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APES Unit 1 Ecosystems Exam Review

Apr 15, 2025

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AP Environmental Science Unit 1 Review: Ecosystems

Presented by Mr. Smees, this lecture is a comprehensive review of Unit 1 for the AP Environmental Science (APES) exam. The focus is on key concepts, important terminology, and exam strategies.

Exam Preparation

  • Ultimate Review Packet:
    • Available in the video description.
    • Includes study guides, practice questions, and two full-length practice exams with answer keys.
    • Emphasizes the importance of FRQ (Free-Response Questions) writing practice.

Key Topics in Unit 1: Ecosystems

1. Definitions

  • Ecosystem: Interaction of living and non-living things in a specific region.
  • Environment: Entire natural world.
  • Habitat: Environmental conditions necessary for a species to survive.

2. Species Interactions

  • Symbiosis vs. Mutualism:
    • Symbiosis: Close living proximity.
    • Mutualism: Both species benefit.
  • Examples: Bees and plants, coral reefs.

3. Biomes

  • Defined by average annual temperature and precipitation patterns.
  • Terrestrial Biomes:
    • Examples: Tropical rainforest, tundra.
  • Aquatic Biomes:
    • Influenced by salinity, flow, depth.
    • Example: Estuaries have unique salinity (brackish water) and high nutrient levels.

4. Biogeochemical Cycles

  • Law of Conservation of Matter: Matter is neither created nor destroyed.

Carbon Cycle

  • Reservoirs: Atmosphere critical.
  • Processes: Photosynthesis removes carbon, respiration returns it.
  • Human Impact: Fossil fuel combustion adds long-circulated carbon.

Nitrogen Cycle

  • Key Differences:
    • Atmospheric nitrogen is biologically unavailable.
    • Nitrogen Fixation: Conversion to usable forms (ammonia/nitrate) by bacteria.

Phosphorus Cycle

  • No gaseous phase, cycles slowly.
  • Major reservoirs: Rocks and sediments.

Water Cycle

  • Driven by sun's energy.
  • Key Processes: Evaporation, condensation, infiltration, transpiration.

5. Energy Flow in Ecosystems

Primary Productivity

  • Definition: Rate of photosynthesis in an area.
  • Terms:
    • Gross Primary Productivity (GPP): Total energy produced.
    • Net Primary Productivity (NPP): Energy stored after respiration losses.

Trophic Levels

  • Trophic Pyramid:
    • Energy flow from producers to apex predators.
    • 10% Rule: Only 10% of energy is transferred to the next level.
      • Primary consumers get 10% from producers.
      • Secondary consumers get 1% from producers.
      • Tertiary consumers get 0.1% from producers.

6. Food Webs and Chains

  • Arrows: Indicate movement of energy and matter.
  • Trophic Cascades: Effects of apex predator removal.

Study Tips

  • Review Ultimate Review Packet for all practice materials and answers.
  • Understand species interactions and biogeochemical cycles thoroughly.
  • Practice calculating primary productivity using given formulas.
  • Consider ecosystem dynamics, especially trophic cascades.

In conclusion, Mr. Smees emphasizes the importance of understanding these foundational concepts to succeed in the APES exam. He encourages utilizing resources like the Ultimate Review Packet for comprehensive preparation.

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