AP Environmental Science — Unit 1: The Living World: Ecosystems

What AP Environmental Science Unit 1 covers

The College Board Course and Exam Description breaks Unit 1 into 11 topics:

1. 1.1 Introduction to Ecosystems
2. 1.2 Terrestrial Biomes
3. 1.3 Aquatic Biomes
4. 1.4 The Carbon Cycle
5. 1.5 The Nitrogen Cycle
6. 1.6 The Phosphorus Cycle
7. 1.7 The Hydrologic Cycle
8. 1.8 Primary Productivity
9. 1.9 Trophic Levels
10. 1.10 Energy Flow and the 10% Rule
11. 1.11 Food Chains and Food Webs

AP Environmental Science Unit 1 practice questions

• What is symbiosis, and what are its three types?

  A lasting two-species bond — mutualism, commensalism, or parasitism. These are the three symbiosis types.

• Two bird species in the same forest eat the same insects. Over time, one species begins hunting at dawn and the other at dusk. What ecological process does this represent?

  Resource partitioning — dividing resource use to reduce competition. Species split by time, place, or method.

• Two regions sit at the same latitude and the same distance from the ocean — yet one is grassland and the other is desert. What single factor most directly explains why they ended up as different biomes?

  Climate — temperature and rainfall define a biome, not latitude. The plant and animal communities adapt to that climate.

• How does a tropical rainforest differ from a temperate seasonal forest in terms of climate and biodiversity?

  Tropical rainforests stay warm and wet year-round, with very high biodiversity. Temperate seasonal forests have cold winters, warm summers, and moderate biodiversity.

• Global temperatures rise significantly over the next century. What happens to the global distribution of terrestrial biomes?

  Biome boundaries shift — species ranges move poleward or to higher elevations, and some biomes shrink or expand.

• What role do algae in marine biomes play in Earth's atmosphere?

  Marine algae supply a large portion of Earth's oxygen and absorb carbon dioxide from the atmosphere.

• Why does fish species diversity vary significantly between a cold, nutrient-rich upwelling zone and a warm, nutrient-poor open ocean region?

  Abiotic factors like temperature, salinity, and nutrient levels control marine resource distribution. Nutrient-rich upwelling supports more diversity.

• A forest grows, and trees photosynthesize for decades. Later, organisms die and decomposers break them down. What happens to carbon during these two processes?

  Photosynthesis fixes CO₂ into organic compounds; respiration and decay release it. Carbon shifts between atmosphere and organisms.

+ 20 more AP Environmental Science cards in the app.

Key terms in Unit 1

These 12 terms show up in the Unit 1 cards. Each one links to its definition in the AP Environmental Science key-term reference.

• Cellular respiration
• Global climate change
• Hydrologic cycle
• Limiting nutrient
• Nitrogen fixation
• Phosphorus cycle
• Photosynthesis
• Positive feedback loop
• Primary productivity
• Resource partitioning
• Species diversity
• Tropical rainforest