AP Environmental Science Exam — Questions and Answers

Question 1: Which type of drought is defined by a deficiency of precipitation over an extended period?

Hydrological drought
Socioeconomic drought
Meteorological drought (Correct answer)
Agricultural drought

Correct answer: Meteorological drought

A meteorological drought is defined purely in terms of the degree of dryness compared to normal precipitation levels over a defined period.

Question 2: The concept of green GDP or genuine savings attempts to correct traditional GDP accounting by:

Subtracting the depletion of natural capital and costs of pollution from conventional national income accounts (Correct answer)
Including only goods and services that meet environmental certification standards
Excluding financial sector earnings that don't contribute to real economic wellbeing
Adding the value of unpaid domestic work and volunteer activities to GDP calculations

Correct answer: Subtracting the depletion of natural capital and costs of pollution from conventional national income accounts

Green GDP (and the World Bank's Genuine Savings indicator) adjusts national accounts to deduct the depreciation of natural capital (forest loss, soil erosion, mineral depletion, pollution damage) that conventional GDP treats as income.

Question 3: The concept of weak sustainability versus strong sustainability concerns:

Whether manufactured capital can substitute for natural capital (weak) or whether natural capital is irreplaceable (strong) (Correct answer)
The strength of scientific evidence required before environmental protection measures are imposed
The degree of enforceability of environmental regulations in different legal systems
The economic strength of a country relative to its ability to invest in environmental protection

Correct answer: Whether manufactured capital can substitute for natural capital (weak) or whether natural capital is irreplaceable (strong)

Weak sustainability allows trade-offs: natural capital can be depleted if equivalent manufactured or human capital is created. Strong sustainability holds that critical natural capital (biodiversity, ozone layer, climate stability) cannot be substituted and must be maintained.

Question 4: Which type of pollution involves the introduction of harmful chemicals into water bodies through agricultural runoff?

Point source pollution
Nonpoint source pollution (Correct answer)
Noise pollution
Thermal pollution

Correct answer: Nonpoint source pollution

Nonpoint source pollution comes from diffuse sources like farmland runoff rather than a single identifiable discharge point.

Question 5: Which nutrient cycle is most directly affected by combustion of fossil fuels?

Nitrogen cycle
Carbon cycle (Correct answer)
Sulfur cycle
Phosphorus cycle

Correct answer: Carbon cycle

Burning fossil fuels releases stored carbon as CO₂, significantly altering the natural carbon cycle.

Question 6: The duck curve in grid management describes a situation where:

Electricity demand rises sharply in the shape of a duck's neck during morning hours
Midday solar generation creates a valley in net load demand, followed by a steep ramp-up in the evening when solar drops off (Correct answer)
Electric vehicle charging patterns create duck-shaped demand peaks after work hours
The shape of a power plant's load curve resembles a duck in cross-section

Correct answer: Midday solar generation creates a valley in net load demand, followed by a steep ramp-up in the evening when solar drops off

As solar penetration increases, the net load (demand minus solar generation) dips deeply midday then ramps steeply in the evening when solar drops and demand rises - the characteristic duck curve shape, challenging grid operators.

Question 7: What is the main purpose of riparian buffer zones along waterways?

To filter runoff and reduce sediment and nutrient loading into streams (Correct answer)
To mark property boundaries
To provide habitat for migratory birds only
To generate hydroelectric power

Correct answer: To filter runoff and reduce sediment and nutrient loading into streams

Riparian buffers of vegetation along stream banks trap sediment, absorb nutrients, and stabilize streambanks.

Question 8: Terracing as an agricultural technique on steep slopes primarily serves to:

Allow heavier farm machinery to operate safely on slopes
Improve drainage of waterlogged soils on hillsides
Create level planting areas that reduce runoff velocity and soil erosion (Correct answer)
Increase sunlight exposure to crops growing on the shadowed side of hills

Correct answer: Create level planting areas that reduce runoff velocity and soil erosion

Terraces cut horizontal steps into hillsides, converting steep, erosion-prone slopes into level or nearly level planting areas that hold water and soil.

Question 9: Lead poisoning in children is particularly harmful because:

Children absorb lead through skin contact more readily than adults do
Lead permanently interferes with neurological development, causing irreversible cognitive and behavioral damage (Correct answer)
Children's smaller body mass makes the same dose proportionally more toxic
Lead is released into breast milk, exposing infants during nursing

Correct answer: Lead permanently interferes with neurological development, causing irreversible cognitive and behavioral damage

Lead permanently damages the developing nervous system - reducing IQ, causing learning disabilities, behavioral problems, and reduced hearing - with no safe blood lead level established for children.

Question 10: What does PM2.5 refer to in air quality monitoring?

Phase 2.5 pollutant standard
Particulate matter 2.5 micrometers or smaller (Correct answer)
Pollution at 2.5 kilometers altitude
Particulate matter 2.5 meters in diameter

Correct answer: Particulate matter 2.5 micrometers or smaller

PM2.5 refers to fine particulate matter with aerodynamic diameter ≤2.5 micrometers, which penetrates deep into the lungs.

Question 11: The triple bottom line (TBL) framework in corporate sustainability reporting measures performance across:

Short-term, medium-term, and long-term financial returns on sustainability investments
Profit (financial), people (social), and planet (environmental) dimensions (Correct answer)
Local, national, and international environmental regulatory compliance
Economic growth, resource efficiency, and waste reduction targets

Correct answer: Profit (financial), people (social), and planet (environmental) dimensions

John Elkington's TBL framework (1994) holds that companies should account for social equity (people) and environmental stewardship (planet) alongside financial profit, recognizing all three as measures of business success.

Question 12: Benefit-Cost Analysis (BCA) in environmental decision-making is limited primarily because:

It is too expensive for government agencies to conduct for all regulatory decisions
Difficult-to-quantify values (biodiversity, human life, future generations) must be monetized, introducing significant uncertainty and ethical controversy (Correct answer)
It is only applicable to pollution control and cannot be used for land use decisions
BCA always favors environmental protection over economic development

Correct answer: Difficult-to-quantify values (biodiversity, human life, future generations) must be monetized, introducing significant uncertainty and ethical controversy

BCA requires assigning monetary values to environmental goods (existence value of a species, value of a statistical life) that are inherently difficult to measure and involve ethical judgments about what can be traded for money.

Question 13: Which land use change is the leading cause of tropical deforestation globally?

Urban expansion
Mining operations
Logging for timber
Agricultural conversion (especially cattle ranching and soy) (Correct answer)

Correct answer: Agricultural conversion (especially cattle ranching and soy)

Agricultural expansion — particularly for cattle pasture and soy cultivation — drives the majority of tropical forest clearing worldwide.

Question 14: The intermittency problem with solar and wind power refers to:

The high upfront capital cost that makes projects financially uncertain
The environmental impact of manufacturing solar panels and wind turbine blades
The limited number of suitable locations for utility-scale renewable installations
The fact that output varies with weather and time of day, creating challenges for grid balancing (Correct answer)

Correct answer: The fact that output varies with weather and time of day, creating challenges for grid balancing

Unlike dispatchable power plants (coal, gas, nuclear) that generate on demand, solar and wind output fluctuates with conditions, requiring storage, backup generation, or grid flexibility to maintain reliable supply.

Question 15: Payments for Ecosystem Services (PES) schemes work by:

Allowing companies to purchase ecosystem credits to offset their biodiversity impacts
Requiring governments to fund restoration of degraded ecosystems as payment for past damage
Charging industrial polluters per unit of ecosystem damage they cause
Compensating landowners or communities for maintaining ecosystems that provide services to others (Correct answer)

Correct answer: Compensating landowners or communities for maintaining ecosystems that provide services to others

PES schemes transfer value from beneficiaries of ecosystem services (e.g., downstream water users) to providers (e.g., upstream landowners maintaining forests for water quality) - creating economic incentives for conservation.

Question 16: Which biodiversity hotspot concept identifies areas for conservation priority based on what criteria?

Largest total species count
Areas with the highest primary productivity
High endemic species richness combined with severe habitat loss (Correct answer)
Regions with the most endangered vertebrates

Correct answer: High endemic species richness combined with severe habitat loss

Biodiversity hotspots are defined by having at least 1,500 endemic plant species and having lost at least 70% of their original habitat.

Question 17: What environmental problem results from mining activities that expose sulfide minerals to water and air?

Acid mine drainage (Correct answer)
Thermal pollution
Heavy metal deposition
Radioactive contamination

Correct answer: Acid mine drainage

Acid mine drainage occurs when oxidation of sulfide minerals in exposed rock produces sulfuric acid that leaches into waterways.

Question 18: Which principle guides the management of international fisheries under UNCLOS and regional fisheries management organizations (RFMOs)?

Maximum sustainable yield (MSY) - harvesting at the level that produces the greatest yield indefinitely (Correct answer)
Exclusive national control over all migratory species
First-come, first-served allocation of fishing rights
Zero-harvest zones to allow complete stock recovery

Correct answer: Maximum sustainable yield (MSY) - harvesting at the level that produces the greatest yield indefinitely

MSY is the theoretical maximum harvest rate a population can sustain indefinitely without being depleted, and it guides most fisheries management frameworks.

Question 19: Which dam removal trend is driven primarily by what environmental concern?

Decreasing sedimentation in reservoirs
Lowering water temperatures
Restoring fish migration routes and natural river flow (Correct answer)
Reducing flood risk downstream

Correct answer: Restoring fish migration routes and natural river flow

Many dams are being removed to allow migratory fish like salmon to access historic spawning grounds and restore natural river ecosystems.

Question 20: The concept of intergenerational equity in sustainable development, as articulated in the Brundtland Report (1987), holds that:

Each generation has an obligation to leave future generations at least as much natural and human capital as it inherited (Correct answer)
Every generation has the right to exploit natural resources without regard to future consequences
Wealthier nations must transfer funds to poorer nations to ensure equal development opportunities
Future generations will develop better technology to solve environmental problems, so current conservation is unnecessary

Correct answer: Each generation has an obligation to leave future generations at least as much natural and human capital as it inherited

The Brundtland definition of sustainable development - meeting the needs of the present without compromising the ability of future generations to meet their own needs - is the classic statement of intergenerational equity.

Question 21: The precautionary principle in environmental policy states that:

When an action risks serious harm, precautionary measures should be taken even if full scientific certainty is lacking (Correct answer)
Governments must prove harm before restricting industrial activities
Environmental regulations should be proportional to economic costs
Polluters must pay for all environmental damage they cause

Correct answer: When an action risks serious harm, precautionary measures should be taken even if full scientific certainty is lacking

The precautionary principle shifts the burden of proof: protective action should be taken in the face of scientific uncertainty when potential harm is serious or irreversible.

Question 22: The net metering policy allows solar PV owners to:

Avoid property taxes on the increased home value from solar panel installation
Sell electricity directly to neighbors without going through a utility company
Install solar panels without permits if system size is below a certain threshold
Export excess electricity to the grid and receive credit against their electricity bill at the retail rate (Correct answer)

Correct answer: Export excess electricity to the grid and receive credit against their electricity bill at the retail rate

Net metering lets customers with rooftop solar offset their consumption: excess generation exported to the grid spins the meter backward (or is credited), with the utility billing only the net consumption.

Question 23: The primary environmental concern associated with coal combustion is:

Emission of sulfur dioxide, nitrogen oxides, mercury, and CO2 (Correct answer)
Thermal pollution of rivers
Radioactive waste generation
Depletion of stratospheric ozone

Correct answer: Emission of sulfur dioxide, nitrogen oxides, mercury, and CO2

Coal combustion emits SO2 (acid rain), NOx (smog/acid rain), mercury (neurotoxin), particulates, and large quantities of CO2 (climate change).

Question 24: What is the zone of an aquatic ecosystem where photosynthesis can occur due to sufficient light penetration?

Benthic zone
Photic zone (Correct answer)
Aphotic zone
Abyssal zone

Correct answer: Photic zone

The photic zone is the sunlit upper layer of water where enough light exists for photosynthesis.

Question 25: Energy efficiency and energy conservation differ in that:

They are synonymous terms used interchangeably in energy policy
Conservation applies only to fossil fuels; efficiency applies to renewables
Efficiency refers to using less energy; conservation means using better technology
Efficiency means getting more useful output per unit of energy input; conservation means reducing overall energy use (Correct answer)

Correct answer: Efficiency means getting more useful output per unit of energy input; conservation means reducing overall energy use

Efficiency = more useful work per energy unit (e.g., LED vs. incandescent bulb); conservation = behavioral reduction in energy use.

Question 26: Which process removes dissolved oxygen from water, harming aquatic life, often caused by excess nutrient runoff?

Acidification
Sedimentation
Eutrophication (Correct answer)
Salinization

Correct answer: Eutrophication

Eutrophication occurs when nutrient overload triggers algal blooms that deplete oxygen as they decompose.

Question 27: Which biome is characterized by permafrost, low precipitation, and very short growing seasons?

Grassland
Tundra (Correct answer)
Temperate deciduous forest
Taiga

Correct answer: Tundra

The tundra biome has permanently frozen subsoil (permafrost) and supports only low-growing vegetation.

Question 28: The Convention on Biological Diversity (CBD) established which global target framework for protecting biodiversity by 2030?

Paris Biodiversity Agreement
Kunming-Montreal Global Biodiversity Framework (Correct answer)
REDD+
Aichi Biodiversity Targets

Correct answer: Kunming-Montreal Global Biodiversity Framework

The Kunming-Montreal Global Biodiversity Framework (2022) includes the '30×30' target to protect 30% of land and ocean by 2030.

Question 29: What is a brownfield site?

Agricultural land left fallow for a season
Abandoned or underused industrial property with potential contamination (Correct answer)
A strip-mined area undergoing reclamation
A wetland converted to farmland

Correct answer: Abandoned or underused industrial property with potential contamination

Brownfields are abandoned or underutilized industrial or commercial properties where redevelopment is complicated by actual or suspected contamination.

Question 30: What is the primary environmental benefit of natural wildfire in many ecosystems?

It prevents all future fires by removing all fuel
It eliminates invasive animal species from the region
It permanently increases soil nitrogen concentrations
It clears accumulated dead biomass and promotes new growth and biodiversity (Correct answer)

Correct answer: It clears accumulated dead biomass and promotes new growth and biodiversity

Natural wildfires clear accumulated dead wood and leaf litter, recycle nutrients into the soil, and open the canopy for light-dependent plant species, ultimately promoting habitat diversity.

Question 31: What is the primary source of energy for most ecosystems on Earth?

Wind
Geothermal heat
Sunlight (Correct answer)
Water

Correct answer: Sunlight

Sunlight is captured by photosynthetic organisms and forms the foundation of most food webs.

Question 32: Which type of flood occurs with little or no warning due to intense, localized rainfall in a short period?

Coastal flood
Riverine flood
Ice-jam flood
Flash flood (Correct answer)

Correct answer: Flash flood

Flash floods develop rapidly—often within six hours—due to intense rainfall over a small area, leaving little time for warning or evacuation.

Question 33: Fracking (hydraulic fracturing) has raised environmental concerns primarily related to:

Increased sea-level rise from coastal drilling platforms
Destruction of coral reefs from offshore waste disposal
Groundwater contamination, induced seismicity, and methane leakage (Correct answer)
Ozone depletion from drilling chemicals

Correct answer: Groundwater contamination, induced seismicity, and methane leakage

Fracking injects high-pressure fluid into rock; concerns include well casing failures contaminating aquifers, disposal-well-induced earthquakes, and fugitive methane emissions.

Question 34: What term describes the increase in concentration of a pollutant as it moves up the food chain?

Bioaccumulation
Biomagnification (Correct answer)
Biodegradation
Bioconcentration

Correct answer: Biomagnification

Biomagnification is the process by which toxin concentrations increase at each successive trophic level.

Question 35: Which greenhouse gas has the highest global warming potential (GWP) over a 100-year timeframe among those listed?

Nitrous oxide (N2O)
Carbon dioxide (CO2)
Sulfur hexafluoride (SF6) (Correct answer)
Methane (CH4)

Correct answer: Sulfur hexafluoride (SF6)

SF6 has a GWP of approximately 23,500 over 100 years, far exceeding CO2 (1), CH4 (~28), and N2O (~265).

Question 36: Which type of ecological relationship exists between a lion and a zebra?

Mutualism
Commensalism
Competition
Predation (Correct answer)

Correct answer: Predation

Predation is a relationship where one organism (predator) kills and eats another (prey) for energy.

Question 37: Which term describes all living organisms and their physical environment interacting as a system?

Ecosystem (Correct answer)
Biome
Community
Population

Correct answer: Ecosystem

An ecosystem includes both the biotic (living) and abiotic (non-living) components interacting together.

Question 38: The U.S. National Environmental Policy Act (NEPA) requires federal agencies to:

Set binding emission limits for all industrial facilities
Ban development in federally designated wilderness areas
Purchase carbon offsets for all government operations
Prepare an Environmental Impact Statement (EIS) for major federal actions significantly affecting the environment (Correct answer)

Correct answer: Prepare an Environmental Impact Statement (EIS) for major federal actions significantly affecting the environment

NEPA (1970) mandates Environmental Impact Statements for significant federal actions, ensuring environmental consequences are analyzed before decisions are made.

Question 39: The competitive exclusion principle states that two species competing for identical resources cannot:

Occupy different niches
Coexist indefinitely (Correct answer)
Evolve together
Share a predator

Correct answer: Coexist indefinitely

Gause's principle holds that two species with the same niche cannot coexist; one will outcompete the other.

Question 40: What is the difference between direct (use) value and indirect (non-use) value of biodiversity?

Direct values are measurable; indirect values cannot be quantified
Direct values come from using species (food, medicine); indirect values include ecological functions like water purification (Correct answer)
Direct values are economic; indirect values are ethical
Direct values apply to wild species; indirect values apply to domesticated species

Correct answer: Direct values come from using species (food, medicine); indirect values include ecological functions like water purification

Direct values include economic uses (food, medicine, materials) while indirect values are ecosystem services (clean water, climate regulation) that don't involve harvesting.

Question 41: Agroforestry differs from conventional agriculture in that it:

Deliberately integrates trees and shrubs with crops and/or livestock to create ecological and economic benefits (Correct answer)
Applies forest management techniques like selective logging to annual croplands
Uses hydroponics to grow crops without soil
Restricts farming to naturally forested areas without clearing trees

Correct answer: Deliberately integrates trees and shrubs with crops and/or livestock to create ecological and economic benefits

Agroforestry intentionally combines perennial woody plants with crops and/or animals to exploit synergies: nitrogen fixation by tree legumes, reduced erosion, diversified income, carbon storage, and microclimate benefits.

Question 42: Green hydrogen is produced through:

Thermal decomposition of ammonia using solar concentrator heat
Electrolysis of water powered by renewable electricity, producing zero lifecycle emissions (Correct answer)
Reforming natural gas with carbon capture and storage (CCS)
Fermentation of biomass to yield hydrogen as a byproduct

Correct answer: Electrolysis of water powered by renewable electricity, producing zero lifecycle emissions

Green hydrogen uses renewable electricity to power an electrolyzer that splits water (H2O) into hydrogen and oxygen, with no greenhouse gas emissions when the electricity comes from solar/wind.

Question 43: Second-generation biofuels differ from first-generation biofuels in that they:

Are derived from non-food feedstocks (cellulosic biomass, agricultural residues, algae) that don't compete with food production (Correct answer)
Are produced from food crops like corn and sugarcane rather than waste biomass
Use the same fermentation processes as first-generation but with more efficient yeast strains
Are liquid fuels burned in conventional engines without any engine modification

Correct answer: Are derived from non-food feedstocks (cellulosic biomass, agricultural residues, algae) that don't compete with food production

Second-generation (advanced) biofuels use lignocellulosic feedstocks (switchgrass, wood chips, corn stover, municipal solid waste) or algae, avoiding the food vs. fuel conflict of corn ethanol and sugarcane ethanol.

Question 44: What is the term for the total mass of living organisms in a given area or trophic level?

Standing crop
Biomass (Correct answer)
Biodensity
Net primary productivity

Correct answer: Biomass

Biomass refers to the total mass of living biological organisms in a particular area or ecosystem.

Question 45: Which heavy metal is most commonly associated with contamination from old lead paint and pipes in U.S. homes?

Cadmium
Arsenic
Mercury
Lead (Correct answer)

Correct answer: Lead

Lead from paint (pre-1978) and old plumbing pipes is a major source of childhood lead poisoning in U.S. homes.

Question 46: Concentrated Animal Feeding Operations (CAFOs) are associated with environmental concerns including:

Land use conflicts with national park boundaries
Large volumes of waste containing nitrogen, phosphorus, pathogens, and pharmaceuticals that can contaminate water bodies (Correct answer)
Excessive water use from on-site irrigation systems
Significant CO2 emissions from animal respiration that directly warm the climate

Correct answer: Large volumes of waste containing nitrogen, phosphorus, pathogens, and pharmaceuticals that can contaminate water bodies

CAFOs concentrate thousands of animals in small areas, producing vast quantities of manure that contain nitrates, phosphorus, bacterial pathogens, antibiotic-resistant organisms, and hormones, which can contaminate groundwater and surface water.

Question 47: Wave energy converters harvest ocean wave energy primarily through:

Heating of seawater by wave action that drives a thermal power cycle
Pressure differences at different ocean depths created by wave troughs and crests
Mechanical motion of floating structures driven by wave movement, converted to electricity by generators or hydraulic systems (Correct answer)
Electrochemical reactions induced by saline wave water in contact with metal electrodes

Correct answer: Mechanical motion of floating structures driven by wave movement, converted to electricity by generators or hydraulic systems

Wave energy converters (WECs) capture the mechanical energy of ocean surface waves - up-and-down or heaving motion - through oscillating water columns, point absorbers, or attenuators connected to electrical generators.

Question 48: Particulate matter (PM2.5) is especially dangerous to human health because:

It reacts with atmospheric ozone to form more toxic compounds before entering the lungs
Its small size allows it to penetrate deep into the lungs and enter the bloodstream, causing respiratory and cardiovascular disease (Correct answer)
PM2.5 carries heavy metals that dissolve in lung fluid and cause kidney damage
It blocks UV radiation, leading to vitamin D deficiency in exposed populations

Correct answer: Its small size allows it to penetrate deep into the lungs and enter the bloodstream, causing respiratory and cardiovascular disease

Particles 2.5 micrometers or smaller can penetrate to the alveoli, enter the bloodstream, and trigger systemic inflammation linked to cardiovascular disease, stroke, and premature death.

Question 49: The circular economy model differs from the traditional linear economy in that:

A circular economy is driven exclusively by government mandates rather than market incentives
A circular economy designs out waste by keeping materials in productive use through reuse, repair, remanufacturing, and recycling (Correct answer)
A circular economy requires all products to be made from biological materials that decompose naturally
A circular economy focuses only on recycling at end of life rather than the full production process

Correct answer: A circular economy designs out waste by keeping materials in productive use through reuse, repair, remanufacturing, and recycling

The circular economy moves from the take-make-dispose linear model to closed loops: products and materials are designed for longevity, repair, remanufacture, and ultimately recycling, minimizing waste and virgin resource extraction.

Question 50: Rising sea levels due to climate change are primarily caused by two processes. What are they?

More rainfall and dam construction
El Niño events and tidal changes
Ocean acidification and increased evaporation
Thermal expansion of seawater and melting land ice (Correct answer)

Correct answer: Thermal expansion of seawater and melting land ice

Warmer water expands (thermal expansion) and melting glaciers/ice sheets add water volume, both raising sea levels.

Question 51: In a food chain, approximately what percentage of energy is transferred from one trophic level to the next?

50%
90%
1%
10% (Correct answer)

Correct answer: 10%

The 10% rule states that only about 10% of energy is passed to the next trophic level; the rest is lost as heat.

Question 52: The primary route of human exposure to methylmercury is through:

Breathing air near coal-burning power plants
Consuming fish and shellfish, particularly large predatory marine fish (Correct answer)
Contact with mercury-containing thermometers or fluorescent light bulbs
Drinking groundwater contaminated by industrial mercury discharges

Correct answer: Consuming fish and shellfish, particularly large predatory marine fish

Inorganic mercury from industrial sources is methylated by anaerobic bacteria, enters aquatic food chains, and biomagnifies; large predatory fish (tuna, swordfish, shark) accumulate highest concentrations.

Question 53: The IPCC (Intergovernmental Panel on Climate Change) primarily does which of the following?

Assesses and synthesizes climate science for policymakers (Correct answer)
Enforces international climate treaties
Sets national emissions targets
Funds renewable energy projects

Correct answer: Assesses and synthesizes climate science for policymakers

The IPCC reviews and synthesizes published climate science to provide authoritative assessment reports for policymakers.

Question 54: Which type of solid waste site is designed with liners and leachate collection systems to prevent groundwater contamination?

Brownfield
Open dump
Sanitary landfill (Correct answer)
Superfund site

Correct answer: Sanitary landfill

Sanitary landfills use engineered barriers including clay and synthetic liners plus leachate collection to protect groundwater.

Question 55: What is the primary greenhouse gas emitted by human activities?

Methane (CH₄)
Carbon dioxide (CO₂) (Correct answer)
Nitrous oxide (N₂O)
Water vapor (H₂O)

Correct answer: Carbon dioxide (CO₂)

CO₂ from fossil fuel combustion and deforestation is the largest contributor to anthropogenic greenhouse gas emissions.

Question 56: The process by which nitrogen-fixing bacteria convert atmospheric N₂ into ammonia is called:

Nitrogen fixation (Correct answer)
Ammonification
Nitrification
Denitrification

Correct answer: Nitrogen fixation

Nitrogen fixation converts inert atmospheric nitrogen gas into biologically available ammonia (NH₃).

Question 57: Acid rain is primarily caused by atmospheric reactions involving which two gases?

SO₂ and NOₓ (Correct answer)
O₃ and CO
CO₂ and CH₄
HFCs and PFCs

Correct answer: SO₂ and NOₓ

SO₂ and NOₓ emitted from power plants and vehicles react with water vapor to form sulfuric and nitric acids.

Question 58: What is contour plowing, and how does it reduce erosion?

Plowing in a grid pattern; distributes soil evenly
Plowing with the slope to drain water; reduces waterlogging
Plowing across the slope following land contours; slows runoff and traps water (Correct answer)
Plowing deep furrows to bury weeds; prevents weed erosion

Correct answer: Plowing across the slope following land contours; slows runoff and traps water

Contour plowing creates furrows that run perpendicular to the slope, slowing water runoff and reducing soil erosion.

Question 59: Life Cycle Assessment (LCA) is a tool that evaluates:

The environmental impacts of a product or process across its entire life from raw material extraction through production, use, and disposal (Correct answer)
The expected operational lifespan of industrial equipment before replacement is needed
The career trajectory of environmental professionals from entry level to executive positions
The lifecycle of regulatory permits from application through renewal and cancellation

Correct answer: The environmental impacts of a product or process across its entire life from raw material extraction through production, use, and disposal

LCA (standardized in ISO 14040/14044) systematically quantifies the environmental inputs (energy, water, materials) and outputs (emissions, waste) of a product system across its full life cycle.

Question 60: The Kyoto Protocol differed from the Paris Agreement primarily in that:

Kyoto covered only developed (Annex I) countries with binding targets; Paris requires all nations to submit nationally determined contributions (Correct answer)
Paris established binding emission limits; Kyoto only set voluntary pledges
Paris was negotiated under the UN; Kyoto was a bilateral U.S.-China agreement
Kyoto addressed ozone depletion; Paris focused on biodiversity

Correct answer: Kyoto covered only developed (Annex I) countries with binding targets; Paris requires all nations to submit nationally determined contributions

Kyoto (1997) set legally binding emission reduction targets for developed nations only; Paris (2015) includes all parties but uses nationally determined contributions (NDCs) that are not legally binding targets.

Question 61: What is phytoremediation?

Photosynthesis-based energy production for cleanup
Using animals to control invasive plant species
Using plants to absorb, contain, or detoxify soil pollutants (Correct answer)
Treating water with plant extracts

Correct answer: Using plants to absorb, contain, or detoxify soil pollutants

Phytoremediation uses hyperaccumulator plants to absorb heavy metals and other contaminants from soil and water.

Question 62: What is the species-area relationship in conservation biology?

Species diversity is proportional to geographic area surveyed
Larger species need larger territories
Island species are smaller than mainland counterparts
Larger habitat areas support more species (Correct answer)

Correct answer: Larger habitat areas support more species

The species-area relationship states that larger habitat areas typically contain more species than smaller areas of the same habitat type.

Question 63: Arsenic in drinking water is a major health problem in Bangladesh and parts of South Asia primarily because:

Arsenic-based pesticides used in rice agriculture contaminate irrigation canals
Industrial discharge from textile factories contaminates rivers used for drinking water
Arsenic-containing coal is used for cooking, and residues contaminate household water storage
Naturally occurring arsenic in deep geological formations leaches into groundwater drawn from tube wells (Correct answer)

Correct answer: Naturally occurring arsenic in deep geological formations leaches into groundwater drawn from tube wells

Arsenic-rich sedimentary deposits in the Bengal Basin release arsenic into groundwater under reducing conditions; millions of tube wells installed to avoid surface water pathogens now tap arsenic-contaminated aquifers.

Question 64: What is carbon capture and storage (CCS)?

Using algae to absorb atmospheric CO₂
Converting CO₂ into fuel
Capturing CO₂ at emission sources and injecting it underground (Correct answer)
Planting trees to absorb CO₂

Correct answer: Capturing CO₂ at emission sources and injecting it underground

CCS involves capturing CO₂ from industrial sources and injecting it into deep geological formations for long-term storage.

Question 65: The Clean Water Act requires municipalities to obtain which type of permit for wastewater discharges?

CERCLA authorization
CAA operating permit
RCRA permit
NPDES permit (Correct answer)

Correct answer: NPDES permit

The National Pollutant Discharge Elimination System (NPDES) permit program regulates point source discharges into U.S. waters.

Question 66: What is the main environmental advantage of municipal solid waste incineration over landfilling?

Lower operating costs
Elimination of all toxins
Significant volume reduction and energy recovery (Correct answer)
No air emissions

Correct answer: Significant volume reduction and energy recovery

Incineration reduces waste volume by up to 90% and can generate electricity, though it requires strict emission controls.

Question 67: The Environmental Kuznets Curve (EKC) hypothesis suggests that:

Economic growth and environmental protection are always mutually exclusive goals
Environmental degradation is linearly proportional to economic growth in all countries
Wealthier countries always have better environmental conditions than poorer countries
Environmental pollution initially increases as a country develops economically but decreases after a certain income threshold (Correct answer)

Correct answer: Environmental pollution initially increases as a country develops economically but decreases after a certain income threshold

The EKC (Grossman and Krueger, 1991) proposes an inverted-U relationship between per-capita income and pollution: at low incomes, development increases pollution; beyond a turning point, higher incomes support cleaner technology and environmental regulation.

Question 68: What is net primary productivity (NPP)?

Total decomposer activity
Total energy in sunlight hitting an area
Energy consumed by herbivores
Total photosynthesis minus plant respiration (Correct answer)

Correct answer: Total photosynthesis minus plant respiration

NPP is gross primary productivity minus the energy plants use for their own respiration, representing available organic matter.

Question 69: What is gray water?

Reclaimed water from sewage treatment plants
Water with high sediment content
Highly contaminated industrial wastewater
Lightly used household water from sinks and showers, not toilets (Correct answer)

Correct answer: Lightly used household water from sinks and showers, not toilets

Gray water is relatively clean wastewater from bathroom sinks, showers, and laundry that can be recycled for irrigation.

Question 70: Which persistent organic pollutant was banned in the U.S. after being linked to raptor population crashes?

Dioxins
PCBs
BPA
DDT (Correct answer)

Correct answer: DDT

DDT caused eggshell thinning in birds of prey, leading to crashes in bald eagle and peregrine falcon populations before its 1972 ban.

Question 71: Which type of symbiosis benefits one organism while the other is neither harmed nor helped?

Commensalism (Correct answer)
Mutualism
Parasitism
Competition

Correct answer: Commensalism

Commensalism describes a relationship where one organism benefits and the other is unaffected.

Question 72: The Green Revolution of the mid-20th century primarily involved:

Organic farming methods that eliminated the need for pesticides
A global shift from meat-based to plant-based diets
International agreements to protect tropical rainforests from agricultural expansion
Development of high-yielding crop varieties, increased irrigation, and synthetic fertilizer use that dramatically raised food production (Correct answer)

Correct answer: Development of high-yielding crop varieties, increased irrigation, and synthetic fertilizer use that dramatically raised food production

The Green Revolution (1940s-1970s) introduced high-yield varieties of wheat and rice, expanded irrigation, and dramatically increased fertilizer and pesticide use, averting famine in much of Asia and Latin America.

Question 73: Environmental justice is concerned primarily with:

Enforcing criminal penalties against corporations that violate environmental laws
The fair distribution of environmental benefits and burdens across all social groups and communities (Correct answer)
International agreements that allocate emission reduction responsibilities between countries
The legal rights of future generations to inherit a clean environment

Correct answer: The fair distribution of environmental benefits and burdens across all social groups and communities

Environmental justice addresses the disproportionate exposure of low-income and minority communities to pollution and environmental hazards, and unequal access to environmental benefits.

Question 74: Which phenomenon involves unusual warming of the central and eastern Pacific Ocean, disrupting global weather patterns?

Arctic Oscillation
El Niño (Correct answer)
North Atlantic Oscillation
La Niña

Correct answer: El Niño

El Niño is a periodic warming of Pacific surface waters that shifts rainfall patterns and can cause droughts and floods globally.

Question 75: Command-and-control environmental regulation differs from market-based instruments in that:

Command-and-control sets specific standards or bans; market-based instruments use prices or permits to achieve goals (Correct answer)
Command-and-control applies only to air pollution; market-based instruments apply to water
Market-based instruments are more common in the U.S.; command-and-control is used only in Europe
Market instruments penalize all pollution; command-and-control allows unlimited emissions

Correct answer: Command-and-control sets specific standards or bans; market-based instruments use prices or permits to achieve goals

Command-and-control regulation specifies what technology to use or sets emission limits; market-based tools like carbon taxes or cap-and-trade use economic incentives.

Question 76: The precautionary approach to chemical risk assessment, as applied in the EU's REACH regulation, requires:

Chemicals to be tested only when they are produced in quantities exceeding 1,000 tonnes per year
Companies to wait for epidemiological evidence of harm before restricting chemical use
Manufacturers to demonstrate the safety of chemicals before marketing rather than waiting for evidence of harm (Correct answer)
Government agencies to conduct all chemical safety testing using public funds

Correct answer: Manufacturers to demonstrate the safety of chemicals before marketing rather than waiting for evidence of harm

EU REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) places the burden of proof on industry to demonstrate safety, in contrast to the U.S. approach where regulators must prove harm before restricting a chemical.

Question 77: In terms of water use efficiency, which of the following irrigation methods uses water most efficiently?

Sprinkler irrigation
Drip (micro) irrigation (Correct answer)
Flood irrigation (surface irrigation)
Furrow irrigation

Correct answer: Drip (micro) irrigation

Drip irrigation delivers water directly to the root zone through emitters, minimizing evaporation and runoff; typical efficiency is 85-95% compared to 60-80% for sprinklers and 25-60% for flood irrigation.

Question 78: The gradual process by which a community changes over time toward a stable climax community is called:

Ecological succession (Correct answer)
Evolution
Adaptive radiation
Biotic turnover

Correct answer: Ecological succession

Ecological succession is the sequential development of communities in an area over time.

Question 79: What is habitat fragmentation and why is it a concern for wildlife?

Breaking up continuous habitat into isolated patches; reduces gene flow and increases extinction risk (Correct answer)
Introduction of invasive species that fragment ecosystems
Loss of individual habitat patches; reduces total habitat area
Conversion of habitat to farmland; eliminates biodiversity

Correct answer: Breaking up continuous habitat into isolated patches; reduces gene flow and increases extinction risk

Fragmentation isolates wildlife populations in smaller patches, limiting movement, reducing genetic diversity, and increasing local extinction risk.

Question 80: What is the term for species that significantly shape their community's structure, often out of proportion to their abundance?

Endemic species
Keystone species (Correct answer)
Invasive species
Pioneer species

Correct answer: Keystone species

Keystone species have a disproportionately large effect on their ecosystem relative to their biomass or numbers.

Question 81: The EPA's risk assessment process for carcinogens typically assumes:

A linear no-threshold (LNT) model where any exposure carries some risk proportional to dose (Correct answer)
Carcinogens are safe below concentrations found in natural background environments
A threshold dose below which no cancer risk exists, as established by animal studies
Cancer risk only applies above the NOAEL established from epidemiological studies

Correct answer: A linear no-threshold (LNT) model where any exposure carries some risk proportional to dose

For genotoxic carcinogens, U.S. EPA typically uses the linear no-threshold (LNT) model, assuming risk is proportional to dose with no completely safe exposure level, to be protective.

AP Environmental Science Exam

The AP Environmental Science exam assesses students' understanding of environmental concepts, natural systems, and human impacts on the environment, testing scientific principles, analysis, and problem-solving through multiple-choice questions covering 9 content units.

Questions

90 min

Time Limit

65%

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