. Guppies found in pools with pike cichlids- a predator fish that preys primarily on larger guppies- reproduce at a young age and are small at maturity. Guppies found in pools with killifish- a different predator fish that preys primarily on smaller guppies- reproduce at an older age and are larger at maturity. Which of the following predicts the most likely outcome of moving a population of guppies from a pool with pike cichlids to a pool with killifish?
After many generations, the offspring of the introduced guppies will mature at an older age and larger size because of selective pressure from the new predator.
The table above shows the types and properties of nitrogen-containing wastes produced by several vertebrates. Which of the following is the best evolutionary explanation of the data?
Ammonia secretion requires a large volume of water and was therefore selected against in terrestrial vertebrates.
The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles: a dominant, wild-type allele that enables an individual (taster) to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual (non-taster) to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the non-taster allele. The nucleotide present at the three positions are shown in the table below. A cladogram representing the evolutionary relatedness of selected primates is shown below. Which of the following conclusions is supported by the data?
Bonobos are more closely related to humans than to gorillas because bonobos and humans share a more recent common ancestor than bonobos and gorillas do.
In the American Southwest, annually emerging cicadas are dependent upon the cottonwood trees in the floodplain. Adult male cicadas perch in the cottonwood trees and chirp to attract females. Females lay their eggs in the branches of the cottonwood, and upon hatching, the cicadas nymphs drop to the ground, burrow into the soil, feed on the tree roots, and later emerge as adults. Other organisms in the floodplain community prey on the cicadas, as shown in the food web. Human activity has caused a decrease in the amount of flooding and an increase in the incidence of wildfires in the floodplain. In an investigation into the recent changes in the floodplain ecosystem, researchers monitored the soil temperature, amount of cottonwood ground coverage (ie. area of the ground that is shaded by leaves), and cicada emergence for a period from mid-June until late July. The results of the investigation are represented in Figure 2 and Figure 3. To assess the impact of wildfires on soil temperature and cicada emergence, the researchers compared mean emergence dates for two natural sites where portions had been affected by wildfire. In addition, cicada emergence was monitored at an experimental site where the soil temperature was experimentally maintained. The data are shown in the table. Based upon the data, which of the following best describes the effect on the timing of cicada emergence if the cottonwood ground cover decreases from 50 percent to 25 percent?
Cicadas will emerge approximately 10 days earlier.
Ciprofloxacin is given as an antibiotic to healthy livestock to promote efficient weight gain. Strains of the bacterium Campylobacter Jejuni naturally colonize the digestive tracts of livestock, and the C. Jejuni can be transferred to people through the handling and consumption of contaminated meat. People infected with C. Jejuni are also treated with Ciprofloxacin. Which of the following is the most likely consequence of adding Ciprofloxacin to animal feed?
Ciprofloxacin-resistant strains of C. Jejuni will have a selective advantage in the digestive tracts of livestock, increasing the risk of serious infections in people.
Bacteriophages are viruses that infect bacteria. In an experiment, bacteriophages were labeled with either radioactive phosphorus or radioactive sulfur. The labeled bacteriophages were incubated with bacteria for a brief amount of time and then removed. The infected bacteria cells were found to contain significant amounts of radioactive phosphorus but not radioactive sulfur. Based on the results of the experiment, which of the following types of molecules did the bacteriophages most likely inject into the bacteria cells?
DNA
A researcher released large numbers of moths into different environments in an attempt to better understand a mechanism of evolution. The moths were released in four trials as described in the table above. Each of the released moths had a small mark on the underside of a wing for identification. After an appropriate amount of time, the researcher recaptured as many of the released moths as possible. Data from the experiment are included in the tale above. Which of the following claims is best supported by the data?
Dark-colored moths were most likely to be recaptured in the polluted environment than in the unpolluted environment, suggesting an increased chance of reproductive success.
The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles: a dominant, wild-type allele that enables an individual (taster) to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual (non-taster) to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the non-taster allele. The nucleotide present at the three positions are shown in the table below. A cladogram representing the evolutionary relatedness of selected primates is shown below. Which of the following scientific questions will best help researchers determine when the non-taster allele arose in the evolutionary history of the selected primates?
Does the non-taster allele exist in any nonhuman primate populations?
The fossils in a layer of rock are significantly different from those in the rock layer directly above it. One hypothesis to explain the difference is that a major extinction event occurred at the point in time represented by the transition between the two rock layers. Which of the following is the best plan for collecting data to use in a test of the hypothesis?
Examining the upper part of the lower rock layer for evidence of a catastrophic event, such as the presence of shocked quartz, iridium, or soot particles.
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 describes the most likely consequence of a negative feedback pathway involving the lac operon?
Expression of the lac operon diminishes as lactose is depleted.
The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles: a dominant, wild-type allele that enables an individual (taster) to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual (non-taster) to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the non-taster allele. The nucleotide present at the three positions are shown in the table below. A cladogram representing the evolutionary relatedness of selected primates is shown below. Toxic substances often have a bitter taste that causes animals who try to eat such substances to spit them out rather than swallow them. Additional data suggest that gorilla populations have a very low frequency of non-tasters. Which of the following best describes the likely evolution of the TAS2R38 locus in the gorilla population?
Gorillas who could taste bitter toxins were more likely to survive and reproduce than non-tasters.
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?
Grasses will have no direct access to chemical components recycled from dead organisms.
In response to elevated blood glucose levels, beta (B) cells in the pancreas release insulin, a regulatory hormone. Insulin signals body cells to take up glucose from the blood, which returns blood glucose levels back to normal. Type 1 diabetes is an autoimmune disorder that destroys B-cells, resulting in elevated blood glucose levels. Researchers have proposed that diabetes could be treated by implanting human embryonic stem cells (hESCs) that have been induced to develop into B-cells (hESC-B). To test the proposed treatment, the researchers set up two groups of genetically identical mice and implanted the mice from the group with hESC-B cells. Several weeks after the hESC-B implant, both groups of mice were given a drug (STZ) that selectively destroys the naturally occurring mouse B-cells but does not affect the implanted hESC-B cells. Figure 1 shows a comparison of average blood glucose levels in both groups of mice. In a continuation of the experiment, the researchers removed the hESC-B implant from one of the mice 16 weeks after STZ treatment. Figure 2 shows the blood glucose levels in the mouse over the duration of the experiment. Which of the following conclusions is best supported by the data presented in Figure 1?
Implanted hESC-B cells are effective at regulating blood glucose levels in the absence of mouse B-cells.
In the American Southwest, annually emerging cicadas are dependent upon the cottonwood trees in the floodplain. Adult male cicadas perch in the cottonwood trees and chirp to attract females. Females lay their eggs in the branches of the cottonwood, and upon hatching, the cicadas nymphs drop to the ground, burrow into the soil, feed on the tree roots, and later emerge as adults. Other organisms in the floodplain community prey on the cicadas, as shown in the food web. Human activity has caused a decrease in the amount of flooding and an increase in the incidence of wildfires in the floodplain. In an investigation into the recent changes in the floodplain ecosystem, researchers monitored the soil temperature, amount of cottonwood ground coverage (ie. area of the ground that is shaded by leaves), and cicada emergence for a period from mid-June until late July. The results of the investigation are represented in Figure 2 and Figure 3. To assess the impact of wildfires on soil temperature and cicada emergence, the researchers compared mean emergence dates for two natural sites where portions had been affected by wildfire. In addition, cicada emergence was monitored at an experimental site where the soil temperature was experimentally maintained. The data are shown in the table. Which of the following statements best predicts the effect of increased cottonwood growth on the food web?
Increased cottonwood growth will provide more resources for cicadas, resulting in an increase in the kestrel population.
In response to elevated blood glucose levels, beta (B) cells in the pancreas release insulin, a regulatory hormone. Insulin signals body cells to take up glucose from the blood, which returns blood glucose levels back to normal. Type 1 diabetes is an autoimmune disorder that destroys B-cells, resulting in elevated blood glucose levels. Researchers have proposed that diabetes could be treated by implanting human embryonic stem cells (hESCs) that have been induced to develop into B-cells (hESC-B). To test the proposed treatment, the researchers set up two groups of genetically identical mice and implanted the mice from the group with hESC-B cells. Several weeks after the hESC-B implant, both groups of mice were given a drug (STZ) that selectively destroys the naturally occurring mouse B-cells but does not affect the implanted hESC-B cells. Figure 1 shows a comparison of average blood glucose levels in both groups of mice. In a continuation of the experiment, the researchers removed the hESC-B implant from one of the mice 16 weeks after STZ treatment. Figure 2 shows the blood glucose levels in the mouse over the duration of the experiment. Based on the data, which of the following best represents how the mice with the implanted hESC-B cells use negative feedback to return blood glucose levels to normal if blood glucose levels increase?
Increased insulin secretion by hESC-B cells --> increased glucose uptake by body cells --> decreased insulin secretion by hESC-B cells
Cortisol is a hormone produced in response to stress, including starvation, in humans. Which of the following is most likely an immediate effect of a starvation induced increase in cortisol secretion?
Increased mobilization of fatty acids from fat cells .
In response to elevated blood glucose levels, beta (B) cells in the pancreas release insulin, a regulatory hormone. Insulin signals body cells to take up glucose from the blood, which returns blood glucose levels back to normal. Type 1 diabetes is an autoimmune disorder that destroys B-cells, resulting in elevated blood glucose levels. Researchers have proposed that diabetes could be treated by implanting human embryonic stem cells (hESCs) that have been induced to develop into B-cells (hESC-B). To test the proposed treatment, the researchers set up two groups of genetically identical mice and implanted the mice from the group with hESC-B cells. Several weeks after the hESC-B implant, both groups of mice were given a drug (STZ) that selectively destroys the naturally occurring mouse B-cells but does not affect the implanted hESC-B cells. Figure 1 shows a comparison of average blood glucose levels in both groups of mice. In a continuation of the experiment, the researchers removed the hESC-B implant from one of the mice 16 weeks after STZ treatment. Figure 2 shows the blood glucose levels in the mouse over the duration of the experiment. Which of the following modifications to the experimental design would improve the reliability of the results presented in Figure 1?
Measuring blood glucose levels in a group of mice that were not given STZ.
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 grow 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. Which of the following conclusions is best supported by the results of the experiments?
Neither population grows as large when cultured together as each does when cultured separately.
A student analyzed a viral genome and found that the genome had the following nucleotide composition. - 28% adenine -20% thymine - 35% cytosine - 17% guanine Which of the following best describes the structure of the viral genome?
Single-stranded DNA
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 the 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?
The blackcaps that migrate to the United Kingdom will become reproductively isolated from the blackcaps that migrate to Spain, resulting in speciation in the blackcap population.
The diagram above depicts a karyotype of an individual human. Which of the following statements concerning the karyotype in the diagram is true?
The diagram illustrates the results of nondisjunction during gamete formation.
The graph above represents the proportions of hatchlings of certain types of reptiles that are male at different egg incubation temperatures. Which of the following claims is best supported by the data?
The expression of sex-determination genes in certain reptiles is influenced by temperature.
The figure above shows an organelle typically found in eukaryotic cells. Which of the following best describes the function of the double membrane system of this organelle?
The inner membrane has specialized proteins that create a hydrogen ion concentration gradient between the inter-membrane space and the matrix.
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?
The lacZ gene is highly expressed only when lactose is available.
In response to elevated blood glucose levels, beta (B) cells in the pancreas release insulin, a regulatory hormone. Insulin signals body cells to take up glucose from the blood, which returns blood glucose levels back to normal. Type 1 diabetes is an autoimmune disorder that destroys B-cells, resulting in elevated blood glucose levels. Researchers have proposed that diabetes could be treated by implanting human embryonic stem cells (hESCs) that have been induced to develop into B-cells (hESC-B). To test the proposed treatment, the researchers set up two groups of genetically identical mice and implanted the mice from the group with hESC-B cells. Several weeks after the hESC-B implant, both groups of mice were given a drug (STZ) that selectively destroys the naturally occurring mouse B-cells but does not affect the implanted hESC-B cells. Figure 1 shows a comparison of average blood glucose levels in both groups of mice. In a continuation of the experiment, the researchers removed the hESC-B implant from one of the mice 16 weeks after STZ treatment. Figure 2 shows the blood glucose levels in the mouse over the duration of the experiment. Based on the data in Figure 2, which of the following best justifies the researchers claim that hESC-B implants can functionally replace the mouse's naturally occurring B-cells?
The mouse with an hESC-B implant successfully regulated blood glucose levels after STZ treatment but not after the implant was removed.
The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles: a dominant, wild-type allele that enables an individual (taster) to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual (non-taster) to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the non-taster allele. The nucleotide present at the three positions are shown in the table below. A cladogram representing the evolutionary relatedness of selected primates is shown below. The TAS2R38 receptor protein has been detected on the surface of cells from individuals who are homozygous for the non-taster allele of the TAS2R38 gene. Which of the following is the most likely effect of the mutations associated with the non-taster allele on TAS2R38 gene expression?
The mutations change the primary structure of the encoded receptor protein.
In response to elevated blood glucose levels, beta (B) cells in the pancreas release insulin, a regulatory hormone. Insulin signals body cells to take up glucose from the blood, which returns blood glucose levels back to normal. Type 1 diabetes is an autoimmune disorder that destroys B-cells, resulting in elevated blood glucose levels. Researchers have proposed that diabetes could be treated by implanting human embryonic stem cells (hESCs) that have been induced to develop into B-cells (hESC-B). To test the proposed treatment, the researchers set up two groups of genetically identical mice and implanted the mice from the group with hESC-B cells. Several weeks after the hESC-B implant, both groups of mice were given a drug (STZ) that selectively destroys the naturally occurring mouse B-cells but does not affect the implanted hESC-B cells. Figure 1 shows a comparison of average blood glucose levels in both groups of mice. In a continuation of the experiment, the researchers removed the hESC-B implant from one of the mice 16 weeks after STZ treatment. Figure 2 shows the blood glucose levels in the mouse over the duration of the experiment. In contrast to type 1 diabetes, where there is no insulin production, type 2 diabetes is characterized by a failure of body cells to respond normally to insulin. Based on the results of the experiment, which of the following best predicts the effectiveness of using hESC-B implantation treat type 2 diabetes?
The treatment would fail because insulin produced by implanted hESC-B cells will not stimulate glucose uptake by body cells.
In the American Southwest, annually emerging cicadas are dependent upon the cottonwood trees in the floodplain. Adult male cicadas perch in the cottonwood trees and chirp to attract females. Females lay their eggs in the branches of the cottonwood, and upon hatching, the cicadas nymphs drop to the ground, burrow into the soil, feed on the tree roots, and later emerge as adults. Other organisms in the floodplain community prey on the cicadas, as shown in the food web. Human activity has caused a decrease in the amount of flooding and an increase in the incidence of wildfires in the floodplain. In an investigation into the recent changes in the floodplain ecosystem, researchers monitored the soil temperature, amount of cottonwood ground coverage (ie. area of the ground that is shaded by leaves), and cicada emergence for a period from mid-June until late July. The results of the investigation are represented in Figure 2 and Figure 3. To assess the impact of wildfires on soil temperature and cicada emergence, the researchers compared mean emergence dates for two natural sites where portions had been affected by wildfire. In addition, cicada emergence was monitored at an experimental site where the soil temperature was experimentally maintained. The data are shown in the table. Yellow-billed cuckoos typically hatch in mid-July. Emerging cicadas are primarily food source for nesting cuckoos. Which of the following best predicts the effect of wildfires on yellow-billed cuckoo populations?
The yellow-billed cuckoo population will decline because the cicadas will emerge before the hatching season begins.
In the American Southwest, annually emerging cicadas are dependent upon the cottonwood trees in the floodplain. Adult male cicadas perch in the cottonwood trees and chirp to attract females. Females lay their eggs in the branches of the cottonwood, and upon hatching, the cicadas nymphs drop to the ground, burrow into the soil, feed on the tree roots, and later emerge as adults. Other organisms in the floodplain community prey on the cicadas, as shown in the food web. Human activity has caused a decrease in the amount of flooding and an increase in the incidence of wildfires in the floodplain. In an investigation into the recent changes in the floodplain ecosystem, researchers monitored the soil temperature, amount of cottonwood ground coverage (ie. area of the ground that is shaded by leaves), and cicada emergence for a period from mid-June until late July. The results of the investigation are represented in Figure 2 and Figure 3. To assess the impact of wildfires on soil temperature and cicada emergence, the researchers compared mean emergence dates for two natural sites where portions had been affected by wildfire. In addition, cicada emergence was monitored at an experimental site where the soil temperature was experimentally maintained. The data are shown in the table. Based on the data, which of the following describes the most likely relationship between wildfires, soil temperature, and the timing of cicada emergence in the same year?
Wildfires caused a reduction in ground cover, which in turn caused increased soil temperatures leading to earlier emergence of cicadas.
