2025 AP Environmental Science Free-Response Questions
Advanced PlacementFree ResponseScience
3 questions30 pts
3 gradable30 rubric criteria0 dependencies
q1
Question 1
Chickadees are a K-selected species of bird that eat insects and spiders. Spiders consume insects, and many insects consume plants as shown in the following food chain. Plants → Insects → Spiders Chickadee habitat includes forests and residential yards. Residential yards often contain nonnative plants, which do not naturally exist in an area, but were introduced by humans. Scientists measured the average number of insects and spiders as related to the percentage of nonnative plants (Figure 1). The scientists also measured the chickadees’ average population growth rate (Figure 2) to determine the impact of nonnative plants on chickadee populations. Figure 1. Percentage of Nonnative Plants and Average Number of Individual Spiders and Insects. The graph shows average number of individuals versus nonnative plants (percent), with spider and insect data. Figure 2. Chickadee Population Average Growth Rate and Percentage of Nonnative. The graph shows chickadee population growth rate (r) versus nonnative plants, with a replacement level at r = 0.0. 1. Respond to parts A, B, C, D, E, F, G, and H, and all subparts. A. Describe one reproductive strategy used by a K-selected species such as the chickadee. B. Based on the information provided, explain how a decrease in spider populations could affect a lower trophic level. C. Based on the data in Figure 1, identify the number of spiders per sample at 25% nonnative plants. D. Based on the data in Figure 1, describe the trend in the number of insects per sample in relation to the percentage of nonnative plants. E. Scientists hypothesized that the population of chickadees would be stable or growing with fewer than 25% nonnative plants. Describe one way that the data in Figure 2 support this hypothesis. F. Insect biodiversity is important to maintain ecosystem health. A group of students was interested in learning about factors that affect ant biodiversity. They located two study sites near their school: a frequently mowed urban park and an unmowed grassland. The students used traps designed to collect ants. They loaded 10 of the traps with the same food and placed them randomly at different locations within each site. Students collected the traps after 24 hours and counted the number of different ant species in each trap to determine species richness. i. Identify a likely scientific question for the students’ investigation of ant diversity. ii. Identify the dependent variable in the students’ investigation. G. The data from the student investigation of ant diversity are shown in the following table. An “X” in the table indicates that the species was present at that site. Ant Species Present in an Urban Park and Unmowed Grassland | Site | Species A | Species B | Species C | Species D | Species E | Species F | |---|---|---|---|---|---|---| | Urban park | X | | | X | X | | | Grassland | X | X | X | X | | X | i. Explain why the ant community of the unmowed grassland would be more likely to recover from a disturbance, such as a flood or fire, than the ant community in the mowed urban park would. ii. Explain how the results of the investigation could have been altered if students had measured ant biodiversity at a paved playground rather than in the grassland. H. Habitat fragmentation has impacts on a variety of species. Paved roads can lead to habitat fragmentation. Describe one effect that a paved road in a forest can have on animal species such as deer or bears.
Rubric Criteria (10)
C1States one reproductive strategy of a K-selected species, such as providing considerable parental care, producing few offspring, expending significant energy per offspring, reproducing more than once during its lifetime, having a long gestation period, or reaching reproductive maturity later.
1.0000pts
C2Explains that a decrease in spider populations would increase insect populations because fewer insects would be preyed upon, or would decrease plant populations because the increased insect population would consume more plants.
1.0000pts
C3Identifies the number of spiders per sample at 25 percent nonnative plants as 2.02.
1.0000pts
C4Describes an inverse, indirect, or negative relationship between the percentage of nonnative plants and the number of insects per sample: as the percentage of nonnative plants increases, the number of insects decreases, or vice versa.
1.0000pts
C5Explains that with fewer than 25 percent nonnative plants, the chickadee growth rate is at or above replacement level, enough reproduction occurs to replace the population, or the population growth rate is positive.
1.0000pts
C6Identifies a scientific question about whether ant species number, species richness, or biodiversity differs between an urban park and a grassland, or whether mowing affects ant species number, species richness, or biodiversity.
1.0000pts
C7Identifies the dependent variable as the number of ant species, ant species richness, or the presence or absence of different ant species.
1.0000pts
C8Explains that the unmowed grassland ant community is more likely to recover because its larger number of species or greater diversity makes it more likely that some species or individuals have adaptations allowing survival, or makes loss of one species less likely to collapse the whole ecosystem.
1.0000pts
C9Explains that measuring ant biodiversity at a paved playground would produce fewer species than in the grassland or urban park because the paved area is unsuitable habitat for many ant species or because humans could trample ants or ant habitat.
1.0000pts
C10Describes one effect of a paved road in a forest on animals such as deer or bears, including vehicle strikes, fragmentation causing isolation or loss of genetic diversity, noise pollution causing hearing damage or stress or masking communication or hunting sounds, altered or prevented movement and migration, or an increase in species that thrive in edge habitats.
1.0000pts
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q2
Question 2
There is a natural climate phenomenon that occurs in the equatorial Pacific Ocean because of periodic fluctuations in sea surface conditions and atmospheric circulation. This phenomenon happens every few years, resulting in shifts in temperature and precipitation in many parts of the world. Figure 1 shows temperature and precipitation patterns associated with one phase of this phenomenon in the equatorial Pacific Ocean. Figure 2 shows the associated temperature and precipitation patterns that occur over North America. Figure 1. Effects of Changes in Sea Surface Conditions in Equatorial Pacific Ocean [Figure 1 map includes the labels “30° North” and “Equator 0°,” and the following legend: “Ocean water cooler than average”; “Ocean water warmer than average”; “Increased chance of precipitation”; “Stronger than normal trade winds.”] Figure 2. Polar Jet Stream and Climate Conditions in North America [Figure 2 map includes a labeled “Polar Jet Stream,” regions labeled “A” and “B,” and the following legend: “Increased chance of precipitation”; “Decreased chance of precipitation”; “Cooler than average”; “Warmer than average.”] 2. Respond to parts A, B, C, D, E, F, G, H, I, and J. A. Identify the sea surface condition for the eastern equatorial area of the Pacific Ocean illustrated in Figure 1. B. Based on the information in Figure 1, identify the climate phenomenon associated with the sea surface conditions shown in the equatorial area of the Pacific Ocean. C. Based on the information in Figure 2, describe a difference in climate patterns between the regions A and B. D. Increases in regional precipitation can lead to increased flooding in certain locations. Describe one reason why there is an increased risk of flooding in urban areas during extended periods of precipitation. E. Propose a realistic solution a city could implement to decrease the risk of flooding in urban areas. F. Justify the solution proposed in part E by providing an additional advantage other than a reduction in the risk of flooding. G. Terrestrial biomes are primarily determined by temperature and precipitation patterns. Describe one difference between the climate of a temperate seasonal forest and that of a savanna. H. Droughts are one environmental problem that can affect the frequency and severity of forest fires. Identify the ecological process that occurs following a forest fire that leaves the soil intact. I. Describe one way burning forests contribute to atmospheric pollution. J. Describe one sustainable forestry practice that could be used to reduce the occurrence or severity of forest fires.
Rubric Criteria (10)
C1Identifies the eastern equatorial Pacific Ocean water shown in Figure 1 as cooler than average.
1.0000pts
C2Identifies the climate phenomenon associated with the depicted equatorial Pacific sea-surface conditions as La Niña.
1.0000pts
C3Describes that Region A has an increased chance of precipitation or is wetter, while Region B has a decreased chance of precipitation or is drier.
1.0000pts
C4Explains that impervious or paved surfaces, including parking lots, roads, buildings, or sidewalks, increase runoff and reduce infiltration or absorption, or that reduced vegetation decreases infiltration or absorption, thereby increasing urban flooding risk.
1.0000pts
C5Proposes a realistic city solution to decrease urban flooding risk, such as using permeable pavement; planting vegetation, establishing parks, creating rain gardens, or building green roofs; or installing retention ponds or stormwater basins.
1.0000pts
C6Justifies the proposed flooding solution by identifying an additional advantage other than reducing flood risk that is consistent with the solution, such as groundwater or aquifer recharge or reduced runoff pollution for permeable pavement; pollutant absorption, carbon storage, oxygen production, reduced erosion, restored habitat, increased biodiversity, reduced urban heat-island effect, aesthetic or quality-of-life benefits, or job creation for vegetation-based solutions; or reduced runoff pollution or increased habitat or biodiversity for retention ponds or stormwater basins.
1.0000pts
C7Describes one difference between a temperate seasonal forest and a savanna: the temperate seasonal forest is cooler, has a stronger or colder winter, has four distinct seasons, receives more annual precipitation, or receives precipitation throughout the year while the savanna has distinct rainy and dry seasons.
1.0000pts
C8Identifies secondary succession as the ecological process following a forest fire that leaves the soil intact.
1.0000pts
C9Describes that burning forests releases carbon dioxide, carbon monoxide, nitrogen oxides, particulate matter, or volatile organic compounds into the atmosphere.
1.0000pts
C10Describes one sustainable forestry practice that reduces the occurrence or severity of forest fires: prescribed burns or brush removal to remove excess fuel, dead leaves, or underbrush; selective cutting to create a firebreak; or agroforestry in which ground crops that could serve as fuel are harvested or removed.
1.0000pts
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q3
Question 3
3. Respond to parts A, B, C, D, E, F, and G. A. One major environmental problem is air pollution. Air pollution can come from natural or anthropogenic sources. Motor vehicles can be a source of particulate matter (PM) and other pollutants. Identify an anthropogenic source of particulate matter, other than from motor vehicles. B. One way to reduce pollutants associated with motor vehicles is to use a vapor recovery nozzle. Describe one way a vapor recovery nozzle is used to reduce atmospheric pollution. C. Acid rain is another air pollutant linked to motor vehicles. Over the past few years, there has been an increase in the number of people working from home, so fewer people are commuting to work in their personal vehicles. Explain how a decrease in the number of people commuting to work in their personal vehicles could lead to a reduction in acid rain. D. The average gas mileage for a small gasoline-powered sport utility vehicle (SUV) is 22 miles per gallon (mpg) in the city. The average gas mileage for a small hybrid SUV is 36 mpg in the city. One commuter sells their gasoline-powered SUV and replaces it with a hybrid SUV. Calculate the percent change in gas mileage between the gasoline-powered SUV and the hybrid SUV based on the data provided. Show your work. E. Both the gasoline-powered SUV and the hybrid SUV have 14-gallon gas tanks. As stated in part D, the average gas mileage for a small gasoline-powered sport utility vehicle (SUV) is 22 miles per gallon (mpg) in the city. The average gas mileage for a small hybrid SUV is 36 mpg in the city. Calculate how many more miles the owner can drive in the hybrid SUV in the city than they could have driven in the gasoline-powered SUV. Show your work. F. In addition to vehicles, buildings such as schools often have high energy consumption. The primary sources of energy use in many buildings are heating, cooling, and lighting. Propose a realistic solution that schools could implement to decrease energy use for heating and cooling, other than a reduction in the amount of time the school building is occupied. G. The school plans to upgrade its lighting to save money and reduce both its electricity use and its ecological footprint. The sustainability committee proposes that the school reduce its electricity use by switching to energy-efficient light-emitting diode (LED) bulbs. The school building uses 2.8 × 10^4 bulbs. The LED bulbs would each use 0.0085 kilowatt per hour. Each bulb would be used for an average of 2,340 hours per year. Calculate the energy use in the school building in kilowatts per year using LED light bulbs. Show your work.
Rubric Criteria (10)
C1Identifies an anthropogenic source of particulate matter other than motor vehicles, such as coal or fossil-fuel combustion, industrial exhaust, construction or demolition, waste incineration, mining, burning biomass, anthropogenically caused wildfires, unpaved roads, or agricultural fields.
1.0000pts
C2Explains that a vapor recovery nozzle prevents fumes or vapors from escaping into the atmosphere while a motor vehicle is being fueled.
1.0000pts
C3Explains that reduced commuting in personal vehicles lowers nitrogen oxide or sulfur oxide emissions from cars or other vehicles, leading to less nitric acid or sulfuric acid in the atmosphere.
1.0000pts
C4Shows the correct setup for calculating the percent change in gas mileage from 22 mpg to 36 mpg, such as (36 mpg − 22 mpg) ÷ 22 mpg × 100.
1.0000pts
C5Calculates the percent change in gas mileage as approximately a 63.6 percent increase, with answers of 63.6 percent, 64 percent, 63.6, or 64 accepted by the rubric.
1.0000pts
C6Shows the correct setup for calculating the additional city miles driven by the hybrid SUV, such as (14 gallons × 36 mpg) − (14 gallons × 22 mpg), (14 × 36) − (14 × 22), or 14 × (36 − 22).
1.0000pts
C7Calculates the additional city distance the hybrid SUV can travel as 196 or 200 miles.
1.0000pts
C8Proposes a realistic school-implemented solution to decrease energy use for heating and cooling other than reducing building occupancy time, such as green-building design features, opening windows to reduce air-conditioning use, energy-efficient heating and cooling equipment, thermostat adjustment to reduce heating or air-conditioning use, or conservation landscaping.
1.0000pts
C9Shows the correct setup for calculating annual school-building energy use with LED bulbs, such as (2.8 × 10^4 bulbs) × 0.0085 kilowatt × 2,340 hours.
1.0000pts
C10Calculates LED-lighting energy use as 556,920 kWh/year, approximately 5.6 × 10^5, or 5.6E5; the rubric also accepts kW/year if units are included.
1.0000pts
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