Learn Extracted exam questions AP Environmental Science 2024 Free Response · Set 2
2024 Free Response · Set 2
Source PDF on the left, extracted YAML on the right. Compare numbering, marks, options and text.
The following diagram shows how an area changed over time. The dominant vegetation in each stage is labeled in the diagram. Each roman numeral represents a stage in the ecological process.
[Diagram: A cross-section showing ecological succession over time, divided into six stages labeled with roman numerals I through VI, with a key showing "Bedrock" (dotted pattern) and "Soil" (solid gray). A horizontal arrow below labeled "Time" points left to right. The cross-section shows bedrock and soil layers progressively deepening from left (mostly exposed bedrock) to right (thick soil layer) as vegetation on top becomes progressively taller and denser. The six stages are labeled below the diagram:
- Stage I: Bare Rock
- Stage II: Lichens
- Stage III: Small Annual Plants and Lichens
- Stage IV: Grasses and Perennials
- Stage V: Grasses, Shrubs, and Shade-Intolerant Trees Such As Pines
- Stage VI: Shade-Tolerant Trees Such As Oaks And Hickory]
Identify the ecological change over time illustrated in the diagram.
Identify the stage in which pioneer species first appear.
Describe how soil forms from stage II to stage III.
Identify a cultural ecosystem service that may be provided by a mature forest.
Researchers are interested in investigating the effect of the removal of trees on the water quality of nearby waterways. To conduct their experiment, the researchers locate two identical forest watersheds, both with a river running through them. Forest A is an intact forest and forest B is a clear-cut forest. Four stream monitoring stations are set up in each forest study area. Each station monitors a variety of water quality indicators, including water temperature, at various locations along the river. The experimental setup is shown in the following diagrams. The arrows shown in the rivers represent the direction of water flow. The triangles in the river show the location of the stream monitoring stations.
[Diagram: Two side-by-side maps labeled "Forest A" and "Forest B", each showing a river flowing from the top of the map down to a "Lake" at the bottom, with 4 numbered triangular stream monitoring stations (labeled 1 at the top near where the river enters, 2, 3, and 4 near the lake) placed along the river's path. Arrows along the river indicate the direction of water flow, flowing downward toward the lake. Forest A is densely covered with many tree symbols (an intact forest). Forest B has only a few scattered tree symbols, showing that most trees have been cleared (a clear-cut forest). A legend below both maps indicates: an arrow icon = "Direction of water flow"; a triangle icon = "Stream monitoring station".]
Identify a testable hypothesis being investigated by the researchers.
Identify the independent variable in the experiment.
Describe the purpose of forest A in the experiment.
Explain why the water temperature might change because of clear-cutting trees in forest B.
After the experiment was completed, land developers constructed a golf course in the clear-cut area of forest B. To prepare the land, developers removed any remaining stumps and newly grown trees and began planting and fertilizing new grass. The researchers are interested in the effect the golf course may have on the water quality of the river. To monitor the river in forest B, the researchers repeated the experiment once the golf course had been constructed.
Explain why an indicator of water quality other than temperature could be altered by the golf course in forest B.
Explain how the aquatic organisms living in the lake illustrated in the diagram of forest B are likely to be affected by the new golf course.
The following graph shows how global uses of habitable land have changed since 1700.
[Bar chart titled "Land Use Changes on Earth, 1700-2018". Y-axis: "Percentage of Habitable Land" from 0% to 100% in increments of 20%. X-axis: "Year", with stacked bars shown for 1700, 1800, 1900, 1950, 2000, and 2018. Each bar is stacked (from bottom to top) with five categories per the legend: Forest (light gray), Crops (dark gray), Grazing (diagonal hatched pattern), Wild grasslands (white), Built-up land (black, thin sliver at the very top). Approximate stacked values read from the graph:
- 1700: Forest ≈ 53%, Crops ≈ 2%, Grazing ≈ 6%, Wild grasslands ≈ 38% (top reaches 100%), Built-up land negligible.
- 1800: Forest ≈ 51%, Crops ≈ 4%, Grazing ≈ 9%, Wild grasslands ≈ 36%, Built-up land negligible.
- 1900: Forest ≈ 49%, Crops ≈ 8%, Grazing ≈ 16%, Wild grasslands ≈ 27%, Built-up land negligible.
- 1950: Forest ≈ 45%, Crops ≈ 12%, Grazing ≈ 31%, Wild grasslands ≈ 12%, Built-up land ≈ small sliver.
- 2000: Forest ≈ 39%, Crops ≈ 15%, Grazing ≈ 32%, Wild grasslands ≈ 13%, Built-up land ≈ small sliver.
- 2018: Forest ≈ 38%, Crops ≈ 15%, Grazing ≈ 33%, Wild grasslands ≈ 13%, Built-up land ≈ small sliver.]
Based on the data in the graph, identify the year with the highest percentage of forest.
Based on the data in the graph, describe the relationship between the land use changes in the wild grasslands and grazing from 1700 to 1950.
Identify an environmental problem associated with overgrazing by livestock.
A student hypothesized that the change in the percentage of forest from 1700 to 2018 has decreased atmospheric carbon dioxide concentrations. Explain whether the hypothesis is supported or refuted based on the data in the graph.
Urban environments have accounted for an increasing percentage of land use within the last few decades.
Describe a water-related environmental problem associated with urbanization.
Describe a potential response to mitigate the environmental problem identified in part (e).
Farmers who own large sections of cropland notice that bobcats, a medium-sized predatory forest cat, were present many years ago but are now virtually absent in the area. Instead, smaller mammal species now inhabit the area. Over time, the farmers have cleared nearly all of the forest on their property and converted it to farmland.
Explain why there are fewer bobcats present on the farmland now compared to several decades ago.
The small mammal species are considered pests by the farmers. The farmers partner with a conservation group to increase the number of bobcats in the area. As a solution, the conservation group will introduce bobcats onto the few isolated patches of the original forested habitat left in the area. They can introduce only a small number of bobcats in each patch.
Describe a disadvantage of introducing only a small population of bobcats.
Propose a solution to improve the chances that the bobcat reintroductions will be successful in reestablishing wild populations.
Justify the solution proposed in part (i) by describing an additional advantage, other than reestablishing the bobcat population near the farms.
The Rocky Mountains, the headwaters for the Colorado River, have experienced a severe drought for many of the past twenty years. States and cities downstream that depend on the river water have had to find solutions to the reduced water flow.
One city located downstream from the Rocky Mountains is Las Vegas, Nevada. In Las Vegas, one solution to reduce the amount of water used for irrigation is to remove landscaping and lawns that use grasses not native to the local area and replace them with desert-tolerant landscaping.
Identify a typical type of plant that would be used in desert-tolerant landscaping.
Justify the removal of landscaping and lawns that use grasses not native to the local area by describing an additional advantage, other than reducing the amount of water needed for irrigation.
Warmer seasonal temperatures in the Rocky Mountains have led to earlier mountain snowmelt and an increased risk of forest fires as soil and vegetation dry out.
Describe how a prescribed burn would reduce the severity and spread of forest fires.
Describe a disadvantage of a prescribed burn in a forested ecosystem.
Lake Powell is a large reservoir on the Colorado River. Lake Powell is formed by a dam with a hydroelectric power plant. At full capacity or full pool, Lake Powell contains 25.16 million acre-feet (maf) of water. Currently, Lake Powell is at 36% full capacity.
Calculate the number of million acre-feet (maf) of water currently in Lake Powell. Show your work.
In 2021, after years of drought, Lake Powell held 7.9 million acre-feet (maf) of water. One million acre-feet is equivalent to $3.26 \times 10^{11}$ gallons.
The watershed of the Upper Colorado River contributes an average of 9.60 maf of water to Lake Powell annually. The melted mountain snow found in the watershed contributes 50% of the average river flow into Lake Powell. In 2021, the river flow was 36% of the annual average. Assuming that all resources to that flow contributed the same proportions as in prior years, calculate the amount of water (in million acre-feet) that was contributed by the melted mountain snow in 2021. Show your work.
The average household in the United States consumes $5.0 \times 10^4$ gallons of water in a year. Calculate the number of households that could be supported for one year by the average flow of 9.60 maf of water into Lake Powell. Show your work.