AP Environmental Science Unit 2 Review – Biodiversity & Ecosystem Resilience | RevisionDojo

Unit 2: Biodiversity is a cornerstone of AP Environmental Science, connecting ecosystem health, stability, and resilience. Understanding how biodiversity works — and why it matters — is crucial for both MCQs and FRQs.

In this RevisionDojo review, we’ll break down the types of biodiversity, threats to biodiversity, and strategies for conservation, with direct AP exam applications.

📌 Key Topics in APES Unit 2

• Types of Biodiversity
  • Species diversity
  • Genetic diversity
  • Ecosystem diversity
• Ecosystem Services
  • Provisioning services
  • Regulating services
  • Cultural services
  • Supporting services
• Island Biogeography
  • Species–area relationship
  • Habitat fragmentation
  • Edge effects
• Ecological Resilience
  • Resistance vs. resilience
  • Disturbance impacts
• Natural Disruptions
  • Climate shifts
  • Sea level change
  • Meteor impacts
• Human Impacts
  • Habitat destruction
  • Pollution
  • Overexploitation
  • Invasive species

🌿 Types of Biodiversity

1. Species Diversity – Variety of species in an ecosystem.
2. Genetic Diversity – Variability of genes within a species; increases adaptability.
3. Ecosystem Diversity – Range of ecosystems in a region.

🌍 Ecosystem Services

Biodiversity provides vital ecosystem services:

• Provisioning – Food, fresh water, timber, medicine.
• Regulating – Climate regulation, flood control, pollination.
• Cultural – Recreation, tourism, spiritual value.
• Supporting – Nutrient cycling, soil formation.

🏝 Island Biogeography

• Larger islands → More species due to more habitats.
• Closer to mainland → Higher immigration rates.
• Fragmentation creates “islands” of habitat, increasing edge effects.

AP Tip: Island biogeography is often tested with graph interpretation questions.

🔄 Ecological Resilience

• Resistance – Ability to remain unchanged during disturbance.
• Resilience – Ability to recover after disturbance.
• High biodiversity → Higher resilience.

🌡 Natural & Human Disruptions

• Natural – Hurricanes, wildfires, volcanic eruptions.
• Human – Deforestation, overfishing, introducing invasive species.

🧠 APES Exam Tips for Unit 2

• Be able to define and give examples of each biodiversity type.
• Memorize the 4 ecosystem service categories with examples.
• Practice island biogeography FRQs with real College Board data.
• Link biodiversity loss to ecosystem function decline in your explanations.

💡 FAQ – Unit 2: Biodiversity

Q: Which biodiversity type is most important for species survival?
A: Genetic diversity — it allows populations to adapt to changing conditions.

Q: How often is biodiversity tested on the APES exam?
A: Unit 2 accounts for about 6–9% of MCQs and appears in at least one FRQ every few years.

Q: What’s the biggest human threat to biodiversity?
A: Habitat destruction is the leading cause.

Final Word from RevisionDojo:
Biodiversity isn’t just a buzzword — it’s the backbone of ecosystem stability. On the AP exam, use specific examples and scientific terms to show mastery.