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Volume I · MMXXVI AP Environmental Science
Library› AP Environmental Science› Unit 2: The Living World: Biodiversity
⁂   AP Environmental Science · Unit 2

2. The Living World: Biodiversity

6–8% of the AP exam. 8 key topics. 4 common errors analyzed.

6–8% exam weight

Unit 2: The Living World: Biodiversity

Unit 2 (The Living World: Biodiversity) addresses environmental systems and human impacts. FRQs in this unit typically ask you to identify problems, propose specific solutions, and explain environmental consequences.

Key topics in this unit

  1. Types of biodiversity: genetic, species, and ecosystem diversity
  2. Ecosystem services (provisioning, regulating, cultural, supporting)
  3. Island biogeography theory (species-area relationship, immigration and extinction rates)
  4. Ecological tolerance and range of tolerance
  5. Natural disruptions to ecosystems (fire, flood, disease, drought)
  6. Ecological succession: primary succession
  7. Ecological succession: secondary succession
  8. Pioneer species and climax communities

Common errors — what the rubric penalizes

These are the most frequently penalized mistakes on AP exam FRQs and MCQs. Review each before your next practice session.

Common error

Confusing primary and secondary succession: the key distinction is substrate — bare rock or lava (no soil) triggers primary succession; disturbed land with soil remaining triggers secondary succession

Common error

Treating island biogeography as only applying to literal islands rather than recognizing its application to habitat fragments, national parks, and conservation design

Common error

Listing ecosystem services without connecting them to specific human welfare outcomes, which costs points on FRQ solution-proposal questions

Common error

Conflating species richness (number of species) with species diversity (richness plus evenness), leading to imprecise FRQ responses

Study checklist

  • Can you list all key topics from memory without this page?
  • Have you worked through at least one FRQ-style question per topic?
  • Can you explain each common error above — and why the correct answer differs?
  • Have you reviewed the relevant College Board CED section and formula sheet entries?
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