AP Biology Unit 8 Practice Test: Ecology
Practise AP Biology Unit 8 Ecology with tests on population growth, community interactions, energy flow, biogeochemical cycles, and biodiversity. AP-style FRQs.
What Unit 8 Covers in AP Biology
Unit 8 situates organisms within the broader context of populations, communities, ecosystems, and the biosphere. AP Biology ecology questions test both conceptual understanding of biological interactions and quantitative skills such as energy transfer calculations and population growth modelling.
Core Topics in Unit 8
Population Ecology
Population growth is modelled exponentially (J-curve, unlimited resources) or logistically (S-curve, limited by carrying capacity K). Key parameters include birth rate, death rate, immigration, emigration, and r (intrinsic rate of increase). AP FRQs present population graphs and ask you to identify growth phases, predict carrying capacity responses, and explain limiting factors.
Community Ecology
Communities are shaped by species interactions:
- Competition (interspecific and intraspecific) — drives resource partitioning and niche differentiation
- Predation and herbivory — affects population dynamics and drives coevolution
- Symbiosis — mutualism, commensalism, and parasitism
- Ecological succession — primary and secondary succession leading to climax communities
Ecosystem Energy Flow
Energy flows unidirectionally through trophic levels. Only approximately 10% of energy transfers to the next level (the 10% rule). Food webs, food chains, and energy pyramids illustrate these relationships. AP questions ask you to calculate energy available at different trophic levels and explain why food chains are typically short.
Biogeochemical Cycles
Carbon, nitrogen, phosphorus, and water cycle through biotic and abiotic components. AP Biology tests the key processes in each cycle (decomposition, nitrification, denitrification, photosynthesis, respiration) and the effects of human disruption.
Human Impacts on Biodiversity
Habitat destruction, invasive species, overexploitation, pollution, and climate change are key drivers of biodiversity loss. AP FRQs may ask you to evaluate conservation strategies or predict ecosystem-level consequences of species removal.
AP Science Practice Skills for Unit 8
- Data analysis: Interpreting population growth graphs, survivorship curves, and energy pyramid diagrams
- Quantitative reasoning: Calculating energy transfer efficiency across trophic levels
- Scientific argumentation: Explaining how disrupting one trophic level affects the entire food web