Getting ready for the AP Environmental Science exam? These 20 free practice questions cover the big ideas from every unit of the course, each with a clear explanation. Try each question on your own first, then tap Show answer to check your thinking.
The questions are written in the style of the multiple-choice section of the exam, including a few quick calculations like the ones you’ll see on test day. They’re a fast way to find out which units you’ve mastered and which ones need more review.
What the AP Environmental Science exam covers
- The Living World: Ecosystems: energy flow, trophic levels, the carbon, nitrogen, phosphorus and water cycles, biomes and primary productivity
- The Living World: Biodiversity: species and genetic diversity, ecosystem services, island biogeography and ecological succession
- Populations: r- and K-selected species, survivorship, carrying capacity, population growth and the demographic transition
- Earth Systems and Resources: plate tectonics, soils, the atmosphere, global wind patterns, watersheds and El Niño
- Land and Water Use: agriculture, irrigation, pest control, forestry, mining, fishing and urbanization
- Energy Resources and Consumption: fossil fuels, nuclear power, renewable energy sources, efficiency and conservation
- Atmospheric Pollution: major air pollutants, photochemical smog, thermal inversions, acid deposition and indoor air pollution
- Aquatic and Terrestrial Pollution: point and nonpoint sources, eutrophication, toxicology, solid waste and sewage treatment
- Global Change: ozone depletion, the greenhouse effect, climate change, ocean acidification, invasive species and biodiversity loss
How to use these questions
Work through the questions without notes, the way you would on test day. Keep a calculator handy, since it’s allowed on the real exam. Track the ones you miss and note which unit each one comes from. Two or three misses in the same unit is a sign to review that unit before moving on.
Don’t just check whether you got the right letter. Read every explanation, even for questions you answered correctly. APES questions often test whether you can explain the mechanism behind an environmental problem, not just name it.
Practice questions
Question 1
A grassland’s producers have a net primary productivity of 25,000 kcal/m²/yr. Using the 10% rule, about how much energy is available to secondary consumers?
A. 2,500 kcal/m²/yr
B. 250 kcal/m²/yr
C. 25 kcal/m²/yr
D. 12,500 kcal/m²/yr
Show answer
Answer: B. About 10% of the energy passes from one trophic level to the next. Primary consumers get about 2,500 kcal/m²/yr, and secondary consumers get about 10% of that, or 250 kcal/m²/yr. The common trap is stopping one level early at 2,500.
Question 2
According to the theory of island biogeography, which island would be expected to support the greatest number of species?
A. A small island far from the mainland
B. A large island close to the mainland
C. A small island close to the mainland
D. A large island far from the mainland
Show answer
Answer: B. Large islands offer more habitat and resources, so extinction rates are lower. Islands close to the mainland receive more colonizing species. An island that is both large and near the mainland has the highest predicted species richness.
Question 3
A volcanic eruption covers an area with lava that cools into bare rock with no soil. Which organisms are most likely to colonize the rock first?
A. Lichens and mosses
B. Tall grasses
C. Shrubs
D. Hardwood trees
Show answer
Answer: A. This is primary succession, which starts with no soil. Pioneer species such as lichens and mosses can grow on bare rock and slowly break it down, building the first thin layer of soil that later plants need.
Question 4
Which set of traits best describes an r-selected species?
A. Many offspring, little parental care, early maturity and high early mortality
B. Few offspring, extensive parental care, late maturity and long life spans
C. Population size that stays close to carrying capacity at all times
D. Offspring that are born large and well developed after a long gestation
Show answer
Answer: A. r-selected species, like many insects and weeds, produce lots of offspring and invest little in each one, so most die young (Type III survivorship). The other choices describe K-selected species, which have few offspring, more parental care and populations near carrying capacity.
Question 5
Moist air from the ocean is pushed up the windward side of a tall mountain range. Compared to the windward side, the leeward side of the range is most likely
A. drier, because the air cooled and lost its moisture as precipitation while rising, then warmed as it descended
B. wetter, because air picks up moisture as it crosses the mountains
C. about the same, because mountains do not affect precipitation
D. colder and wetter, because the leeward side is always at a higher elevation
Show answer
Answer: A. Rising air cools, and cooler air can’t hold as much water vapor, so most precipitation falls on the windward side. The air that sinks down the leeward side warms and is dry, creating a rain shadow, often a desert.
Question 6
Which description best fits integrated pest management (IPM)?
A. Spraying broad-spectrum pesticides on a fixed schedule whether or not pests are present
B. Combining methods such as crop rotation, biological control, monitoring and limited, targeted pesticide use
C. Planting only genetically modified crops so that no other methods are needed
D. Removing all insects from a farm so that no pests can return
Show answer
Answer: B. IPM uses several strategies together and applies pesticides only when monitoring shows they are needed. A common trap is thinking IPM bans pesticides entirely. It reduces and targets their use rather than eliminating them.
Question 7
A household replaces a 60-watt incandescent bulb with a 10-watt LED bulb that gives the same light. The bulb is used 5 hours per day for 365 days. How much electricity does the switch save in one year?
A. 18.25 kWh
B. 91.25 kWh
C. 109.5 kWh
D. 91,250 kWh
Show answer
Answer: B. The savings is 60 W minus 10 W, or 50 W. Multiply by time: 50 W × 5 h/day × 365 days = 91,250 Wh. Divide by 1,000 to convert to kilowatt-hours: 91.25 kWh. Choice D is the trap of forgetting to convert watt-hours to kilowatt-hours.
Question 8
During a thermal inversion, air pollution in a valley city often becomes much worse. Why?
A. A layer of warm air sits above cooler air near the ground, so the cooler air and its pollutants cannot rise and disperse
B. A layer of cold air sits above warm surface air, which speeds up mixing
C. Strong winds blow pollutants into the valley from other regions
D. The stratospheric ozone layer thickens and traps pollutants near the surface
Show answer
Answer: A. Normally, air gets cooler with altitude, so warm surface air rises and carries pollutants upward. In an inversion, a warm layer acts like a lid over cooler, denser surface air, trapping smog and particulates close to the ground where people breathe them.
Question 9
In laboratory tests on rats, Pesticide X has an LD50 of 5 mg/kg and Pesticide Y has an LD50 of 500 mg/kg. Which conclusion is best supported?
A. Pesticide X is more toxic, because a much smaller dose kills half of the test population
B. Pesticide Y is more toxic, because its LD50 value is larger
C. The two pesticides are equally toxic, because both have an LD50
D. LD50 values cannot be used to compare the toxicity of two chemicals
Show answer
Answer: A. LD50 is the dose that kills 50% of a test population. The lower the LD50, the less of the substance it takes to be lethal, so the substance is more toxic. A bigger number means a less toxic chemical, which is the reverse of what many students expect.
Question 10
As the oceans absorb more carbon dioxide from the atmosphere, which effect is most likely?
A. Ocean pH rises, making it easier for corals to build skeletons
B. Ocean pH falls and carbonate ions become less available, making it harder for corals and shellfish to build calcium carbonate shells and skeletons
C. Ocean salinity drops sharply as carbon dioxide replaces dissolved salts
D. Dissolved oxygen increases, causing algae populations to crash
Show answer
Answer: B. Carbon dioxide reacts with seawater to form carbonic acid, which lowers pH. The extra hydrogen ions bind with carbonate ions, so less carbonate is available for organisms that build calcium carbonate shells and skeletons. This process is called ocean acidification.
More practice from the AP+ workbook
These next 10 questions come straight from our AP+ Review Workbook, with the same explanations you’ll find in its answer key.
Question 11
Which process returns carbon stored in the slow carbon cycle back to the atmosphere most rapidly?
A. Decomposition of leaf litter
B. Photosynthesis
C. Ocean upwelling
D. Combustion of fossil fuels
Show answer
Answer: D. Fossil fuels hold carbon that has been locked away in the slow carbon cycle for millions of years. Burning them releases that carbon to the atmosphere within seconds, far faster than natural geologic processes ever would.
Question 12
Timber harvested from a sustainably managed forest is an example of which kind of ecosystem service?
A. Provisioning
B. Regulating
C. Cultural
D. Supporting
Show answer
Answer: A. Provisioning services are the goods people take directly from ecosystems, such as timber, food and fresh water. Regulating services, like flood control, and cultural services, like recreation, are benefits rather than harvested products.
Question 13
A country has a crude birth rate of 30 per 1,000 and a crude death rate of 10 per 1,000, with no net migration. Its annual growth rate is
A. 0.2%
B. 2.0%
C. 20%
D. 40%
Show answer
Answer: B. Subtract the death rate from the birth rate to get 20 per 1,000, then divide by 10 to convert to a percent: (30 − 10) ÷ 10 = 2.0% per year.
Question 14
During a La Niña event, conditions in the eastern tropical Pacific typically include
A. cooler surface water and stronger upwelling off South America.
B. warmer surface water and weaker upwelling.
C. the complete disappearance of the trade winds.
D. a permanent reversal of ocean currents.
Show answer
Answer: A. La Niña strengthens the trade winds, which push warm surface water west and increase the upwelling of cold, nutrient-rich water off South America. Warmer water and weaker upwelling describe El Niño instead.
Question 15
Rows of trees planted along the edges of fields (windbreaks) reduce soil erosion mainly by
A. lowering wind speed across the soil surface.
B. increasing the salinity of topsoil.
C. raising the water table.
D. adding nitrogen to the soil.
Show answer
Answer: A. Windbreaks slow the wind as it moves across a field. Slower wind lifts and carries away less topsoil, so less soil is lost to wind erosion.
Question 16
Which is a primary environmental concern associated with hydraulic fracturing (fracking)?
A. Elimination of all natural gas reserves
B. Zero energy output
C. Increased ozone layer depletion
D. Potential groundwater contamination and induced seismic activity
Show answer
Answer: D. Fracking injects fluid deep underground at high pressure to release natural gas. It has been linked to risks of groundwater contamination and, in some regions, small induced earthquakes.
Question 17
Two lakes receive the same amount of acid deposition. Lake X’s pH stays nearly constant while Lake Y becomes more acidic. The most likely explanation is that Lake X
A. is deeper than Lake Y.
B. receives more sunlight.
C. sits on limestone bedrock that neutralizes (buffers) acids.
D. contains more dissolved nitrogen gas.
Show answer
Answer: C. Limestone is made of calcium carbonate, which reacts with and neutralizes hydrogen ions from acid deposition. That buffering keeps Lake X’s pH nearly steady while the unbuffered lake becomes more acidic.
Question 18
A modern sanitary landfill uses a clay or plastic liner and a leachate collection system mainly to
A. speed up the decomposition of plastics.
B. prevent contaminated liquid from reaching groundwater.
C. capture solar energy.
D. increase methane release to the atmosphere.
Show answer
Answer: B. Leachate forms as rainwater percolates through buried waste and picks up contaminants. The liner and collection pipes keep that liquid from seeping into the groundwater below.
Question 19
Hydrofluorocarbons (HFCs) replaced many CFCs in refrigerators and air conditioners. Which statement best describes the trade-off?
A. HFCs destroy more ozone than CFCs.
B. HFCs are not greenhouse gases.
C. HFCs are toxic to all plants.
D. HFCs cause little ozone depletion but are potent greenhouse gases.
Show answer
Answer: D. HFCs contain no chlorine, so they do little damage to the ozone layer. However, they trap heat very strongly, which is why the Kigali Amendment to the Montreal Protocol phases them down.
Question 20
A region investing in both renewable energy AND drought-resistant crops is demonstrating:
A. Mitigation only
B. Adaptation only
C. Both mitigation and adaptation strategies
D. Neither mitigation nor adaptation
Show answer
Answer: C. Investing in renewable energy is mitigation, because it reduces greenhouse gas emissions. Planting drought-resistant crops is adaptation, because it helps people cope with climate impacts that are already happening. The region is doing both.
How did you do?
If you got 17 or more right, you have a strong foundation. Focus your review on the explanations for any you missed. If you got 12 to 16 right, you’re on track, but a few units need more practice. If you got 11 or fewer right, start with the unit reviews before doing more practice questions.
Our AP+ Environmental Science Review Workbook covers every unit with clear summaries, worked calculation examples, data labs and full exam-style practice with answers and explanations. It’s available as an instant PDF download or a paperback.
See the AP+ Environmental Science Review Workbook →
Studying for more than one AP exam? Browse the full AP+ Exam Prep series.
Frequently asked questions
Are these questions like the real AP Environmental Science exam?
They’re written in the style of the multiple-choice section and cover the same units and skills, including quick calculations. Official practice materials from the College Board are also worth using alongside them.
What’s the best way to study for AP Environmental Science?
Review one unit at a time, learn the cause-and-effect mechanism behind each environmental problem, and practice calculations with units written out. Doing mixed practice questions regularly and reading every explanation builds the understanding the exam rewards.
When is the AP Environmental Science exam?
AP exams are given each May. Check the College Board’s AP website for the current exam schedule.
AP is a registered trademark of the College Board, which was not involved in the production of, and does not endorse, this page or our workbooks.