AP Environmental Science Quiz: Human Impacts On Ecosystems

What this quiz covers

This quiz focuses on Human Impacts On Ecosystems, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Environmental Science.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. Urbanization altering hydrology and increasing erosion/sedimentation, degrading aquatic habitat (correct answer)
2. Overexploitation of gravel by fish reducing reproduction
3. Invasive species introduction increasing streambank stability
4. Ozone depletion increasing evaporation and lowering peak flows

Explanation: Urbanization alters hydrology by increasing impervious surfaces, leading to rapid runoff, higher peak flows, erosion, and sedimentation that degrade aquatic habitats like fish spawning gravel. New storm drains cause these changes in the stream, burying gravel. This describes the impact, unlike overexploitation of gravel or invasives increasing stability. Ozone depletion is unrelated. The correct answer is urbanization altering hydrology and increasing erosion because it explains the habitat degradation. Permeable pavements can mitigate urban runoff effects.

Question 2

1. Increased gene flow between patches leading to higher heterozygosity
2. Habitat fragmentation causing reduced dispersal and increased inbreeding (correct answer)
3. Eutrophication increasing dissolved oxygen and boosting amphibian survival
4. Overexploitation reducing predator pressure and increasing biodiversity

Explanation: Habitat fragmentation is a key human impact where large, continuous habitats are divided into smaller, isolated patches, often by infrastructure like roads, affecting species dispersal and genetic diversity. The new highway fragments the temperate forest, creating barriers that increase amphibian mortality during crossings and reduce gene flow in small mammals, leading to inbreeding and lower genetic diversity. This isolation can exacerbate edge effects and stochastic events in small populations, potentially driving local extinctions. Eutrophication or overexploitation are not relevant here, as the scenario focuses on physical division and its genetic consequences. Option B accurately links the highway's impact to reduced dispersal and increased inbreeding, highlighting a common outcome of fragmentation in ecosystems.

Question 3

1. Increased habitat connectivity reducing dispersal success
2. Edge effects resulting from habitat fragmentation (correct answer)
3. Overexploitation of birds through subsistence hunting only
4. Acid deposition increasing soil pH

Explanation: Edge effects are a consequence of habitat fragmentation, where human activities create more boundaries between habitats, altering conditions like light, wind, and predation near edges, favoring generalist species over specialists. In this tropical rainforest logging scenario, clearing for pasture fragments the forest into small patches, increasing edge habitat. This leads to fewer interior-forest birds, which are sensitive to edge changes, while generalists thrive. Unlike increased habitat connectivity or acid deposition raising pH, edge effects directly explain the species shift. Overexploitation through hunting is not the primary issue here. The correct answer is edge effects from fragmentation because it captures the loss of interior species. Recognizing edge effects informs conservation strategies like larger protected areas to minimize edges.

Question 4

1. Nutrient pollution leading to eutrophication and algal overgrowth (correct answer)
2. Overexploitation of coral by commercial harvest for jewelry
3. Habitat fragmentation of the reef by tectonic activity
4. Invasive species introduction of reef-building corals increasing competition

Explanation: Nutrient pollution from sewage and fertilizers causes eutrophication, where excess nutrients fuel algal overgrowth that shades and competes with corals, leading to reef decline. The tourist town's discharge and runoff increase nutrients, expanding algae and reducing coral cover. This is the primary driver, unlike overexploitation for jewelry or fragmentation by tectonics. Invasive corals increasing competition is not the issue. The correct answer is nutrient pollution leading to eutrophication because it explains the algal dominance. Reducing runoff is essential for coral reef protection.

Question 5

1. Large carnivores require large territories; habitat loss and fragmentation reduce viable population size and increase extinction risk (correct answer)
2. Carnivores are primary producers and cannot survive without sunlight
3. Carnivores are less affected by fragmentation because they have the smallest home ranges
4. Prey biomagnify territory size, forcing carnivores to migrate

Explanation: Large carnivores need extensive territories; habitat loss and fragmentation shrink viable areas, increasing extinction risk as populations become too small to sustain. The shrinking, isolated forest patch eliminates the carnivore first, despite prey presence. This is the reason, unlike carnivores being producers or having smallest ranges. Prey biomagnifying territory is nonsense. The correct answer is carnivores requiring large territories because it explains their vulnerability. Protecting large, connected habitats is key for apex predators.

Question 6

1. Increased biodiversity because monocultures create more niches
2. Reduced species richness due to habitat loss, fragmentation, and chemical pollution (correct answer)
3. No change in ecosystem services because all forests function identically
4. Higher genetic diversity because pesticides select for more species

Explanation: Converting diverse forests to monoculture plantations results in habitat loss, fragmentation of remnants, and chemical pollution from pesticides, all reducing species richness compared to original ecosystems. Small patches on slopes are vulnerable, and pesticides harm non-target species. Increased biodiversity or no change are incorrect for such transformations. Option B correctly predicts reduced richness from these impacts, contrasting ecosystem services between diverse forests and plantations.

Question 7

1. Physical habitat simplification reduces shelter and spawning habitat (habitat degradation) (correct answer)
2. Chemical pollution must be the cause because channelization cannot affect fish
3. Overexploitation by fish increases because concrete provides food
4. Invasive species are eliminated automatically when rivers are straightened

Explanation: Channelization simplifies physical habitats by removing features like debris, degrading shelter and spawning areas for fish despite unchanged chemistry. This leads to population declines. Chemical pollution or overexploitation are not indicated. Option A links simplification to degradation, explaining engineering's effects on rivers.

Question 8

1. Habitat loss and fragmentation plus invasive species introduction (correct answer)
2. Reduced edge effects and increased interior habitat quality
3. Only pollution impacts, with no changes to habitat structure
4. Overexploitation of fossil fuels directly increasing keystone predators

Explanation: Urban expansion often combines habitat loss, where native areas are converted to built environments, with fragmentation of remnants and introduction of invasive species, all of which reduce native biodiversity. Replacing prairie with housing and shopping centers destroys and fragments grassland habitat, while escaped ornamental plants act as invasives, outcompeting natives. This leads to smaller, isolated patches more susceptible to edge effects and invasion, diminishing ecosystem resilience. Reduced edge effects or sole pollution impacts are incorrect, as structural changes and species introductions are prominent. Option A best captures this combination, illustrating how multiple impacts compound to alter grassland ecosystems.

Question 9

1. Overexploitation plus habitat destruction of benthic communities (correct answer)
2. Only pollution because nets release toxins into seawater
3. Only habitat fragmentation because fish are not removed
4. Invasive species introduction as the main effect of trawling

Explanation: Bottom trawling combines overexploitation by removing fish with habitat destruction of benthic areas like seagrass, affecting community structure. Scraping damages long-term. Pollution or fragmentation alone miss the dual nature. Option A describes combined impacts, highlighting unsustainable fishing practices.

Question 10

1. Higher water clarity and increased coral larval settlement
2. Shift toward algal dominance due to nutrient enrichment and turbidity stress (correct answer)
3. Increased calcification rates because sediments provide carbonate
4. No community change because reefs are unaffected by sewage inputs

Explanation: Nutrient enrichment and sedimentation from sewage and construction can stress coral reefs, promoting algal overgrowth and reducing coral recruitment by altering water quality and light availability. This shift to algal dominance disrupts the reef's balance, favoring algae over corals. Higher clarity or no change ignore these stressors' effects. Option B correctly predicts algal dominance due to nutrient and turbidity stress, explaining urban development's role in reef degradation.

Question 11

1. Overexploitation, because fish are removed faster than they can reproduce
2. Habitat fragmentation, because fields split the lake into smaller patches
3. Pollution (nutrient runoff) leading to eutrophication and hypoxia (correct answer)
4. Invasive species introduction, because algae blooms only occur when nonnative algae are released

Explanation: This scenario describes cultural eutrophication, a form of water pollution caused by excess nutrients from human activities. Nitrogen-rich fertilizer runoff acts as a pollutant when it enters aquatic systems, triggering excessive algae growth (algal blooms). When these algae die and decompose, bacteria consume oxygen, creating hypoxic conditions that kill fish. This is not overexploitation (no harvesting), not fragmentation (the lake remains whole), and not necessarily invasive species (native algae can bloom with excess nutrients). Option C correctly identifies this as pollution through nutrient runoff leading to eutrophication. The chain of events - fertilizer application, runoff, algal bloom, oxygen depletion, fish kills - is a classic example of agricultural pollution impacts.

Question 12

1. Overexploitation reduced the breeding population, lowering recruitment and potentially reducing genetic diversity (correct answer)
2. Habitat fragmentation increased reproduction by creating more spawning sites
3. Nutrient pollution increased dissolved oxygen, delaying recovery
4. Invasive species introduction always speeds population recovery by adding new predators

Explanation: Overexploitation reduces breeding populations by harvesting immature individuals, slowing recovery due to low recruitment and potential genetic bottlenecks. Heavy harvesting before reproductive age crashes the fish population, with slow rebound even after fishing drops. This accounts for recovery, unlike fragmentation increasing sites or pollution increasing oxygen. Invasives speeding recovery is wrong. The correct answer is overexploitation reducing breeding because it explains the demographic impacts. Age-structured regulations aid sustainable fisheries.

Question 13

1. A trophic cascade due to overexploitation of a top predator (correct answer)
2. Increased genetic diversity due to selective harvest of large individuals
3. Reduced primary productivity due to decreased nutrient inputs
4. Elimination of edge effects due to larger habitat patches

Explanation: A trophic cascade is an ecological consequence of human impacts like overexploitation, where removing a top predator causes ripple effects through the food web, altering populations at lower levels. In this offshore fishery, targeting the top predator leads to its decline, allowing mid-level forage fish to increase unchecked. The decreased catch per unit effort and smaller average size indicate overexploitation pressure. This cascade disrupts the balance, unlike increased genetic diversity or reduced productivity, which do not fit the observed increases in forage fish. Edge effects are irrelevant in an open ocean context. The correct answer is a trophic cascade due to overexploitation because it explains the ecosystem-wide changes from predator removal. This highlights the importance of sustainable fishing quotas to maintain trophic structures.

Question 14

1. Habitat alteration/destruction reducing structural complexity and niches (correct answer)
2. Overexploitation of fish due to increased angling access
3. Introduction of invasive fish via aquarium releases
4. Stratospheric ozone loss increasing UV in the channel

Explanation: Habitat alteration or destruction by humans simplifies ecosystems, reducing structural complexity and available niches for species, which decreases biodiversity. Widening the river channel and lining it with concrete removes natural features like pools, riffles, and riparian plants, making the habitat less suitable for diverse native fish. This directly causes the observed decline in fish diversity. Unlike overexploitation from angling or invasive species introductions, the primary issue is the physical change to the habitat. Ozone loss increasing UV is not the main factor. The correct answer is habitat alteration reducing complexity because it explains the biodiversity loss. This illustrates why maintaining natural river structures is key for aquatic health.

Question 15

1. Loss of wetland habitat reducing flood control and water purification (correct answer)
2. Overexploitation of wetland plants decreasing primary succession
3. Increased albedo from wetlands causing local cooling
4. Reduced biomagnification due to removal of predators

Explanation: Habitat loss disrupts ecosystem services, which are benefits humans derive from ecosystems, such as flood control and water purification provided by wetlands. Draining and filling the wetland for an industrial park removes its ability to absorb floodwaters and filter sediments and nutrients. This results in more frequent downstream flooding and declined water quality. Unlike overexploitation of plants or increased albedo causing cooling, the loss directly impacts these services. Reduced biomagnification is not relevant. The correct answer is loss of wetland habitat reducing flood control and purification because it matches the scenario's outcomes. This underscores the value of preserving wetlands for their natural regulatory functions.

Question 16

1. Invasive species introduction leading to increased predation pressure (correct answer)
2. Overexploitation of birds by tourists collecting eggs
3. Habitat restoration from campground construction
4. Stratospheric ozone depletion increasing nest success

Explanation: Invasive species introductions, often via human activities like transport, can increase predation and disrupt native populations, as seen with rats preying on birds in the park. Feeding wildlife and accessible trash facilitate establishment. Habitat restoration or ozone depletion do not fit. Option A identifies invasive species causing increased predation, showing tourism's unintended ecological consequences.

Question 17

1. Pollution from chemical runoff reducing aquatic invertebrate populations (correct answer)
2. Overexploitation of insects by increased predation
3. Habitat fragmentation increasing gene flow among stream insects
4. Invasive species introduction through ballast water

Explanation: Pollution from chemical runoff is a human impact where pesticides and other substances applied to landscapes wash into waterways, harming aquatic life like insect larvae. In this suburban scenario, replacing native vegetation with lawns and using pesticides leads to runoff into the stream after storms. This directly causes the decline in aquatic insect larvae, as the chemicals are toxic to them. Unlike overexploitation by predation or habitat fragmentation increasing gene flow, which do not apply here, pollution targets the invertebrates chemically. Invasive species via ballast water is unrelated to lawn chemicals. The correct answer is pollution from chemical runoff because it best represents the scenario's impact on stream ecosystems. This example emphasizes the need for reduced pesticide use and natural landscaping to protect water quality.

Question 18

1. Roads primarily cause habitat fragmentation, while hunting represents overexploitation (correct answer)
2. Roads primarily cause eutrophication, while hunting represents habitat restoration
3. Roads primarily cause ozone depletion, while hunting represents invasive species control
4. Roads primarily increase genetic connectivity, while hunting increases population resilience

Explanation: Selective logging alters forest structure, but access roads facilitate further impacts like hunting, which represents overexploitation by removing individuals beyond sustainable levels. Roads fragment habitats and enable deeper penetration by hunters, increasing pressure on fruiting species and overall biodiversity. This comparison highlights how infrastructure can amplify direct exploitation. Eutrophication or ozone depletion are unrelated to the described activities. Option A best compares roads' fragmentation role with hunting's overexploitation, illustrating compounded human impacts in tropical forests.

Question 19

1. Habitat fragmentation plus overexploitation increasing mortality and reducing viable habitat (correct answer)
2. Thermal pollution plus ozone depletion increasing heat stress
3. Eutrophication plus acid deposition reducing soil nutrients
4. Increased primary succession plus habitat restoration increasing carrying capacity

Explanation: Human impacts like habitat fragmentation and overexploitation can combine to accelerate species declines, as roads provide access for hunters to exploit remote areas, compounding habitat loss. Selective logging and roads in the rainforest fragment the habitat while enabling overexploitation of large mammals. This leads to rapid population declines. Unlike thermal pollution with ozone or eutrophication with acid, the combination directly explains the mortality and habitat reduction. Increased succession is not occurring. The correct answer is fragmentation plus overexploitation because it captures the synergistic effects. This shows why integrated conservation must address multiple threats.

Question 20

1. Point-source thermal pollution from a power plant raising water temperature
2. Nonpoint-source nutrient pollution driving eutrophication (correct answer)
3. Overexploitation of algae by zooplankton causing algal blooms
4. Habitat fragmentation increasing reservoir depth and mixing

Explanation: Nonpoint-source pollution involves diffuse contaminants, like agricultural runoff, entering waterways and causing issues such as eutrophication, where excess nutrients promote algal blooms and deplete oxygen. Clearing riparian forests and increasing fertilizer use in the river valley lead to higher nitrate and phosphate levels, fueling algal growth in the downstream reservoir. This process disrupts aquatic ecosystems by creating hypoxic conditions that harm fish and other organisms. Point-source pollution or overexploitation do not fit, as the nutrients come from widespread farming practices rather than a single outlet or direct harvesting. Option B correctly identifies nonpoint-source nutrient pollution as the driver of eutrophication, explaining the reservoir's changes effectively.