Learn Extracted exam questions AP Environmental Science 2026 Free Response
2026 Free Response
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The following information applies to parts A, B, C, D, and E.
Climate change can affect both terrestrial and marine organisms. Researchers studying the effect of climate change on bird distribution mapped elevation zones at which five bird species lived within a tropical mountain range. Birds are distributed in part according to climate-related adaptations. Researchers modeled where the birds would most likely live in the future based on climate change predictions.
The results of this study are shown in the following diagram. Each unique shape in the diagram represents a different bird species, labeled A through E. Current distribution is shown on the left side of the figure, and predicted future distribution is shown on the right.
Bird Species Distribution
[Diagram: a pyramid-shaped chart titled "Bird Species Distribution," split into a "Current Distribution" half (left) and "Predicted Future Distribution" half (right), divided by a vertical center line. The pyramid is divided into four horizontal elevation bands, from top (narrowest) to bottom (widest): "High Elevations," "Mid-High Elevations," "Mid-Low Elevations," and "Low Elevations," separated by dashed lines. Each band shows bird-shape icons above the letters A, B, C, D, E (Current side) and A, B, C, D, E (Predicted Future side), indicating which species is present at that elevation. A legend defines a black bird silhouette = "Species present at elevation" and a gray bird silhouette = "Extinct species."
Current Distribution:
- High Elevations: Species A and Species C present.
- Mid-High Elevations: Species A present.
- Mid-Low Elevations: Species B and Species D present.
- Low Elevations: Species B, Species C, Species D, and Species E present.
Predicted Future Distribution:
- High Elevations: Species A present; Species E shown extinct (gray icon).
- Mid-High Elevations: Species B and Species D present.
- Mid-Low Elevations: Species A, Species C, and Species D present.
- Low Elevations: Species A present.]
The following information applies to parts F, G, and H.
Some organisms such as birds can move in response to environmental changes, while other organisms such as corals cannot. Researchers studying the effect of climate change on marine organisms conducted two experiments involving photosynthetic algae that have a symbiotic relationship with corals.
In Experiment 1, the researchers placed photosynthetic algal colonies living in corals in three different saltwater tanks. The temperature of Tank 1 was set to 27°C, the average temperature at which most corals live. Water circulation in each tank mimicked natural ocean currents. After 30 days, the researchers counted the number of bleached corals. The tank setups are shown in the following list.
- Tank 1: 27°C and no sediment
- Tank 2: 32°C and no sediment
- Tank 3: 37°C and no sediment
In Experiment 2, the researchers used the same photosynthetic algae living in corals but modified the conditions of the tanks as shown in the following list. Water circulation kept the sediment in the tanks suspended. After 30 days, the researchers counted the number of bleached corals.
- Tank 1: 27°C and no sediment
- Tank 2: 27°C and moderate sediment
- Tank 3: 27°C and high sediment
1. Respond to parts A, B, C, D, E, F, G, H, I, and J.
Based on the information in the diagram, identify the elevation zone that has the highest species richness for the current distribution.
Describe a climate condition at high elevations that is different than it is at low elevations.
A predator at low elevations currently feeds on Species C and D. Based on the information in the diagram, describe what could happen to the predator species in the future in response to the predicted changes in the prey community.
Species C is considered a generalist, while Species E is considered a specialist. Explain why Species C and E are predicted to respond differently to climate change.
Based on the information in the diagram, explain why the bird community at low elevations in the future would be less likely to recover from natural disruptions than the current low-elevation bird community.
Identify the independent variable in Experiment 1.
Identify a likely scientific question for Experiment 1.
In Experiment 2 the temperature of the tanks was held constant, while the amount of sediment was varied. Explain how this modification could affect the results of this experiment.
Changes in climate also affect Arctic ecosystems. One impact of climate change is the loss of ice and snow in polar regions. Describe a positive feedback loop that results from the loss of ice and snow in polar regions.
Describe one problem that Arctic species, such as polar bears or ringed seals, face because of warming in polar regions.
The following information applies to parts A, B, C, D, E, F, and G.
The following graph shows the number of quadrillion British thermal units (BTUs) that were consumed in the United States using five different energy sources from 1950 to 2020.
Energy Consumption by Source in the United States, 1950-2020
[Line graph titled "Energy Consumption by Source in the United States, 1950-2020"; x-axis "Year" from 1950 to 2020 in increments of 10; y-axis "Energy Consumption (quadrillion BTU)" from 0 to 50 in increments of 10. Five lines, per the legend: Coal (thin solid line), Natural gas (dashed line), Petroleum (thick dotted line), Nuclear (thick solid line), Renewables (thin dotted line).
- Petroleum (thick dotted): starts around 14 in 1950, rises steadily to a peak near 38 around 1978, dips to about 30 around 1983, rises again with fluctuations to a peak near 40 around 2005, declines to about 34 around 2012, rises slightly then drops sharply to about 33 by 2020.
- Natural gas (dashed): starts around 6 in 1950, rises to about 22 by 1970, dips slightly through the 1970s-80s to about 18, rises again through the 1990s-2000s to about 23 around 2000-2010, then rises sharply after 2010 to about 32 by 2020.
- Coal (thin solid): starts around 13 in 1950, dips to about 9 by 1960, rises gradually with fluctuations to about 23 by the early 2000s, stays around 20-22 through the 2000s, then declines sharply after 2010 to about 9 by 2020.
- Nuclear (thick solid): near 0 from 1950 to about 1970, rises steadily from the 1970s to about 8 by 2000, continues rising slightly to about 8-9 through 2010-2020.
- Renewables (thin dotted): near 0-1 from 1950 to 1970, rises slowly with fluctuations to about 6 by 2000, rises gradually to about 8-9 by 2020, converging with Nuclear near the end.]
The following information applies to parts H and I.
Researchers studied an aquatic ecosystem near an area of land that had been converted to agricultural use. They reported an increase in nutrients, such as nitrates and phosphates, in the water.
2. Respond to parts A, B, C, D, E, F, G, H, and I, and all subparts.
Identify one renewable energy source that is used to generate electricity.
Based on the data in the graph, identify the energy source that had the highest consumption in 2010.
Based on the data in the graph, describe the pattern in the energy consumption from coal in the United States from 1960 to 2020.
Based on the data in the graph and your knowledge of energy consumption, explain one likely reason why the use of coal for energy changed between 2010 and 2020.
Explain how fossil fuels are used to generate electricity.
In addition to fossil fuels, nuclear power can be used to generate electricity. Identify one negative impact associated with nuclear energy.
Fossil fuel combustion leads to ocean warming. Describe one environmental problem other than coral bleaching that is associated with warming oceans.
Explain how an increase in nutrients, such as nitrates and phosphates, can negatively affect an aquatic ecosystem.
Propose a realistic solution that would reduce nutrient pollution of waterways, while still allowing cultivation of crops.
Justify the solution proposed in part I (i) by explaining one potential advantage other than reducing nutrient runoff.
The following information applies to parts A, B, C, D, E, and F.
Ocelots are small wildcats that were previously found in 25 counties in Texas where shrubland is prevalent. As a result of land use changes, only 74 ocelots remain in 4 counties in Texas today. Rodents such as pocket mice are the main source of food for ocelots, but ocelots also prey on other small animals such as snakes and lizards.
3. Respond to parts A, B, C, D, E, and F, and all subparts.
Identify one environmental consequence that could result from having a smaller population of ocelots.
Calculate the percent change in the number of Texas counties where ocelots have been found historically as compared to today. Show your work.
Researchers expect the ocelot population to grow at a constant rate of 2.8% per year. Calculate the number of years it will take for the ocelot population to double based on a constant rate of growth. Show your work.
Pocket mice eat plants in the shrubland, while snakes are carnivores. Explain why the amount of primary production energy available to ocelots would change if ocelots ate only carnivores such as snakes and not pocket mice.
Ocelots need 720 grams of food per day. Pocket mice weigh an average of 43 grams each. If the ocelot diet consists of 46% pocket mice by weight, calculate how many pocket mice an ocelot would need to consume in one day, assuming each mouse weighs the average amount. Show your work.
As urbanization has increased in southern Texas, motor vehicle collisions have become the main cause of death in ocelots, which poses an added threat to the remaining ocelots.
Propose a realistic solution to reduce the number of ocelots killed by vehicles.
Justify the solution proposed in part F (i) by explaining an additional advantage, other than reducing the number of ocelots killed by vehicles.