AP Environmental Science Midterm Exam — 2026/2027
80 Questions | Units 1–5 | College Board CED–Aligned | Latest
Update
,About This Examination
This AP Environmental Science Midterm Examination is a comprehensive practice assessment
designed for students preparing for the Advanced Placement Environmental Science exam. The
examination covers Units 1 through 5 as outlined in the College Board Course and Exam
Description (CED), encompassing the foundational topics of ecosystem dynamics, biodiversity,
population ecology, earth systems, and land and water use. The exam consists of 80 multiple-choice
questions distributed across five units, each targeting key concepts and scientific principles
essential for success on the AP exam. All questions are aligned with the latest College Board
curriculum framework and reflect the style and rigor of actual AP examination items. This practice
test includes complete answer keys with detailed rationales to support self-assessment and targeted
review. It is intended exclusively for educational study purposes and does not represent an official
College Board examination.
Table of Contents
About This Examination .............................................................................................. 2
Table of Contents......................................................................................................... 2
Unit 1: The Living World: Ecosystems .......................................................................... 1
Unit 2: The Living World: Biodiversity ........................................................................ 4
Unit 3: Populations ..................................................................................................... 6
Unit 4: Earth Systems & Resources ............................................................................. 8
Unit 5: Land & Water Use ........................................................................................... 11
References .................................................................................................................. 13
2
, Unit 1: The Living World: Ecosystems
1. Which terrestrial biome has the highest net primary productivity (NPP)?
A) Temperate deciduous forest
B) Tropical rainforest
C) Temperate grassland
D) Tundra
Answer: B) Tropical rainforest
Rationale: Tropical rainforest has highest net primary productivity due to abundant sunlight,
warm temperatures, and year-round growing season.
2. Approximately what percentage of energy is transferred from one trophic level to
the next?
A) 10%
B) 50%
C) 90%
D) 1%
Answer: A) 10%
Rationale: Approximately 10% of energy transfers between trophic levels.
3. Which process converts atmospheric nitrogen (N₂) into a form usable by plants?
A) Denitrification
B) Ammonification
C) Nitrogen fixation
D) Assimilation
Answer: C) Nitrogen fixation
Rationale: Nitrogen fixation by bacteria converts atmospheric N2 into ammonia NH4+.
4. Which biome is characterized by permafrost, low biodiversity, and extremely cold
temperatures?
A) Temperate rainforest
B) Tundra
C) Savanna
D) Taiga
Answer: B) Tundra
Rationale: Tundra — low biodiversity due to harsh cold temperatures and permafrost.
5. Which biogeochemical cycle does NOT have a significant atmospheric component?
A) Carbon cycle
B) Nitrogen cycle
C) Water cycle
D) Phosphorus cycle
Answer: D) Phosphorus cycle
Rationale: Phosphorus cycle has no significant atmospheric component — cycles through
rock/soil/water.
6. Which aquatic biome is characterized as a transition zone where freshwater meets
saltwater?
A) Coral reef
B) Lake
C) Estuary
D) Open ocean
Answer: C) Estuary
Rationale: Estuary — where freshwater meets saltwater, high nutrient levels, breeding
ground for many species.
1
80 Questions | Units 1–5 | College Board CED–Aligned | Latest
Update
,About This Examination
This AP Environmental Science Midterm Examination is a comprehensive practice assessment
designed for students preparing for the Advanced Placement Environmental Science exam. The
examination covers Units 1 through 5 as outlined in the College Board Course and Exam
Description (CED), encompassing the foundational topics of ecosystem dynamics, biodiversity,
population ecology, earth systems, and land and water use. The exam consists of 80 multiple-choice
questions distributed across five units, each targeting key concepts and scientific principles
essential for success on the AP exam. All questions are aligned with the latest College Board
curriculum framework and reflect the style and rigor of actual AP examination items. This practice
test includes complete answer keys with detailed rationales to support self-assessment and targeted
review. It is intended exclusively for educational study purposes and does not represent an official
College Board examination.
Table of Contents
About This Examination .............................................................................................. 2
Table of Contents......................................................................................................... 2
Unit 1: The Living World: Ecosystems .......................................................................... 1
Unit 2: The Living World: Biodiversity ........................................................................ 4
Unit 3: Populations ..................................................................................................... 6
Unit 4: Earth Systems & Resources ............................................................................. 8
Unit 5: Land & Water Use ........................................................................................... 11
References .................................................................................................................. 13
2
, Unit 1: The Living World: Ecosystems
1. Which terrestrial biome has the highest net primary productivity (NPP)?
A) Temperate deciduous forest
B) Tropical rainforest
C) Temperate grassland
D) Tundra
Answer: B) Tropical rainforest
Rationale: Tropical rainforest has highest net primary productivity due to abundant sunlight,
warm temperatures, and year-round growing season.
2. Approximately what percentage of energy is transferred from one trophic level to
the next?
A) 10%
B) 50%
C) 90%
D) 1%
Answer: A) 10%
Rationale: Approximately 10% of energy transfers between trophic levels.
3. Which process converts atmospheric nitrogen (N₂) into a form usable by plants?
A) Denitrification
B) Ammonification
C) Nitrogen fixation
D) Assimilation
Answer: C) Nitrogen fixation
Rationale: Nitrogen fixation by bacteria converts atmospheric N2 into ammonia NH4+.
4. Which biome is characterized by permafrost, low biodiversity, and extremely cold
temperatures?
A) Temperate rainforest
B) Tundra
C) Savanna
D) Taiga
Answer: B) Tundra
Rationale: Tundra — low biodiversity due to harsh cold temperatures and permafrost.
5. Which biogeochemical cycle does NOT have a significant atmospheric component?
A) Carbon cycle
B) Nitrogen cycle
C) Water cycle
D) Phosphorus cycle
Answer: D) Phosphorus cycle
Rationale: Phosphorus cycle has no significant atmospheric component — cycles through
rock/soil/water.
6. Which aquatic biome is characterized as a transition zone where freshwater meets
saltwater?
A) Coral reef
B) Lake
C) Estuary
D) Open ocean
Answer: C) Estuary
Rationale: Estuary — where freshwater meets saltwater, high nutrient levels, breeding
ground for many species.
1
