apes chapter 7 review
The graph below depicts the various components of smog for a densely populated urban area in the Northern Hemisphere. Each plotted line (AA, BB, CC, and DD) is a different component of smog. Which of the different components of smog depicted in the graph are most likely released from automobile exhaust? a. A and B b. B and C c. A, B, and C d. B, C, and D
A
If the air layers in the diagram were relabeled to illustrate normal atmospheric conditions, the correct labeling from the air layer closest to the Earth's surface to the one farthest from the Earth's surface would be a. cool air, cooler air, warm air b. warm air, cool air, cooler air c. cooler air, warm air, cool air d. cooler air, cool air, warm air
B
Scientists have observed that the health of people living in moderately developed regions, which have developed transportation and industry but lack environmental control measures, is more likely to be affected by urban outdoor pollution than by indoor air pollution. Which of the following activities would most likely account for the levels of indoor air pollution in India and sub-Saharan Africa, as shown in the graph? A Construction of homes with more efficient insulation and increased ventilation B Use of biomass fuel sources such as wood and charcoal for cooking C Industrial power plants burning fossil fuels for electrical energy generation D Use of chemical pesticides on croplands
D
Which of the following is most likely responsible for the indoor air pollutant shown in the graph? A Cracks in the basement foundation B Synthetic fiber in carpets and furniture C Leaking water D Pet hair
a
A paper company located on the banks of a river discharges its treated wastewater into the river. Which of the following would be the best location to obtain a water sample from to determine if the paper plant is affecting the acidity of the river? A Immediately downstream from the paper plant B Immediately upstream from the paper plant C At an upstream tributary to the river D At a downstream tributary to the river
A
Scientists have observed that the health of people living in moderately developed regions, which have developed transportation and industry but lack environmental control measures, is more likely to be affected by urban outdoor pollution than by indoor air pollution. Which of the following conclusions can be drawn from the data presented in the graph? A In moderately developed regions such as China and Latin America, an individual's health is more or as likely to be affected by urban outdoor pollution than by indoor pollution. B Developing regions such as sub-Saharan Africa are less affected by indoor air pollution because there is no source of radon in the region. C Indoor air pollutants decrease and urban outdoor pollutants increase as countries become more industrialized. D The amount of both indoor and outdoor air pollution is directly linked to the size of each region.
A
Which of the following conclusions can best be drawn from the data in the graph? A Location A has the greatest need for remediation because the radon levels in the building are the highest and exceed the EPA action level. B Location B has the lowest need for remediation because the radon levels in the building are below the suggested action level. C Location C has the greatest need for remediation because the radon levels in the soil are the highest. D Location D has the lowest need for remediation because there is no measurable radon in the air or the soil samples.
A
Based on the layers in the diagram, which of the following best explains why a thermal inversion tends to concentrate pollutants in the air layer closest to the Earth's surface? A The air layer that is the second closest to the Earth's surface is less dense than the layer above it. B The inversion layer is warmer than the air layer that is farthest from the Earth's surface. C The air layer closest to the Earth's surface is denser than the layer above it. D The air layer that is farthest from the Earth's surface contains the coolest air.
C
The graph below depicts the various components of smog for a densely populated urban area in the Northern Hemisphere. Each plotted line (AA, BB, CC, and DD) is a different component of smog. Which of the curves on the graph depicts the concentration of ozone, which require sunlight to form? a. A b. B c. C d. D
C
A paper company located on the banks of a river discharges its treated wastewater into the river. Which of the following would be the best control group to evaluate the treated wastewater from the paper company? A A sample of distilled water B A sample of water from a nearby river C A sample of water downstream from the same river D A sample of water upstream from the same river
D
Which of the following sources should be examined in a study to determine the impact of a geologic source on levels of CO2 in the atmosphere? A Photosynthesis B Cellular respiration C Decomposition D Volcanoes
D
A researcher wants to determine if ponds and lakes downwind of a coal-burning power plant are affected by the plant's emissions. Which of the following would be the best parameter from the water in the ponds and lakes to measure in order to determine the effect of the plant's emissions on the aquatic ecosystems? A pH B Biological oxygen demand (BOD) C Carbon dioxide D Volatile organic compounds (VOCs)
a
Which of the following points on the graph best illustrates the location where pollutants are most likely to accumulate as a result of a thermal inversion? A Point A B Point B C Point C D Point D
d
The graph shows the average distance traveled by individuals in a population in an urban area in the southwestern United States. Based on the data, which of the following months most likely experiences the highest levels of photochemical smog? A July B August C November D December
a
In the figure above, the letters AA, BB, and CC represent the different thermal layers present in an inversion. Which of the following shows the correct sequence of thermal layers as one moves vertically upwards from the surface of Earth? A Warm sea breeze →→ Cool →→ Warm B Warm sea breeze →→ Warm →→ Cool C Cool sea breeze →→ Warm →→ Cool D Cool sea breeze →→ Cooler →→ Coolest
C
The graph below depicts the various components of smog for a densely populated urban area in the Northern Hemisphere. Each plotted line (AA, BB, CC, and DD) is a different component of smog. The data that was used to create this graph was collected in the winter. Which of the following best descrives how the graph would be different if te data were collected in the middle of the summer? a. the peaks for every data line would be at a lower concentration. b. concentrations for component C would be higher throughout the graph c. concentrations for all the data lines would be the horizontal throughout the day. d. components A, B, and D would peak in the afternoon instead of in the morning.
B
A paper company located on the banks of a river discharges its treated wastewater into the river. Which of the following water quality indicators should be measured to best determine if the wastewater is increasing the acidity of the river? A The amount of dissolved oxygen B The total suspended solids C The amount of hydrogen ions D The species richness
C
Scientists have been monitoring CO2CO2 in the atmosphere from Mauna Loa in Hawaii since 1958. Which of the following units is used by scientists to measure CO2CO2 in the atmosphere? A Dobson units B Percent saturation C Parts per million D pH
C
Scientists are testing the effect of different scrubber technologies on the removal of pollutants from coal power plants. The scrubbers use a slurry of limestone and water. Which of the following best describes the impact of modifying the slurry by increasing the amount of limestone? A The amount of sulfur dioxide released will decrease. B The amount of ground-level ozone released will decrease. C The amount of water released will increase. D The amount of carbon monoxide released will increase.
a
Which of the following is most responsible for the change in the emissions of volatile organic compounds ( VOC ) from 1970 to 2020 as shown in the graph? A A decrease in the number of vehicles fitted with catalytic converters and an increase in the number of hybrid vehicles beginning in 1970. B A decrease in the average driving distance in the United States from 1970 to 2020 that resulted from increased urbanization. C An increase in air emission standards that began in 1970 that regulated corporate average fuel economy ( CAFE) standards. D An increase in VOC emissions from car exhausts that resulted from increased driving distances from 1970 to 2020.
c
Based on the data in the graph, which of the following insulation options is ineffective at insulating a home and greatly contributes to indoor air pollution? A Blown cellulose B Mineral fiber batt C Expanded polystyrene D Rigid foam
b
Scientists have discovered that Volatile Organic Compounds (VOCs) emitted from trees can contribute to photochemical smog formation. Data in the table above were collected in 2006 and 2014 in Berlin, Germany. Isoprene is a VOC released by some tree species. Impact factor refers to the percentage of ozone attributed to the isoprene. Which of the following best describes the relationship between variables in the data table? a. Impact factor causes a change in temperature maximum. b. Isoprene levels vary depending on traffic and urbanization. c. Ozone maximum is correlated to average and maximum temperature. d. Changes in average temperature are linked to changes in land use in Berlin.
c
Noise Exposure and Public Health Exposure to noise constitutes a health risk. There is sufficient scientific evidence that noise exposure can induce hearing impairment, hypertension and heart disease, annoyance, sleep disturbance, and decreased school performance. For other effects such as changes in the immune system and birth defects, the evidence is limited. Most public health impacts of noise were already identified in the 1960s, and noise abatement is less of a scientific but primarily a policy problem. A subject for further research is the [clarification] of the mechanisms underlying noise-induced cardiovascular disorders and the relationship of noise with annoyance and nonacoustical factors modifying health outcomes. A high-priority study subject is the effect of noise on children, including cognitive effects and their reversibility. Noise exposure is on the increase, especially in the general living environment, both in industrialized nations and in developing world regions. This implies that in the twenty-first century noise exposure will still be a major public health problem. Which of the following best describes why the authors do not claim that noise exposure induces birth defects in humans? A There is sufficient evidence that exposure to noise induces some health risks in humans. B There is insufficient evidence to support that noise exposure induces birth defects in humans. C Noise exposure can induce hearing impairment and decreased school performance. D A high-priority study subject is the effect of noise on children.
B
A student is setting up a model to study the carbon cycle and natural sources of carbon dioxide. They create a microenvironment that contains soil, leaf debris, an earthworm, heterotrophic bacteria, and a sun lamp. What natural source of carbon dioxide and major metabolic process was left out of the model? A There is no representation of decomposition in the model environment. B There is no representation of cellular respiration in the model environment. C There is no representation of photosynthesis in the model environment. D There is no representation of ingestion in the model environment.
C
Canada has proposed an action plan to address climate change and air pollution. The action plan will reduce the impact of greenhouse gases and pollutants on the environment and human health. Which of the following claims about the Canadian action plan is best supported by the data in the graph? A The plan encourages the transition from electricity generation from nuclear power to electricity generation from cleaner-burning natural gas. B The plan focuses on increasing regulation on installation and maintenance of catalytic converters in vehicle exhaust systems. C The plan supports phasing out traditional coal power plants and transitioning to sources like hydroelectricity, wind, and solar power. D The plan provides a strategy for reducing the amount of plastic wastes in landfills through the production of long-lasting and durable plastics.
C
Noise Exposure and Public Health Exposure to noise constitutes a health risk. There is sufficient scientific evidence that noise exposure can induce hearing impairment, hypertension and heart disease, annoyance, sleep disturbance, and decreased school performance. For other effects such as changes in the immune system and birth defects, the evidence is limited. Most public health impacts of noise were already identified in the 1960s, and noise abatement is less of a scientific but primarily a policy problem. A subject for further research is the [clarification] of the mechanisms underlying noise-induced cardiovascular disorders and the relationship of noise with annoyance and nonacoustical factors modifying health outcomes. A high-priority study subject is the effect of noise on children, including cognitive effects and their reversibility. Noise exposure is on the increase, especially in the general living environment, both in industrialized nations and in developing world regions. This implies that in the twenty-first century noise exposure will still be a major public health problem. Which of the following best describes why the authors claim that reducing noise exposure is currently more of a public policy problem than a scientific problem? A There is sufficient scientific evidence that noise exposure can induce hypertension and heart disease. B The relationship of noise with annoyance that negatively impacts human health is a subject for future research. C Most public health impacts of noise were already identified in the 1960s. D It is unclear whether negative cognitive effects are reversible in humans.
C
Over a three-year period, a city's environmental protection department measured the particulate matter ( PM2.5 ) in a ten-square-mile area around one of the city's coal-fired power plants. The annual mean level of PM2.5 measured was 20.0μgm3 over the three-year study period. The National Ambient Air Quality Standard ( NAAQS ) for PM2.5 is an annual mean level of 12.0μgm3 , averaged over three years. The city instructs the manager of the power plant to propose a plan to aid the city in meeting the NAAQS for PM2.5 in the area around the power plant over the next ten years. Which of the following would be the most effective plan for the manager to propose to the city? A Install catalytic converters at the plant. B Install vapor recovery nozzles at the plant. C Install electrostatic precipitators at the plant. D Burn lignite coal instead of bituminous coal at the plant.
C
Noise Exposure and Public Health Exposure to noise constitutes a health risk. There is sufficient scientific evidence that noise exposure can induce hearing impairment, hypertension and heart disease, annoyance, sleep disturbance, and decreased school performance. For other effects such as changes in the immune system and birth defects, the evidence is limited. Most public health impacts of noise were already identified in the 1960s, and noise abatement is less of a scientific but primarily a policy problem. A subject for further research is the [clarification] of the mechanisms underlying noise-induced cardiovascular disorders and the relationship of noise with annoyance and nonacoustical factors modifying health outcomes. A high-priority study subject is the effect of noise on children, including cognitive effects and their reversibility. Noise exposure is on the increase, especially in the general living environment, both in industrialized nations and in developing world regions. This implies that in the twenty-first century noise exposure will still be a major public health problem. Which of the following best describes why the authors claim that noise exposure will be a major health problem in the twenty-first century? A There is sufficient evidence to support that noise exposure negatively impacts the immune system. B Further research is needed concerning the mechanisms underlying noise-induced cardiovascular disorders. C There is insufficient evidence to support that noise exposure induces sleep disturbance in humans. D Noise exposure is on the increase in both industrialized nations and in developing regions.
D
Which of the following best explains the cause of the trend shown in the graph for lead emissions in the United States from 1970 to 2011 ? A By 1990, all new model cars were equipped with internal fabric filters that effectively filtered car exhaust and reduced lead emissions. B Beginning in 1975, The Clean Air Act required new cars to have catalytic converters, which effectively converted the lead found in gasoline to water vapor. C New air-scrubber technologies were introduced in the late 1970s that effectively removed lead in the air and converted it into water vapor. D Unleaded gasoline was first introduced in 1974, and amendments to the Clean Air Act required cars with the model year 1975 or later to use only unleaded gasoline.
D
In addition to a nearby mountain range, which of the following environmental conditions would be required for the process in the diagram to occur? A A cool sea breeze and a high pressure system B A warm mountain breeze and a low pressure system C A cool sea breeze and a low pressure system D A cool mountain breeze and a high pressure system
a
Which of the following devices is correctly paired to the air pollutant it would be used to measure? A Measuring Device Gas sensor Pollutant Measured CO2 B Measuring Device Electrostatic precipitator Pollutant Measured CO C Measuring Device Sound pressure level sensor Pollutant Measured Particulate Matter D Measuring Device Catalytic converter Pollutant Measured docs
a
Effects of Noise on Wildlife Sound, just like the availability of nesting materials or food sources, plays an important role in the ecosystem. Activities such as finding desirable habitat and mates, avoiding predators, protecting young, and establishing territories are all dependent on the acoustical environment. [Wildlife is] being forced to adapt to increasing noise levels. Research shows that males of at least one frog species are adapting to traffic noise by calling at a higher pitch. This could be problematic for the females, because they prefer lower-pitched calls, which indicate larger and more experienced males. In general, studies indicate that animals are stressed by noisy environments. The endangered Sonoran pronghorn avoids noisy areas frequented by military jets; female frogs exposed to traffic noise have more difficulty locating the male's signal; bats avoid hunting in areas with road noise. Combined with other stressors such as winter weather, disease, and food shortages, sound impacts can have important implications for the health and vitality of wildlife populations within a park. National parks are under increasing noise pressure. Noise levels in park transportation corridors today are many times the natural level. Sound levels during peak periods in a high air traffic corridor in the Yellowstone backcountry, for example, were elevated by up to 5 decibels. The result is as much as a 70% reduction in the size of an area in which predators can hear their prey. Increasingly, careful consideration of the impacts of human-generated noise on wildlife is a critical component of management for healthy ecosystems in our parks. What is one potential impact of increased noise pollution in national parks that is supported by the article? A Predator-prey interactions will intensify in national parks because of stress caused by noise pollution. B Prey populations are likely to increase in national parks because predators have a decreased ability to hear prey sounds. C Prey populations are likely to experience biomagnification of noise pollution. D Predator species will expand their range beyond park boundaries because of increased noise pollution.
b
Which of the following best describes how a scientist could accurately study the effects of soil buffering on plant growth in a region that is affected by acid deposition downwind of a coal-burning power plant? A Measure changes in plant height over a year in a two different groups of trees; one group is 5km from the power plant and one group is 10km from the power plant. B Measure the changes in plant height over a year in two different groups of trees the same distance from the power plant; one group is in topsoil and one group is in topsoil with limestone added. C Measure changes in plant biomass over a year in two different groups of trees the same distance from the power plant; one group is not manipulated and one group is watered daily to dilute the deposition's acidity. D Measure changes in plant biomass over a year in two different groups of trees; one group is 5km from the power plant over limestone bedrock and one group is 10km from the power plant that has nitrogen and phosphorus added to the topsoil.
b
Which of the following best describes the process shown in the diagram above? a. Less-dense, cool air rises up and mixes with the denser warm air above it, increasing the amount of thermal pollution in the atmosphere. b. Less-dense, warm air creates a temperature inversion between more-dense layers, trapping pollutants near the ground. c. Dense, warm air from the mountains on the right pushes into the less-dense, cool air mass, causing an inversion layer. d. Movement of air currents over urban areas decreases the amount of photochemical smog during summer months.
b
Scientists have been collecting atmospheric CO2 data for many years to monitor changes over time. Which of the following best describes why an island location, such as the Mauna Loa Observatory in Hawaii, is an ideal location to measure global CO2 concentrations? A The island is also a dormant volcano, so there will be only anthropogenic atmospheric CO2 measured at the site. B The location is below the inversion layer, making it less prone to local effects from industry and transportation. C The location is far from any continent, providing atmospheric air samples that are less likely to be affected by industry and transportation. D The impact of primary producers in the surrounding Pacific Ocean is negligible, reducing the effect of photosynthesis and respiration on CO2 levels.
c
Scientists have discovered that Volatile Organic Compounds (VOCs) emitted from trees can contribute to photochemical smog formation. Data in the table above were collected in 2006 and 2014 in Berlin, Germany. Isoprene is a VOC released by some tree species. Impact factor refers to the percentage of ozone attributed to the isoprene. Which of the following claims is best supported by the data shown in the table? a. Ozone levels are not a serious air quality concern in Berlin. b. Ozone levels in Berlin were consistently higher in 2014 than in 2006. c. Isoprene's contribution to ozone levels in Berlin was greatest in July of both years. d. Isoprene levels were negatively correlated with maximum temperature.
c
Scientists want to examine the effects of a coal-burning power plant on the pH of a lake that is downwind of the power plant. They take samples from a lake that is not downwind of the power plant to serve as a control. However, they did not realize that the lake they chose as a control group was a geothermal hot spring with acidic water. Which of the following best describes how their choice of control group could affect the results of their experiment? A Using this control would not have an effect on the outcome because the high temperature of the hot spring reduces the acidity of the water in the lake. B The coal-burning power plant would appear to have a much larger effect on the pH of the experimental group because the pH in the control lake would be elevated from the acidic water. C The coal-burning power plant would not appear to have a large impact because the pH levels of the two lakes would be similar. D The coal-burning power plant would affect both lakes because the Coriolis effect and weather patterns would circulate pollutants in the atmosphere.
c
Which of the following is the most likely reason for the trend shown in the graph of fluctuating indoor radon levels over the course of a year? A Home windows are often closed during summer months, causing the levels of radon in the house to build up. B Barometric pressure changes from summer storms can cause radon levels to increase. C Radon levels tend to increase in the colder months because of the difference in temperature inside and outside the home, which creates a vacuum pulling radon into the home at a higher rate. D Increased levels of radon are linked to burning biomass indoors, which increases in winter months when more biomass is burned for cooking and heating.
c
Air pollution from a power plant is being monitored for levels of nitrogen dioxide and ground-level ozone. The levels are measured daily at the same time. Which of the following best predicts the impact of a dark and cloudy day on the readings for the levels of air pollutants measured? A There will be no change in the levels of nitrogen dioxide or ground-level ozone. B There will be a decrease in the level of nitrogen dioxide and an increase in the level of ground-level ozone. C There will be an increase in the levels of both nitrogen dioxide and ground-level ozone. D There will be an increase in the level of nitrogen dioxide and a decrease in the level of ground-level ozone.
d
An air pollution expert set up a monitoring program to determine the amount of particulate matter (PM) leaving a farmer's field after crops were harvested and the soil was bare. She set up high-volume air samplers 10 meters from each edge of the square field and collected samples weekly for two months. When she looked at her data, she was surprised by how much the PM levels varied, both from site to site on a given date and over time at each site. Which of the following parameters would have been best to measure to help explain the variation in her results? A Percent of cloudy days over the two months B Particle size of the soils in the field C Depth of the organic matter in the soil D Wind direction and speed
d
An experiment to evaluate the efficiency of wet and dry scrubber networks that filter particulate gas at different flow rates was conducted under different flow rate conditions. The results are shown below. Based on the data in the graph, which of the following methods would be most effective at removing the greatest amount of particulate matter from coal-burning power plant emissions? A Dry scrubbers using a flow rate of 200Lmin are best suited to remove small particles. B Dry scrubbers using a flow rate of 450Lmin are best suited to remove large particles. C Wet scrubbers using a flow rate of 300Lmin are best suited to remove small particles. D Wet scrubbers using a flow rate of 450Lmin are best suited to remove large particles.
d
An experiment to evaluate the efficiency of wet and dry scrubber networks that filter particulate gas at different flow rates was conducted under different flow rate conditions. The results are shown below. Which of the following best describes the efficiency of dry scrubbers at removing particles that are less than 2 micrometers in diameter? A Dry scrubbers are less than 20% efficient at removing particles less than 1μm and increase to over 50% efficiency at removing particles between 1 and 2μm. B Dry scrubbers are between 50% and 90% efficient at removing particles less than 2μm, depending on the flow rate. C Dry scrubbers are between 5% and 40% efficient at removing particles less than 2μm in size. D Dry scrubbers are less than 10% efficient at removing particles less than 1μm in size.
d
Atmospheric deposition is receiving increased attention in the scientific community, and has become the subject of a specific research area in the environmental sciences. Acid rain is detrimental to our ecosystems and can be measured in several ways. Which of the following methods would best identify changes from acid deposition in an area over time? A Calculating the change in sulfur dioxide emissions from coal-burning power plants over time B Mapping out coal-burning power plant locations over the past 50 years C Measuring the pH of rainwater and surface water in affected areas D Monitoring the long-term chemical and biological parameters of an ecosystem
d
Effects of Noise on Wildlife Sound, just like the availability of nesting materials or food sources, plays an important role in the ecosystem. Activities such as finding desirable habitat and mates, avoiding predators, protecting young, and establishing territories are all dependent on the acoustical environment. [Wildlife is] being forced to adapt to increasing noise levels. Research shows that males of at least one frog species are adapting to traffic noise by calling at a higher pitch. This could be problematic for the females, because they prefer lower-pitched calls, which indicate larger and more experienced males. In general, studies indicate that animals are stressed by noisy environments. The endangered Sonoran pronghorn avoids noisy areas frequented by military jets; female frogs exposed to traffic noise have more difficulty locating the male's signal; bats avoid hunting in areas with road noise. Combined with other stressors such as winter weather, disease, and food shortages, sound impacts can have important implications for the health and vitality of wildlife populations within a park. National parks are under increasing noise pressure. Noise levels in park transportation corridors today are many times the natural level. Sound levels during peak periods in a high air traffic corridor in the Yellowstone backcountry, for example, were elevated by up to 5 decibels. The result is as much as a 70% reduction in the size of an area in which predators can hear their prey. Increasingly, careful consideration of the impacts of human-generated noise on wildlife is a critical component of management for healthy ecosystems in our parks. Based on the author's claim in the article, which of the following statements best describes the effect of noise pollution on wildlife? A Noise pollution is being managed in such a way as to not significantly interfere with wildlife in national parks. B Noise in national parks has an overall positive effect on wildlife and has led to an increase in biodiversity. C Stressors such as winter weather, disease, and food shortages are having a greater effect on wildlife than noise pollution. D Noise pollution has a negative effect on wildlife activities such as mating, establishing territories, and predator-prey interactions.
d
Effects of Noise on Wildlife Sound, just like the availability of nesting materials or food sources, plays an important role in the ecosystem. Activities such as finding desirable habitat and mates, avoiding predators, protecting young, and establishing territories are all dependent on the acoustical environment. [Wildlife is] being forced to adapt to increasing noise levels. Research shows that males of at least one frog species are adapting to traffic noise by calling at a higher pitch. This could be problematic for the females, because they prefer lower-pitched calls, which indicate larger and more experienced males. In general, studies indicate that animals are stressed by noisy environments. The endangered Sonoran pronghorn avoids noisy areas frequented by military jets; female frogs exposed to traffic noise have more difficulty locating the male's signal; bats avoid hunting in areas with road noise. Combined with other stressors such as winter weather, disease, and food shortages, sound impacts can have important implications for the health and vitality of wildlife populations within a park. National parks are under increasing noise pressure. Noise levels in park transportation corridors today are many times the natural level. Sound levels during peak periods in a high air traffic corridor in the Yellowstone backcountry, for example, were elevated by up to 5 decibels. The result is as much as a 70% reduction in the size of an area in which predators can hear their prey. Increasingly, careful consideration of the impacts of human-generated noise on wildlife is a critical component of management for healthy ecosystems in our parks. Which of the following claims is best supported by the evidence provided by the article? A Frog populations may increase in size as a result of the changes in male vocalizations. B Female frogs are beginning to prefer male frogs with higher pitched calls. C More experienced male frogs are no longer preferred by female frogs. D Frog populations may decrease in size as a result of males changing the pitch of their calls.
d
