Learn Extracted exam questions AP Environmental Science 2021 Free Response · Set 2
2021 Free Response · Set 2
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Soil erosion is one of the most serious soil-degrading processes. Each year tons of soil erode from cropland, pastures, forests, and other places. The amount of erosion varies dramatically among various land-use types. The figure above shows the effects of different agricultural practices and slopes on annual erosion rates.
[Line graph titled "EFFECT OF PERCENT SLOPE ON ANNUAL EROSION FOR FOUR AGRICULTURAL PRACTICES"; x-axis "Slope (%)" from 0 to 30 (gridlines at 0, 5, 10, 15, 20, 25, 30); y-axis "Annual Erosion (tons/acre)" from 0 to 30 (gridlines at 0, 5, 10, 15, 20, 25, 30). A dashed horizontal line at about y = 4 is labeled "T = tolerable loss". Four curves, all starting near (0,0): "Tillage" (solid thick line) rises steeply, reaching about 12 tons/acre at 5% slope and about 30 tons/acre at roughly 7-8% slope (curve goes off the top of the chart just past slope 7%); "No-till" (dotted line) rises more gradually, crossing the tolerable-loss line around 10% slope and reaching about 29 tons/acre at 30% slope; "No-till + cover crop" (dashed line) rises even more gradually, crossing the tolerable-loss line around 15% slope and reaching about 20 tons/acre at 30% slope; "Crop rotation" (thin solid line) rises the most gradually, staying below the tolerable-loss line until about 20% slope and reaching only about 8 tons/acre at 30% slope.]
Identify the scientific question that resulted in the data presented in the graph.
Identify the agricultural practice that could be used on a 15% slope without leading to a higher than tolerable loss of soil.
Describe the effect of adding a cover crop compared to using the no-till method.
Identify one natural mechanism of soil erosion.
Sediment from erosion can enter streams and affect water quality. One way sediment can enter a stream is from nearby road construction. Two methods to reduce sediment run-off in streams are to either put down straw bales or plant grass. The hypothesis to be tested is that straw bales reduce more sediment run-off than planted grass does. To test the hypothesis, two plots near a road under construction are measured. On one plot (A), straw bales are used to cover the soil, while a second plot (B) is planted with grass. The sediment discharge from each plot is measured after rainfall.
Identify the dependent variable stated in the hypothesis.
Describe one way to add a control to improve the design of the study.
Identify one variable that was not discussed that could affect the results of the study.
Sediments reaching streams affect water clarity, which is tested by determining turbidity. Turbidity can be determined by measuring the depth at which a submerged object can no longer be seen from the surface.
| Sample Group | Turbidity |
|---|---|
| Straw bale plots (plot A) | 12 cm |
| Planted grass plots (plot B) | 28 cm |
Based on the data in the table above, make a claim about the stated hypothesis.
Several fish species lay their eggs in the gravel in the streams under investigation in the study.
Describe the type of survivorship curve expected for these fish species.
Explain why the input of sediment to a stream can negatively affect reproduction of fish that lay their eggs in the gravel of the streambed.
Biodiversity around the world is changing as a result of anthropogenic influences.
[World map titled "GLOBAL AMPHIBIAN SPECIES RICHNESS", drawn in an oval (Robinson-style) projection with latitude lines labeled 60°, 30°, 0°, 30°, 60° (top to bottom) and longitude lines labeled 180°, 120°, 60°, 0°, 60°, 120°, 180° (left to right). A legend "Number of species" shows four shading categories: diagonal hatching = 0-20 species; light gray = 21-50 species; medium gray = 51-100 species; black = 101-136 species. The map shows the darkest shading (101-136 species, highest richness) concentrated in a band along the equator (0°) in South America (the Amazon basin) and a small patch in central Africa; medium-gray shading (51-100 species) in a broader band around the tropics in South America, Central America, sub-Saharan Africa, and parts of Southeast Asia/South Asia (e.g., India, Myanmar/Thailand region); lighter shading (21-50 species) in a band through central Africa and parts of South America; and diagonal-hatch shading (0-20 species, lowest richness) at higher latitudes including North America, Europe, northern Asia/Russia, and most of Australia.]
The map represents species richness of amphibians around the globe. Use the map to answer the following questions.
Identify the latitudinal range with the greatest amphibian species richness.
Identify what biome this range most likely represents.
Describe one reason amphibian species richness would tend to be highest in this region.
There are many environmental threats facing amphibians today, such as deforestation. Describe one possible anthropogenic reason for deforestation.
Many factors influence biodiversity.
Explain how the species richness of an ecosystem influences its response to environmental stressors.
Explain why amphibian biodiversity is declining globally, other than from deforestation.
Currently, wildlife species are going extinct at an alarming rate. To combat this threat, governments around the world have enacted legislation and signed treaties to protect species threatened by extinction.
Identify one specific piece of legislation that has been designed to protect species threatened by extinction.
Explain how the requirements of the legislation identified in part (d)(i) specifically protect species threatened by extinction.
A town is considering selling an undeveloped parcel of land along its border for residential developments. The square parcel of land consists of approximately 30% wetland and 70% pasture. The wetland runs through the middle of the property for its entire width and is home to three native frog species.
Propose a viable solution that will result in the protection of the native frog species while still allowing for maximum profit of the property development.
Justify the solution proposed in (e)(i) by describing a potential advantage of the plan, other than frog protection.
Approximately 350 coal-fired power plants in the United States are older than the 30-year anticipated life-span for a coal generator. One problem with these aging power plants is that many lack the necessary modern air pollution controls. Additionally, there are concerns about rising fuel costs, so many utility companies are planning to retire coal-fired plants and build new natural-gas power plants.
Describe why coal is considered a nonrenewable energy source.
Describe one potential environmental advantage of replacing a coal-fired power plant with a natural-gas power plant.
Describe one economic advantage of using natural gas, rather than coal, in producing electricity.
When natural gas is used to heat homes, it can produce carbon monoxide gas, which can lead to carbon monoxide poisoning in humans. Propose a solution to reduce the incidence of carbon monoxide poisoning in humans.
Particulate matter is another common pollutant in emissions from vehicles, coal-fired power plants, and various other sources. One size of particulates, $\text{PM}_{2.5}$, presents a particular risk to human health.
ATMOSPHERIC CONCENTRATION OF PARTICULATE MATTER IN 1990 AND 2016
| Year | Average Annual Atmospheric Concentration of $\text{PM}_{2.5}$ ($\mu\text{g/m}^3$) |
|---|---|
| 1990 | 85 |
| 2016 | 188 |
Calculate the percent change in the average annual $\text{PM}_{2.5}$ concentration in the air from 1990 to 2016. Show your work.
Trees can remove $\text{PM}_{2.5}$ from the atmosphere when particulates settle on the leaves and are subsequently washed onto soil by rain. The average annual removal of $\text{PM}_{2.5}$ is 2.3 kilograms per hectare. Calculate the decrease in $\text{PM}_{2.5}$ removal in kilograms if logging reduced a forested area from 50,000 hectares to 43,000 hectares. Show your work.
Research has shown that hospital admissions for cardiovascular problems increase 1% with every 10% increase in $\text{PM}_{2.5}$ concentration. A city experienced a 23% increase in $\text{PM}_{2.5}$ concentration and had 7,390 hospital admissions for cardiovascular issues over a one-year period. Calculate the anticipated increase in the number of hospital admissions for cardiovascular issues during the next year if the $\text{PM}_{2.5}$ concentration continues to rise at an identical rate. Show your work.