AP Environmental Science Unit 1 - Ecosystems

2 min readoctober 14, 2021

AP Environmental Science ♻️

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AP Environmental Science Ecosystems Review

Here's an organized outline for AP Environmental Science Unit 1 reviews. This outline has been adapted from the 2019 Course Description published by College Board. You can use this to build an AP Enviro Unit 1 study guide.


The Earth is a complex system made up of relationships and interdependencies among species. 
  • Limited resources can cause competition within or between species in an ecosystem.
  • Primary productivity is the production of organic compounds from solar energy via photosynthesis. 

Resources are distributed unevenly across ecosystems resulting in diverse biomes and species interactions. 
  • A biome contains communities of plants and animals that exhibit characteristic adaptation to that specific climate.
  • Only about 10% of the energy is passed on from one trophic level to the next.
  • Energy is continuously flowing into ecosystems while matter is transferring between the environment and organisms via biogeochemical cycles. 


Biogeochemical cycles drive all live processes and the transfer of energy. 
  • Carbon cycles between photosynthesis and cellular respiration in living things. 
  • Burning of fossil fuels releases stored carbon into the atmosphere in the form of carbon dioxide.  
  • Nitrogen fixation is the chemical processes by which atmospheric nitrogen is converted into a form that plants can utilize by microorganisms as part of the nitrogen cycle.
  • The hydrologic cycle is the flow of water in all its forms, solid, liquid and gaseous as it moves around the biosphere. This process is driven with energy from the sun.

 Unit 1 Vocab

  • Biogeochemical cycles
  • Energy flow
  • Food web
  • Gross primary productivity
  • Major aquatic biomes
  • Major terrestrial biomes
  • Net primary productivity
  • Nitrogen fixation
  • Photosynthesis
  • Resource partitioning
  • Symbiosis
  • The carbon cycle
  • The hydrologic cycle
  • The nitrogen cycle
  • The phosphorus cycle
  • Trophic levels
Browse Study Guides By Unit
🏜Unit 1 – The Living World: Ecosystems
🐠Unit 2 – The Living World: Biodiversity
👪Unit 3 – Populations
🌏Unit 4 – Earth Systems & Resources
🏖Unit 5 – Land & Water Use
⚡️Unit 6 – Energy Resources & Consumption
💨Unit 7 – Atmospheric Pollution
♻️Unit 8 – Aquatic & Terrestrial Pollution
🔥Unit 9 – Global Change
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